As filed with the Securities and Exchange Commission on March 19,May 24, 2004

Registration No. 333-            333-113760

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

AMENDMENT NO. 3
to
FORM S-1
REGISTRATION STATEMENT
UNDER
THE SECURITIES ACT OF 1933

DIGIRAD CORPORATION
(Exact Name of Registrant as Specified in its Charter)

Approximate date of commencement of proposed sale to the public:
As soon as practicable after this Registration Statement becomes effective.

        If any of the securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933, check the following box.    o

        If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.    o

        If this Form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.    o

        If this Form is a post-effective amendment filed pursuant to Rule 462(d) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.    o

        If delivery of the prospectus is expected to be made pursuant to Rule 434, check the following box.    o

CALCULATION OF REGISTRATION FEE

(1)

Includes 825,000 shares subject to the underwriters' overallotment option.

(2)

Estimated solely for the purpose of calculating the amount of the registration fee pursuant to Rule 457(o) under the Securities Act of 1933.

(3)

Of this amount, $10,928 has been previously paid.

        The Registrant hereby amends this Registration Statement on such date or dates as may be necessary to delay its effective date until the Registrant shall file a further amendment which specifically states that this Registration Statement shall thereafter become effective in accordance with Section 8(a) of the Securities Act of 1933, as amended, or until the Registration Statement shall become effective on such date as the Commission, acting pursuant to said Section 8(a), may determine.

The information in this preliminary prospectus is not complete and may be changed. We may not sell these securities until the registration statement filed with the Securities and Exchange Commission is effective. This prospectus is not an offer to sell these securities and it is not soliciting offers to buy these securities in any state where the offer or sale is not permitted.

Subject to Completion
Preliminary Prospectus dated ,May 24, 2004

PROSPECTUS

5,500,000 Shares

Common Stock

        This is our initial public offering of shares of our common stock. We are offering 5,500,000 shares. We expect the initial public offering price to be between $$12.00 and $$14.00 per share.

        Currently, no public market exists for the shares. After pricing of the offering, we expect that the shares will be quoted on the Nasdaq National Market under the symbol "DRAD."

        Investing in the common stock involves risks that are described in the "Risk Factors" section beginning on page 7 of this prospectus.

        The underwriters may also purchase up to an additional 825,000 shares of common stock from us at the public offering price, less the underwriting discounts and commissions, within 30 days from the date of this prospectus to cover over-allotments.

        Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

        The shares will be ready for delivery on or about                        , 2004.

Joint Book-Running Managers

The date of this prospectus is                        , 2004.

TABLE OF CONTENTS

        You should rely only on the information contained in this prospectus. We have not, and the underwriters have not, authorized any other person to provide you with different information. If anyone provides you with different or inconsistent information, you should not rely on it. We are not, and the underwriters are not, making an offer to sell these securities in any jurisdiction where the offer or sale is not permitted. You should assume that the information appearing in this prospectus is accurate only as of the date on the front cover of this prospectus. Our business, financial condition, results of operations and prospects may have changed since that date.

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PROSPECTUS SUMMARY

        This summary does not contain all of the information you should consider before buying shares of our common stock. You should read the entire prospectus carefully, especially the "Risk Factors" section and our consolidated financial statements and the related notes appearing at the end of this prospectus, before deciding to invest in shares of our common stock. References in this prospectus to our certificate of incorporation and bylaws refer to the certificate of incorporation and bylaws that will be in effect upon completion of this offering.

Digirad Corporation

        We are a leader in the development, manufacture and distribution of solid-state medical imaging products and services for the detection of cardiovascular disease and other medical conditions. We designed and commercialized the first solid-state gamma camera. Our initial focus is on nuclear cardiology imaging procedures performed with gamma cameras, which we believe generate revenue of approximately $10.0 billion annually in the United States. Our target markets are primarily physician practices and outpatient clinics, which we believe constitute approximately 25% of the total market, or $2.5 billion.

        Our gamma cameras use small semiconductors to replace the bulky vacuum tubes used historically in gamma cameras. By utilizing solid-state technology, we believe that our imaging systems maintain image quality while offering significant advantages over vacuum tube-based systems, including mobility through reduced size and weight, enhanced operability and reliability and improved patient comfort and utilization. Our imaging systems, consisting of a gamma camera and accessories, easily fit into spaces as small as seven feet by eight feet. Due to the size and other limitations of vacuum tube cameras, nuclear imaging has traditionally been confined to dedicated and customized space within a hospital or imaging center. The mobility of our imaging systems enables us to deliver nuclear imaging procedures in a wide range of clinical settings—physician offices, outpatient clinics or within multiple departments in a hospital.

        We sell our imaging systems to physicians, outpatient clinics and hospitals. In addition, through our wholly-owned subsidiary,subsidiaries, Digirad Imaging Solutions, Inc. and Digirad Imaging Systems, Inc., orwhich we refer to collectively as DIS, we also offer a comprehensive and mobile imaging leasing service, called FlexImaging®, for physicians who wish to perform nuclear cardiology imaging procedures in their offices but do not have the patient volume, capital or resources to justify purchasing a gamma camera. DIS provides our physician customers with an imaging system, certified personnel, required licensure and other support for the performance of nuclear imaging procedures under the supervision of our physician customers. Physicians enter into annual contracts for imaging services delivered on a per-day basis ranging from one day per month to several days per week. DIS currently operates 2321 regional hubs and seveneight fixed sites and performs services in 17 states.states and the District of Columbia.

        Our unique dual sales and leasing distribution model offers physicians, clinics and hospitals versatile delivery options that appeal to medical establishments of all sizes, capabilities and imaging expertise. The mobility of our imaging systems and the flexibility of our DIS service allow cardiologists to provide nuclear imaging procedures in their offices to patients that they historically had to refer to hospitals or imaging centers. As a result, we provide physicians with more control over the diagnosis and treatment of their patients and enable physicians to capture revenue from procedures that would otherwise be referred to these hospitals and imaging centers.

        Nuclear imaging is a clinical diagnostic tool, with established reimbursement codes, that has been in use for over 40 years. According to industry sources, approximately 18.4 million nuclear imaging procedures were performed in the United States in 2002, of which approximately 9.9 million were cardiac procedures, a volume that is expected to grow by approximately 25% annually over the next three years. We believe the growth in nuclear cardiology imaging will be driven by an increase in coronary heart disease resulting from the aging of baby boomers and the record rate of obesity and diabetes in all age groups. We estimate that the growth rate in 2002 for nuclear imaging procedures performed in physician offices was approximately 44% and in hospitals was approximately 6%. We expect the mobility of our imaging systems

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to continue to allow us to capitalize on this shift in the delivery of nuclear cardiology imaging services from hospitals to physician offices.

        The target market for our products is the approximately 30,000 cardiologists in the United States that perform or could perform nuclear cardiology procedures. To date, we have sold or provided imaging services through DIS to approximately 500 physicians. In 2003, DIS performed over 66,000 patient procedures.

        We sold our first gamma camera in March 2000, and we established DIS in September 2000. We had consolidated revenues and net losses of $41.5 million and $12.8 million, respectively, in fiscal 2002, and $56.2 million and $1.7 million, respectively, in fiscal 2003.2003 and $15.9 million and $266,000, respectively, for the three months ended March 31, 2004. Revenues from DIS and from our camera sales constituted 62% and 38%, respectively, of our 2003 consolidated revenues.revenues and 66% and 34%, respectively, of our consolidated revenues for the three months ended March 31, 2004. We believe DIS will continue to provide us with recurring annual contractual revenue and comprise the largest component of our consolidated revenues.

Our Competitive Strengths

        We believe that our position as a market leader in the nuclear cardiac imaging market is a product of the following competitive strengths:

•

Leading Solid-State Technology. We were the first company to develop and commercialize solid-state technology for nuclear imaging applications.



•

Mobile Applications Through Reduced Size and Weight. Our solid-state technology has allowed us to reduce the size and weight of gamma cameras, resulting in the only in-office mobile cardiac gamma camera on the market.



•

Image Quality. We believe our imaging systems maintain a high-quality image despite the rigors of a mobile environment.



•

Enhanced Operability and Reliability. We believe our imaging systems provide more convenient operation, better power efficiency and increased durability as compared to vacuum tube cameras.



•

Improved Patient Comfort and Utilization. We believe the upright and open architecture of our patient chair can reduce patient claustrophobia and increase patient comfort when compared to traditional vacuum tube-based systems and may increase patient utilization.



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Unique Dual Distribution. We have implemented a unique dual distribution model by offering our physician and hospital customers the ability to either purchase or lease our imaging systems through DIS.



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Intellectual Property Portfolio. We have developed an intellectual property portfolio that includes product, component and process patents covering various aspects of our imaging systems. Currently, we have 21 patents issued and 10 pending patent applications in the United States, and we have two patents issued and 21 pending patent applications internationally.

Our Business Strategy

        We intend to continue to expand our business, improve our market position and increase our revenue and profits by pursuing the following business strategies:

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Continued Innovation in Solid-State Imaging Technology. We intend to maintain our leadership position in solid-state imaging technology by continuing to invest resources in research and development.

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Expand Our DIS Business. We plan to expand our DIS business into several new states, add new hub locations in states in which we currently operate and increase hub utilization by adding physician

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customers and routes. We also intend to pursue cardiology opportunities for DIS in hospitals and new clinical applications for DIS in neurology, oncology and surgery.





•

Increase Market Share in Camera Sales. We believe that we can grow our market share by capitalizing on the recent trend of nuclear cardiology procedures shifting from the hospital to the physician office.



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Expand International Sales and Marketing Presence. We intend to increase our presence internationally by entering into relationships with distributors that have the experience, expertise and service network to sell and support our products internationally.



•

Drive Margin Improvements and Growth. We plan to enhance our product margins by achieving operating efficiencies, reducing manufacturing costs and increasing product reliability.

Corporate Information

        Our business was originally incorporated in California in November 1985 and we reincorporated in Delaware in January 1997. Our principal executive offices are located at 13950 Stowe Drive, Poway, California 92064 and our telephone number is (858) 726-1600. We maintain a website on the Internet atwww.digirad.com. The information contained in, or that can be accessed through, our website is not a part of this prospectus. Unless the context requires otherwise, as used in this prospectus the terms "Digirad," "we," "us" and "our" refer to Digirad Corporation, a Delaware corporation, and its subsidiaries.

        We have trademark registrations in the United States for 2020tc Imager®, CardiusSST®, Digirad®, Digirad Logo®, Digirad Imaging Solutions®, FlexImaging® and SPECTour®. We have trademark applications pending in the United States for the following marks: Cardius™, DigiServ^SM, DigiSpect^SM, DigiTech^SM and Solidium^SM. We have obtained and sought trademark protection for some of the above listed marks in the European Community and Japan.

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THE OFFERING

        The number of shares of common stock to be outstanding after this offering is based on the shares of common stock outstanding as of DecemberMarch 31, 2003.2004. This number excludes as of DecemberMarch 31, 2003:2004:

•

4,831,1381,581,519 shares of our common stock subject to outstanding options under our 19951991 Stock Option/Stock Issuance Plan,Option Program, our 1997 Stock Option/Stock Issuance Plan and our 1998 Stock Option/Stock Issuance Plan, having a weighted average exercise price of $0.52$2.42 per share;



•

1,018,14758,904 shares of our common stock available for future issuance under our 19951991 Stock Option/Stock Issuance Plan,Option Program, our 1997 Stock Option/Stock Issuance Plan and our 1998 Stock Option/Stock Issuance Plan; and



•

205,39663,971 shares of our common stock issuable upon exercise of outstanding warrants (including warrants to purchase preferred stock that are convertible into common stock), having a weighted average exercise price of $10.26$33.39 per share.

