Evaluation of human brain tumor heterogeneity using multiple T 1 ‐based MRI signal weighting approaches

Vascular‐space‐occupancy (VASO) MRI without contrast injection was explored for imaging cerebral blood volume (CBV) and tissue heterogeneity in gliomas ( n = 10). VASO contrast complemented contrast‐enhanced T 1 ‐weighted (GAD‐ T 1 w), FLAIR and T 1 w magnetization‐prepared‐rapid‐gradient‐echo (MPRAGE) images. High‐grade gliomas showed a VASO‐outlined hyperintense zone corresponding to long‐ T 1 regions in MPRAGE and to nonenhancing regions in GAD‐ T 1 w images. FLAIR, MPRAGE, and VASO data were used to segment tumors into multiple zones of different T 1 . After removal of known resection areas using pre‐ and postsurgical MRI, the volume of overlap between the hyperintense VASO‐zone and the long‐ T 1 MPRAGE zone correlated with that of GAD‐ T 1 w enhancement (R 2 = 0.99) and tumor grade. Based on these correlations, this remaining long T 1 overlap area was tentatively assigned to necrosis. In one promising case the collective T 1 ‐weighted approach accurately identified a low‐grade glioma despite the presence of contrast enhancement in GAD‐ T 1 w images consequential to chemoradiation‐associated treatment effect. The results suggest that this collective T 1 ‐weighted approach may provide useful information for regional assessment of heterogeneous tumors and for guiding treatment‐related decisions in patients with gliomas. Magn Reson Med, 2008. © 2008 Wiley‐Liss, Inc.