Susceptibility-based imaging of glioblastoma microvascularity at 8 T: correlation of MR imaging and postmortem pathology.

BACKGROUND AND PURPOSE Imaging methods are currently being optimized in an attempt to assess and monitor angiogenesis in vivo. The purpose of this investigation was to determine whether areas of apparently increased tumor vascularity, as identified on 8-T gradient-echo (GE) imaging of a known glioblastoma multiforme (GBM), corresponds to foci of increased microvascularity on histopathologic analysis. METHODS We performed postmortem in situ, high-resolution GE 8-T MR imaging of the brain in a 53-year-old woman with GBM. Ten histopathologic specimens in the region of the tumor bed were studied by using hematoxylin-eosin and reticulin stains. MR and histopathologic results were assessed and compared for microvascular size and density. RESULTS 8-T GE images showed small, penetrating vessels in the gray matter and white matter. The images, however, were partly inhomogeneous as a result of local magnetic field inhomogeneities adjacent to the skull base and aerated paranasal sinus structures. 8-T MR images demonstrated serpiginous areas of signal intensity loss, which were thought to represent areas of increased microvascularity. Areas of lower microvascularity in the tumor bed corresponded to areas of lower vascularity on histopathologic sections with smaller vessel diameters. There was concurrence between vascular size predicted by histopathologic analysis and 8-T MR imaging in nine of nine biopsy samples. Vascular density agreed in seven of nine biopsy samples. CONCLUSION Our pilot data suggest that microvascularity in GBM can be identified by use of high-resolution, GE, 8-T MR imaging.