【作者】 程晓青；

【导师】 田建明； 陆建平； 左长京； 王莉； 刘崎；

【作者基本信息】 第二军医大学 ， 影像医学与核医学， 2010， 博士

【摘要】 目的：利用CT灌注(CT perfusion,CTP)探讨不同程度慢性单侧大脑中动脉(middle cerebral artery, MCA)狭窄及单侧颈动脉闭塞患者脑血流动力学情况,并联合CT血管成像(CT angiography, CTA)和数字减影血管造影(digital subtraction angiograph, DSA)研究狭窄分级与脑血流灌注参数的相关性,Willis环完整性在脑血流代偿的中的意义,以及颈动脉闭塞患者其不同侧枝代偿方式血流动力学损伤情况的差异。对部分单侧颈内／大脑中动脉狭窄行介入治疗的患者,对手术前后的脑灌注成像进行比较分析,探讨颅内外动脉狭窄支架置人术对血液动力学改善情况以及外科疗效评价。材料和方法：1.89例MCA狭窄患者根据其狭窄程度分为三组.分别计算各组中MCA供血区各灌注参数(CBF、CBV、TTP)的均值和狭窄侧／对侧比值(rCBF、rCBV、rTTP),利用配对t检验评价各组的脑血流动力学改变；利用Spearmen等级相关性分析分别评价各组rCBF、rCBV、rTTP与狭窄程度等级相关性；利用CTA联合DSA评估Willis环发育情况,及其与灌注参数的关系。2.38例单侧颈动脉闭塞患者.分别计算感兴趣区CTP的均值(CBF、CBV、TTP)和闭塞侧／对侧比值(rCBF、rCBV、rTTP),利用配对t检验评价其脑血流动力学差异；根据DSA对不同侧枝代偿途径进行分组,利用两样本比较的Wilcoxon秩和检验(Wilcoxon rank sum test)比较两组不同侧枝代偿途径的患者血流动力学的统计学差异。3.对22例单侧颈内／大脑中动脉狭窄行介入治疗的患者,术前术后行CT灌注联合CT血管成像,计算感兴趣区CTP的均值(CBF、CBV、TTP),利用配对t检验分别评价术前狭窄侧与对侧以及术后支架侧与对侧的脑血流动力学差异；利用配对t检验联合Wilcoxon配对秩和检验(Wilconxon signed-rank test)对同一感兴趣区的术前狭窄侧／对侧比值和术后支架侧／对侧比值(rCBF、rCBV、rTTP)进行统计学分析,评价术前术后脑血流动力学改变。结果：1.Ⅰ组中,狭窄侧与对侧CBF、CBV和TTP相比无统计学差异：Ⅱ组中,CBF与CBV无统计学差异,TTP值有统计学意义(t=2.83,P<0.05)；Ⅲ组中,CBF维持稳定,无统计学差异,狭窄侧的CBV和TTP较对侧具有统计学意义(CBV：t=6.04,P<0.01；TTP：t=13.18,P<0.01)。rTTP与狭窄程度具有较强的等级相关性(r=0.713,P<.01)；rCBV有弱相关性(r=0.365,P<.01)；rCBF与狭窄程度无相关性(r=0.193,p>0.05)。对于Willis环发育异常或狭窄患者,其rTTP明显延长,提示脑血流动力学损害严重。2.38例单侧颈动脉闭塞患者,其闭塞侧与对侧CBF维持稳定,两侧相比无统计学差异(t=1.08,P=0.285)；闭塞侧与对侧的CBV和TTP相比具有统计学差异(CBV：t=5.27,P<0.01；TTP：t=10.11,P<0.01)。将两组不同侧枝代偿途径的患者的各灌注参数的相对比值进行比较：rCBF分别为1.00(0.97,1.01)和1.01(0.97,1.04),两组相比无统计学差异(Z=0.68,p=0.494)；rCBV分别为1.03(0.99,1.05)和1.06(1.02,1.12),两组相比具有统计学差异(Z=2.32,p=0.020<0.05)；rTTP分别为1.10(1.06,1.15)和1.27(1.20,1.34),两组之间差异具有统计学意义(Z=4.50,p<.0001)。3.术前,单侧颈内／大脑中动脉狭窄患者长期处于”代偿期”状态,CBF维持稳定,两侧相比无统计学差异(t=0.54,P=0.592)；狭窄侧CBV值升高与对侧相比差异具有统计学意义(t=2.10,P=0.048)；狭窄侧TTP较对侧明显延长,两者之间差异具有统计学意义(t=-4.83,P<0.01)。术后,患者的脑血流动力学改善,支架侧与对侧血流灌注相比,CBF仍维持稳定,支架侧CBV降低,与对侧相比无统计学差异(t=0.34,P=0.737),支架侧TTP明显缩短,与对侧相比无统计学差异(t=0.80,P=0.432)；手术前后的rCBF无显著性差异(t=0.52,P=0.608)；而手术前后的rCBV(t=2.22 P=0.038)与rTTP(S=126.5 P<0.01)有显著性统计学差异。结论1.CTP联合血管成像,能够准确反映MCA狭窄脑血流动力学损伤情况。大部分患者脑血流动力学稳定,但对于部分多血管狭窄合并大脑动脉环发育欠佳患者,其脑血流动力学损伤较严重,则需要积极进行治疗预防卒中。2.颈动脉闭塞患者长期处于脑血流”代偿期”,但通过次级侧枝代偿的患者,其血流动力学损伤较初级侧枝代偿患者严重。3.CTP准确地反映颅内外血管狭窄患者支架成形术前后的的血流动力学状况,为临床治疗疗效的评估提供客观的影像学依据。更多还原

