Tomosynthesis sharpens digital mammography results
Adding three-dimensional breast imaging, known as tomosynthesis, to standard digital mammography significantly increases diagnostic accuracy and significantly reduces false-positive recall rates, according to the findings of a recent study.
Whereas a screening digital mammogram involves two x-ray images of each breast, breast tomosynthesis, which was approved by the FDA in February 2011 and can be performed on the same equipment as digital mammography, captures multiple, low-dose images from different angles around the breast. The images are then used to produce a three-dimensional reconstruction of the breast, as explained in a statement from the Radiological Society of North America (RSNA). The study, by Elizabeth A. Rafferty, MD, director of Breast Imaging at the Avon Comprehensive Breast Center at Massachusetts General Hospital in Boston, and colleagues, was published by the RSNA journal Radiology.
Rafferty's group obtained images from 1,192 women in order to measure radiologists' diagnostic accuracy and recall rates for breast tomosynthesis combined with digital mammography compared with digital mammography alone. Ultimately, diagnostic accuracy increased for all 27 radiologists participating in the study when tomosynthesis was added to digital mammography. In addition, the diagnostic sensitivity of the combined exam increased by 10.7% in one reader study of 312 cases (including 48 cancer cases) involving 12 radiologists and 16% in a second reader study of 312 cases (including 51 cancer cases) involving 15 radiologists.
The increased sensitivity was greatest for invasive cancers: 15% in the first reader study and 22% in the second reader study, vs 3% for in-situ cancers in both studies. Absolute recall-rate reductions of 38.6% and 17.1% were seen in the first and second reader studies, respectively.
“In the clinical setting, we would expect that type of reduction in recall rate to translate into a substantial number of unnecessary diagnostic tests being avoided,” pointed out Rafferty in the RSNA statement.