In addition, except where we state otherwise, the information we present in this prospectus reflects:

•

the automatic conversion of all our outstanding preferred stock into 43,555,36712,444,294 shares of common stock upon the completion of this offering;



•

the adoption of our restated certificate of incorporation and restated bylaws to be effective upon the completion of this offering;



•

no exercise of the underwriters' over-allotment option;



•

a 1-for-200 reverse stock split of our capital stock effected in October 2002; and



•

a 1-for-1-for-3.5 reverse stock split to be effected prior to completion of this offering.our common stock, which was approved by our stockholders on April 30, 2004.

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SUMMARY CONSOLIDATED FINANCIAL INFORMATION

        The following table summarizes our consolidated financial information for the periods presented which are derived from our audited financial statements.presented. You should read this information together with our consolidated financial statements and the related notes appearing elsewhere in this prospectus and the "Management's Discussion and Analysis of Financial Condition and Results of Operations" section of this prospectus. The summary financial data at March 31, 2004 and for the three months ended March 31, 2003 and 2004 are derived from our unaudited financial statements which are included elsewhere in this prospectus.

(1)

Please see our consolidated statement of operations on page F-4 and Note 1 to our consolidated financial statements for additional information on stock-based compensation.

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(2)

Please see Note 1 to our consolidated financial statements for an explanation of the method used to calculate the historical and pro forma net loss per share and the number of shares used in the computation of per share amounts.

(3)

The as adjusted column in the balance sheet data reflects the automatic conversion of all of our preferred stock outstanding as of DecemberMarch 31, 20032004 into 43,555,36712,444,294 shares of our common stock in connection with this offering, the sale of 5,500,000 shares of our common stock at an assumed initial public offering price of $$13.00 per share, the mid-point of the range on the cover of this prospectus, after deducting the estimated underwriting discounts and commission and the estimated expenses payable by us in connection with this offering, and the repayment of $9.4$9.7 million due under our short-term lines of credit.credit and notes payable.

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RISK FACTORS

        An investment in our common stock involves a high degree of risk. You should carefully consider the risks and uncertainties described below, together with all of the other information included in this prospectus, including the consolidated financial statements and the related notes appearing elsewhere in this prospectus, before making an investment decision. If any of the following risks actually occurs, our business, financial condition, results of operations and future prospects would likely be materially and adversely affected. In that event, the market price of our common stock could decline and you could lose all or part of your investment.

Risks Related to Our Business and Industry

        If our imaging systems and DIS services are not accepted by physicians or hospitals, we may be unable to develop a sustainable, profitable business.

        We expect that substantially all of our revenue in the foreseeable future will be derived from sales of our products in the nuclear imaging market and our leasing services offered through our wholly owned subsidiary,subsidiaries, Digirad Imaging Solutions, Inc. and Digirad Imaging Systems, Inc., orwhich we refer to collectively as DIS. Our solid-state gamma cameras and DIS services represent a new approach in the nuclear imaging market, and we have sold our products only in limited quantities and leased our services for only a limited time.market. We began full commercial release of our imaging systems in March 2000 and established DIS in September 2000. Because of the recent commercial introduction of our nuclear imaging systems, we have limited product and brand recognition and our imaging systems have been used by a limited number of physicians and hospitals. Physicians and hospitals may generally be slow to adopt our products and leasing services for a number of reasons, including:

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perceived liability risks generally associated with the use of new technologies for nuclear imaging;



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availability of reimbursement from health care payors for procedures using our system;



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lack of experience with our products and services;



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costs associated with the purchase or lease of our products and services;



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the presence of competing products sold by companies with longer operating histories, more recognizable names and more established distribution networks;



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the introduction or existence of competing products and services or technologies that may be more effective, easier to use or that produce better images; and



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physician and hospital perceptions of our imaging systems as compared to those of competitors.

        Our success in the nuclear imaging market depends on whether physicians and hospitals view our imaging systems and DIS services as effective and economically beneficial. We believe that physicians and hospitals will not adopt our imaging systems or lease our DIS services unless they determine, based on experience and other factors, that our imaging systems and DIS services are an attractive alternative to vacuum tube imaging systems. We also believe that recommendations and support of our products and services by influential physicians and other health care providers are essential for market acceptance and adoption. We cannot assure you that physicians or hospitals will adopt or accept our imaging systems or DIS services. If physicians and hospitals do not adopt our imaging systems or DIS services, our operating results and business will be harmed.

        We sell our imaging systems and provide our services in a highly competitive industry, and we often compete against large, well-established competitors that have significantly greater financial resources than we have.

        The medical device industry, including the market for imaging systems and services, is highly competitive, subject to rapid change and significantly affected by new product introductions and market activities of other industry participants. Our primary competitors with respect to imaging systems include several large medical device manufacturers, including Philips Medical Systems, General Electric Healthcare, Siemens Medical Systems and Toshiba Medical Systems. All of these competitors offer a full line of imaging cameras for each diagnostic imaging technology, including x-ray, magnetic resonance

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imaging, computerized tomography, ultrasound and nuclear medicine. The existing imaging systems sold by our competitors have been in use for a longer time than our products and are more widely recognized and used by physicians and hospitals for nuclear imaging. Many of our competitors and potential competitors enjoy significant competitive advantages over us, including:

•

significantly greater name recognition and financial, technical and marketing resources;



•

established relationships with healthcare professionals, customers and third-party payors;



•

established distribution networks;



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additional lines of products and the ability to offer rebates or bundle products to offer discounts or incentives; and



•

greater resources for product development, sales and marketing.

        The competitive nature of the nuclear imaging industry has had an impact on the price of our dual-head gamma cameras. For example, for the three months ended March 31, 2004 we experienced a moderate decline in the selling price for our dual-head gamma cameras when compared to the three months period ended March 31, 2003. While we anticipate demand for our dual-head gamma cameras to continue to increase, we believe these pricing pressures will continue to impact our gamma camera product revenue and gross profit.

        In providing comprehensive mobile nuclear imaging solutions, we generally compete against small businesses employing traditional vacuum tube cameras that must be transported in large vehicles and cannot be moved in and out of physician offices.

        We are aware of certain major medical device companies that are attempting to develop solid-state cameras and we believe these efforts will continue. In addition, we are aware of a privately-held company, Gamma Medica, which is currently marketing a solid-state gamma camera for breast imaging. We do not believe that this camera can be used in a cardiac application. However, we cannot assure you that Gamma Medica will not attempt to modify its existing camera for use in the cardiac segment in the future, or develop another gamma camera for cardiac applications. Because of the size of the potential market, we anticipate that companies will dedicate significant resources to developing competing products and services. Current or future competitors may develop technologies and products that demonstrate better image quality, ease of use or mobility than our imaging systems. Our ability to compete successfully will depend on our ability to develop proprietary products that reach the market in a timely manner, receive adequate reimbursement and are less expensive than alternatives available for the same purpose. If we are unable to compete effectively against our existing and future competitors our sales will decline and our business will be harmed.

        Changes in domestic and international legislation, regulation, or coverage and reimbursement policies of third-party payors may adversely impact our ability to market and sell our products and services.

        Physicians and hospitals purchasing and using our products rely on adequate third-party payor coverage and reimbursement to maintain their operations. Changes in domestic and international legislation, regulation or coverage and reimbursement policies of third-party payors may adversely affect the demand for our existing and future products and services and may limit our ability to market and sell our products and services on a profitable basis. For example, on December 8, 2003, President Bush signed into law the Medicare Prescription Drug, Improvement and Modernization Act of 2003, (the "Medicareor the Medicare Modernization Act"),Act, which contains a wide variety of changes that impact Medicare reimbursement to physicians and hospitals. We cannot predict what additional changes will be made to such legislation, regulation, or coverage and reimbursement policies, but we believe that future coverage and reimbursement may be subject to increased restrictions both in the United States and in international markets. Additionally, we cannot be certain that under prospective payment systems, or established fee schedule payment formulas, under which healthcare providers may be reimbursed a fixed amount based on the patient's condition or the type of procedure performed, the costs of our products and services will be

justified and incorporated into the overall payment for the procedure. Third-party payors continue to act to contain or reduce healthcare costs through various means, including the movement to managed care systems where healthcare providers contract to provide comprehensive healthcare for a fixed fee per patient. These continued efforts to reduce healthcare costs may result in third-party payors refusing to reimburse patients or healthcare providers for our imaging services or allowing only specific providers to provide imaging services. As a result, sales of our gamma cameras would suffer and we may receive

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pressure from our customers to terminate or otherwise modify the lease arrangements for our DIS services. Under such circumstances, our business, financial condition and results of operations could be materially adversely affected.

        Because our imaging systems and DIS services are not widely diversified, a decrease in sales of our products and leasing services could seriously harm our business.

        Our current product and leasing service offerings consist primarily of our line of gamma cameras, including our Cardius-1, Cardius-2, 2020tc Imager and SPECTpak PLUS camera systems, each of which is used in the nuclear imaging market segment and all of which utilize the same solid-state technology. In addition, we offer a mobile imaging leasing service through DIS, which includes an imaging system, certified personnel, required licensure and other support for nuclear imaging procedures. As such, our line of products and services is not as diversified as those of some of our competitors. Consequently, if sales of our products or leasing services decline precipitously, our business would be seriously harmed, and it would likely be difficult for us to recover because we do not have the breadth of products or services that would enable us to sustain our business while seeking to develop new types of products or services or other markets for our existing products and services. In addition, because our technical know-how and intellectual property have limited applications, we may be unable to leverage our technical know-how and intellectual property to diversify our products and services or to develop other products or sources of revenue outside of the nuclear imaging market.

        Our imaging systems and DIS services may become obsolete, and we may not be able to timely develop new products, product enhancements or services that will be accepted by the market.

        Our nuclear imaging system and DIS services may become obsolete or unmarketable if other products or services utilizing new technologies are introduced by our competitors or new industry standards emerge. We cannot assure you that we will be able to successfully develop or market new products and services, or enhancements to our existing products, or that our future products and enhancements will be accepted by our current or potential customers or the third-party payors who financially support many of the procedures performed with our products. Any of these circumstances may cause us to lose customers, disrupt our business operations and harm our product sales and services. To be successful, we will need to enhance our products or services and to design, develop and market new products that successfully respond to competitive developments, all of which may be expensive and time consuming.

        The success of any new product offering or enhancement to an existing product will depend on several factors, including our ability to:

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properly identify and anticipate physician and patient needs;



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develop new products or enhancements in a timely manner;



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obtain the necessary regulatory approvals or clearances for new products or product enhancements in a timely manner;



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provide adequate training to users of our products;



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price our products competitively;



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obtain appropriate coverage and receive adequate reimbursement notifications and respond to them in a commercially viable way;



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comply with changing or new regulatory requirements; and



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develop an effective marketing, sales and distribution network.

        If we do not develop and obtain regulatory approvals or clearances for new products, services or product enhancements in time to meet market demand, or if there is insufficient demand for these products, services or enhancements, our business, financial condition and results of operations will likely suffer. In addition, even if our customers acquire new products, services or product enhancements we may

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offer, the revenues from any such products, services or enhancements may not be sufficient to offset the significant costs associated with offering such products, services or enhancements to customers. In addition, any announcements of new products, services or enhancements may cause customers to decline or cancel their purchasing decisions in anticipation of such products, services or enhancements.

        If we experience problems with the technologies used in our imaging systems or if delivery of our DIS services are delayed, public perception of us could be harmed and cause us to lose customers and revenue.

        Our gamma cameras have only recently been introduced into the marketplace. Most of our cameras currently in use are less than three years old. We have experienced some reliability issues with a prior version of our detector heads. In July 2003, we began selling most of our gamma cameras with a new version of our detector heads that we believe offers increased reliability. In addition, as the period of use of our cameras increases, other significant defects may occur. If significant defects do arise with our gamma cameras, our reputation among physicians and hospitals could be damaged.

