Direct comparison of local cerebral blood flow rates measured by MRI arterial spin-tagging and quantitative autoradiography in a rat model of experimental cerebral ischemia
Direct comparison of local cerebral blood flow rates measured by MRI arterial spin-tagging and quantitative autoradiography in a rat model of experimental cerebral ischemia
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DOI：
10.1097/01.wcb.0000046147.31247.e8
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发表时间：
2003-02-01
影响因子：
6.3
通讯作者：
Fenstermacher, JD
中科院分区：
文献类型：
--
作者：
Ewing, JR;Wei, L;Fenstermacher, JD
本研究使用两种不同的磁共振成像（MRI）动脉自旋标记（AST）方法和c -14-碘安替比林（IAP）定量放射自显像（QAR）测定大鼠的脑血流量（CBF）， QAR是一种用于成像和定量CBF的标准但终末技术，并比较所得数据集以评估不同技术的精度和准确性。8只大鼠经腔内缝合永久性闭塞大脑中动脉（MCA）造成脑缺血2小时后，使用单线圈AST在2.0 mm冠状面切片上测量MRI-CBF，并通过自旋回波（SE）或可变尖角梯度回波（VTA-GE）读数评估组织磁化。随后（类似于MCA闭塞后2.5小时），用血流指标C-14-IAP用QAR测定CBF，产生沿喙尾轴每0.4 mm局部血流率的冠状图像。选择跨越2毫米MRI切片的IAP-QAR图像，通过传统方法（涉及读者互动和避免切片伪影）和全膜扫描技术（以最小的用户偏差近似整个MRI切片中的总放射性）测量区域流率（即局部CBF [ICBF]）并在这组图像中平均。在比对和共配后，对两个QAR方法和两个AST方法产生的CBF率在每个半球的9个感兴趣区域进行一致性检查。传统的组织放射性分析方法的QAR-ICBF率高于mri模拟方法，尽管两组率高度相关，但散点很广。由于这三种方法在组织“采样”方面的相似性，因此选择用全膜扫描技术获得的流速作为后续与MRI-CBF结果的比较。正如之前的模型所预测的那样，QAR-ICBF给出的“真实”流量往往略低于SE测量的流量，明显低于VTA-GE评估的流量。当同时考虑缺血半球和对侧半球时，SE-CBF和VTA-GE-CBF均与QAR-ICBF高度相关（P < 0.001）。然而，如果通过流量范围进行评估，则在高流量（对侧）区域（cbfbb0 ~ 80ml）估计SE-CBF更准确。100g（-1）。min(-1))，而VTA-GE-CBF值在低流量（同侧）区域（CBF小于或等于60 mL）更准确。100g（-1）。分钟(1))。因此，同时使用两种AST-MRI方法或单独使用VTA-GE技术将是首选的人类中风研究方法。
The present study determined cerebral blood flow (CBF) in the rat using two different magnetic resonance imaging (MRI) arterial spin-tagging (AST) methods and C-14-iodoantipyrine (IAP)-quantitative autoradiography (QAR), a standard but terminal technique used for imaging and quantitating CBF, and compared the resulting data sets to assess the precision and accuracy of the different techniques. Two hours after cerebral ischemia was produced in eight rats via permanent occlusion of one middle cerebral artery (MCA) with an intraluminal suture, MRI-CBF was measured over a 2.0-mm coronal slice using single-coil AST, and tissue magnetization was assessed by either a spin-echo (SE) or a variable tip-angle gradient-echo (VTA-GE) readout. Subsequently (similar to2.5 hours after MCA occlusion), CBF was assayed by QAR with the blood flow indicator C-14-IAP, which produced coronal images of local flow rates every 0.4 mm along the rostral-caudal axis. The IAP-QAR images that spanned the 2-mm MRI slice were selected, and regional flow rates (i.e., local CBF [ICBF]) were measured and averaged across this set of images by both the traditional approach, which involved reader interaction and avoidance of sectioning artifacts, and a whole film-scanning technique, which approximated total radioactivity in the entire MRI slice with minimal user bias. After alignment and coregistration, the concordance of the CBF rates generated by the two QAR approaches and the two AST methods was examined for nine regions of interest in each hemisphere. The QAR-ICBF rates were higher with the traditional method of assaying tissue radioactivity than with the MRI-analog approach, although the two sets of rates were highly correlated, the scatter was broad. The flow rates obtained with the whole film-scanning technique were chosen for subsequent comparisons to MRI-CBF results because of the similarity in tissue "sampling" among these three methods. As predicted by previous modeling, "true" flow rates, assumed to be given by QAR-ICBF, tended to be slightly lower than those measured by SE and were appreciably lower than those assessed by VTA-GE. When both the ischemic and contralateral hemispheres were considered together, SE-CBF and VTA-GE-CBF were both highly correlated with QAR-ICBF (P < 0.001). If evaluated by flow range, however, SE-CBF estimates were more accurate in high-flow (contralateral) areas (CBF > 80 mL . 100 g(-1) . min(-1)), whereas VTA-GE-CBF values were more accurate in low-flow (ipsilateral) areas (CBF less than or equal to 60 mL . 100 g(-1) . min(-1)). Accordingly, the concurrent usage of both AST-MRI methods or the VTA-GE technique alone would be preferred for human studies of stroke.