Fig 1. A 46-year-old man with right parietal and corpus callosal GBM. Transverse T2* susceptibility echo-planar perfusion image (left) and contrast-enhanced SPGR T1-weighted image (right) (A) and corresponding T2* susceptibility signal intensity time curves of T2 lesion (red) and contrast-enhancing lesion (green) (B) demonstrate variation in signal intensity characteristics in the tumor. T2* susceptibility signal intensity time curve (C, left) is converted to R2* curve (right) by using the following formula: R2* = –ln(S_t/S₀)/TE, where ln is natural log and S_t and S₀ are signal intensities at time t and 0. In the R2* curve (right), the peak height is represented as a, and the percentage of signal intensity recovery is the percentile of b/a. Transverse contrast-enhanced SPGR T1-weighted image (D) is overlaid with areas of abnormal peak height (blue) and percentage of signal intensity recovery less than 50% (red) and shows a large area of increased vascularity (blue) with a peripheral region of high permeability (red) in this GBM.