        Additionally, physicians rely on our DIS services to provide nuclear imaging procedures to their patients on the dates and at the times they have requested. Many factors could prevent us from delivering our DIS services on a timely basis, including weather and the availability of staffing, transportation and necessary supplies. If we are unable to provide physicians or hospitals our DIS services in a timely and effective manner, our reputation among physicians and hospitals could be damaged.

        The performance and reliability of our products and services are critical to our reputation and to our ability to achieve market acceptance of those products and services. Widespread or other failures of our cameras and other products to consistently meet the expectations of purchasers or customers that use our DIS services could adversely affect our reputation, our ability to provide our DIS services, our relations with current customers and our business operations. Such failures could also reduce the attractiveness of our products and services to potential customers. Equipment failures could result from any number of causes, including equipment aging, ordinary wear and tear due to regular transportation and relocation, failure to perform routine maintenance and latent hardware or software defects of which we are unaware. Such failures, whether actual or perceived, could adversely affect our business even if we correct the underlying problems.

        Our manufacturing operations are highly dependent upon third-party suppliers, making us vulnerable to supply problems and price fluctuations, which could harm our business.

        We rely on a limited number of third parties to manufacture and supply certain of the key components of our products. While many of the components used in our products are available from multiple sources, we obtain some components from single sources. For example, key components of the detector heads and the acquisition and control software utilized in our gamma cameras are manufactured or supplied by a single source. To be successful, our contract manufacturers and suppliers must provide us with the components of our systems in requisite quantities, in compliance with regulatory requirements, in accordance with agreed-upon specifications, at acceptable cost and on a timely basis. Segami Corporation, or Segami, has developed image acquisition and processing software for our camera under a non-exclusive license agreement. In the event that Segami attempts to terminate the license agreement, refuses to extend the term of the license or seeks to impose unreasonable pricing or terms, we would have to find an alternative software system to use in our gamma camera. Our reliance on these outside suppliers subjects us to a number of risks that could harm our business, including:

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suppliers may make errors in manufacturing components that could adversely affect the efficacy or safety of our products or cause delays in shipment of our products;

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we may not be able to obtain adequate supply in a timely manner or on commercially reasonable terms;



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we may have difficulty locating and qualifying alternative suppliers for our components;

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•

once we identify alternative suppliers, we could experience significant delays in production due to the need to evaluate and test the products delivered by alternative suppliers and to obtain regulatory qualification for them;



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we are not a major customer of many of our suppliers, and these suppliers may therefore give other customers' needs higher priority than ours;



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we use some suppliers that are small, privately-held companies, and these suppliers could encounter financial or other difficulties that could cause them to modify or discontinue their operations at any time;



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our suppliers manufacture products for a range of customers, and fluctuations in demand for the products those suppliers manufacture for others may affect their ability to deliver components to us in a timely manner; and



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our suppliers may encounter financial hardships unrelated to our demand for components, which could inhibit their ability to fulfill our orders and meet our requirements.

        Any interruption or delay in the supply of components or materials, or our inability to obtain components or materials from alternate sources at acceptable prices in a timely manner, could impair our ability to meet the demand of our customers and cause them to cancel orders or switch to competitive procedures. These events could harm our business and operating results.

        We have limited marketing, sales and distribution capabilities, and our efforts in those areas are dependent in part on third parties.

        We began commercial production and shipped our first imaging products in 2000, and therefore have limited experience in marketing, selling and distributing our products and services. Additionally, while we have a direct sales team focused on domestic marketing, sales and distribution, we also use four independent distributors in the United States and two independent, international sales distributors to market, sell and distribute our products and services. As a result, we are dependent in part upon the marketing, sales and distribution efforts of our third-party distributors. To date, one of our domestic third-party distributors is permitted to market, sell and distribute competing imaging services and products. Additionally, one of our domestic third-party distributors, as well as one of our international distributors, is generally permitted to market, sell and distribute competing imaging products that are used or refurbished and meet specified age requirements. Our other international distributor is prohibited from promoting or distributing any other gamma camera product, but is not prohibited from offering competing services.

        Our future revenue growth will depend in large part on our success in maintaining and expanding our marketing, sales and distribution channels, which will likely be an expensive and time-consuming process. We are highly dependent upon the efforts of our sales force and third-party distributors to increase our revenue. We face intense competition for qualified sales employees and may be unable to hire, train, manage and retain such personnel, which could adversely affect our ability to maintain and expand our marketing, sales and distribution network, which would negatively affect our ability to compete effectively as a distributor of nuclear imaging devices. Additionally, even if we are able to expand our sales force and enter into agreements with additional third-party distributors on commercially reasonable terms, they may not commit the necessary resources to effectively market, sell and distribute our products and services domestically and internationally. If we are unable to maintain and expand our direct and third-party marketing, sales and distribution networks, we may be unable to sell enough of our products and imaging services for our business to be profitable and our financial condition and results of operations will likely suffer accordingly.

        If we failare unable to meet the demand forsuccessfully operate and manage our imaging systems and DIS services as we transition manufacturing operations to a singleat our new facility, we may experience a decrease in sales.

        We are currently inrecently completed the processtransition of transitioning our manufacturing operations from several separate facilities to a single facility. We must complete construction of and equipAs we scale-up operations at our new facility, and obtain U.S.

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Food and Drug Administration, or FDA, and California Food and Drug Branch approval prior to manufacturing our imaging systems at such facility. The completion of this process could be delayed bywe may encounter unforeseen circumstances, including:

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difficulties with facility construction;



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inability to obtain critical equipment on a timely basis;



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failure to obtain necessary regulatory approvals or operating permits in a timely fashion, if at all;



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shortages of qualified personnel to operate equipment and manage manufacturing operations;



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shortages of key raw materials or component inputs to the manufacturing process; and



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difficulties associated with moving from smaller-scale production to higher volumes.

        As we scale-up operations at our new facility,In addition, we may also experience difficulties in producing sufficient quantities or quality of products or in achieving sufficient quality and manufacturing yield levels. If we are unable to commencesuccessfully operate and manage our manufacturing operations at our new facility on schedule or otherwise fail to meet our manufacturing needs, we may not be able to provide our customers with the quantity or quality of products they require, and we could lose customers and suffer reduced revenues.

        We are subject to the financial risks associated with providing services through our DIS business.

        There are numerous risks associated with any leasing arrangement, including the possibility that physicians may fail to make the required payments under the terms and provisions of their lease commitments. Our DIS business is also affected by the ability of physicians to pay us, which in turn may be affected by general economic and business conditions and the availability of reimbursement for the physicians. Such circumstances could adversely affect our business and financial condition.

        If we are unable to expand our DIS business, our business could be materially harmed.

        We plan to grow our DIS business by expanding into several new states, adding new hub locations in states in which we currently operate and increasing hub utilization by adding physician customers and routes. As we undertake this expansion, we will need to hire, train and retain qualified personnel. We cannot assure you that physicians or hospitals in these new markets will accept our imaging products or services. Our expansion into additional domestic markets is subject to inherent risk, including the burden of complying with applicable state regulations, including but not limited to regulations concerning the use, storage, handling and disposal of radioactive materials, the difficulties in obtaining the necessary radioactive licensures and difficulties in staffing and managing operations. Further, certain states have regulations that willFurthermore, physician self-referral laws currently in effect in the State of New York do not allow the conduct of our DIS business as it is currently structured or at all.all, and we may find the laws of other states in which we do not currently operate to require us to change the structure of our DIS business to operate in such states.

        A loss of key executives or failure to attract qualified managers, engineers and imaging technologists could limit our growth and adversely affect our business.

        Our success is dependent on the efforts of our key technical, sales and managerial personnel and our ability to retain them, particularly David M. Sheehan, Paul J. Early, Herb Bellucci, Todd P. Clyde, Richard Conwell and Vera P. Pardee. The loss of any one or more of these individuals could place a significant strain on our remaining management team and we may have difficulty replacing any of these individuals. Furthermore, our future growth will depend in part upon our ability to identify, hire and retain additional key personnel, including nuclear imaging technologists, or CNMTs, paramedics, nurses, radiation safety officers, engineers, management, sales personnel and other highly skilled personnel. Hiring qualified management and technical personnel will be difficult due to the limited number of qualified candidates. Competition for these types of employees, particularly CNMTsnuclear imaging technologists and engineers, is intense in the medical imaging field. Given the competition for such qualified personnel, we cannot assure you that we

will be able to continue to attract, hire and retain the personnel necessary to maintain and develop our business. Failure to attract, hire and retain key personnel could have an adverse effect on our business, financial condition and results of operations. We do not have any employment agreements with, or key person insurance on, any of our employees.

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        If we choose to acquire new or complementary businesses, products or technologies instead of developing them ourselves, we may be unable to complete those acquisitions or to successfully integrate them in a cost-effective and non-disruptive manner.

        Our success depends on our ability to continually enhance and broaden our product and service offerings in response to changing customer demands, competitive pressures and technologies. While we have no current plans or commitments regarding any acquisitions of new or complementary businesses, products or technologies, we may in the future choose to pursue such acquisitions instead of developing those businesses, products or technologies ourselves. We cannot assure you, however, that we would be able to successfully complete any acquisition we choose to pursue, or that we would be able to successfully integrate any acquired business, product or technology into our company in a cost-effective and non-disruptive manner. Furthermore, there is no certainty that we would be able to attract, hire or retain key employees associated with any acquired businesses, products or technologies.

        Integrating any acquired businesses, products or technologies could be expensive and time consuming, disrupt our ongoing business and divert the attention and resources of our management. If we are unable to integrate any acquired businesses, products or technologies effectively, our business will likely suffer. Additionally, any amortization of assets or charges resulting from the costs of acquisitions could harm our business and operating results.

        We will face additional risks as we expand into international markets.

        We have sales distributors for our imaging systems in Canada and Russia and are beginning to build an international sales organization. As we expand internationally, we will need to hire, train and retain qualified personnel in countries where language, cultural or regulatory impediments may exist. We cannot assure you that distributors, physicians or other involved parties in foreign markets will accept our nuclear imaging products, services and business practices. Our international operations will be subject to inherent risks, including:

•

costs of localizing product and service offerings for foreign markets;



•

difficulties in staffing and managing foreign operations;



•

reduced protection for intellectual property rights in some countries;



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difficulties and delays in enforcing agreements and in collecting receivables through the legal systems of foreign countries;



•

fluctuating currency exchange rates;



•

the possibility that foreign countries may impose additional withholding taxes or otherwise tax our foreign income, impose tariffs or adopt other restrictions on foreign trade;



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changes in political, regulatory, or economic conditions in a country or region;



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our ability to obtain U.S. export licenses and other required export or import licenses or approvals;



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burdens of complying with a wide variety of foreign laws, regulations specific to the delivery of and payment for healthcare services, regulations and licensing requirements relating to the use, storage, handling and disposal of radioactive materials, labor practices; and



•

conforming our business model to operate under government-run healthcare systems.

        Our manufacturing operations and executive offices will be located at a single facility that may be at risk from fire, earthquakes or other natural or man-made disasters or crises.

        Our manufacturing operations and executive offices will soon beare located at a single facility in Poway, California, near known fire areas and earthquake fault zones. This facility is located a short distance from the recent wildfires that destroyed many homes and businesses in San Diego County, California. We have taken precautions to safeguard our facilities, including insurance and health and safety protocols.

