Mammography vendors pursue better operability

November 2, 2005

Digital mammography is maturing. Full-field digital systems are becoming more flexible, endowed with screening and diagnostic capabilities, while physicians are experimenting with 3D capabilities that promise to eliminate poor visualization and clutter on 2D mammograms. Workstations designed to display digital mammograms are becoming more cosmopolitan. Like workstations built for CT and MR, they can exchange and display imaging data from multiple sources and modalities.

Digital mammography is maturing. Full-field digital systems are becoming more flexible, endowed with screening and diagnostic capabilities, while physicians are experimenting with 3D capabilities that promise to eliminate poor visualization and clutter on 2D mammograms. Workstations designed to display digital mammograms are becoming more cosmopolitan. Like workstations built for CT and MR, they can exchange and display imaging data from multiple sources and modalities.

These developments are rooted in software that translates data from different detectors with varying pixel and matrix sizes and, even more challenging, proprietary image processing packages. The strategic decisions about how to develop and apply this software, however, are as much a part of the products to be shown at the RSNA meeting as the software itself.

Hologic has decoupled imaging processing from its soft-copy workstation and shifted it to the acquisition station. As a result, Hologic can make rapid changes in its software upgrades, and its digital mammography systems can send full presentation images to any DICOM-calibrated workstation for viewing, said Andrew Smith, principal scientist.

Manufacturers of general-purpose workstations are producing models that work with mammography as well as MRI and CT. This may be the preferred solution for small hospitals that have limited reading room space and read mammograms only about 10% of the time, Smith said.

"It's not just a space or cost issue but a user training issue," he said. "You don't want to have to learn two different workstations. So those customers find it convenient to put mammography images on their general-purpose workstations."

Major breast imaging centers read enough mammograms to justify a dedicated mammography workstation that includes productivity tools for optimizing reading. Hologic will show software productivity enhancements for these centers at its RSNA booth. The tools include separate hanging protocols for diagnostic and screening mammograms and better integration with third-party software such as mammography reporting systems. Productivity enhancements also handle special cases, including mammograms of women with breast implants, as well as efficient display of the large number of images obtained in diagnostic mammography, Smith said.

Hologic will also highlight a multimodality workstation incorporating a third monitor. Current mammography workstations use two high-resolution monochrome monitors, but Hologic is adding a color monitor to allow display and reading of ultrasound and MRI right next to mammography.

GE Healthcare is moving its digital mammography technology closer to clinical applications. The vendor will show its next-generation mammography detector, which has an active area of 24 x 30.7 cm. The larger detector can be used in traditional 2D mammography to avoid the need for multiple views of patients with large breasts to capture all the anatomy needed for the radiologist's review.

"We anticipate that it would be less necessary for hospitals to take images with multiple views on patients with very large breasts, so it should significantly improve workflow and potentially improve the overall dose to that population," said Vince Polkus, a mammography applications product manager for GE Healthcare.

The detector was also designed to accommodate the incline of the x-ray beam in tomosynthesis. In that technique, the x-ray beam sweeps from a minus- to a plus-30 degrees position in relation to the central portion of the breast. Because of this steep angle, areas in the axial plane may not be imaged with a small detector.

Tomosynthesis generates 50 or more images per breast, and GE is displaying a soft-copy reader that allows radiologists to review images quickly so they can make an accurate and confident diagnosis, Polkus said.

Hologic, which has also been developing tomosynthesis for breast imaging, has test sites in Ohio, New Hampshire, and Massachusetts, and expects to complete clinical trials in preparation for submission to the FDA in 2006. One of its goals is to streamline algorithms that will reduce reconstruction time to seconds. Tomosynthesis obtains data by acquiring a series of low-dose mammograms. The data then must be reconstructed into three dimensions. For tomosynthesis to be practical, reconstruction must be accomplished quickly, particularly if this technique is to have a future in guiding breast biopsies.

"If you see something suspicious on tomosynthesis that you can't see on mammography, you have to biopsy the lesion, and you have to have some method of directing a needle to that location," Smith said. "We are developing a process of needle localization or guidance based on tomosynthesis images. And because a woman is under compression, you have to complete the reconstruction as rapidly as possible so the doctor can point out the suspicious area and insert a needle to that location and take a tissue sample without subjecting her to prolonged discomfort."

Although GE sees tomosynthesis as an important emerging application for mammography, it is also looking carefully at other offshoots of full-field digital mammography. One is a combination of ultrasound and mammography. GE recently installed a combined 3D tomosynthesis system that has 3D ultrasound capability at the University of Michigan and at a private center in Kansas.

Although its clinical potential is not yet clear, combined ultrasound and mammography may illuminate lesions that x-rays cannot detect, particularly occult lesions in patients with mammographically dense breasts.

"There is a strong possibility that this could be useful for younger patients, who often get a more aggressive form of cancer," Polkus said.

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