3D Mammography Helps Avoid Unnecessary Biopsies

CHICAGO—Three-dimensional digital mammography appears a promising technique in helping confirm benign disease in women with suspicious x-ray mammograms, Andrew Maidment, PhD, said at the 83rd Scientific Assembly and Annual Meeting of the Radiological Society of North America (RSNA).

Dr. Maidment presented the preliminary results of an ongoing study being conducted by his group at Thomas Jefferson University Hospital, Philadelphia, and by Emily Conant, MD, at the University of Pennsylvania.

Of 44 women with suspicious findings on mammography, the 3D technique correctly ruled out cancer in 18 of 30 women whose lesions were shown at biopsy to be benign, and correctly identified cancer in all 14 of the lesions that were confirmed as cancer on biopsy.

Conventional x-ray mammography was 36% accurate, compared to 64% with 2-dimensional images obtained with a stereotactic digital breast biopsy system and 77% when 3D images were created, Dr. Maidment said.

“The motivation behind our research is to reduce the number of unnecessary biopsies in women who have benign disease, without missing cancers,” said Dr. Maidment, director of Radiological Imaging Physics at Thomas Jefferson.

He pointed out that the equipment for acquiring digital breast images —stereotactic breast biopsy tables with digital detectors—is currently in wide use for performance of needle-guided biopsies. Software developed by his group allows 3D modeling of the 2D digital images produced by these machines.

Dr. Maidment envisions digital mammography as becoming part of the standard workup of indeterminate mammograms, “a step between the suspicious mammogram and biopsy.”

Although the software for producing the 3D images is not yet available for widespread use, Dr. Maidment urged physicians to take advantage of the digital 2D viewing capabilities currently available in about 1,000 US institutions. “Digital mammograms provide better images with more detail than film images,” he said.

A More Confident Diagnosis

In a typical scenario, he said, a woman with a suspicious mammogram would come to an imaging center for further workup such as magnification views or ultrasound. If the lesion appeared benign but the radiologist still had doubts, a 2D digital image could be obtained.

“We have found that it gives the radiologist more confidence in the diagnosis,” he said. “With digital imaging, the lesions appear more obviously benign or more obviously malignant.”

The technique may be especially useful in cases with calcifications, which represent more than half of all breast cancers and more than 90% of all small (in situ) cancers, he said.

“Rendering an image in 3D makes the interrelationship of calcifications more clear,” he said. “The obscuring and sometimes confusing superimposed tissue is removed, and the 3D data that result represent a more accurate image to the radiologist.”

The study, funded by the Department of Defense, is ongoing through July, Dr. Maidment said. The researchers also have a second grant from the DOD to support efforts to automate the technique and further boost the quality of the 3D images, so that ultimately, he said, 3D capability can be added to existing digital workstations nationwide.