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However, any future natural disaster, such as a fire or an earthquake, could cause substantial delays in our operations, damage to or destroy our manufacturing equipment or inventory, and cause us to incur additional expenses. A disaster could significantly harm our business and results of operations. The insurance we maintain against fires, earthquakes and other natural disasters may not be adequate to cover our losses in any particular case.

        Additionally, electrical power is vital to our operations and we rely on a continuous power supply to conduct our business. California has experienced significant electrical power shortages and price volatility in recent years, and such shortages and price volatility may occur in the future. In the event of an acute power shortage, the California system operator has on some occasions implemented, and may in the future implement, rolling blackouts throughout California. If our energy costs substantially increase or blackouts interrupt our power supply frequently or for more than a few days, we may have to reduce or temporarily discontinue our normal operations. In addition, the cost of our research and development efforts may increase because of the disruption to our operations. Any such reduction or disruption of our operations at our facilities could harm our business.

        We are exposed to risks relating to product liability, product recalls, property damage and personal injury for which insurance coverage is expensive, limited and potentially inadequate, and our business may be impacted by increased insurance costs.

        Our operations entail a number of risks, including risks relating to product liability claims, product recalls, property damage and personal injury. We currently maintain insurance that we believe is adequate with respect to the nature of the risks insured against, including product liability insurance, professional liability insurance, automobile insurance, property insurance, workers compensation insurance and general liability insurance. In many cases such insurance is expensive and difficult to obtain, and no assurance can be given that we will be able to maintain our current insurance or that we will be able to obtain or maintain comparable or additional insurance in the future on reasonable terms, if at all. Additionally, we may be negatively affected by increased costs of insurance, including workers compensation insurance. For example, in October 2003, the Governor of California signed a bill which, if it takes effect, will require California businesses with 50 or more employees either to pay at least 80% of the premiums for a basic individual health insurance package for each of its employees and their families, or to pay a fee into a state pool for the purchase of health insurance for uninsured, low income workers.

Risks Related to Our Financial Results and Need for Financing

        We have incurred significant and recurring operating losses since our inception in 1985 and we expect to incur increased operating expenses in the near term.

        We have incurred significant net losses since our inception in November 1985, including losses of approximately $19.9 million in 2001, $12.8 million in 2002, and $1.7 million in 2003.2003, and $927,000 and $266,000 for the three months ended March 31, 2003 and 2004, respectively. As of DecemberMarch 31, 20032004 we had an accumulated deficit of $80.2$80.5 million. We expect to incur increased operating expenses in the near term as we, among other things:

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expand our manufacturing operations and DIS business;



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increase marketing, sales and distribution of our current products; and

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conduct research and development to develop next-generation products and to enhance our existing products.

        As a result of these activities, we may not be able to achieve profitability. If our revenue grows more slowly than anticipated, or if our operating expenses exceed our expectations, our ability to achieve our development and expansion goals would be adversely affected.

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        Our quarterly financial results are difficult to predict and are likely to fluctuate significantly from period to period because our business prospects are uncertain and due to the seasonality of our DIS leasing services business.

        Our revenue and results of operations at any given time will be primarily based on the following factors, many of which we cannot control:

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physician, healthcare provider and patient acceptance of our products and services;



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demand and pricing of our products and services;



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success and timing of new product offerings, acquisitions, licenses or other significant events by us or our competitors;



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our ability to establish and maintain a productive manufacturing, marketing, sales and distribution force;



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the ability of our suppliers to timely provide us with an adequate supply of necessary components;



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timing and magnitude of our expenditures;



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our ability to reduce our expenses, including our debt service obligations, quickly enough to respond to any declines in revenue;



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regulatory approvals and legislative changes affecting the products we may offer or those of our competitors;



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the effect of competing technological and market developments;



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our addition or termination of research programs or funding support;



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levels of third-party reimbursement for our products and services;



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interruption in the manufacturing or distribution of our products and services; and



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changes in our ability to obtain FDA approval or clearance for our products.

        Additionally,Furthermore, we have experienced seasonality in the leasing services offered by DIS. While our physicians are obligated to pay us for all lease days to which they have committed, our contracts permit some flexibility in scheduling when services are to be performed. This accounts for some of the seasonality of our DIS revenues. For example, our daily services have typically declined from our second fiscal quarter to our third fiscal quarter due to summer holidays and vacation schedules. We have also experienced declining daily services in December due to holidays and in our first quarter due to weather conditions in certain parts of the United States. We cannot predict with certainty the degree to which seasonal circumstances such as the summer slowdown, winter holiday variations and weather conditions may make our revenue unpredictable or lead to fluctuations in our quarterly operating results in the future.

        In addition, due to the way that customers in our target markets allocate and spend their budgeted funds for acquisition of our products, a large percentage of our sales of gamma cameras is booked at the end of each quarterly accounting period. As such, a sales delay of only a few days may significantly impact our quarter-to-quarter comparisons.

For these reasons, we believe that quarterly sales and operating results may vary significantly in the future and that period-to-period comparisons of our results of operations are not necessarily meaningful and should not be relied upon as indicators of future performance. We cannot assure you that our sales will

increase or be sustained in future periods. Accordingly, we may experience significant, unanticipated quarterly losses. Because of these and other factors, our operating results in one or more future quarters may fail to meet the expectations of securities analysts or investors, which could cause our stock price to decline significantly.

        Our reliance on a limited number of customers may cause our sales to be volatile.

        We currently have a small number of customers, whom we typically bill after the delivery of our products and imaging services. If orders for our gamma cameras were to be cancelled, or our leasing service customers stopped using us or do not renew their lease agreements with us, our business would be adversely affected. Furthermore, in view of our small customer base, our failure to gain additional customers, the loss of any current customers or a significant reduction in the level of leasing services

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provided to any one customer could disrupt our business, harm our reputation and adversely affect our sales.

        The sales cycle for our gamma cameras is typically lengthy, which may result in significant fluctuations in our revenue.

        Our sales efforts for our gamma cameras are dependent on the capital expenditures budgets of the physicians and hospitals to which we market. Often physicians and hospitals require a significant amount of lead time to plan for a major acquisition such as the purchase of our imaging systems. We may spend substantial time, effort and expense long before we actually consummate a sale of our cameras and with no assurance that we will ultimately be successful in achieving any such sales. As a result, we may experience significant fluctuations in our revenues. Furthermore, evaluating and predicting our future sales and operating performance is difficult and may not be as accurate as it could be if we had shorter sales cycles.

        Our future capital needs are uncertain and we may need to raise additional funds in the future, and such funds may not be available on acceptable terms, if at all.

        We believe that the net proceeds from this offering, together with our current cash, cash equivalents and short-term investments, will be sufficient to meet our projected operating requirements for at least the next 12 months. Our capital requirements will depend on many factors, including:

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the revenue generated by sales of our products and services;



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the costs associated with expanding our manufacturing, marketing, sales and distribution efforts;



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the rate of progress and cost of our research and development activities;



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the costs of obtaining and maintaining FDA and other regulatory clearance of our products and products in development;



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the costs of obtaining and maintaining radioactive materials licenses and radiation safety procedures;



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the effects of competing technological and market developments;



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the number and timing of acquisitions and other strategic transactions; and



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the costs associated with our expansion, if any.

        As a result of these factors, we may need to raise additional funds, and we cannot be certain that such funds will be available to us on acceptable terms, if at all. Furthermore, if we issue equity or debt securities to raise additional funds, our existing stockholders may experience dilution and the new equity or debt securities may have rights, preferences and privileges senior to those of our existing stockholders. In addition, if we raise additional funds through collaboration, licensing or other similar arrangements, it may be necessary to relinquish potentially valuable rights to our future products or proprietary technologies, or grant licenses on terms that are not favorable to us. If we cannot raise funds on acceptable terms, we may not be able to expand our operations, develop new products, take advantage of future opportunities or respond to competitive pressures or unanticipated customer requirements.

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Risks Related to Government Regulation

        We must be licensed to handle and use hazardous materials and may be liable for contamination or other harm caused by hazardous materials that we use.

        We use hazardous and radioactive materials in our research and development and manufacturing processes, as well as in the provision of our imaging services. We are subject to federal, state and local regulations governing use, storage, handling and disposal of these materials and waste products. We are currently licensed to handle such materials in all states in which we operate, but there can be no assurances that we will be able to retain those licenses in the future. In addition, we must become licensed in all states in which we plan to expand. Obtaining those additional licenses is an expensive and time consuming process, and in some cases we may not be able to obtain those licenses at all.

        Although we believe that our procedures for use, handling, storing and disposing of these materials comply with legally prescribed standards, we cannot completely eliminate the risk of contamination or injury resulting from hazardous materials and we may incur liability as a result of any such contamination or injury. In the event of an accident, we could be held liable for damages or penalized with fines, and the liability could exceed our resources and any applicable insurance.

        We have also incurred and may continue to incur expenses related to compliance with environmental laws. Such future expenses or liability could have a significant negative impact on our business, financial condition and results of operations. Further, we cannot assure you that the cost of complying with these laws and regulations will not materially increase in the future.

        Compliance with extensive product regulations could be expensive and time consuming, and any failure to comply with those regulations could harm our ability to sell and market our products and imaging services.

        U.S. and foreign regulatory agencies, including the FDA, govern the testing, marketing and registration of new medical devices or modifications to medical devices, in addition to regulating manufacturing practices, reporting, labeling and recordkeeping procedures. The regulatory process makes it longer, harder and more costly to bring our products to market, and we cannot assure you that any of our future products will be approved. All of our planned services, products and manufacturing activities, as well as the manufacturing activities of third-party medical device manufacturers who supply components to us, are subject to these regulations. Generally, we and our third-party manufacturers are or will be required to:

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undergo rigorous inspections by domestic and international agencies;



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obtain the prior approval of those agencies before we can market and sell our medical device products; and



•

satisfy content and format requirements for all of our sales and promotional materials.

        Compliance with the regulations of those agencies may delay or prevent us from introducing new or improved products, which could in turn affect our ability to achieve or maintain profitability. We may be subject to sanctions, including monetary fines and criminal penalties, the temporary or permanent suspension of operations, product recalls and marketing restrictions, if we fail to comply with the laws and regulations applicable to our business. Our third-party component manufacturers may also be subject to the same sanctions and, as a result, may be unable to supply components for our products. Any failure to retain governmental approvals that we currently hold or obtain additional similar approvals could prevent us from successfully marketing our products and technology and could harm our operating results. Furthermore, changes in the applicable governmental regulations could prevent further commercialization of our products and technologies and could harm our business.

        Even if regulatory approval or clearance of a product is granted, regulatory agencies could impose limitations on uses for which the product may be labeled and promoted. Further, for a marketed product,

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its manufacturer and manufacturing facilities are subject to periodic review and inspection. Later discovery of problems with a product, manufacturer or facility may result in restrictions on the product, manufacturer or facility, including withdrawal of the product from the market or other enforcement actions.

        Our products are subject to reporting requirements and recalls even after receiving FDA clearance or approval, which could harm our reputation, business and financial results.

        We are subject to medical device reporting regulations that require us to report to FDA or similar governmental bodies in other countries if our products cause or contribute to a death or serious injury or malfunction in a way that would be reasonably likely to contribute to death or serious injury if the malfunction were to recur. In addition, the FDA and similar governmental bodies in other countries have the authority to require the recall of our products in the event of material deficiencies or defects in design or manufacture. A government mandated or voluntary recall by us could occur as a result of component failures, manufacturing errors or design defects, including defects in labeling. Any recall would divert management attention and financial resources and harm our reputation with customers. A recall involving our product could harm the reputation of the product and our company and would be particularly harmful to our business and financial results.

        If we fail to obtain, or are significantly delayed in obtaining, FDA clearances or approvals for future products or product enhancements, or if we fail to comply with FDA's Quality System Regulation, our ability to commercially market and distribute our products will suffer.

