Non-enhancing asymmetries on screening contrast-enhanced mammography: Is further diagnostic workup required?

Asymmetries on screening contrast-enhanced mammography (CEM) often lead to patient recall. However, in diagnostic settings, negative CEM has effectively classified these as normal or benign, questioning the need for further workup of non-enhancing asymmetries (NEAs).

A computational search of all screening CEM examinations performed between December-2012 and June-2021 was conducted to identify cases reporting NEAs. Their diagnostic workup was reviewed, and the positive predictive value for cancer was statistically compared to that of enhancing asymmetries on screening CEMs.

During the study period, 97 cases of 106 NEAs were identified among 3,482 screening CEM exams (2.8 %). NEAs were classified as asymmetry (n = 83), focal asymmetry (n = 22), and global asymmetry (n = 1), with no cases of developing asymmetry. The mean size of NEAs was 1.0 ± 0.7 cm (range: 0.3-4.9 cm). Diagnostic workup for NEAs included additional mammographic views (AMV) (n = 63), AMV plus ultrasound (n = 30), AMV plus MRI (n = 1), and all three modalities (n = 3), leading to four biopsies. None of the NEAs were malignant on follow-up, as opposed to enhancing asymmetries (P < 0.05).

NEAs detected on CEM were relatively uncommon and were usually investigated with additional mammographic views and US, yielding no cancer. Ruling out malignancy based on lack of enhancement without further workup may reduce patient recall rates and improve CEMs specificity.