Impact of pre-operative MRI on surgical management of screening digital breast tomosynthesis-detected invasive lobular carcinoma

Purpose The purpose of this study is to determine the impact of pre-operative MRI on surgical management of screening digital breast tomosynthesis (DBT)-detected invasive lobular carcinoma (ILC). Methods A retrospective medical record analysis was conducted of women with screening DBT-detected ILC and subsequent surgery from 2017–2021. Clinical, imaging, and pathological features were compared between women who did and did not undergo MRI, and between women with and without additional disease detected on MRI, using the Pearson’s chi-squared test and Wilcoxon signed-rank test. Concordance between imaging and surgical pathology sizes was also evaluated. Results Of 125 women (mean age 67 years, range 44–90) with screening-detected ILC, MRI was obtained in 62 women (49.6%) with a mean age of 63 years (range 45–80). Compared to women without MRI, women who had MRI examinations were younger, more likely to have dense breast tissue, and more likely to undergo mastectomy initially rather than lumpectomy ( p < 0.001–0.01). Eighteen biopsies were performed based on MRI findings, of which 55.6% (10/18) were malignant. Conventional imaging more frequently underestimated ILC span at the biopsy site than MRI, using a 25% threshold difference (17.5% [7/40] versus 58.5% [24/41], p < 0.001). MRI detected more extensive disease at the biopsy site in six patients (9.7%, 6/62), additional ipsilateral disease in six patients (9.7%, 6/62), and contralateral disease in one patient (1.6%, 1/62). MRI therefore impacted surgical management in 21.0% (13/62) of patients. Conclusion MRI led to the detection of additional disease, thus impacting surgical management, in one-fifth of patients with ILC.