Cerebral Blood Volume Mapping by MR Imaging in the Initial Evaluation of Brain Tumors

Purpose: To assess the contribution of magnetic resonance (MR) cerebral blood volume (CBV) mapping in the initial evaluation of brain tumors.

Methods: 63 patients presenting a brain tumor underwent dynamic susceptibility-contrast MR imaging before surgery or biopsy: 28 high grade gliomas, 8 low grade gliomas, 2 pilocytic astrocytomas, 4 lymphomas, 12 metastases, 9 meningiomas. The CBV maps were obtained for each patient and the relative CBV (rCBV) in different areas was calculated using the ratio between the CBV in the pathological area (CBVp) and in the contralateral normal tissue(CBVn). The maximum rCBV (rCBVmax) for each tumor was determined and the mean values of rCBVmax in each group of tumors were compared using an unpaired Student t test (p=0.05).

Results: The rCBVmax for high grade gliomas (mean +/- SD: 2.6 +/- 1,2) was statistically different from low grade gliomas (0.9 +/- 0.4) (p<0.001), lymphomas (0.7 +/- 0.2) (p=0.002), meningiomas (9.1 +/- 4.4) (p<0.001) and kidney metastases (8.9 +/- 2.1) (p<0.001). The two pilocytic astrocytomas had a much lower rCBVmax than high grade gliomas. No statistically significant difference was found between high grade gliomas and lung metastases (2.4 +/- 0.9) (p=0.72).

Conclusion: CBV mapping provides additional information on the vascularity of the lesions, which is not available with conventional MR imaging. It might be useful for differentiating certain lesions showing contrast enhancement, mainly high grade gliomas from kidney metastases, meningiomas, lymphomas or pilocytic astrocytomas.