ABSTRACT
Non-mass enhancement (NME) is an area of contrast enhancement that does not belong to a three-dimensional mass on magnetic resonance imaging (MRI) and cannot be defined as a focus, and can be evaluated morphologically and kinetically. While NME may belong to benign lesions, it may also be the MRI appearance of an in situ or invasive cancer. Differential diagnosis and management are especially important because the features of benign and malignant lesions overlap and may require MRI-guided biopsy when they cannot be identified by conventional methods. NME is evaluated by its distribution and internal structure properties. Clustered ring internal structure and segmental distribution are the most suspicious findings, and it may be difficult to differentiate with background contrast enhancement. Although it shows the most common type 2 kinetic curve, morphological findings seem to be more valuable in the evaluation. Breast Imaging-Reporting and Data System (BI-RADS) classification recommends the fourth and fifth categories as there is not yet sufficient evidence for the BI-RADS 3 definition. Artificial intelligence also shows promise in this field with its role in digital biopsy.