New breast imaging detects smallest tumors

A technique called molecular breast imaging (MBI) is highly sensitive in detecting small lesions and can also spot tumors missed by mammography and ultrasound, researchers report.

The results with the first 100 patients are "just staggering," Dr. Deborah J. Rhodes of the Mayo Clinic College of Medicine in Rochester, Minnesota, told AMN Health. "This technique really has many, many implications and many potential applications, but we certainly need further studies."

The detection system involves injection of a standard short-lived isotope, which is taken up in breast tissue and preferentially by tumors. The team built a gamma camera specifically designed to pick up the isotope signal and image the breast.

In their article, Rhodes' team describes the results when they tested the detection system with 40 patients. All of the women had small lesions that had been identified on a mammogram as "highly suggestive of malignancy," and were scheduled for needle biopsy.

That showed that 26 of the women had a total of 36 malignant lesions. When they were examined with the MBI system, it detected 33 of the lesions, as well as four lesions missed by both mammography and ultrasound.

The system the researchers developed not only identifies small lesions, they note; it also uses lighter compression than mammography, making it more tolerable to patients.

MBI may be particularly useful in patients with dense breasts, in whom standard mammography is much less sensitive, or women who are at greater risk of breast cancer, the researchers note.

The disadvantages of MBI, they continue, include the necessity of injecting radiotracers and the longer time required (40 to 50 minutes compared to 15 minutes) for the scan. However, Rhodes said her group is developing a new version of their MBI camera that will cut imaging time in half.

On the other hand, MBI has a number of advantages over MRI for detecting breast cancer, according to Rhodes. For instance, while MRI requires radiologists to sift through hundreds of images and interpretation is subjective, with MBI the picture is more clearcut. "There's either an abnormality or there's not," she said.

SOURCE: Mayo Clinic Proceedings, January 2005.