【Abstract】 PURPOSE:To investigatet the diagnostic value of computed tomography perfusion (CTP) in patients who had unilateral middle cerebral artery (MCA) and carotid artery stenosis or occlusion, combining with CT angiography (CTA) and digital subtraction angiograph (DSA) to evaluate the relationship between findings of CTP and the degree of MCA stenosis. In patients with unilateral carotid artery occlusion (CAO), we investigate hemodynamic parameter and to evaluate whether patients with secondary in addition to primary pathways have a worse hemodynamic state of the brain than those without secondary pathways. We also assess the utility of CTP for evaluating cerebral hemodynamic changes before and after interventional therapy in patients with unilateral ICA/MCA high-grade stenosis.METHODS:1. Eighty-nine patients with MCA steno-occlusion were classified into three groups according to the severity of the stenosis. Mean values(CBF、CBV、TTP) and the affected-to-contralateral ratio (rCBF、rCBV、rTTP) of CTP parameters were measured and compared to evaluate the cerebral hemodynamics and its relationship with the degree of stenosis, respectively. Furthermore, the circle of Willis and collateral pathways were investigated.2. Thirty-eight patients with unilateral CAO underwent CTP and DSA.The CBF、CBV、and TTP absolute values of both hemispheres were measured. We then calculated the CBF、CBV and TTP ratios (rCBF、rCBV、rTTP) by dividing the mean values on the affected side by the mean values on the contralateral side. Two-tailed paired t tests were used to compare the mean perfusion parameter values in affected hemispheres with those in contralateral hemispheres. Wilcoxon rank sum test were used to compare the difference of the rCBF、rCBV、and rTTP between patients with and without secondary collateral.3. Twenty-two patients with unilateral ICA/MCA high-grade stenosis underwent percutaneous transluminal angioplasty and stent (PTAS). CTP was performed before and one week after the stent-placement procedure. The CBF、CBV、and TTP values were measured and compare the difference by two-tailed paired t tests. The rCBF、rCBV and rTTP before and after therapy were evaluated and comparied by two-tailed paired t tests and Wilconxon signed-rank test.RESULTS:1. In GroupⅠ, there were no significant differences in the values between the affected and contralateral sides. In GroupⅡ, CBF values remained stable and CBV values increased slightly with increasing degrees of stenosis, but showed no significant difference between the two sides; however, TTP values significantly increased in the affected hemispheres (t=2.83,P<0.05). In GroupⅢ, CBF values also remained stable and showed no significant difference between the affected hemispheres and the contralateral hemispheres, but CBV and TTP values were significantly increased in the affected hemispheres compared with the contralateral hemispheres (CBV:t=6.04,P<0.01; TTP:t=13.18,P<0.01). The rTTP was significantly correlated with the degree of stenosis (r=0.713, P<.01), whereas the CBV ratio was weakly correlated with the degree of stenosis (r=0.365, P <.01). In addition, Patients with an abnormal circle of Willis and multiple cerebrovascular stenosis lesions had marked increase in the rTTP, which aggravated the impairment of hemodynamics.2. In 38 patients with unilateral CAO, the CBF values remained stable and there were no significant differences in the values between the affected and contralateral sides (t=1.08,P=0.285). CBV and TTP values were significantly increased in the affected hemispheres compared with the contralateral hemispheres (CBV:t=5.27,P<0.01; TTP: t=10.11,P<0.01). The radio of CBV and TTP were significantly higher in patients with secondary collaterals than in patients with only primary collaterals (CBV:Z=2.32,p=0.020<0.05; TTP:Z=4.50,p<.001). The presence of any second collateral flow was associated with increased CBV and TTP ipsilateral to the occlusion in comparison with patients without second collateral flow.3. Before operation, there was significant heterogeneity of cerebral hemodynamics in patients with a unilateral ICA/MCA high-grade stenosis, with stable CBF value and increased CBV and TTP value in the hemisphere ipsilateral to the occlusion(CBV: t=2.10,P=0.048;TTP:t=4.83,P<0.000). After operation, a significant normalization of the perfusion parameters was observed after the stent-placement procedure, there were no significant differences in the CBV and TTP values between the affected and contralateral sides(CBV:t=0.34,P=0.737; TTP:t=0.80,P=0.432). In addition, there was statistically significant difference between the values of rCBV and rTTP before and after therapy (rCBV:t=2.22 P=0.038; rTTP:S=126.5 P<0.0001).CONCLUSIONS:1. CTP and angiography measurement provided an effective way to evaluate hemodynamics and angiographic data in patients with unilateral chronic MCA steno-occlusion. Most patients have stable hemodynamic constitutions, but those with multiple steno-occlusive lesions and an abnormal circle of Willis could have increased risk of ischemic events.2. There was significant heterogeneity of cerebral hemodynamics in patients with a unilateral CAO, with stable CBF value and increased CBV and TTP value in the hemisphere ipsilateral to the occlusion. In addition, the patterns of collateral pathways are important factors determining the severity of haemodynamic impairment. The presence of any second collateral flow was associated with serious impaired cerebral hemodynamics in comparison with patients without second collateral flow.3. CTP is a useful technique for the assessment of the hemodynamic modifications in patients with unilateral ICA/MCA high-grade stenosis. The quantitative evaluation of cerebral perfusion makes it are liable tool for the follow-up of patients who undergo PTAS.更多还原