GE finds national stage for work in full-field digital mammography

Vendor hopes to leapfrog CCD-based detectors

GE Medical Systems in March found an influential audience with whom to discuss its ongoing work on full-field digital mammography. The Milwaukee vendor presented the progress of its full-field R&D to members of Congress who had gathered for an update on the Missiles to Mammography program, a federal effort to convert defense technology to women's health applications.

GE's development of full-field digital mammography has been relatively low-key compared with competitors Fischer Imaging of Denver and Trex Medical of Danbury, CT. GE began to reveal some of its plans at last year's Radiological Society of North America meeting, where it showed a work-in-progress digital spot mammography detector and panels on a full-field system (SCAN 12/18/96).

GE has taken a two-pronged approach to digital mammography development, using technology based on charge-coupled devices (CCDs) for the spot system, while the full-field detector uses more advanced amorphous silicon technology. At the Missiles to Mammography presentation on Capitol Hill on March 6, GE displayed a full-field digital mammography system that has been integrated with a mobile mammography van called Mobile Breast Care Center.

GE officials speaking at the presentation unveiled a full-field digital mammography system using an amorphous silicon array that can discern pixels 50 microns in diameter. Debate in the radiology community has focused on whether 50- or 100-micron pixels are necessary to generate diagnostic-quality mammograms. That range of pixel sizes can be achieved with current CCD-based systems, but not with amorphous silicon technology-or so it seemed.

Many companies developing digital mammography systems have been trying to work with CCDs in one way or another-bonding them into mosaics, optically coupling them, or integrating them into a slot-scanning device that mechanically sweeps the breast. Even Trex Medical, which has the R&D support of industrial giant ThermoTrex, has opted to first come out with a CCD-based sensor, noting that a detector based on amorphous silicon is still one to two years away. GE believes its use of amorphous silicon may give it an edge.

"We have been working for 10 years on this technology," said Mona Theobald, marketing and product sales manager of women's imaging at GE. "The use of an amorphous silicon detector and low-noise electronics will differentiate us in the mammography marketplace."

Amorphous silicon detectors have advantages in digital mammography because of their one-piece fabrication, compared with bonded CCD mosaics, and their lack of mechanical components compared with slot-scanning devices. Amorphous silicon also has potential for the capture of dynamic images in near real-time, which opens new diagnostic opportunities for radiologists.

One such application is the imaging of tumor vascularity following the injection of a contrast agent. Such studies might deliver images similar to x-ray angiograms.

"Popular thought in the medical community indicates that malignant pathology is often very vascular, and imaging this vascularity may help in making a differential diagnosis," Theobald said.

GE's large installed base. Delivering such extraordinary clinical utility might not be extraordinarily expensive. GE engineers have designed the new digital technology to fit into Senographe DMR, the company's premium mammography system, which is widely installed at sites around the world. The large installed base gives GE an advantage, Theobald said.

"We can manufacture a lot of (field upgrades) and provide a product that may be more cost-effective (than our competitors) for that customer," Theobald said.

Theobald emphasized that until clinical trials are completed and 510(k) clearance from the Food and Drug Administration is received, GE's full-field digital system will not be available commercially. The clinical trials that will generate data to support an FDA review are ramping up, but the company has already proven the validity of its approach, she said.

One of GE's full-field digital mammography systems based on amorphous silicon arrays has been operating at Massachusetts General Hospital in Boston for several months. Another operational unit is installed in the Mobile Breast Care Center van featured in the March demonstration to Washington, DC, legislators. Three more such units are scheduled for installation at other sites in coming months.

The mobile van was developed with funding from the U.S. Public Health Service's Office on Women's Health, the National Cancer Institute, and the Department of Defense as part of the Missiles to Mammography program. The program's goal is to develop a comprehensive system for breast cancer prevention and early detection.

Accompanying the digital mammography system in the mobile van was GE's Logiq 400 MD ultrasound scanner, as well as teleradiology equipment capable of beaming digital mammograms to radiologists for immediate interpretation. A major goal of the mobile van is to administer digital mammograms in rural and underserved areas and to military women stationed in remote areas of the world.

"This mobile concept was developed to allow the diagnosis of a patient and to determine the next step while the patient is there," Theobald said. "This way, we might improve patient compliance for breast care."

While digital mammography using flat-panel sensors represents enormous potential in the evaluation of breast disease, this application of the technology is only a stepping stone to far more expansive applications, such as the direct capture of conventional x-ray exams.

"Mammography is the most challenging technology because of the spatial resolution requirements," Theobald said. "If you do well in that kind of environment, you will do well in other areas. Radiography would certainly be a logical next step."