New technologies offer hope for bone densitometry market

Once-hot vendors struggled through difficult 1997

For the bone densitometry market, 1997 might be a year best forgotten. The momentum generated by the approval of Merck's Fosamax osteoporosis drug in 1995 appeared to be fading as bone measurement vendors posted flat or lower revenues. In addition, companies struggled for nearly half the year due to the publication of erroneous Medicare reimbursement numbers in June. The confusion put a damper on purchasing for the rest of the year.

Bone densitometry vendors appeared to be putting the pieces back in place by the time December's Radiological Society of North America meeting rolled around. The Health Care Financing Administration just prior to the meeting published new Medicare reimbursement rates that corrected the earlier numbers (SCAN 11/12/97). In addition, vendors at the RSNA show displayed a range of new technologies that will help expand markets and result in better products at lower prices.

One such technology is digital-detector-based densitometry systems. Digital detectors for the radiography market have received more attention thus far, but bone density scanners using the detectors are also under development. Schick Technologies of Long Island City, NY, displayed its accuDEXA densitometer, a digital-detector-based densitometer that cleared the Food and Drug Administration in the middle of the RSNA conference.

The digital detectors used in accuDEXA enable Schick to deliver high performance at a reasonable cost, according to the company. The system's $10,995 price tag is about one-third the cost of the lowest priced DEXA machines now on the market and is well within the price range of primary-care physicians, who constitute Schick's main market.

The detector used in accuDEXA is based on CMOS (complementary metal-oxide semiconductor), a semiconductor manufacturing process that is cheaper than that used to make CCDs.

Other selling points of the new system include its compactness, as the machine has dimensions similar to those of a bread machine; its ease of use, which means very little technical training is needed; and its speed of operation, rendering results in just 30 seconds. Schick has been building a direct sales force to sell accuDEXA; the company has 25 sales people and plans to have 75 by the end of the year.

Another company developing a digital x-ray densitometer is Manhattan Beach, CA-based CompuMed, which is best known for its OsteoGram 2000 phantom-based densitometry product. OsteoGram uses standard hand x-rays to determine bone density, and CompuMed plans to incorporate a digital detector obtained from Varian Associates of Palo Alto, CA, to acquire images. The move distinguishes CompuMed as the first company to produce bone density measurements with an amorphous silicon detector.

"This is a very high-resolution imaging device that enables us to perform radiograph absorptiometry with software based on the OsteoGram software product under license to Merck," according to William Robbins, a representative of CompuMed.

The image's gray-scale data correlates with bone density as compared with a phantom imaged alongside the patient's fingers, Robbins said. The experimental device is also being studied for possible use in monitoring the progression of rheumatoid arthritis, which can be documented by high-resolution images, according to Robbins.

Conventional developments. While companies like Schick and CompuMed pursue digital detectors, developers of DEXA-based products sought to tweak the conventional technology that has brought them to their current leadership positions in the marketplace. Hologic of Waltham, MA, unveiled QDR 4000, which features a pencil-beam x-ray system in place of the fan-beam system found on QDR 1000.

The new system also features a 200-MHz Pentium computer and a Jaz drive capable of holding data on 7000 patients, all packaged into the base of the scanner's table to provide a sleeker, more modern look. Hologic's product line is now DICOM-compatible, and the company during 1998 plans to switch to Windows-based operating and patient data reporting software.

At Lunar's RSNA booth, the Madison, WI, company displayed DPX IQ Net, a networking system for tying several bone densitometers together using an Ethernet backbone and DICOM compatibility. IQ Net, which will begin shipping early this year on the DPX-IQ densitometer, allows true parallel processing of patient data, according to James Hanson, vice president of marketing. The intent is to improve efficiency by shaving several minutes off each exam.

"This new feature allows true multitasking," Hanson said. "A spine and femur scan requires roughly 10 minutes. Using this multitasking IQ Net, we're able to take four minutes off that."

Additionally, the company pointed to PIXI (peripheral instantaneous x-ray imager), a lightweight, compact instrument for measuring bone density at peripheral sites, including the heel and forearm. The company is targeting outpatient medical sites, including clinics and physician offices, framing PIXI as the means to identify patients who are likely to have bone loss. Once identified, these patients would be referred for an axial scan, which provides more precise measurements.

