Data_Sheet_1_Perioperative cerebral blood flow measured by arterial spin labeling with different postlabeling delay in patients undergoing carotid endarterectomy: a comparison study with CT perfusion.XLSX

BackgroundArterial spin labeling (ASL) is a non-invasive technique for measuring cerebral perfusion. Its accuracy is affected by the arterial transit time. This study aimed to (1) evaluate the accuracy of ASL in measuring the cerebral perfusion of patients who underwent carotid endarterectomy (CEA) and (2) determine a better postlabeling delay (PLD) for pre- and postoperative perfusion imaging between 1.5 and 2.0 s.
MethodsA total of 24 patients scheduled for CEA due to severe carotid stenosis were included in this study. All patients underwent ASL with two PLDs (1.5 and 2.0 s) and computed tomography perfusion (CTP) before and after surgery. Cerebral blood flow (CBF) values were measured on the registered CBF images of ASL and CTP. The correlation in measuring perioperative relative CBF (rCBF) and difference ratio of CBF (DRCBF) between ASL with PLD of 1.5 s (ASL1.5) or 2.0 s (ASL2.0) and CTP were also determined.
ResultsThere were no significant statistical differences in preoperative rCBF measurements between ASL1.5 and CTP (p = 0.17) and between ASL2.0 and CTP (p = 0.42). Similarly, no significant differences were found in rCBF between ASL1.5 and CTP (p = 0.59) and between ASL2.0 and CTP (p = 0.93) after CEA. The DRCBF measured by CTP was found to be marginally lower than that measured by ASL2.0_1.5 (p = 0.06) and significantly lower than that measured by ASL1.5_1.5 (p = 0.01), ASL2.0_2.0 (p = 0.03), and ASL1.5_2.0 (p = 0.007). There was a strong correlation in measuring perioperative rCBF and DRCBF between ASL and CTP (r = 0.67–0.85, p < 0.001). Using CTP as the reference standard, smaller bias can be achieved in measuring rCBF by ASL2.0 (−0.02) than ASL1.5 (−0.07) before CEA. In addition, the same bias (0.03) was obtained by ASL2.0 and ASL1.5 after CEA. The bias of ASL2.0_2.0 (0.31) and ASL2.0_1.5 (0.32) on DRCBF measurement was similar, and both were smaller than that of ASL1.5_1.5 (0.60) and ASL1.5_2.0 (0.60).
ConclusionStrong correlation can be found in assessing perioperative cerebral perfusion between ASL and CTP. During perioperative ASL imaging, the PLD of 2.0 s is better than 1.5 s for preoperative scan, and both 1.5 and 2.0 s are suitable for postoperative scan.

背景：动脉自旋标记成像（Arterial spin labeling, ASL）是一种用于检测脑灌注的非侵入性技术，其检测准确性易受动脉转运时间影响。本研究旨在达成两个目标：其一，评估动脉自旋标记成像在颈动脉内膜切除术（Carotid endarterectomy, CEA）患者脑灌注检测中的准确性；其二，在1.5~2.0秒的区间内，为术前后脑灌注成像筛选更优的标记后延迟时间（Postlabeling delay, PLD）。
方法：本研究共纳入24例因重度颈动脉狭窄拟行CEA的患者。所有患者分别于术前及术后，采用两种PLD（1.5秒与2.0秒）的ASL技术以及CT灌注成像（Computed tomography perfusion, CTP）进行扫描。对配准后的ASL与CTP脑血流量（Cerebral blood flow, CBF）图像进行脑血流量数值提取。同时分析分别采用PLD为1.5秒的ASL（记为ASL1.5）、PLD为2.0秒的ASL（记为ASL2.0）与CTP检测围手术期相对脑血流量（Relative CBF, rCBF）及脑血流量差值比（Difference ratio of CBF, DRCBF）时的相关性差异。
结果：术前检测rCBF时，ASL1.5与CTP的检测结果无显著统计学差异（p=0.17），ASL2.0与CTP的检测结果亦无显著统计学差异（p=0.42）。CEA术后，ASL1.5与CTP的rCBF检测结果仍无显著差异（p=0.59），ASL2.0与CTP的rCBF检测结果同样无显著差异（p=0.93）。经CTP检测得到的DRCBF略低于ASL2.0_1.5的检测结果（p=0.06），且显著低于ASL1.5_1.5（p=0.01）、ASL2.0_2.0（p=0.03）及ASL1.5_2.0（p=0.007）的检测结果。ASL与CTP在围手术期rCBF及DRCBF的检测中呈现较强相关性（r=0.67~0.85，p<0.001）。以CTP作为参考标准，术前检测rCBF时，ASL2.0的偏倚（-0.02）小于ASL1.5的偏倚（-0.07）。术后检测时，ASL2.0与ASL1.5的偏倚均为0.03，二者表现相当。ASL2.0_2.0（0.31）与ASL2.0_1.5（0.32）在DRCBF检测中的偏倚相近，且均小于ASL1.5_1.5（0.60）与ASL1.5_2.0（0.60）的偏倚。
结论：ASL与CTP在围手术期脑灌注评估中具有较强的相关性。在围手术期ASL成像中，术前扫描选用2.0秒的PLD要优于1.5秒；而术后扫描则1.5秒与2.0秒的PLD均适用。