        Our products are subject to rigorous regulation by the FDA, and numerous other federal, state and foreign governmental authorities. In the U.S., the FDA regulates virtually all aspects of a medical device's testing, manufacture, safety, labeling, storage, recordkeeping, reporting, promotion and distribution. Our failure to comply with those regulations could lead to the imposition of administrative or judicial sanctions, including injunctions, suspensions or the loss of regulatory approvals, product recalls, termination of distribution, or product seizures. In the most egregious cases, criminal sanctions or closure of our manufacturing facilities are possible. The process of obtaining regulatory approvals to market a medical device, particularly from the FDA, can be costly and time consuming, and there can be no assurance that such approvals will be granted on a timely basis, if at all. In particular unless exempt, the FDA permits commercial distribution of a new medical device only after the device has received 510(k) clearance or is the subject of an approved Premarket Approval Application, or PMA. The FDA will clear marketing of a medical device through the 510(k) process if it is demonstrated that the new product is substantially equivalent to other 510(k)-cleared products. The PMA approval process is more costly, lengthy and uncertain than the 510(k) clearance process, and must be supported by extensive data, including data from preclinical studies and human clinical trials. Because we cannot assure you that any new products we develop, or any product enhancements, will be subject to the shorter 510(k) clearance process, significant delays in the introduction of any new products or product enhancements may occur. There is no assurance that the FDA will not require a new product or product enhancement go through the lengthy and expensive PMA approval process. Further, pursuant to FDA regulations, we can only market our products for approved uses. If our products are used for purposes other than those approved by the FDA, the FDA could object to such off-label uses.

        Our manufacturing processes and those of our third-party manufacturers are required to comply with the FDA's Quality System Regulation, or QSR, which covers the design, testing, production processes, controls, quality assurance, labeling, packaging, storage and shipping of our devices. In addition, we must engage in extensive recordkeeping and reporting and must make available our manufacturing facility and records for periodic unscheduled inspections by federal, state and foreign agencies, including the FDA. Our or our third-party manufacturers' failure to pass a QSRQuality System Regulation inspection or to comply with these and other applicable regulatory requirements could result in disruption of our operations and manufacturing delays,

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and a failure to take adequate corrective action could result in, among other things,

withdrawal of our medical device clearances, seizure or recall of our devices, or other civil or criminal enforcement actions.

        Foreign governmental authorities that regulate the manufacture and sale of medical devices have become increasingly stringent and, to the extent we now or in the future market and sell our products in foreign countries, we may be subject to rigorous regulation by those foreign governmental authorities. In such circumstances, we would rely significantly on our foreign independent distributors to comply with the varying regulations, and any failures on their part could result in restrictions on the sale of our products in foreign countries.

        Modifications to our products may require new 510(k) clearances or premarket approvals, or may require us to cease marketing or recall the modified products until clearances are obtained.

        Any modification to a 510(k)-cleared device that could significantly affect its safety or effectiveness, or that would constitute a major change in its intended use, design, or manufacture, requires a new 510(k) clearance or, possibly, approval of a PMA. The FDA requires every manufacturer to make this determination in the first instance, but the FDA may review any manufacturer's decision. The FDA may not agree with our decisions regarding whether new clearances or approvals are necessary. If the FDA requires us to seek 510(k) clearance or PMA for modification of a previously cleared product for which we have concluded that new clearances or approvals are unnecessary, we may be required to cease marketing or to recall the modified product until we obtain clearance or approval, and we may be subject to significant regulatory fines or penalties. Further, our products could be subject to recall if the FDA determines, for any reason, that our products are not safe or effective. Any recall or FDA requirement that we seek additional approvals or clearances could result in delays, fines, costs associated with modification of a product, loss of revenue and potential operating restrictions imposed by the FDA.

        We will spend considerable time and money complying with federal, state and foreign regulations and, if we are unable to fully comply with such regulations, we could face substantial penalties.

        We are directly or indirectly through our clients, subject to extensive regulation by both the federal government and the states and foreign countries in which we conduct our business. The laws that directly or indirectly affect our ability to operate our business include, but are not limited to, the following:

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the federal Medicare and Medicaid Anti-Kickback Law, which prohibits persons from knowingly and willfully soliciting, offering, receiving or providing remuneration, directly or indirectly, in cash or in kind, to induce either the referral of an individual, or furnishing or arranging for a good or service, for which payment may be made under federal healthcare programs such as the Medicare and Medicaid Programs;



•

other Medicare laws and regulations that prescribe the requirements for coverage and payment for services performed by us and our DIS customers, including the amount of such payment;



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the federal False Claims Act, which imposes civil and criminal liability on individuals and entities who submit, or cause to be submitted, false or fraudulent claims for payment to the government;



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the federal Health Insurance Portability and Accountability Act of 1996, or HIPAA, which prohibits executing a scheme to defraud any healthcare benefit program, including private payors and, further, requires us to comply with standards regarding the privacy and security of individually identifiable health information and conduct certain electronic transactions using standardized code sets. In addition, regulations have been issued under HIPAA that will require us to comply with additional security regulations by April 2005 and to adopt unique health identifiers for use in filing and processing healthcare claims and other transactions by May 2007;



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the federal False Statements Statute, which prohibits knowingly and willfully falsifying, concealing or covering up a material fact or making any materially false statement in connection with the delivery of or payment for healthcare benefits, items or services;

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•

the federal physician self-referral prohibition, commonly known as the Stark Law, which, in the absence of a statutory or regulatory exception, prohibits the referral of Medicare or Medicaid patients by a physician to an entity for the provision of certain designated healthcare services, if the physician or a member of the physician's immediate family has a direct or indirect financial relationship, including an ownership interest in, or a compensation arrangement with, the entity and also prohibits that entity from submitting a bill to a federal payor for services rendered pursuant to a prohibited referral;



•

the federal Food, Drug and Cosmetic Act, which regulates the manufacture, labeling, marketing, distribution and sale of prescription drugs and medical devices;



•

state and foreign law equivalents of the foregoing;



•

federal and state radioactive materials laws, which govern the procurement, use, transfer and storage of radioactive materials;



•

state food and drug laws, pharmacy acts and state pharmacy board regulations, which govern the sale, distribution, use, administration and prescribing of prescription drugs;



•

state laws that prohibit the practice of medicine by non-physicians and fee-splitting arrangements between physicians and non-physicians, as well as state law equivalents to the federal Medicare and Medicaid Anti-Kickback Law and the Stark Law, which may not be limited to government reimbursed items or services; and



•

federal laws and regulations that permit physicians to bill and receive payment for certain diagnostic tests under the Medicare Physician Fee Schedule only if certain conditions are satisfied, including the requirement that the physician personally perform, or adequately supervise the performance of, the test.test using equipment they own or lease, and that prohibit physicians from marking up the cost of tests they "purchase," rather than perform or supervise, for Medicare patients.

        We implemented a compliance program in 2002 to help assure that we remain in compliance with these laws. Like most companies with active and effective compliance programs, we occasionally discover compliance concerns. For example, we have discovered certain isolated arrangements that we entered into in good faith but that, upon review by our compliance personnel, raised some compliance concerns under these laws. In accordance with our compliance program, we took immediate remedial steps. We cannot assure you that these remedial steps will insulate us from liability associated with these isolated arrangements.

If our past or present operations are found to be in violation of any of the laws described above or the other governmental regulations to which we or our customers are subject, we may be subject to the applicable penalty associated with the violation, including civil and criminal penalties, damages, fines, exclusion from the Medicare and Medicaid programs and the curtailment or restructuring of our operations. Similarly, if our customers are found non-compliant with applicable laws, they may be subject to sanctions, which could also have a negative impact on us. In addition, if we are required to obtain permits or licensure under these laws that we do not already possess, we may become subject to substantial additional regulation or incur significant expense. Any penalties, damages, fines, curtailment or restructuring of our operations would adversely affect our ability to operate our business and our financial results. The risk of our being found in violation of these laws is increased by the fact that many of them have not been fully interpreted by the regulatory authorities or the courts, and their provisions are open to a variety of interpretations, and additional legal or regulatory change. Any action against us for violation of these laws, even if we successfully defend against it, could cause us to incur significant legal expenses, divert our management's attention from the operation of our business and damage our reputation. For a more detailed discussion of the various state and federal regulations to which we are subject, and how they apply to our operations and activities, see "Business—Government Regulations."

        Legislative or regulatory reform of the healthcare system may affect our ability to sell our products profitably.

        In both the United States and certain other foreign jurisdictions, there have been a number of legislative and regulatory proposals to change the healthcare system in ways that could impact our ability to sell our products and services profitably. In the United States, federal and state lawmakers regularly propose and, at times, enact new legislation establishing significant changes in the healthcare system. Recently, President Bush signed into law the Medicare Modernization Act, which contains a wide variety of reforms that impact Medicare reimbursements to hospitals and physicians including changes to Medicare payment methodologies for radiopharmaceuticals and other drugs dispensed by hospital

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outpatient departments and for drugs dispensed by physician offices and independent diagnostic testing facilities. These changes reduced payment amounts for some of the drugs used in conjunction with our imaging procedures, although the physician fee schedule payment rates applicable to nuclear cardiology increased slightly. Downward changes to Medicare reimbursement rates may adversely impact reimbursement to customers or potential customers that use or could use our cameras and services. We cannot predict the full impact that this new legislation will have nor whether new federal legislation will be enacted in the future. The potential for adoption of healthcare reform proposals on a state-by-state basis could require us to develop state-specific marketing and sales approaches. In addition, we may experience pricing pressures in connection with the sale of our products and services due to additional legislative proposals or healthcare reform initiatives. Our results of operations and our business could therefore be adversely affected by future healthcare reforms.

        The impact of regulatory changes could have a negative impact on camera sales to and leases with hospitals desiring to use our cameras and services in their outpatient facilities.

        In order for hospitals to receive certain payments for their outpatient facilities as hospital outpatient services, including services that utilize our products, these services must be furnished in a "provider- based""provider-based" organization or facility or be covered services furnished "under arrangement" with the hospital. Failure to meet these requirements may result in reduced payments to the hospitals for their services. The Medicare program has published and revised rules establishing criteria for classifying a facility as "provider-based" or a service as furnished "under arrangement." These ratesrules require an analysis of the facts and circumstances surrounding the delivery by a hospital of a particular service, and hospitals that use our products or DIS services in their outpatient facilities will need to determine if they meet the applicable "provider-based" or "under arrangement" requirements. Hospitals that cannot obtain sufficient payments for these services may not purchase a camera from us or enter into arrangements with us for provision of services.

        The application of state certificate of need regulations could harm our business and financial results.

        Some states currently require, or may require in the future, a certificate of need or similar regulatory approval prior to the acquisition of high-cost capital items, including diagnostic imaging systems, or provision of diagnostic imaging services by us or our clients. In many cases, a limited number of these certificates are available in a given state. If we or our clients are unable to obtain the applicable certificate or approval or additional certificates or approvals necessary to expand our operations, these regulations may limit or preclude our operations in the relevant jurisdictions.

        If we fail to comply with various licensure, or certification standards, we may be subject to loss of licensure or certification, which would adversely affect our operations.

        All of the states in which we operate require that the imaging technicians that operate our cameras be licensed or certified. Obtaining such licenses may take significant time as we expand into additional states. Further, we are currently enrolled by Medicare contractors, or "carriers," as an independent diagnostic testing facility or IDTF, in nine states and are seeking such enrollment by Medicare contractors in one additional state. Enrollment is essential for us to receive payment for healthcare services directly from Medicare. There can be no assurances we will be able to maintain such enrollment or that we will be able to gain such

enrollment in other states. Any lapse in our licenses or enrollment, or the licensure or certification of our technicians, could increase our costs and adversely affect our operations and financial results.