Ultrasound systems. Sales of peripheral scanners in the U.S. may soon include ultrasound-based products. Last fall, Hologic's Sahara was recommended for approval by an FDA advisory committee. If approved, the 22-pound device will be targeted for placement into physicians' offices, but might also be used as a mobile unit to be taken from place to place. Sahara assesses the os calcis, or heel bone, using ultrasound gel as the interface between patient skin and dual transducers, one for transmitting and the other for receiving.

Sahara's premarket approval (PMA) application may be delayed, however, due to an FDA warning letter the company received on Nov. 21. The letter cites several good manufacturing practices (GMP) deficiencies uncovered by an FDA inspection of Hologic's Waltham plant. The GMP deficiencies were related to record-keeping procedures rather than actual product issues, however.

Had Hologic been able to file a 510(k) for Sahara, the company's application could not be delayed due to provisions in the FDA Modernization Act, which goes into effect in February. The act prevents the FDA from delaying the review of 510(k)s due to GMP violations or other issues that do not represent a serious risk to human health (SCAN 12/17/97). Because Sahara is being reviewed as a PMA, however, it will not receive this protection. Representatives from Hologic were not available for comment as of press time on the impact the warning letter might have on Sahara's review.

Hologic's main rival in the U.S. densitometry market, Lunar, also displayed an ultrasound densitometry product. Achilles+ uses a 3-oz water bath in place of the gel used in Sahara. Immersed along with the heel are two transducers, an ultrasound transmitter on one side of the bath and an ultrasound receiver on the other. Bone stiffness is calculated using the speed of the sound as it passes through the bone, and signal attenuation, indicated by broadband ultrasound attenuation (BUA).

Norland showed an ultrasound-based product called Paris, which is already selling in Canada and will be released early this year in other markets, including Latin America and Asia. The company, based in Fort Atkinson, WI, also plans to bring Paris to the U.S. In the Paris system, water fills two bladders, one on each side of the heel, and dual transducers send and capture low-frequency ultrasound. The velocity of the sound through the bone and the BUA are used to calculate a "soundness index," which indicates bone density. The system monitors the temperature of the water to ensure that conditions surrounding the test are stable, thereby improving reproducibility.

"We're able to get a stable reading so the changes we see (over time) are actually changes in the patient," said Thomas Sanchez, who handles Latin America and Pacific Rim sales support for the company.

A relative newcomer to the U.S. densitometry marketplace, Diagnostic Medical Systems (DMS) of Montpelier, France, has sold bone densitometers and ultrasound equipment in 35 countries around the world, particularly in Asia, the Middle East, and Europe. At the RSNA meeting, the company exhibited an ultrasound densitometer called UBIS 5000, and two new DEXA bone densitometers, Performer for the forearm and Challenger for sampling the hip, spine, and wrist.

The ultrasound system produces an image of the heel, which is constructed by scanning the bone and mapping the density values for different points to individual pixels, according to Pascal Giat, a DMS applications specialist.

"Because we have an image, you can do densitometry such that you cannot do with any other device working with ultrasound without the image," Giat said. "The image is coded in gray-scale levels, the black pixels corresponding to soft tissue with very low density and the brightest pixels corresponding to high density, as determined by values of BUA."

Among the most precise measurements of bone density are calculations made using CT scanners. These products historically have been provided by independent software developers, but some CT vendors either offer or are developing their own products. At the RSNA show, Siemens Medical Systems of Iselin, NJ, showed OsteoCT, work-in-progress software for CT-based densitometry. Although OsteoCT received 510(k) clearance in June, the introduction of the product on the U.S. market may be held up while the company tries to sort out potential patent infringement issues with an unnamed CT densitometry software company.

In its RSNA booth, MindWays Software of South San Francisco, CA, displayed OCT Pro, which like OsteoCT uses quantitative CT to generate bone density measurements.

Another CT software developer, Image Analysis of Columbia, KY, hopes to expand with a novel new bone densitometer. Image Analysis originally planned to have the product completed in 1996, but the project's timeline has been pushed back somewhat, according to Roger Schulte, vice president of sales and marketing at Image Analysis.

"We're on a different time schedule than maybe we were a year ago and that's because we've made some fairly serious changes in our philosophy and what the product will be," Schulte said. "Maybe it's a good delay in the end."

Schulte refused to offer any details about whether the product was based on x-ray or ultrasound, saying only that progress had been made.

The same could be said about the future of bone densitometry. While there has been a great deal of progress technologically, how the market will respond to the new product selections-x-ray or ultrasound-has yet to be determined.