Dynamic, contrast‐enhanced perfusion MRI in mouse gliomas: Correlation with histopathology

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Abstract
The aim of this study was to develop an MRI protocol to evaluate the growth and vascularity of implanted GL261 mouse gliomas on a 7T microimaging system. Both conventional T1‐ and T2‐weighted imaging and dynamic, contrast‐enhanced T2*‐weighted imaging were performed on 34 mice at different stages of tumor development. MRI measurements of relative cerebral blood volume (rCBV) were compared to histological assessments of microvascular density (MVD). Enhancement on postcontrast T1‐weighted images was compared to histological assessments of Evan's blue extravasation. Conventional T2‐weighted and postcontrast T1‐weighted images demonstrated tumor growth characteristics consistent with previous descriptions of GL261 glioma. Furthermore, measurements of rCBV from MRI data were in good agreement with histological measurements of MVD from the same tumors. Postcontrast enhancement on T1‐weighted images was observed at all stages of GL261 glioma progression, even before evidence of angiogenesis, indicating that the mechanism of conventional contrast enhancement in MRI does not require neovascularization. These results provide quantitative support for MRI approaches currently used to assess human brain tumors, and form the basis for future studies of angiogenesis in genetically engineered mouse brain tumor models. Magn Reson Med 49:848–855, 2003.