FIG 1. (A–C): Three patients experienced HT. Images from all 3 are shown from the initial MR imaging at presentation (upper left: DWI; upper middle: permeability map; upper right: dynamic enhancement time course; lower left: post-Gd T1 SE) and from follow-up scans after 24–72 hours (lower middle: 3D-GRE-MR imaging; lower right: CT). Progressive signal intensity increase on serial T1-weighted images demonstrates a clear positive increasing slope (upper right), and a corresponding hyperintensity on a pixel-by-pixel map of microvascular permeability (yellow arrows). In only 1 case (A) is enhancement clearly visible on the T1-weighted SE (white arrows). Follow-up CT shows hyperintensity characteristic of HT in the same area (orange arrows), but this appearance varies from subtle to frank; hemorrhage is additionally depicted on gradient recalled echo MR imaging (orange arrows). In Fig 1B, follow-up CT was performed 1 day after the follow-up MR imaging. The top arrow shows subtle evidence of hemorrhage corresponding to 3D-GRE-MR imaging; the bottom arrow shows new hemorrhage that must have developed after the follow-up MR imaging and that corresponds to the permeability abnormality on the initial MR imaging.