Digital tomosynthesis cuts callbacks and detects more masses than conventional mammography

Digital tomosynthesis detects more breast masses, better categorizes those masses, and produces lower callback rates than conventional mammography, according to research presented at the RSNA meeting. In a study of symptomatic patients, tomosynthesis was not superior to mammography, but a combination of the two techniques detected more carcinomas than either alone. Citing results gathered from 30 subjects in an ongoing study, Dr. Mark A. Helvie, director of breast imaging at the University of Michigan Health System, reported that experienced readers detected more masses using digital tomosynthesis than mammography. Tomosynthesis provided better margin assessment and malignant characterization, and it identified cancer that was hidden on mammography. Helvie reported that 100% of cancers were detected using digital tomosynthesis, compared with 83% using mammography. Average results from three experienced readers showed that 36% more masses were found by tomosynthesis, which visualized 48% more margin than mammography. Malignant cases were rated as 48% more likely to be malignant on digital tomosynthesis compared with mammography, while benign cases had the same malignancy rating (18%).Digital tomosynthesis can also reduce callback rates, according to research presented by Dr. Richard Moore, director of breast imaging research at Massachusetts General Hospital. In a screening setting, patients who had prior studies and were then imaged using digital tomosynthesis had a callback rate of 5.1%, 25.1% lower than the baseline radiologist rate of 6.8% and 37% lower than the average mammography rate of 8%. Available prior studies reduced callback rates about 5% for both mammography and tomosynthesis.The research compared 2233 mammography screening studies performed on 2115 women with 2233 digital tomosynthesis studies performed on 2114 women between June 2005 and September 2007. Both types of studies were read in batch mode. Among patients with no prior studies, the callback rate was 12.9% for mammography and 11.6% for tomosynthesis. For patients with prior studies, rates were 8.1% and 5.1%, respectively. The research also suggested that the tomosynthesis callback rate improves with experience. In the first eight months using the system, the callback rate was 6.3% for patients who had received prior studies. In the third eight-month period, that rate dropped to 4.5%.Moore warned that the appearance of previous surgery on digital tomosynthesis can be jarring when radiologists first begin using the system, as a surgical scar can mimic a new lesion.A final study threw some cold water on the digital tomosynthesis lovefest, however. Dr. Hendrik Teertstra of the Netherlands Cancer Institute in Amsterdam presented research suggesting that the ability to detect malignant lesions was not significantly different for digital tomosynthesis and mammography and that the role of tomosynthesis has yet to be established in symptomatic patients. A combination of the two techniques did detect more carcinomas than either technique alone.

The study of 113 carcinomas in 933 symptomatic breasts determined that the rate of false negatives produced using digital tomosynthesis was 6.2%, while that using mammography was 7%. Using a combination of the two techniques, false negatives dropped to 2.65%.

Lesion detected using conventional mammography (left) is compared with same lesion detected using digital tomosynthesis. (Provided by H. Teertstra)