REGIONAL RELATIVE BLOOD-VOLUME MR MAPS OF MENINGIOMAS BEFORE AND AFTER PARTIAL EMBOLIZATION

Purpose: Our goal was to evaluate the role of relative blood volume (r BV) measurements in monitoring the embolization effect in meningiomas by using maps of susceptibility-weighted first pass MR data. Method: E ighteen examinations of nine patients before and following partial emb olization were performed on a 1.5 T scanner. Embolization was achieved by injection of particles (45-150 mu m). During dynamic imaging a bol us (0.2 mmol/kg) of gado-pentetate dimeglumine was injected. Results: The tumor rBV/gray matter rBV ratio was 3.11 +/- 1.40 for untreated tu mors and 0.12 +/- 0.09 for successfully embolized tumors. The regional rBV in embolized meningiomas was significantly lower than that in unt reated meningiomas (t test, p < 0.001). Vital tumor tissue showed posi tive enhancement in T1 and high rBV; nonvital tissue lacked T1 enhance ment and bolus effect in the first pass, thus leading to low or missin g rBV values. However, we also observed lack of bolus formation despit e T1 enhancement (6/9 postembolization regions), possibly due to slow collateral flow. One of the patients treated with embolization bled du ring surgery. Conclusion: Maps of relative regional cerebral BV provid e hemodynamic information in meningiomas and monitor the treatment eff ect of embolization in meningiomas more precisely than T1-weighted con trast-enhanced imaging.