Holographic Ultrasound Clears Path To Tumor Detection Through Dense Breast Tissue

By Samuel O. Pine

When Rose got the news that she had breast cancer last year, it was not entirely surprising. Her sister, Dory, had received the same diagnosis one year earlier, and women on both sides of their family had been diagnosed with invasive breast carcinomas years before regular mammograms were recommended. Because they were having regular annual exams, their cancers, a treatable form called ductal carcinoma in situ, or DCIS, were caught early. They each received treatment that was prompt and enjoyed a fair amount of success. However, many women in similar situations are not so lucky. For those women, the bad news comes at a later cancer stage, and from there it usually only gets worse.

The American Cancer Society estimates that 40,000 women will die in the U.S. from breast cancer this year, and over 175,000 more will be diagnosed. This makes breast cancer the most probable cancer diagnosis for U.S. women, with a one in eight chance of being diagnosed with breast cancer sometime in their lives. Today, a breast cancer diagnosis does not have to be the death sentence it once was. The diagnosis and treatment that follows a positive screening exam can be very effective, but the denser a women's breast tissue, the more difficult it is to accurately detect tumors with current imaging technologies.

Imaging dense breast tissue is exactly what Advanced Imaging Technologies, Inc. (AIT) now hopes to improve. The Richland, Wash.-based company has developed a new ultrasound technology that won Frost and Sullivan's 2007 Technology Innovation Award in March for North American ultrasound imaging technologies.

AIT's ARIA Breast Imaging System uses holography combined with through-transmission ultrasound to create three-dimensional images of breast tissue by using sound waves that pass completely through the breast tissue. Current ultrasound machines work by bouncing waves off the tissue structures like an echo.

The ability to peer inside a breast to image the tissue is no small feat. "It's like trying to image tree roots,” says Todd Garlick, lead engineer at AIT, and dense tissue complicates the issue further. Imaging dense breasts is like trying to see through a smoky room versus a clear one, and the denser the breast tissue, the harder it is to see cancerous tissue in and among the complex breast anatomy.

By allowing the sound waves to pass completely through the breast, the images created by AIT's holographic ultrasound technology are not clouded by denser breast tissue. A second wave is used simultaneously to create a 3D hologram, and the resulting picture captures fine details that are missed by current ultrasound techniques.

The ARIA system has received FDA clearance for breast imaging and image-guided biopsy, and AIT expects to begin shipping commercial units in 2008. Differences in cost when compared to normal ultrasound or comparable techniques will depend on clinical acceptance and integration into current workflows. In the meantime, a currently available solution to image dense breast tissue is magnetic resonance imaging, or MRI.

MRI lets a radiologist see right through the densest breast tissue without a problem, but it is not a complete solution by itself. For instance, in a screening exam neither MRI nor ultrasound can visualize some early markers of breast cancer such as the calcifications that clued Rose's radiologist to her DCIS. X-ray mammography is still needed for this. Also, with the current price of MRI ten times higher than mammograms, it is unclear how much insurance companies will pay for MRI screening, and what portion women will be able to afford.

While ultrasound remains a purely diagnostic tool, MRI has been gaining acceptance for screening high-risk women who have a family history of breast cancer, like Rose and Dory.

Connie Lehman, director of breast imaging at the Seattle Cancer Care Alliance in Seattle, Washington, describes the combined use of mammography and MRI as the best technique available to detect breast cancer early. Her recent studies showed that screening with MRI found the most cancers, but the high costs associated with MRI currently limits its use for screening to high-risk groups.

Samuel Pine is a doctoral candidate in Pathobiology at the University of Washington's Department of Global Health.

Images

Top: The ARIA Breast Imaging System is able to provide digital 3-D images of breast tissue in real-time that are significantly sharper than current ultrasound images. Advanced Imaging Technologies, Inc. of Richland, Washington plans to begin marketing the new technology to radiology clinics in 2008. Photo: Pacific Northwest National Laboratory

Bottom: A schematic showing the process of how AIT's holographic ultrasound technology produces a 3-D image from sound waves. The intensity levels of ultrasound energy needed are about 100 times lower than current technologies, because the sound wave passes through tissue instead of reflecting off of it like an echo. Image: Advanced Imaging Technologies, Inc.