| Part1:Study of cerebral hemodynamics in patients with internal carotid artery stenosis before and after stent placement using perfusing CTObjective To evaluate the value of 64-slice brain CT perfusion (CTP) in investigating cerebral hemodynamics changes in patients with internal carotid artery stenosis before and after stent placement,and assess whether there is any CTP parameter correlating with cerebral hemodynamics changes in patients with internal carotid artery stenosis before and after stent placement.Materials and Methods Sixty-four cases in 32 subjects (25 men,7 women; mean age, 60.39 years) with internal carotid artery stenosis were evaluated with SIMENS Sensation 64 multi-slice spiral CT scanner. Firstly, routine CT scans were performed, and then CTP study was made by selecting the basal ganglia slice and its adjacent slice. Scanning was performed at 80 kV,150 mA, with a 512x512 matrix and 9.6-mm section thickness. CTP was performed pre-and post-surgical stent placement. Perfusion CT values (CBF, CBV, TTP and TS) of ipsilateral lesion in the region of interest and contralateral mirroring areas of abnormal perfusion in functional maps were measured, and relative CBF (rCBF), relative CBV (rCBV), relative TTP (rTTP), relative TS (rTS) were obtained. Differences in perfusion CT values pre-and post operation were assessed with the paired t test or student’s t test.Results All the patients in moderate-grade group and in high-grade group had abnormal perfusion characterized by TS or TTP color perfusion maps. Before operation, among the absolute perfusion values, the CBF of posterior washeld regions in moderate-grade group, the CBF and CBV of the basal ganglia, the TS, TTP in the region of middle cerebral artery, the basal ganglia, the anterior and posterior washeld regions in high-grade group had significantly statistical significance compared to contraside(t=-2.41,P=0.0391;t=-2.22,P=0.0262;t=-2.09,P=0.0362;t=2.69,P=0.0137; t=3.60,P=0.0017;t=3.01,P=0.0067;t=2.91,P=0.0084;t=2.44,P=0.0149;t=2.61,P=0.01 63;t=3.01,P=0.0067;t=3.36,P=0.0030; respectively).Among the relative perfusion values, the rTS, rTTP in the region of middle cerebral artery, the rTTP of the anterior washeld regions and the rTS of the posterior washeld regions had significantly statistical significance between two groups before operation (t=-2.17, t=-2.52, t=-2.26, t=-2.38, respectively;p<0.05 for all). No significantly statistical difference was found in other pre-operation perfusion values. After operation, among the absolute perfusion values, except for the CBV and CBF of the frontal lobes in high-grade group, all perfusion values had not significantly statistical significance compared to contraside in two groups. Among the relative perfusion values, the rCBF,rCBV,rTS,rTTP of all regions had not significantly statistical difference between pre-and post operation in moderate-grade group; in high-grade group, the rTTP of the basal ganglia regions, the regions of middle cerebral artery,the anterior and posterior washeld regions and the rTS of the basal ganglia regions and the posterior washeld regions had significantly statistical significance between pre-and post operation (t=3.3O,P=O.OO33;t= 3.30,P=0.0034;t=2.83,P=0.0101;t=2.51,P=0.0204;t=3.00,P=0.0027;t=276,P=0.0117; respectively). The rCBF and rCBV of all regions had not significantly statistical significance between pre-and post operation in high-grade group.Conclusion 64-slice CT has the potential for the non-invasive assessment of brain hemodynamic changes in patients with internal carotid artery stenosis before and after stent placement. Absolute TS, TTP and relative TS, TTP are the most sensitive parameters to detect the changes in cerebral perfusion.Part2:Evaluation of the whole-brain CT cerebral perfusion imaging and 4D-CT angiography in patients with stenosis or occlusion of cerebral arteryObjective To evaluate the whole-brain cerebral CT perfusion(CTP)and 4D-CT angiography(CTA)in patients with stenosis or occlusion of cerebral artery.Materials and Methods The whole-brain cerebral CT perfusion were performed in 42 patients with unilateral or bilateral MCA stenosis or occlusion.The parameter maps of cerebral blood flow(CBF),cerebral blood volume(CBV), mean transit time (MTT), time to peak (TTP) and Infarct Index (Ⅱ) were analyzed. Meanwhile the whole-brain plain images and 4D-CTA images were also generated from volumetric data acquired in the whole-brain CTP. The significance of the differences of CBF, CBV, MTT, TTP and II between the affected side and the contralateral side was assessed using matched-pairs t test or matched-pairs signed-ranks test.Results In 34 Patients with unilateral stenosis or occlusion of MCA,CTP was found abnormal.MTT and TTP of affected side[(8.11±2.67) s,(23.19±5.99) s] were significantly prolonged compared to contralateral