急性缺血性卒中机械取栓患者CT灌注成像的应用研究

CT cerebral perfusion imaging for patients with mechanical thrombectomy in acute ischemic stroke

目的探讨脑CT灌注(CTP)成像评价急性缺血性卒中(AIS)机械取栓的应用价值。方法回顾性连续纳入2019年12月至2022年4月首都医科大学宣武医院急性卒中绿色通道收治的行机械取栓治疗的AIS患者。收集患者入院后一般资料,包括性别、年龄、入院距最后正常时间、基线美国国立卫生研究院卒中量表(NIHSS)评分、入院Alberta卒中项目早期CT评分(ASPECTS)等。收集手术相关资料,包括血管闭塞部位(颈内动脉和大脑中动脉M1段、M2段)、是否术前静脉溶栓、术后血管再通程度[改良脑梗死溶栓(mTICI)分级]以及术后患者临床预后情况。所有患者机械取栓治疗前及术后3 d内行头部CT平扫及CTP。通过CTP图像识别灌注异常区,灌注异常表现为缺血区域脑血流量(CBF)减低、伴或不伴脑血容量(CBV)减低,且对比剂平均通过时间(MTT)、达峰时间(TTP)、残余功能达峰时间(Tmax)延迟。比较手术前后灌注异常区范围及各灌注参数相对值[病变侧数值除以健侧数值,包括相对脑血流量(rCBF)、相对脑血容量(rCBV)、对比剂相对平均通过时间(rMTT)、相对达峰时间(rTTP)、残余功能相对达峰时间(rTmax)]。根据机械取栓术后CTP图像灌注异常范围的改变情况将患者分为灌注异常范围无改善组(灌注异常范围增大或无明显变化)、灌注异常范围减小组及灌注异常范围消失组。采用NIHSS评分评估机械取栓术后7 d或出院神经功能改变情况,将ΔNIHSS评分(基线NIHSS评分与术后7 d或出院NIHSS评分差值)>4分或术后7 d或出院NIHSS评分0~1分定义为NIHSS评分改善。临床结局为通过门诊或电话随访评估的术后90 d改良Rankin量表(mRS)评分,0~2分为预后良好,3~6分为预后不良。结果共纳入AIS患者67例,其中男42例,女25例;年龄34~97岁,平均(65±12)岁;入院距最后正常时间0~19 h,中位时间6(2,10)h;基线NIHSS评分4~26分,中位评分13(10,19)分;26例行静脉溶栓+机械取栓桥接治疗,41例仅行机械取栓治疗。经术中造影证实闭塞血管部位为颈内动脉19例,大脑中动脉M1段43例,大脑中动脉M2段5例。67例患者机械取栓术后即刻成功再通62例(92.5%),其中mTICI分级3级40例(59.7%),2b级22例(32.8%)。67例患者中59例(88.1%)术前CT平扫发现早期脑缺血征象;所有患者术前CTP均发现与临床表现相符合的脑灌注异常区,表现为CBF减低、伴或不伴CBV减低,且MTT、TTP、Tmax延迟。术后原灌注异常区rCBF、rCBV值较术前显著增高,rMTT、rTTP、rTmax值较术前显著减低,差异均有统计学意义(均P<0.05)。67例患者中,术后灌注异常范围无改善10例,灌注异常范围减小28例,灌注异常范围消失29例。灌注异常范围消失组患者术后7 d或出院NIHSS评分改善比例显著高于灌注异常范围无改善组(P=0.001)及灌注异常范围减小组(P=0.011)。灌注异常范围消失组术后90 d预后良好比例显著高于灌注异常范围无改善组及灌注异常范围减小组(均P<0.01)。结论CTP能够监测机械取栓治疗前后的脑血流动力学变化,可为评估治疗后脑血流灌注恢复程度提供一定的影像学依据。