        In the healthcare industry, various types of organizations are accredited to facilitate meeting certain Medicare certification requirements, expedite third-party payment and fulfill state licensure requirements. Some managed care providers prefer to contract with accredited organizations. Thus far, we have not found it necessary to seek or obtain accreditation from any established accreditation agency. If it becomes necessary for us to do so in the future in order to satisfy the requirements of third-party payors or

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regulatory agencies, there can be no assurances that we will be able to obtain or continuously maintain this accreditation.

        Audits or denials of our claims, or claims submitted by our DIS customers, by government agencies or contractors could reduce our revenues or profits and expose us to claims.

        Under our "mixed bill" model, we submit claims directly to and receive payments directly from the Medicare program. Therefore, we are subject to extensive government regulation, including requirements for maintaining certain documentation to support our claims. Government agencies and Medicare contractors also may conduct inspections or surveys of our facilities, payment reviews and other audits of our claims and operations. For example, as part of a national audit conducted pursuant to the 2003 work plan, the Office of the Inspector General of the U.S. Department of Health and Human Services, or the OIG, conducted a review of one of our IDTFindependent diagnostic testing facilities in early 2003 to review the appropriateness of Medicare payments received. This audit was concluded without any action being taken by the OIG. While we believe this audit will have no impact on us, we cannot assure you that the OIG may not take some follow-up action. We may be subject to investigations, payment reviews and audits and cannot assure you that such scrutiny will not result in material delays in payment, as well as material recoupments or denials, which could reduce our revenue or profits. Our DIS customers also submit claims to Medicare and other third-party payors, are subject to the same types of regulation and scrutiny, and may experience the same types of problems. This could adversely affect our ability to market our leases and services and to maintain existing contracts.

Risks Related to Our Intellectual Property and Potential Litigation

        Our ability to protect our intellectual property and proprietary technology through patents and other means is uncertain.

        Our success depends significantly on our ability to protect our proprietary rights to the technologies used in our products. We rely on patent protection, as well as a combination of copyright, trade secret and trademark laws, and nondisclosure, confidentiality and other contractual restrictions to protect our proprietary technology. However, these legal means afford only limited protection and may not adequately protect our rights or permit us to gain or keep any competitive advantage. Our pending U.S. and foreign patent applications, which include claims to material aspects of our products and procedures that are not currently protected by issued patents, may not issue as patents in a form that will be advantageous to us. Any patents we have obtained or do obtain may be challenged by re-examination or otherwise invalidated. Both the patent application process and the process of managing patent disputes can be time consuming and expensive. Competitors may attempt to challenge or invalidate our patents, or may be able to design alternative techniques or devices that avoid infringement of our patents, or develop products with functionalities that are comparable to ours. Although we have taken steps to protect our intellectual property and proprietary technology, including entering into confidentiality agreements and intellectual property assignment agreements with our employees, consultants, advisors and corporate partners, such agreements may not be enforceable or may not provide meaningful protection for our trade secrets or other proprietary information in the event of unauthorized use or disclosure or other breaches of the agreements. Furthermore, the laws of some foreign countries may not protect our intellectual property rights to the same extent as do the laws of the United States.

        In the event a competitor infringes upon our patent or other intellectual property rights, litigation to enforce our intellectual property rights or to defend our patents against challenge, even if successful, could be expensive and time consuming and could require significant time and attention from our management. We may not have sufficient resources to enforce our intellectual property rights or to defend our patents against challenges from others.

        We have entered into a royalty-bearing license for one U.S. patent with a third-party for use in nuclear imaging, which license is co-exclusive with the U.S. government. We do not believe that our current

22

products implement the licensed patent; however, the licensor does not agree. We are currently negotiating to amend the license to resolve our dispute with the licensor. If we were to terminate the license, the licensor or subsequent licensee may allege that our current product infringes the patent, or such third-party licensee may develop and commercialize a competitive photodiode for use in gamma cameras.

        The medical device industry is characterized by patent litigation and we could become subject to litigation that could be costly, result in the diversion of our management's time and efforts, and require us to pay damages.

        The medical device industry is characterized by extensive litigation and administrative proceedings over patent and other intellectual property rights. Whether a product infringes a patent involves complex legal and factual issues, the determination of which is often uncertain. Our competitors may assert that our products, their components or the methods we employ in the use of our products are covered by U.S. or foreign patents held by them. In addition, they may claim that their patents have priority over ours because their patents were filed or invented earlier. Because patent applications can take many years to issue, there may be applications now pending of which we are unaware, which may later result in issued patents that our products may infringe. There could also be existing patents that one or more components of our products may be infringing of which we are unaware. As the number of participants in our industry increases, the possibility of patent infringement claims against us also increases.

        Any litigation or claims against us may cause us to incur substantial costs, could place a significant strain on our financial resources, divert the attention of our management from our core business and harm our reputation. If the relevant patents were upheld as valid and enforceable and we were found to be inadvertently infringing, we could be required to pay substantial damages and/or royalties and could be prevented from selling our products unless we could obtain a license or were able to redesign our system to avoid infringement. Any such license may not be available on reasonable terms, if at all. If we fail to obtain any required licenses or make any necessary changes to our products or technologies, we may be unable to commercialize one or more of our products.

        We rely significantly on a license agreement with Segami Corporation for the imaging acquisition and processing software for our digital gamma camera, and the loss of the license could result in delivery delays, loss of customers and loss of revenue.

        Segami Corporation, or Segami, has developed image acquisition and processing software for our camera under a non-exclusive license agreement. In the event that Segami attempts to terminate the license agreement, refuses to extend the term of the license or seeks to impose unreasonable pricing or terms, we would have to find an alternative software system to use in our gamma camera. To our knowledge, there are a limited number of companies that would be able to develop and implement a software system similar to what we use in our gamma camera. As a result, in the event that we were unable to continue to use the software under the license from Segami, we could have delays in the production of our gamma camera as we attempted to find a substitute software provider. Furthermore, we cannot guarantee that alternative software providers would be able to meet our requirements or that their software would be available to us at favorable prices, if at all. To the extent we were unable to find an alternative source for the software, we may have to develop our own software system. We cannot guarantee that we could internally develop such a software system or that such efforts would not divert resources away from the development of other features of our camera. As a result, locating an alternative software

system or developing our own software system could interrupt the manufacture and delivery of our products for an extended period of time and may cause the loss of customers and revenue.

        We may be subject to damages resulting from claims that we, or our employees, have wrongfully used or disclosed alleged trade secrets of their former employers.

        Many of our employees were previously employed at other medical device companies, including our competitors or potential competitors. Although no claims against us are currently pending, we may be subject to claims that we or our employees have inadvertently or otherwise used or disclosed trade secrets

23

or other proprietary information of their former employers. Litigation may be necessary to defend against these claims. Even if we are successful in defending against these claims, litigation could result in substantial costs and be a distraction to management. If we fail in defending such claims, in addition to paying money damages, we may lose valuable intellectual property rights or personnel. A loss of key research personnel or their work product could hinder or preclude our ability to commercialize our products, which could severely harm our business.

        If we become subject to product liability or warranty claims, we may experience reduced demand for our products or be required to pay damages that exceed our insurance coverage.

        The sale and support of our products entails the risk of product liability or warranty claims, such as those based on claims that the failure of one of our products resulted in a misdiagnosis, among other issues. The medical device industry has been subject to significant products liability litigation. We may incur significant liability in the event of any such litigation, regardless of the merit of the action. Although we maintain product liability insurance, we cannot be sure that this coverage is adequate or that it will continue to be available on acceptable terms, if at all. We also may face warranty exposure, which could adversely affect our operating results. Any unforeseen warranty exposure or insufficient insurance could harm our business, financial condition and results of operations. Finally, even a meritless or unsuccessful product liability claim could harm our reputation in the industry, lead to significant legal fees and could result in the diversion of management's attention from managing our business.

        We may be subject to lawsuits and actions brought by our employees.

        We may from time to time be subject to employment claims or disputes. Recently one former and three present employees have retained counsel and have claimed that they are due overtime pay because of an alleged misclassification of their positions as non-exempt rather than exempt employees. These employees have claimed damages equal to back pay of up to thirty days, liquidated damages of twice the amount of overtime pay found due and attorneys' fees. We deny any wrongdoing and intend to defend against these claims vigorously. However, we cannot assure you that we will be successful, or that additional former or present employees may not join in any such action. Any employment claims could significantly divert our management's time and attention and could materially affect our business.

Risks Related to the Securities Markets and Ownership of Our Common Stock

        There has been no prior public market for our common stock and an active trading market may not develop.

        Prior to this offering, there has been no public market for our common stock. An active public trading market for our common stock may not develop or be sustained after the offering. We will negotiate and determine the initial public offering price with representatives of the underwriters and this price may not be indicative of prices that will prevail in the trading market. As a result, you may not be able to sell your shares of common stock at or above the offering price. An inactive market may also impair our ability to raise capital by selling shares and may impair our ability to acquire other businesses, products or technologies by using our shares as consideration.

        Future sales of our common stock may cause our stock price to decline.

        Our current stockholders hold a substantial number of shares of our common stock that they will be able to sell in the public market in the near future. Significant portions of these shares are held by a small number of stockholders. Sales by our current stockholders of a substantial number of shares after this offering, or the expectation that such sale may occur, could significantly reduce the market price of our common stock. Moreover, after this offering, the holders of approximately 12,451,260 shares of common stock, including shares issued upon conversion of our preferred stock and shares issued upon the exercise of certain of our warrants, will have rights, subject to some conditions, to require us to file registration statements to permit the resale of their shares in the public market or to include their shares in registration statements that we may file for ourselves or other stockholders. Although the holders of most

24

of our outstanding capital stock have agreed with the underwriters of this offering to be bound by a 180-day lock-up agreement that prohibits these holders from selling or transferring their stock, other than in specific circumstances, Merrill Lynch, Pierce, Fenner & Smith Incorporated and J.P. Morgan Securities Inc., at their discretion, can waive the restrictions of the lock-up agreement at an earlier time without prior notice or announcement and allow our stockholders to sell their shares of our common stock in the public market. If the restrictions of the lock-up agreement are waived, shares of our common stock will be available for sale into the market, subject only to applicable securities rules and regulations, which may cause our stock price to decline.

        We also intend to register all common stock that we may issue under our 2004 Stock Incentive Plan and 2004 Non-Employee Director Stock Option Program and 2004 Employee Stock Purchase Plan.Program. Once we register these shares, they can be freely sold in the public market upon issuance, subject to restrictions under the securities laws and the lock-up agreements described above. If any of these stockholders cause a large number of securities to be sold in the public market, the sales could reduce the trading price of our common stock. These sales also could impede our ability to raise future capital.

        Our stock price may be volatile, and you may lose all or a substantial part of your investment.

        Following this offering, the market price for our common stock is likely to be volatile, in part because our shares have not been traded publicly. In addition, the market price of our common stock may fluctuate significantly in response to a number of factors, most of which we cannot control, including:

•

volume and timing of orders for our products and services;



•

the introduction of new products, product enhancements, services or technologies by us or our competitors;



•

quarterly variations in our or our competitors' results of operations;



•

conditions or trends in the medical device industry and the imaging service industry;



•

disputes or other developments with respect to intellectual property rights;



•

our ability to develop, obtain regulatory clearance for, and market, new and enhanced products on a timely basis;



•

product liability claims or other litigation;



•

additions or departures of key personnel;



•

sales of large blocks of our common stock, including sales by our executive officers and directors;



•

changes in governmental regulations or in the status of our regulatory approvals or applications;



•

changes in the availability of third-party reimbursement in the United States or other countries;



•

changes in earnings estimates or recommendations by securities analysts; and

•

general market conditions and other factors, including factors unrelated to our operating performance or the operating performance of our competitors.

