双参数3D-ASL在单侧大脑中动脉慢性闭塞的侧支循环评估中的应用价值分析

Double-parameter three-dimension arterial spin labeling to evaluate collateral circulation in patients with unilateral chronic middle cerebral artery occlusion

目的探讨双参数3D动脉自旋标记灌注成像（3D-ASL）在单侧大脑中动脉（MCA）慢性闭塞患者的侧支循环评估中的应用价值。方法采用3．0TMRj扫描仪，对烟台山医院神经内科自2015年5月至2017年11月收治的24例单侧MCA慢性闭塞患者行MRI常规序列、弥散加权成像（DWI）、三维时间飞跃法MRI血管成像（3D-TOF．MRA）及3D．ASL[标记后延迟时间（PLD）分别采用1．5s、2．5s]检查，测量MCA闭塞侧皮层区感兴趣区及对侧正常脑组织脑血流量（Ct3V）值，并采用统计学方法分析3D-ASL（PLD=I．5s1与3D-ASL（PLD=2．5s）测量的CBF值的差异。结果在24例单侧MCA慢性闭塞患者中，3D．ASL（PLD=1．5s）均显示MCA闭塞侧供血区呈明显低灌注．而3D-ASL（PLD=2．5s、显示两侧大脑半球MCA供血区脑灌注基本一致，未见明显低灌注。3D-ASL（PLD2．5x-PLD1．5s）减影图像显示MCA闭塞侧皮层区存在片状高信号区。3D-ASL（PLD=2．5s）与3D-ASL（PLD=1.5s）测量的对侧正常脑组织的CBF值[（56．39±5．01）mL／（100g·min）vs．（55．87±6．89）mL／000g·min）]差异无统计学意义（胗0．05）；3D-ASL（PLD=1．5s）测量的MCA闭塞侧皮层区感兴趣区的CBF值[（23．34±4．53）mL／000g·min）]较对侧正常脑组织[（55．87±6．89）mL／000g·min）]明显降低，差异有统计学意义（P〈0．05）；3D-ASL（PLD=2．5s）测量的MCA闭塞侧皮层区感兴趣区的CBF值[（53．93±8．59）mE／（100g·min）]较3D-ASL（PLD=1．5s）[（23．34±4．53）mL／000g·min）]明显升高，差异有统计学意义（P〈0．05），但其与3D-ASL（PLD=2．5s）测量的对侧正常脑组织的CBF值比较差异无统计学意义（P〉0．05）。结论3D-ASL采用PLD=1.5s与PLD=2．5S成像能够无创、直观地评估单侧MCA慢性闭塞患者的侧支循环，其中3D-ASL（PLD=1.5s）能够反映出患者建立了一级侧支循环代偿，3D-ASL（PLD=2．5s）能够准确反映患者建立了二级侧支循环代偿。

Objective To explore the application of double-parameter three-dimension arterial spin labeling （3D-ASL） in evaluating collateral circulation in patients with unilateral chronic middle cerebral artery （MCA） occlusion. Methods From May 2015 to November 2017, 24 patients with unilateral chronic MCA occlusion were scanned in Yantaishan Hospital by conventional MRI, DWI, 3D-TOF-MRA and 3D-ASL （post-labeling delays： 1.5 s and 2.5 s respectively） using a 3.0 T MR scanner. The cerebral blood flow （CBF） values were measured in region of interest in the occlusive cortical area and in the contralateral normal cerebral area. The differences in CBF value measured by 3D-ASL （PLD=1.5 s and PLD=2.5 s） were analyzed by statistical methods. Results All the patients （n=24） on 3D-ASL （PLD=1.5 s） presented with apparent hypoperfusion in the MCA occlusion territory; but 3D-ASL （PLD=2.5 s） demonstrated the basically same perfusion in bilateral MCA territories, without apparent hypoperfusion in one cerebral hemisphere. The subtraction images of 3D-ASL （PLD 2.5 s-PLD 1.5 s） presented laminated high signal areas in the cortical region of MCA occlusion. There was no statistically significant difference in CBF value of the contralateral normal cerebral area between measurements by 3D-ASL （PLD=1.5 s） and by 3D-ASL （PLD=2.5 s） （6.39±5.01 mL/100 g.min versus 55.87±6.89 mL/100 g·min） （P〉0.05）. The CBF value of region of interest in the occluded cortical area （23.34±4.53 mL/100 g·min） was significantly lower than that in the contralateral normal cerebral area （55.87±6.89 mL/100 g·min） by 3D-ASL （PLD=1.5 s） （P〈0.05）. The CBF value of region of interest in the occluded cortical area （53.93±8.59 mL/100 g·min） by 3D-ASL （PLD=2.5 s） was significantly higher than that by 3D-ASL （PLD=1.5 s） （23.34±4.53 mL/100 g·min） （P〈0.05）. There was no statistically significant difference between the CBF value of region of interest in the occluded cortical area and that in the contralateral normal cerebral area by 3D-ASL （PLD=2.5 s） （P〉0.05）. Conclusions 3D-ASL （PLD=1.5 s and PLD=2.5 s） can noninvasively and intuitively demonstrate the collateral circulation compensation in patients with chronic MCA occlusion. 3D-ASL （PLD=1.5s） can reflect the first-order collateral circulation compensation while 3D-ASL （PLD=2.5 s） can reflect accurately the secondary collateral circulation compensation.