Solitary MET with peritumoral T2 prolongation of grade I. Postcontrast axial T1WI shows a heterogeneously enhancing lesion in the left frontal and anterior parietal lobes with a maximal diameter of 3.94 cm (A). On the same section as A, axial T2WI demonstrates medium peritumoral T2 prolongation, which is smaller in area than the tumor (B). On this section, 2 ROIs are placed in the prolonged region (black ring), with 2 mirror ROIs in the contralateral area (white ring). On the section superior to B, another 2 ROIs with 2 mirror ROIs are positioned in the prolongation region and the contralateral region, respectively (C). For this measurement, the mean value of signal intensity is 818.0 for the prolonged region and 280.5 for the intact contralateral region, respectively. Thus, the nSI is 2.92 (818.0/280.5).