256 Slice CT Perfusion And CT Angiography Evaluation In Moyamoya Disease Before And After Surgical Revascularization

Objective:To investigate the changes of cerebral hemodynamlcs in moyamoya disease before and after the revascularization operation by using 256 slice CT cerebral perfusion imaging; to explore the sensitive cerebral hemodynamic parameters which can reflect the different clinical outcomes after revascularization. Meanwhile, we use CTA, DSA, MRA and NOVA to show the patency of revascularization graft. Methods: 30 cases of moyamoya disease patients diagnosed by DSA or MRA were performed with superficial temporal artery-middle cerebral artery anastomosis with encephaloduromyosynaniosis (STA-MCA bypass+EDMS). By using intraoperative Noninvasive Optimal Vessel Analysis (NOVA), postoperative conventional CTA (in 1 week) and DSA, MRA (within 1 week-6 months) we observed the vascular reconstruction graft patency. Whole brain CT perfusion (CTP) examination 1 week before and after operation were performanced on all patients,9 patients had a whole brain CTP re-examination 6months or longer after operation. The cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT), time to peak (TTP) maps were obtained, then we manually drew ROI of operative side, ipsilateral cerebellar hemisphere and the contralateral mirroring area, absolute perfusion parameter values (CBF, CBV, MTT and TTP) were obtained and preoperative, postoperative relative perfusion parameter values (rCBF, rCBV, rMTT and rTTP) were calculated by using surgical side/ipsilateral cerebellar reference values. Differences in CT perfusion values pre-and post-operation were assessed with the paired t test or paired rank sum test. Difference would be considered statistically significant if P<0.05. Patients were divided into good-improvement group (n=22) and poor-improvement group (n=8) according to postoperative clinical follow-up results, relative perfusion parameter values by surgical side/ipsilateral cerebellar reference (rCBF, rCBV, rMTT and rTTP) 1 week after operation were annalyzed using binary Logistic regression analysis, to explore the sensitive index of clinical outcomes. Results:1) Intraoperative NOVA and postoperative CTA、MRA、DSA examination showed all patients’bridge graft vessles were with good patency, which could be well demonstrated on CTA and was similar to DSA and MRA.2) Preoperative perfusion parameter maps showed there were different levels of abnormal cerebral blood perfusion area in the operative hemispheres in 30 patients. Absolute perfusion values of ROI showed that CBV increased (P>0.05),CBF decreased (P<0.05),MTT、TTP lengthened (P<0.05) in the operative side compared with the contralateral mirroring area.3) As for relative perfusion values of the operative side ROI one week before and after revascularization:rCBF increased (P<0.05), rCBV decreased (P>0.05), rMTT、rTTP shortened (P<0.05) after revascularization.4) In 9 patients with 6 months or longer CTP reexamination, rMTT、rTTP further shortened (P<0.05), rCBV decreased (P>0.05), rCBF value increased (P>0.05) compared with the relative values 1 week after operation.5) Binary Logistic regression analysis of the postoperative (1 week after operation) relative perfusion values (rCBF, rCBV, rMTT and rTTP) of good and poor improvement group indicated the postoperative rTTP value was sensitive to indicate adverse postoperative outcome. With ROC curve analysis, took rTTP= 1.12 as the best judgment of critical point of poor prognosis, the sensitivity was 87.5%, specificity was 68.2%, the positive predictive value was 57.2%, and the negative predictive value was 91.8%. Conclusions:The 256 slice CT cerebral perfusion imaging can determine the abnormal perfusion area and period in moyamoya disease before operation, and brain CT perfusion before/after operation showed that cerebral perfusion pressure and cerebral microcirculation of the operative side improved in the early postoperative period, as time passed by, cerebral perfusion conditions further improved after surgery. Perfusion parameters rCBF, rMTT and rTTP, especially rMTT and rTTP are sensitive indexs of early and long-term postoperative perfusion evaluation.Early postoperative rTTP value may be used as a preliminary index of clinical outcomes.