Enhancement on breast MRI may be classified as focus, mass and non-mass enhancement (NME). Areas of enhancement which do not meet the criteria of a mass, i.e. three-dimensional space-occupying lesions with convex borders, or is not a focus, i.e. a non-space-occupying enhancement <5 mm, and demonstrates intervening fat or normal fibroglandular parenchyma, are referred to as non-mass enhancements. It shows enhancement characteristics distinct from the background parenchymal enhancement and may be spread over a small or wide area in the parenchyma. Description is based on the distribution and internal enhancement characteristics of the NME. Various patterns and enhancement characteristics such as segmental, clumped or clustered ring patterns have a strong positive predictive value for malignancy.