Factors associated with histological outcomes of MRI-guided biopsy in the lumpectomy bed

PURPOSE: To evaluate the association between clinical and MRI characteristics and histological outcomes of MRI-guided vacuum-assisted biopsies (MVAB) performed in the lumpectomy bed after malignant breast-conserving surgery (BCT). MATERIAL AND METHODS: This retrospective study analyzed all MVABs performed in malignant lumpectomy beds between 2016 and 2022, evaluating the relationship between demographic and imaging characteristics and pathological outcomes (benign vs. malignant) using appropriate statistical methods. RESULTS: Malignancy was diagnosed in 14 of 72 biopsies (19%), most commonly invasive ductal carcinoma (50%). Fat necrosis was the predominant benign finding (38%). On univariate analysis, benign outcomes were more frequent in younger patients (median 60 vs. 69 years), those with prior radiation therapy (90% vs. 69%, P = 0.048), lesions adjacent to a postoperative cavity (28% vs. 7%, P = 0.1), and when coarse calcifications were present on mammography (43% vs. 0%, P = 0.011). Benign results were also more common for biopsies performed within one year or beyond six years after lumpectomy (97%, P = 0.087). No MRI morphological or kinetic features reliably distinguished benign from malignant lesions. CONCLUSION: MVAB of lumpectomy bed lesions yielded a 19% malignancy rate, with benign outcomes often associated with specific clinical and imaging features. Larger studies are warranted to validate these findings and refine patient selection.