        Anti-takeover provisions in our organizational documents and Delaware law may discourage or prevent a change in control, even if an acquisition would be beneficial to our stockholders, which could affect our stock price adversely and prevent attempts by our stockholders to replace or remove our current management.

        Our restated certificate of incorporation and restated bylaws contain provisions that may delay or prevent a change in control, discourage bids at a premium over the market price of our common stock and

25

adversely affect the market price of our common stock and the voting and other rights of the holders of our common stock. These provisions include:

•

dividing our board of directors into three classes serving staggered three-year terms;



•

prohibiting our stockholders from calling a special meeting of stockholders;stockholders unless they hold not less than 20% of the total number of votes to be cast at such a meeting;



•

permitting the issuance of additional shares of our common stock or preferred stock without stockholder approval;



•

prohibiting our stockholders from making certain changes to our restated certificate of incorporation or restated bylaws except with 66²/3% stockholder approval; and



•

requiring advance notice for raising matters of business or making nominations at stockholders' meetings.

        We are also subject to provisions of the Delaware corporation law that, in general, prohibit any business combination with a beneficial owner of 15% or more of our common stock for five years unless the holder's acquisition of our stock was approved in advance by our board of directors. Although we believe these provisions collectively provide for an opportunity to receive higher bids by requiring potential acquirors to negotiate with our board of directors, they would apply even if the offer may be considered beneficial by some stockholders. In addition, these provisions may frustrate or prevent any attempts by our stockholders to replace or remove our current management by making it more difficult for stockholders to replace members of our board of directors, which is responsible for appointing the members of our management.

        We may become involved in securities class action litigation that could divert management's attention and harm our business.

        The stock market in general, and the Nasdaq National Market and the market for medical device companies in particular, has experienced extreme price and volume fluctuations that have often been unrelated or disproportionate to the operating performance of the companies in those markets. In addition to our performance, these broad market and industry factors may materially harm the market price of our common stock, regardless of our operating performance. In the past, following periods of volatility in the market price of a particular company's securities, securities class action litigation has often been brought against that company. We may become involved in this type of litigation in the future. Litigation often is expensive and diverts management's attention and resources, which could materially harm our financial condition and results of operations.

        As a new investor, you will experience immediate and substantial dilution as a result of this offering and future equity issuances and, as a result of such dilution, our stock price could decline.

        The initial public offering price will be substantially higher than the pro forma net tangible book value per share of our outstanding common stock. As a result, investors purchasing common stock in this offering will incur immediate dilution of $$8.95 per share. This dilution is due in large part to earlier investors in our company having paid substantially less than the initial public offering price when they purchased their shares. Investors who purchase shares of common stock in this offering will contribute approximately %46% of the total amount we have raised to fund our operations but will own only

approximately %31% of our common stock. We believe that the net proceeds from this offering, together with our current cash, cash equivalents and short-term investments, will be sufficient to meet our projected operating requirements for at least the next 12 months. Because we may require additional funds to develop new products and continue to expand our business, however, we may conduct substantial future offerings of equity securities. The exercise of outstanding options and warrants and future equity issuances, including future public offerings or future private placements of equity securities and any additional shares issued in connection with acquisitions, will result in further dilution to investors.

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        If our officers, directors and principal stockholders choose to act together, they may be able to control our management and operations, acting in their best interests and not in the best interests of other stockholders.

        After this offering, our officers, directors and holders of 5% or more of our outstanding common stock will beneficially own approximately %36.4% of our common stock, after giving effect to the conversion of all outstanding shares of our preferred stock, but assuming no exercise of the underwriters' over-allotment option and no exercise of outstanding options or warrants. As a result, these stockholders, acting together, will be able to significantly influence all matters requiring approval by our stockholders, including the election of directors and the approval of mergers or other business combination transactions. The interests of this group of stockholders may not always coincide with our interests or the interests of other stockholders, and they may act in a manner that advances their best interests and not necessarily those of other stockholders. As a result of their actions or inactions our stock price may decline.

        Our management team may invest or spend the proceeds of this offering in ways with which you may not agree or in ways which may not yield a return.

        Our management will have considerable discretion in the application of the net proceeds of this offering. We expect to use a majority of the net proceeds from this offering to manufacture and market our gamma cameras, build our sales and marketing capabilities, expand our DIS business and repay outstanding lines of credit and notes payable of approximately $9.4 million.$9.7 million as of March 31, 2004. To a lesser extent, we anticipate using the remaining net proceeds of this offering for further research and development relating to our existing products and new product opportunities, to finance regulatory approval activities and for general corporate purposes. We may also use a portion of the net proceeds of this offering to acquire or invest in complementary businesses, products, or technologies, or to obtain the right to use such complementary technologies, although we are not currently involved in any negotiations and have no commitments with respect to any such transactions. We cannot specify with certainty how we will use the net proceeds of this offering or our existing cash balance. The net proceeds may be used for corporate purposes that do not increase our operating results or market value. Until the net proceeds are used, theywe plan to invest such proceeds of this offering in short- and medium-term, interest-bearing obligations, investment-grade instruments, certificates of deposit or direct or guaranteed obligations of the U.S. government. These investments may be placed in investments that do not produce income or that losemaintain their value.

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SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS

        This prospectus contains forward-looking statements that are based on our management's beliefs and assumptions and on information currently available to our management. The forward-looking statements are contained principally in the sections entitled "Prospectus Summary," "Risk Factors," "Management's Discussion and Analysis of Financial Condition and Results of Operations," "Use of Proceeds" and "Business." In some cases, you can identify forward-looking statements by terms such as "anticipates," "believes," "could," "estimates," "expects," "intends," "may," "plans," "potential," "predicts," "projects," "should," "will," "would" and similar expressions intended to identify forward-looking statements.

        Forward-looking statements involve known and unknown risks, uncertainties and other factors that may cause our actual results, performance or achievements to be materially different from any future results, performances or achievements expressed or implied by the forward-looking statements. We discuss many of these risks in this prospectus in greater detail under the heading "Risk Factors." Given these uncertainties, you should not place undue reliance on these forward-looking statements. Also, forward-looking statements represent our management's beliefs and assumptions only as of the date of this prospectus. You should read this prospectus and the documents that we reference in this prospectus and have filed as exhibits to the registration statement, of which this prospectus is a part, completely and with the understanding that our actual future results may be materially different from what we expect.

        Except as required by law, we assume no obligation to update these forward-looking statements publicly, or to update the reasons actual results could differ materially from those anticipated in these forward-looking statements, even if new information becomes available in the future.

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USE OF PROCEEDS

        We estimate that the net proceeds from this offering will be approximately $$64.8 million, based upon an assumed initial public offering price of $$13.00 per share, the midpoint of the range on the cover of this prospectus, and after deducting estimated underwriting discounts and commissions and offering expenses. If the underwriters exercise their over-allotment option in full, we estimate that our net proceeds will be approximately $$74.8 million.

        We expect to use a majority of the net proceeds of this offering to manufacture and market our gamma cameras, build our sales and marketing capabilities, expand our DIS business and repay outstanding lines of credit and notes payable of approximately $9.4$9.7 million.

        To a lesser extent, we anticipate using the remaining net proceeds of this offering:

•

for further research and development relating to our existing products and new product opportunities and to finance regulatory approval activities; and



•

for general corporate purposes.

        In addition, we may use a portion of the net proceeds from this offering to acquire products, technologies or businesses that are complementary to our own, but we currently have no commitments or agreements relating to any of these types of transactions.

        Of the approximately $9.4$9.7 million of net proceeds that we intend to use to repay outstanding lines of credit and notes payable, we will use approximately $4.83$4.7 million to repay in full our outstanding balance as of DecemberMarch 31, 20032004 under our secured credit facility with Silicon Valley Bank. The secured credit facility may be used to borrow against accounts receivable and fixed assets and our outstanding balance matures in October 2004. The secured credit facility bears an interest rate equal to the lender's prime rate, plus 1.75% per annum, but in no event less than 5.75%.

        Additionally, of the approximately $9.4$9.7 million of net proceeds that we intend to use to repay outstanding lines of credit and notes payable, we will use approximately $4.53$4.5 million to repay in full our outstanding balance as of DecemberMarch 31, 20032004 under our credit facility with GE Healthcare Financial Services. The total amount outstanding under the line of credit matures in December 2004 and the interest rate under such agreement is the greater of the lender's prime rate plus 1.25% per annum, or 6%.

        Furthermore, of the approximately $9.7 million of net proceeds that we intend to use to repay outstanding lines of credit and notes payable, we intend to repay the principal amount outstanding under notes payable held by two of our stockholders which matures within 60 days of the completion of this offering. As of March 31, 2004, the outstanding principal amount under these notes was approximately $490,000 and the notes bear an interest rate of 6.35% per year. We may also enter into a similar agreement to repay the principal amount outstanding under a note held by another stockholder. As of March 31, 2004, the outstanding principal amount under such note, which bears an interest rate of 6.35% per year, was approximately $245,000.

        As of the date of this prospectus, we cannot specify with certainty all of the particular uses for the net proceeds to be received upon the completion of this offering. The amount and timing of our expenditures will depend on several factors, including the amount of revenue generated from our operations, the progress of our commercialization efforts, and the amount of cash used in our operations. Accordingly, our management will have broad discretion in the application of the net proceeds and investors will be relying on the judgment of our management regarding the application of the proceeds of this offering. We reserve the right to change the use of these proceeds as a result of certain contingencies such as the results of our commercialization efforts, competitive developments, opportunities to acquire products, technologies or businesses and other factors.

        Pending the uses described above, we plan to invest the net proceeds of this offering in short- and medium-term, interest-bearing obligations, investment-grade instruments, certificates of deposit or direct or guaranteed obligations of the U.S. government.

DIVIDEND POLICY

        We have never declared or paid any cash dividends on our capital stock. We currently intend to retain all available funds and any future earnings to support operations and finance the growth and development of our business and do not intend to pay cash dividends on our common stock for the foreseeable future. Any future determination related to our dividend policy will be made at the discretion of our board of directors.

CAPITALIZATION

        The following table sets forth our capitalization as of DecemberMarch 31, 2003:2004:

•

on an actual basis; and



•

on an as adjusted basis to give effect to (1) the automatic conversion of all shares of preferred stock outstanding as of DecemberMarch 31, 20032004 into 43,555,36712,444,294 shares of common stock upon completion of this offering, (2) the filing of our restated certificate of incorporation, which provides for authorized capital stock of 150,000,000 shares of common stock and 10,000,000 shares of preferred stock, (3) the sale by us of 5,500,000 shares of our common stock in this offering at an assumed initial public offering price of $$13.00 per share, the midpoint of the range on the cover of this prospectus, and the receipt of the estimated net proceeds therefrom, after deducting estimated underwriting discounts and commissions and estimated offering expenses payable by us and (4) the repayment of $9.4$9.7 million of outstanding short-term lines of credit.credit and notes payable.

        You should read this table together with "Management's Discussion and Analysis of Financial Condition and Results of Operations" and the consolidated financial statements and accompanying notes included elsewhere in this prospectus.

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        The number of shares in the table above excludes, as of DecemberMarch 31, 2003:2004:

•

4,831,1381,581,519 shares of our common stock subject to outstanding options under our 19951991 Stock Option/Stock Issuance Plan,Option Program, our 1997 Stock Option/Stock Issuance Plan and our 1998 Stock Option/Stock Issuance Plan, having a weighted average exercise price of $0.52$2.42 per share;



•

1,108,14758,904 shares of our common stock available for future issuance under our 19951991 Stock Option/Stock Issuance Plan,Option Program, our 1997 Stock Option/Stock Issuance Plan and our 1998 Stock Option/Stock Issuance Plan; and



•

205,39663,971 shares of our common stock issuable upon exercise of outstanding warrants (including warrants to purchase preferred stock that are convertible into common stock), having a weighted average exercise price of $10.26$33.39 per share.

