Blood Volume of Intraaxial Brain Tumor: Evaluation with Dynamic Contrast-Enhanced T2*-Weighted MR Imaging

ABSTRACT

PURPOSE: To evaluate the utility of dynamic contrast-enhanced T2*-weighted MR imaging in assessing the cerebral blood volume (CBV) in intra-axial brain tumors. MATERIALS AND METHODS: Ten malignant gliomas (five glioblastomas, three anaplastic astrocytomas, two anaplastic oligodendrogliomas), five metastatic tumors and three hemangioblastomas were included in this study. In conjunction with T1- and T2-weighted imagings, all patients underwent dynamic contrast-enhanced T2*-weighted imaging, using the conventional gradient-echo technique (TR/TE/flip angle 40/26/10degree; 64x128 matrix; 5-6 mm thickness) during the bolus injection of 15 mmol/kg Gd-DTPA. From these dynamic images, CBV was calculated on a pixel-by-pixel basis and a CBV map was obtained. The CBVs of the tumor and contralateral normal white matter were measured by placing the ROI on the CBV map. The CBV ratios of tumor/normal white matter were compared among the three tumor groups. RESULTS: CBV maps were successfully created in all cases. CBV ratios varied from 1.7 to 13.0 (mean 6.1) in malignant gliomas, from 3.9 to 11.4 (mean 7.3) in metastatic tumors and from 17.8 to 26.4 (mean 22.2) in hemangioblastomas (malignant gliomas vs hemangioblastomas, p.05). CONCLUSION: Hypervascular hemangioblastomas have the highest CBV, and this allows for easy differentiation from malignant gliomas and metastatic tumors. Both show a similar, moderately increased range of CBV suggesting thatthere is no significant difference in vascularity between the two tumor groups. Dynamic contrast-enhanced T2* imaging is a clinically useful technique which provides information about tumor vascularity not provided by standard MRI techniques.