A retrospective study was conducted on a cohort of 20 female patients, aged between 40 and 60 years, who presented with non-mass enhancement (NME) on breast MRI between January 2020 and December 2023. Patients were selected from the radiology records of a specialized breast imaging center. All MRIs were performed using a 1.5T. MRI with gadolinium-based contrast administration. The imaging protocol included T1-weighted fat-suppressed sequences, T2-weighted sequences, diffusion-weighted imaging (DWI), and dynamic contrast-enhanced imaging with subtraction techniques. NME findings were evaluated according to the BI-RADS (Breast Imaging Reporting and Data System) classification, focusing on distribution patterns—such as focal, linear, segmental, regional, multiple regions, and diffuse—and internal enhancement characteristics, including homogeneous, heterogeneous, clumped, and clustered ring patterns. [1]

MRI findings were correlated with histopathological data obtained through stereotactic or MRI-guided vacuum-assisted core biopsy, with a minimum of five cores sampled per lesion. Biopsy specimens were analyzed by experienced pathologists and categorized into benign lesions (e.g., hyperplasia, adenosis, fibrosis, papilloma), high-risk lesions (e.g., atypical ductal hyperplasia, radial scar/complex sclerosing lesion, flat epithelial atypia, intraductal papilloma), and malignant lesions (e.g., ductal carcinoma in situ [DCIS], invasive ductal carcinoma, invasive lobular carcinoma, or other rare histologic subtypes) [Fig1]. [1] [2]

According to the literature, NME accounts for approximately 10–20% of all abnormalities detected on breast MRI and is associated with a malignancy rate ranging from 20% to 42%, depending on distribution patterns and internal enhancement characteristics [Fig3]. [2]

In our study, segmental NME was more frequently associated with malignancy, with a malignancy rate of 55%, whereas focal NME was predominantly benign, with a malignancy rate of 12%. These observations align with previous studies indicating that segmental distribution is more commonly associated with malignant lesions [Fig2]. [3]

The analysis of DWI sequences revealed that malignant lesions had significantly lower apparent diffusion coefficient (ADC) values than benign lesions. In our cohort, the mean ADC values were 0.89 ± 0.12 × 10⁻³ mm²/s for malignant lesions and 1.45 ± 0.18 × 10⁻³ mm²/s for benign lesions, with a statistically significant difference (p < 0.001). These results are consistent with prior research suggesting that lower ADC values are indicative of malignancy in breast lesions. [1][3]

The primary objective of this study was to identify the most predictive radiological criteria for malignancy in cases of NME to improve risk stratification and optimize the diagnostic approach for patients.