Clinical significance of lesion conspicuity on contrast-enhanced mammography

To determine if lesion conspicuity on contrast-enhanced mammography (CEM) is independently associated with malignancy.

This retrospective, single-institution study identified consecutive abnormal screening and diagnostic CEMs between January 2019 and December 2021. The conspicuity of enhancing lesions on CEM recombined images was graded (low, moderate, or high) by one or both breast radiologists assigned as readers for the study, blinded to two-year imaging follow-up or biopsy pathology results. The positive predictive value (PPV) for malignancy was determined for each level of conspicuity.

Across 476 CEM examinations in 455 women (median age, 49 years; IQR: 44-57), there were 563 enhancing lesions (55 malignant, 508 benign). Of the 563 enhancing lesions, 52% (292/563) were low conspicuity, 38% (213/563) moderate, and 10.3% (58/563) high. The PPV to predict cancer was 9% (95% CI: 6-12%), 11% (95% CI: 7-16%), and 10% (95% CI: 4-21%) for low, moderate, and high conspicuity (low vs high, p = 0.68; low vs moderate, p = 0.34; moderate vs high, p = 0.83). Of the 55 cancers, most high-conspicuity cancers presented on both recombined images and low-energy images (5/6; 83%), while most low- (21/25; 84%) and moderate-conspicuity cancers (17/24; 71%) presented on recombined images only (p = 0.006). Inter-reader agreement was almost perfect for 100 lesions graded by both breast radiologists (κ = 0.94).

Lesion conspicuity is not independently associated with malignancy. Most enhancing lesions, including most cancers, show low or moderate conspicuity on CEM.

Question Is lesion conspicuity on CEM, determined on the recombined images, an independent predictor of malignancy? Findings The PPV for low, moderate, and high conspicuity to predict malignancy was 8.6%, 11.3%, and 10.3%, respectively (non-significant differences between low, moderate, and high conspicuity). Clinical relevance Lesion conspicuity is not an independent predictor of malignancy. Enhancing lesions seen on recombined images should not be considered benign based on low conspicuity alone, as most low-conspicuity cancers presented with enhancement only and lacked a correlate finding on low-energy images.