New computerized systems that give doctors a "second pair of eyes" for looking at mammograms and other breast scans are showing great promise for detecting breast cancer, distinguishing it from benign problems without a biopsy, and tracking changes in a woman's breast over time.

The systems, all developed at the University of Michigan Health System, are in various stages of readiness for clinical use. But UMHS researchers report that they have made significant progress in using computers to increase the accuracy of interpretation of digital mammograms and breast ultrasound images.

The team presented results from several of the computer-aided diagnosis, or CAD, systems at the annual meeting of the Radiological Society of North America (RSNA).

One of the most encouraging results shows that a CAD system improved the ability of highly experienced radiologists to tell cancerous tumors from benign growths on ultrasound breast scans. Such scans are often performed after a suspicious finding on a screening mammogram, to help determine if a biopsy is needed.

The new result was achieved using ultrasound images of 102 breast masses that were later confirmed as benign or malignant by a biopsy. No cysts were included. The three-dimensional images were acquired using a conventional ultrasound machine and a mechanical transducer-guiding system developed at UMHS. Then, they were analyzed by a CAD system, and read by five breast radiologists.

After the physicians scored each mass on a scale of the likelihood of malignancy, they were shown the score assigned by the CAD system to the same mass, based on algorithms for mass shape, shadowing, and border characteristics. The physicians altered their score about one third of the time, mostly in the direction that correctly reflected the nature of the mass on biopsy. In the clinic, these score changes might mean that fewer women with benign disease would be subjected to an invasive biopsy procedure.

Of course, no one thinks computers will take over from human doctors anytime soon. "In the near future, it won't be possible for computers to replace radiologists for this kind of test, because a radiologist looks at the patient's entire case, not just her ultrasound images," says associate research professor Berkman Sahiner, Ph.D. "But if radiologists work with computers, they could improve their accuracy and spare some women benign biopsies."

In all, the team aims to use computers to improve they way radiologists detect and interpret cancers on mammograms and ultrasound images. They also hope to spare women some of the "worried waiting" and additional imaging sessions that follow an abnormal mammogram, to make additional imaging for such patients as accurate as possible, and to minimize the number of women who endure a biopsy only to find out their condition is benign.

Several commercial CAD systems for reading traditional film mammograms to increase detection - but not classification - have been on the market for a few years. But Sahiner and his colleagues hope their CAD research will advance the field by improving mammogram classification of lesions as malignant or benign, enhancing breast ultrasound imaging, aiding with detection and classification on film and digital mammograms, and allowing precise tracking of an individual woman's case over time.

The U-M team is also working on their ultimate goal: combining ultrasound and mammogram images to give a complete view of a breast mass. They're developing ways to combine the two very different kinds of images digitally, and are collaborating with industry to develop a breast imaging machine that can acquire an ultrasound image and a mammogram simultaneously.

SOURCE:
University of Michigan Health System (http://www.umich.edu)