三维准连续动脉自旋标记技术中不同PLD值对单侧大脑中动脉狭窄或闭塞患者脑血流灌注的评估

Cerebral perfusion varieties using 3D pseudo-continuous arterial spin labeling with different PLD in patients with unilateral middle cerebral artery stenosis or occlusion

目的评估不同标记延迟时间(post labeling delay,PLD)状态下脑血流灌注的差异及临床价值。材料与方法搜集单侧大脑中动脉(middle cerebral artery,MCA)严重狭窄或闭塞患者30例,行常规MRI、三维时间飞跃法磁共振血管成像(three-dimensional time of flight magnetic resonance angiography,3D-TOF-MRA)、扩散加权成像(diffusion weighted imaging,DWI)以及三维准连续动脉自旋标记技术(three-dimensional pulsed continuous arterial spin labeling,3D pCASL)(PLD=1.5 s,2.5 s)序列扫描。根据表观扩散系数(apparent diffusion coefficient,ADC)信号改变分为DWI(+)组和DWI(-)组。2名观察者测量DWI(+)组梗死灶及DWI(-)组责任侧MCA供血区脑血流量(cerebral blood flow,CBF)值、ADC值,低灌注及DWI高信号面积相对值,16例患者具有NIHSS评分。使用ICC检验结果一致性,χ~2检验分析低灌注检出率差异;独立样本t检验、配对样本t检验分析组间CBF值、组内CBF值及面积相对值差异;Pearson及Spearman相关法分析CBF值与ADC值、NIHSS评分的相关性。结果 2名观察者的测量结果一致性良好(ICC=0.98,P<0.05)。所有患者、DWI(+)组、DWI(-)组CBF_(1.5)值均低于CBF_(2.5)值(t=-7.207,P=0.000;t=-7.071,P=0.000;t=-3.641,P=0.004)。DWI(+)组CBF_(1.5)值、CBF_(2.5)值、ADC值均低于DWI(-)组(t=-8.243,P=0.000;t=-5.536,P=0.000;t=-10.764,P=0.000)。PLD=1.5 s低灌注检出率高于PLD=2.5 s(χ~2=7.239,P=0.007),低灌注面积相对值大于PLD=2.5 s(0.59±0.11,0.21±0.09,t=4.200,P=0.006)。DWI(+)组高信号面积相对值为0.12±0.05,小于PLD=1.5 s低灌注面积相对值,但与PLD=2.5 s时无显著差异(t=4.622,P=0.001;t=2.282,P=0.71)。DWI(+)组CBF_(2.5)值和ADC值呈中度正相关,CBF_(1.5)值和NIHSS评分呈中度负相关(r=0.50,P=0.035;r=-0.55,P=0.028)。结论PLD=1.5 s对低灌注敏感,显示缺血面积较大,与临床状态具有较好的一致性;PLD=2.5 s、PLD=1.5 s联合应用能更好地评估侧支循环。

Objective To assess the differences of different postlabeling delay （PLD） state of cerebral blood perfusion and clinical value. Materials and Methods： Patients with unilateral middle cerebral artery stenosis or occlusion were collected （n=30）, who underwent MRI, three-dimensional time of flight magnetic resonance angiography （3D-TOF-MRA）, diffusion weighted imaging （DWI） and three-dimensional pulsed continuous arterial spin labeling （3D pCASL） （PLD=1.5 s, PLD=2.5 s） scanning. All patients were divided into DWI （＋） and DWI （-） according to ADC value. Cerebral blood fow （CBF） values （CBF1.5, CBF2.5） and ADC values of lesions in DWI （＋） and MCA territory in responsible side in DWI （-） were measured by two observers, the relative areas of low perfusion and high DWI signal region were further calculated and NIHSS scores were recorded （n=16）. ICC was used to assess the consistency between the two measurers; the difference of low perfusion detection rate was analyzed by Chi-square test, the differences of CBF values between two groups were analyzed by independent sample t test, the differences of CBF values in a group and then the relative areas were analyzed by paired sample t test. Pearson and Spearman correlation analysis were used to analyze the correlation between CBF values vs. ADC values and NIHSS scores. Results： The good consistency was acquired between the two measurers （ICC=0.98, P〈0.05）. CBF1.5 values were lower than those of CBF2.5 in all patients or DWI （＋） or DWI （-） （t=-7.207, P=0.000. t=-7.071, P=0.000. t=-3.641, P=0.004）. Compared with DWI （-）, CBF1.5 values and CBF2.5 values and ADC values of DWI （＋） were decreased （t=-8.243, P=0.000. t=-5.536, P=0.000, t=-10.764, P=0.000）. The detection rate of low perfusion was higher and the relative area value of low perfusion was larger with PLD=1.5 s than 2.5 s （χ2=7.239, P=0.007. 0.59±0.11, 0.21±0.09, t=4.20, P=0.006）. The relative areas of high signal was 0.12±0.05 in DWI （＋）, which was lower than those of low perfusion with PLD=1.5 s, but not differed to those with PLD=2.5 s （t=4.622, P=0.001. t=2.282, P=0.71）. There was moderate positive correlation between CBF2.5 values and ADC values in DWI （＋） group, moreover there was a moderate negative correlation between CBF1.5 values and NIHSS scores （r=0.50, P=0.035. r=-0.547, P=0.028）. Conclusions： PLD of 1.5 s is sensitive to hypoperfusion and shows large ischemic area, which is in good consistency with clinical status. The combined application of PLD of 2.5 s and 1.5 s is better to assess collateral circulation.