New type of sonography creates planar images of soft tissues

Developer plans commercial launch at RSNA show

After five years of research and development, Advanced Diagnostics is poised to begin delivering its first commercial product, the Avera Diffractive Energy Imaging (DEI) system. This system promises to generate an image that looks more like a radiograph than a sonogram.

The company, based in Preston, WA, has shown unusual patience getting to this point. Although the product was cleared by the FDA in December 2000, it has not been shown at an RSNA meeting, not even as a work-in-progress. Instead, Avera DEI will make its first appearance at the 2001 RSNA as a finished product. Delivery could begin in the first quarter of 2002. Because the company is relatively small-there are only 15 employees-no introductory splash is planned other than the RSNA presentation, company officials said.

Unlike traditional ultrasound, which uses sound reflected off tissue to generate images, DEI measures the changes in sound as it

passes through tissue. The pattern of diffraction depends on the interaction of ultrasound waves with tissue, information that can offer insights into the underlying health of the patient.

The patient is situated between the transducer and a detector. Acoustic lenses collect the sound waves’ energy, which is interpreted holographically and then converted into a 2-D image using light.

Three-D data sets can be constructed, typically from a 60-image scan of sequentially stacked focal planes. The result more closely resembles a radiograph than a traditional ultrasound image, said Denis O’Connor, Advanced Diagnostic’s CEO.

Eventually, this technology might be used to assess a range of soft tissues such as joints, ligaments, and tendons. Its first application, however, will be to image the breast and guide the biopsy of suspicious lesions.

Conventional ultrasound travels through fluid and is then reflected by tissue, which is why sonography is so effective at distinguishing tumors from cysts. Engineers at Advanced Diagnostics, however, have designed Avera to generate ultrasound waves that are less dramatically changed by tissue. Their interaction with tissue allows the reconstruction of tissue boundaries throughout a volume.

“Physicians will like it because (the images) look more like a common mammogram than an ultrasound,” O’Connor said. “But they’ll also get a lot of information they wouldn’t typically get with mammography or traditional ultrasound. We’re very much a hybrid technology.”

The FDA has cleared Avera DEI as both a general imaging tool and as an adjunct to screening mammography. Diffractive energy ultrasound and mammography are comparable in several regards, O’Connor said. Both have a large field-of-view, they provide similar information, and they present it in similar fashion. DEI has an advantage over mammography in that it’s a real-time, multiplanar imaging technique that requires no painful compression and uses no ionizing radiation.

“Because we’re volumetric and slice-based, we can use our technology in real-time to do biopsies, to stage cancer, and to do surgical planning,” he said.

The company believes DEI will benefit women for whom mammography is either ineffective or inappropriate, including those with dense breast tissue that often renders mammograms inconclusive. Others who may benefit are patients at risk for breast cancer and those who fall outside the current screening guidelines. Avera DEI might be recommended, for example, following a positive screening mammogram or a diagnostic mammogram, O’Connor said.

While Avera DEI is new, the basis for this imaging technique dates back to the late 1960s, O’Connor said. Back then, however, technology was crude. Medical applications depended on the development of modern transducer, laser, and computer technology.

ADI was formed in 1995 specifically to carry the work of several decades earlier to the next level. The company holds many of the technology’s core patents, and O’Connor knows of no other firm with a similar product.

Clinical studies aimed at documenting the clinical benefits of the system are under way at the University of Washington and Virginia Mason Medical Center, both in Seattle. O’Connor said the results thus far have been encouraging.

“We have several instances in which we’ve been able to detect lesions that were not detected using mammography or (conventional) reflected ultrasound,” he said.

How successful the company will be in its attempts to sell Avera DEI to mainstream physicians will depend heavily on proving its clinical effectiveness. Only then can ADI clear the next hurdle-reimbursement. The firm has already begun exploring how its new product might qualify for coverage under existing CPT codes pertaining to ultrasound. It is also making plans to file for a CPT code specific to the technology. Despite those uncertainties, ADI has high hopes. O’Connor believes the Avera will eventually compete with mammography as a screening tool.

“We’d need to go through the premarket approval process with the FDA to make a claim on that,” he said. “But we have a large field of view and excellent spatial and contrast resolution. Our long-term goal would be to offer a viable option for that population of women who may fall outside the ACR protocol for screening mammography.”

In the meantime, O’Connor and colleagues hope to recruit up to 25 physicians to pioneer their new product, the initial price of which will be between $175,000 and $250,000.