        We expect to complete a 1-for-A 1-for-3.5 reverse stock split prior to completion of this offering.our common stock was approved by our stockholders on April 30, 2004. All share amounts in this prospectus have been adjusted to give effect to this stock split.

DILUTION

        As of DecemberMarch 31, 2003,2004, we had a negative net tangible book value of $(76.2) million, or $(923.97)$(1,402.47) per share of common stock, not taking into account the conversion of our outstanding preferred stock. Net tangible book value per share is equal to our total tangible assets (total assets less intangible assets) less total liabilities (including redeemable convertible preferred stock), divided by the number of shares of our outstanding common stock. Our pro forma net tangible book value as of DecemberMarch 31, 20032004 was approximately $8.1 million, or $0.18$0.65 per share of common stock. Pro forma net tangible book value per share represents the amount of our total tangible assets less our total liabilities, divided by the pro forma number of shares of common stock outstanding as of DecemberMarch 31, 2003.2004. Our pro forma net tangible book value and pro forma net tangible book value per share amounts give effect to the conversion of all outstanding shares of our convertible preferred stock into shares of common stock.

        Dilution in pro forma net tangible book value per share represents the difference between the amount per share paid by purchasers of shares of common stock in this offering and the pro forma net tangible book value per share of common stock immediately after the completion of this offering. After giving effect to our sale of 5,500,000 shares of common stock in this offering at an assumed initial public offering price of $$13.00 per share, the midpoint of the range set forth on the cover page of this prospectus, and after deducting estimated underwriting discounts and commissions and offering expenses payable by us, our adjusted pro forma net tangible book value as of DecemberMarch 31, 20032004 would have been $$72.9 million, or $$4.05 per share. This amount represents an immediate increase in pro forma net tangible book value of $$3.40 per share to our existing stockholders and an immediate dilution in pro forma net tangible book value of $$8.95 per share to new investors. The following table illustrates this per share dilution:

        If the underwriters exercise their over-allotment option to purchase additional shares in this offering, our adjusted pro forma net tangible book value at DecemberMarch 31, 20032004 will be $$82.9 million, or $$4.40 per share, representing an immediate increase in pro forma net tangible book value of $$3.75 per share to our existing stockholders and an immediate dilution in pro forma net tangible book value of $$8.60 per share to new investors purchasing shares in this offering.

        The following table summarizes, on a pro forma basis as of DecemberMarch 31, 2003,2004, after giving effect to the conversion of all outstanding shares of our convertible preferred stock into common stock, the total number of shares of common stock purchased from us, the total consideration paid to us and the average price per share paid by existing stockholders and by new investors, based on an assumed initial public

32

offering price of $$13.00 per share, the midpoint of the range set forth on the cover page of this prospectus,

before deducting estimated underwriting discounts and commissions and offering expenses payable by us:us (consideration in millions):

        If the underwriters exercise their over-allotment option in full, our existing stockholders would own %66% and our new investors would own %34% of the total number of shares of our common stock outstanding after this offering.

        The above discussion and tables assume no exercise of any stock options or warrants outstanding as of DecemberMarch 31, 2003.2004. As of DecemberMarch 31, 2003,2004, there were:

•

4,831,1381,581,519 shares of our common stock subject to outstanding options under our 19951991 Stock Option/Stock Issuance Plan,Option Program, our 1997 Stock Option/Stock Issuance Plan and our 1998 Stock Option/Stock Issuance Plan, having a weighted average exercise price of $0.52$2.42 per share;



•

1,108,14758,904 shares of our common stock available for future issuance under our 19951991 Stock Option/Stock Issuance Plan,Option Program, our 1997 Stock Option/Stock Issuance Plan and our 1998 Stock Option/Stock Issuance Plan; and



•

205,39663,971 shares of our common stock issuable upon exercise of outstanding warrants (including warrants to purchase preferred stock that are convertible into common stock), having a weighted average exercise price of $10.26$33.39 per share.

        After this offering and assuming the exercise of all in-the-money stock options and warrants outstanding as of March 31, 2004, our pro forma net tangible book value as of March 31, 2004 would be $3.83 per share, representing an immediate increase in pro forma net tangible book value of $3.18 per share to existing stockholders and an immediate dilution in pro forma net tangible book value of $9.17 per share to new investors.

        The following table summarizes, on a pro forma basis as of March 31, 2004, after giving effect to the conversion of all outstanding shares of our convertible preferred stock into common stock and the exercise of all outstanding in-the-money options and warrants, the total number of shares of common stock purchased from us, the total consideration paid to us and the average price per share paid by existing stockholders and by new investors, based on an assumed initial public offering price of $13.00 per share, the midpoint of the range set forth on the cover page of this prospectus, before deducting estimated underwriting discounts and commissions and offering expenses payable by us (consideration in millions):

In April 2004, our board of directors approved, effective upon the completion of this offering, our 2004 Stock Incentive Plan, under which 1,400,000 shares have been reserved for future issuance, our 2004 Non-Employee Director Stock Option Program, under which            shares have been reserved for future issuance and our 2004 Employee Stock Purchase Program, under which            shares have been reserved for acquisition by our employees.issuance. To the extent that any outstanding options or warrants are exercised or shares acquired, there will be further dilution to new investors.

        In addition, we may choose to raise additional capital due to market conditions or strategic considerations even if we believe we have sufficient funds for our current or future operating plans. To the extent that additional capital is raised through the sale of equity or convertible debt securities, the issuance of these securities could result in further dilution to our stockholders.

SELECTED CONSOLIDATED FINANCIAL DATA

        The selected consolidated statement of operations data for the years ended December 31, 2001, 2002 and 2003 and the selected balance sheet data as of December 31, 2002 and 2003, are derived from the audited financial statements for such years and as of such dates, which are included elsewhere in this prospectus. The selected consolidated statement of operations data for the years ended December 31, 1999 and 2000, and the selected balance sheet data as of December 31, 1999, 2000 and 2001, are derived from audited financial statements, which have been audited by Ernst & Young LLP, our independent auditors, for such years and as of such dates, which are not included in this prospectus. The selected consolidated statements of operations data for the three months ended March 31, 2003 and 2004 and the selected balance sheet data as of March 31, 2004 are derived from our unaudited financial statements included elsewhere in this prospectus. The unaudited consolidated financial statements include, in the opinion of management, all adjustments, consisting only of normal, recurring adjustments, that management considers necessary for a fair statement of the results of those periods. Historical results are not necessarily indicative of future results. The following selected financial data should be read together with "Management's Discussion and Analysis of Financial Condition and Results of Operations" and our financial statements and related notes included elsewhere in this prospectus. The selected financial data in this section is not intended to replace the financial statements.

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(1)

Please see Note 1 to our consolidated financial statements for an explanation of the method used to calculate the historical and pro forma net loss per share the number of shares used in the computation of per share amounts.

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MANAGEMENT'S DISCUSSION AND ANALYSIS OF
FINANCIAL CONDITION AND RESULTS OF OPERATIONS

        You should read the following discussion and analysis of our financial condition and results of operations together with our consolidated financial statements and the related notes appearing at the end of this prospectus. Some of the information contained in this discussion and analysis or set forth elsewhere in this prospectus, including information with respect to our plans and strategy for our business and related financing, includes forward-looking statements that involve risks and uncertainties. You should review the "Risk Factors" section of this prospectus for a discussion of important factors that could cause actual results to differ materially from the results described in or implied by the forward-looking statements contained in the following discussion and analysis.

Overview

        We are a leader in the development, manufacture and distribution of solid-state medical imaging products and services. We were the first company to develop and commercialize a solid-state medical gamma camera for the detection of cardiovascular disease and other medical conditions. Our high performance imaging systems are mobile and provide enhanced operability and reliability and improved patient comfort and utilization when compared to traditional vacuum tube cameras. The cameras and accompanying equipment fit easily into spaces as small as seven feet by eight feet and facilitate the delivery of nuclear medicine procedures directly in a physician's office, an outpatient hospital setting or within multiple departments of a hospital. As of DecemberMarch 31, 2003,2004, we had an installed base of 300326 gamma cameras, over 95% of which were in the United States, including 5459 cameras operated by our wholly-owned subsidiary,subsidiaries, Digirad Imaging Solutions, Inc. and Digirad Imaging Systems, Inc., orwhich we refer to collectively as DIS.

        According to industry reports, the growth rates in 2002 for procedures performed in physician offices was approximately 44% and in hospitals was approximately 6%. We believe this trend is driven by the desire of cardiologists to control their patients' diagnosis and treatment and to generate revenue that would otherwise be lost if the patient were referred to a hospital or imaging center. The mobile feature of our technology also provides us with a significant advantage in the delivery of nuclear cardiology imaging services. Through DIS, we offer FlexImaging, our mobile and comprehensive leasing service for physicians who wish to perform nuclear cardiology and nuclear medicine procedures in their offices, but do not have the patient volume, capital or personnel to justify purchasing an imaging system. DIS is currently offered in 17 states.states and the District of Columbia. Physicians enter into annual contracts for imaging services delivered on a per-day basis. Our annual lease contracts typically provide for one day of service per week. We sell our imaging systems to physician practices, outpatient clinics and hospitals primarily in the United States and have sold a limited number of imaging systems internationally. Our product revenue consists of sales of our solid-state gamma cameras, custom designed chairs and accessories, such as printers, viewing workstations, connectivity and collimators and revenue from our maintenance contracts.

        In 2000, we sold our first solid-state gamma camera and launched our DIS business. From 2000 to 2003, our consolidated revenues grew from $7.1 million to $56.2 million.million, and were $15.9 million for the three months ended March 31, 2004. DIS and product revenues accounted for 62.0% and 38.0%, respectively, of our consolidated revenues for the year ended December 31, 2003.2003 and 65.6% and 34.4%, respectively, of our consolidated revenues for the three months ended March 31, 2004. Given the recurring contractual revenue stream from our DIS business and our strategy to continue to expand the number of areas where we offer DIS services, we expect DIS revenue to continue to grow at a higher rate than product revenue and to continue to represent a large percentage of consolidated revenues. We attribute the overall growth of our business to geographical expansion, increased market penetration, awareness and acceptance, and the shift in the delivery of nuclear cardiology imaging procedures from hospitals to physician offices.

        We reduced our net loss by $11.1 million from $12.8 million in 2002 to $1.7 million in 2003.2003 and from $927,000 for the three months ended March 31, 2003 to $266,000 for the three months ended March 31, 2004. Furthermore, we have incurred substantial operating losses since our inception. As of DecemberMarch 31, 2003,2004, our accumulated deficit was $80.2$80.5 million. We believe that we will achieve our first full year of profitability

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in 2004, and intend to continue to enhance profitability through increased volume and improved margins, although we may incur losses in any given quarter.

        We experience some seasonality in our DIS business as a result of winter holidays, inclement weather and summer slowdowns principally relating to vacations. Historically, these variables have had the least impact on our second quarter operating results.

        We are currently inIn April 2004, we completed the processtransition of transitioning our manufacturing operations from several separate facilities to a single facility in Poway, California. We believe this will consolidate our operations and improve efficiencies. We currently purchase some components from sole source providers and are qualifying or seeking second source providers in an effort to diversify our providers.

Results Of Operations

        The following table sets forth our results from operations, expressed as percentages of revenues for the years ended December 31, 2001, 2002 and 2003:2003, and for the three months ended March 31, 2003 and 2004: