Evaluation of incidental lesions detected in the contralateral breast on preoperative breast magnetic resonance imaging(MRI) in patients diagnosed with breast cancer

AIM Breast cancer is the most common cancer in women; the sensitivity of mammography (MG) decreases in patients with dense breast parenchyma, and ultrasonography (US) has certain limitations. The primary objective of this study was to evaluate the effectiveness of preoperative magnetic resonance imaging (MRI) in newly diagnosed breast cancer cases. To demonstrate its contribution to the detection of incidental lesions in the contralateral breast and to investigate the relationship between these imaging findings and patient demographic data and malignancy. MATERIAL AND METHOD In this single-center, ethically approved (2025/334) retrospective study, cases diagnosed through biopsy between January 2010 and July 2025 were screened; those who underwent preoperative breast MRI between January 2020 and July 2025 were examined. After the exclusion criteria, MRI contralateral, one hundred and twenty-four patients with incidental lesions were analyzed. Ultrasonography, mammography, and 1.5T dynamic contrast-enhanced MRI were performed using standard protocols. Radiological and histopathological features of the patients were recorded. RESULTS In our findings, 76.4% of contralateral incidental lesions were found to be benign, and 23.6% were found to be malignant; Malignancy was detected on MRI. Irregular contour, heterogeneous enhancement, Type-III kinetic curve, DWI restriction, and T1/T2 hypointense were associated with microcalcification, distortion, and retraction was more common. The detection rate of additional cancer in the contralateral breast for MRI was measured as 0.53% (13/2461). In the ≥40 age group, MG/ US eligibility was higher; ER and PR rates were higher in this group, and HER2 was found to be lower. CONCLUSION Pre-operative MRI is valuable in distinguishing malignancy; type III pattern, diffusion restriction, and heterogeneous contrast enhancement are the most significant parameters; multidimensional ( morphology + kinetics + diffusion ) evaluation allows early diagnosis while reducing unnecessary biopsies.