Second-Look Ultrasonography for Evaluating BIRADS 3 and 4 Non Mass-Enhancement: A Cross-Sectional Study

Breast MRI is a highly sensitive imaging modality for assessing suspected breast lesions; nevertheless, its specificity is poor, ranging from 40% to 80% in various studies. Second-look ultrasound (SLUS) is a tool for the validation of MRI-identified breast abnormalities. This study aimed to assess the role of SLUS as a complementary method for evaluating suspicious non mass-enhancement (NME) on breast MRI.

Fifty patients with 52 non-mass enhancing lesions, classified as BIRADS 3 or 4 on MRI by an expert breast radiologist, were rechecked by SLUS. The relationship between age, breast cancer history, MRI indication, imaging features, and BIRADS classification of the lesions with the sonographic detection rate and pathology findings was analyzed.

Out of 52 lesions, 23 were identified on SLUS, 21 patients referred to biopsy. Seven out of 21 biopsies had malignant pathologies. Age less than 40 years, pathological breast discharge, and BIRADS-MRI 4 had a positive relationship with the identification on SLUS. Five of 29 lesions that had no sonographic findings were referred to stereotactic biopsy due to suspicious findings on mammography, and four were malignant on pathology. The only variable that showed a significant relationship with the lesion malignancy was the BIRADS category on MRI.

NMEs with BIRADS 4 on MRI were more detectable on SLUS than BIRADS-MRI 3. If detected, ultrasound could not downgrade the BIRADS category of the lesions or exempt them from biopsy.