A new scoring system for differentiating malignant from benign "second-look" breast lesions detected by MRI in...

To propose a scoring system made of reproducible and objective criteria to aid in differentiating malignant from benign "second-look" breast lesions detected at magnetic resonance imaging (MRI).

Data were collected retrospectively for "second-look" lesions identified on breast MRI studies performed at the University Hospitals of Leicester NHS Trust breast unit over a 2-year period (from January 2020 to January 2022). Ninety-five "second look" MRI-detected lesions were included in this retrospective study. Lesions were assessed according to margins, T2 signal, internal enhancement patterns, contrast kinetics, and diffusion-weighted imaging (DWI) patterns.

Fifty-two per cent of the included lesions were confirmed at histopathology to be malignant. The most common contrast kinetics identified in malignant lesions was the plateau pattern followed by the washout pattern while the most common pattern in benign lesions was the progressive pattern. The apparent diffusion coefficient (ADC) cut-off value for separating benign and malignant lesions at the unit was found to be 1.1 × 10^-3 mm²/s. Based on the MRI features described above, a scoring system is suggested to help differentiate benign from malignant "second-look" lesions. According to the present results, setting a score of 2 or more points as an indication for biopsy was 100% reliable in identifying malignant lesions and avoiding biopsies in >30% of lesions.

The suggested scoring system could avoid biopsy of >30% of the "second-look" lesions detected by MRI without missing any malignant lesions.