Breast magnetic resonance imaging: focus/foci
Focus refers to a tiny non-specific spot of enhancement. Different BI-RADS-MRI literature applies different focus classifications. Some literature regards focus as a special type of nonmasslike enhancement (NMLE), while others classify it as an independent enhancement type dependent from mass and NMLE (Figures 1,2,3). Focus usually is independent tiny spot enhancement, but can also be multiple diverselydistributed spotty enhancement. The lesion has spaceoccupying effect, with a diameter less than 5 mm.