Comparison of False-Positive Versus True-Positive Findings on Contrast-Enhanced Digital Mammography

BACKGROUND. Contrast-enhanced digital mammography (CEDM) has been shown to outperform standard mammography while performing comparably to contrast-enhanced MRI. OBJECTIVE. The purpose of our study was to compare imaging characteristics of false-positive and true-positive findings on CEDM. METHODS. This retrospective study included women who underwent baseline screening CEDM between January 2013 and December 2018 assessed as BI-RADS category 0, 3, 4, or 5 and who underwent biopsy with histopathologic diagnosis or had a 2-year imaging follow-up. Lesion characteristics were extracted from CEDM reports. A true-positive finding was defined as a lesion in which biopsy yielded malignancy. A false-positive finding was defined as a lesion in which biopsy yielded benign or benign high-risk pathology or in which 2-year imaging follow-up was negative. RESULTS. Of 157 patients (median age, 52 years), 24 had a total of 26 true-positive lesions, and 133 had a total of 147 false-positive lesions. Of the 26 true-positive lesions, one (4%) exhibited only a mammographic finding on low-iodine images, 13 (50%) exhibited only a contrast finding on iodine images, and 12 (46%) exhibited both a mammographic finding on low-energy images and a contrast finding on iodine images. A true-positive result was more likely (p = .02) for lesions present on both low-energy images and iodine images (31%) than on low-energy images only (4%) or iodine images only (12%). Among lesions present on both low-energy and iodine images, a true-positive result was more likely (p < .001) when the type of mammographic finding was an asymmetry (46%) or calcification (80%) than a mass (11%) or distortion (0%). A true-positive result was more likely (p = .01) among those with, versus those without, an ultrasound correlate (36% vs 9%) and also was more likely (p = .02) among those with, versus those without, an MRI correlate (18% vs 2%). Of 25 false-positive calcifications, 24 had no associated mammographic enhancement; of five true-positive calcifications, four had mammographic enhancement. CONCLUSION. A low-energy mammographic finding with associated enhancement or a finding with a sonographic or MRI correlate predicts a true-positive result. Calcifications with associated enhancement had a high malignancy rate. Nonetheless, half of true-positive lesions enhanced on iodine images without a mammographic finding on low-energy images. CLINICAL IMPACT. These observations inform radiologists' management of abnormalities detected on screening CEDM.