side[(4.1±2.66) s,(19.6±4.35) s] (t=12.48,P=0.0000;t=5.70,P=0.0000;respectively).CBV and II of affected side [(3.58±1.23) ml·100g-1,(0.77±0.30)]were significantly increased compared to contralateral side [(2.96±1.87)ml·100g-1,(0.61±0.28)](t=2.13,P=0.0406;t=3.94,P= 0.0005;respectively).CBF of affected side [24.38(21.08～36.48) ml·100g-1min-1]was significantly decreased compared to contralateral side[47.88(30.41～69.55) ml·100g-1·min-1] (z=-5.04;P=0.0000).In 8 patients with bilateral stenosis or occlusion of MCA, CTP was also observed abnormal. CBF, MTT and TTP of affected side [(24.29±12.77) ml·100g-1·,min-1, (8.24±4.42) s, (22.7±4.35) s] were significantly different from those of contralateral side [(39.26±19.43) ml·100g-1·min-1, (4.25±2.49) s, (19.54±3.55) s] (t=-3.84,t=4.17,t=5.41, respectively; P＜0.01 for all), the differences of CBV and II were not significant compared with those of contralateral brain tissues (P>0.05 for all).On whole-brain 4D-CTA images, unilateral stenosis of MCA were observed in 16 patients (6 right MCA and 10 left MCA), unilateral occlusion were observed in 18 patients (12 right MCA and 6 left MCA) and bilateral MCA stenosis or occlusion were observed in 8 patients. Whole-brain 4D-CTA can display stenosis or occlusion of MCA as same as conventional CTA or DSA.Conclusion The whole-brain CTP and 4D-CTA have the potential for the non-invasive assessment of both whole-brain hemodynamic changes and the abnormalities of intracranial arteries in patients with MCA stenosis or occlusion with administration of one contrast medium bolus in a single examination.Part3:256-slice whole-brain CT perfusion and 4D-CT angiography assessment in Moyamoya disease before and after surgical revascularizationObjective:To evaluate the feasibility of 256-slice whole-brain CT perfusion (CTP) in confirming the graft patency with vessel images obtained in the artery phase of CTP as well as investigating cerebral hemodynamics changes in Momymoy disease before and after surgical revascularization.Materials and Methods:Seventy-eight cases in 39 subjects (16 men,23 women; mean age,40.8 years) with Moyamoya disease were evaluated with 256-slice CT. CTP was performed pre-and post-surgical revascularization. The whole-brain plain images,4D-CTA and whole-brain perfusion images were obtained. The volumetric CT angiographic (CTA) images were generated from volumetric data acquired in the arterial phase of CTP. Two readers independently evaluated CT data. Perfusion CT values (CBF, CBV, TTP and MTT) of ipsilateral lesion in the region of middle cerebral artery and contralateral mirroring areas of abnormal perfusion in functional maps were measured and relative CBF (rCBF), relative CBV (rCBV), relative TTP (rTTP), relative MTT (rMTT) were obtained. Differences in perfusion CT values pre-and post operation were assessed with the paired t test or matched-pairs signed-ranks test.Results:There were abnormal density in brain tissue in mostly of patients, in which 33 cases has brain infaction including 8 cases of brain hemorrhage with encephalomalacia and 2 cases of atrophy of brain.There were 6 cases normal density. The stenosis and occlusion of multiple cerebral vessels can be well demonstraled on CTA and was similar to DSA.No significant differences between volumetric CTA and conventional CTA; All the direct graft patencies were displayed by volumetric CTA.Pre-operative CBF,MTT and TTP [33.45(24.75-48.85) ml·100g-1-min-1, 5.42(4.62～7.85) s,(20.23±4.17) s]of ipsilateral lesion in the region of middle cerebral artery were significantly different from those of contralateral side[50.47(34.8～96.82) ml·100g-1·min-1,3.84(2.08～5.97) s,(18.58±3.62) s](z=-4.58,z=4.26,t=3.30, respect-tively;P<0.01 for all).Postoperative CBF, rCBF and rCBV values [57.99 (34.17～86.21) ml100g-1·min-1,1.29(1.12～1.82),1.23(0.84～1.86)] of ipsilateral lesion in the region of middle cerebral artery were significantly higher than those [33.45 (24.75～48.85) ml100g-I-min-1,0.72(0.42～0.94),0.94(0.8～1.14)] before operation (z=-3.92, z=-4.81, z=-3.21, respectively; P＜O.01 for all). Postoperative MTT, TTP, rMTT and rTTP values [3.71(2.05～5.04) s,17.73(16.24～20.77) s,0.95(0.77～1.30), 0.99(0.95～1.02)] of ipsilateral lesion in the region of middle cerebral artery were significantly lower than those[5.42(4.62～7.85) s,(20.23±4.17) s,1.18(1.04～1.96), 1.03(1.00～1.15)] before operation(z=2.87,P=0.0041;z=2.49,P=0.0126;z=3.24,p= 0.0012;z=4.08,P=0.0000;respectively). However, no significant difference was detected for changes of CBV after revascularization (P>0.05).Conclusion:The 256-slice whole-brain CTP and 4D-CTA have the potential for the non-invasive assessment of the abnormalities of intracranial arteries, the graft patency and cerebral hemodynamics changes in moyamoya disease before and after surgery with administration of one contrast medium bolus in a single examination. |
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