MR measurement of regional relative cerebral blood volume in epilepsy

The purpose of this study was to evaluate the utility of magnetic resonance (MR) relative cerebral blood volume (rCBV) maps for studying regional hemodynamic changes in interictal and ictal epilepsy patients. Ten epilepsy patients were examined on a 1.5 T MR system. Nine patients were investigated interictally and one patient ictally. In the nine interictal patients, the dynamic plane was defined coronally through the hippocampus symmetrically. For the ictal patient, an axial dynamic plane was defined and the patient was scanned during seizure. Positron emission tomography (PET) studies were performed in 8 of the 10 patients. Lower rCBV of the left hippocampus was predicted by rCBV maps in seven of the nine interictal patients. The mean ratios of rCBV were 1.96 for left hippocampus/white matter and 2.49 for right hippocampus/white matter. The difference between these two ratios is statistically significant (P = 0.01, t-test). In two of the nine interictal temporal lobe epilepsy patients, lower rCBV areas were observed in the right hippocampus. In the ictal patient, the regional rCBV map demonstrated increased blood volume in the lesions. In eight of eight patients who underwent PET studies, MR rCBV findings were consistent with PET findings. The results show that regional hemodynamic changes in epilepsy can be evaluated with dynamic contrast-enhanced MR imaging. MR rCBV maps are sensitive to characterize seizure foci both ictally and interictally.