Objective To explore the value of CT perfusion(CTP)in evaluating mechanical thrombectomy for patients with acute ischemic stroke.Methods Consecutive patients who were treated in the AIS Greenway Department of Xuanwu Hospital,Capital Medical University and underwent thrombectomy for AIS from December 2019 to April 2022 were analyzed retrospectively.General data were collected,including gender,age,time from last normal to admission,baseline National Institutes of Health stroke scale(NIHSS)score and admission Alberta stroke program early CT score(ASPECTS),etc.Data relative to thrombectomy were collected,including occlusion site(internal carotid artery,middle cerebral artery M1 and M2),whether intravenous thrombolysis before thrombectomy,postoperative vascular recanalization condition(evaluated by modified thrombolysis in cerebral infarction score[mTICI])and postoperative clinical outcome.Noncontrast CT and CTP were performed before thrombectomy and within 3 days after thrombectomy.Abnormal perfusion lesion was recognized based on the CTP imaging,presenting as cerebral blood flow(CBF)decreased,with or without cerebral blood volume(CBV)decreased,and mean transit time(MTT),time to peak(TTP)and time to maximum of the residual function(Tmax)delayed.The difference of abnormal perfusion lesion and the relative value of each perfusion parameter(calculated by dividing the value of affected side by the unaffected side,including relative cerebral blood flow[rCBF],relative cerebral blood volume[rCBV],relative mean transit time[rMTT],relative time to peak[rTTP]and relative time to maximum of the residual function[rTmax])before and after thrombectomy were compared.According to the changes of abnormal perfusion lesion on CTP imaging after thrombectomy,patients were divided into the group with abnormal perfusion lesion had no improvement(abnormal perfusion lesion increased or changed little),the group with abnormal perfusion lesion decreased and the group with abnormal perfusion lesion disappeared.The NIHSS score was used to evaluate 7-day after thrombectomy or discharged neurological function changes.NIHSS score improvement was defined asΔNIHSS score(baseline minus 7-day after thrombectomy or discharged NIHSS score)>4 or 7-day after thrombectomy or discharged NIHSS score 0-1.Clinical outcome was assessed by outpatient or telephone,the 90-day modified Rankin scale(mRS)score after thrombectomy was used.mRS 0-2 score was defined as good outcome,3-6 score was defined as poor outcome.Results 67 patients were included in this study,42 males and 25 females,with age 34-97 years old,the average age(65±12)years old.Time from last normal to admission 0-19 hours,the median time 6(2,10)hours.Baseline NIHSS score 4-26 score,the median score 13(10,19)score.26 cases received bridging with intravenous thrombolysis before thrombectomy and 41 patients received only thrombectomy.The occlusion site was confirmed with DSA during thrombectomy,19 cases with internal carotid artery,43 cases with middle cerebral artery M1 and 5 cases with middle cerebral artery M2.Immediate DSA after thrombectomy showed that successful recanalization was achieved in 62(92.5%)patients after thrombectomy,with 40 cases of mTICI 3 and 22 cases of mTICI 2b.Of the 67 patients,59(88.1%)showed early ischemic sign on noncontrast CT before thrombectomy.Abnormal perfusion lesion corresponding to clinical presentations were found in all 67cases on CTP before thrombectomy,including CBF decreased,with or without CBV decreased,and MTT,TTP and Tmax delayed.Compared with CTP before thrombectomy,rCBF and rCBV significantly increased,rMTT,rTTP,rTmax significantly decreased(all P<0.05)of the original abnormal perfusion lesion after thrombectomy.Of the 67 patients,abnormal perfusion lesion had no improvement in 10 cases,decreased in 28 cases and disappeared in 29 cases after thrombectomy.The group with abnormal perfusion lesion disappeared had a higher rate of 7-day after thrombectomy or discharged NIHSS score improvement than the group with abnormal perfusion lesion had no improvement(P=0.001)and decreased(P=0.011).The group with abnormal perfusion lesion disappeared had a higher rate of 90-day favorable outcome after thrombectomy than the group with abnormal perfusion lesion had no improvement and decreased(both P<0.01).Conclusion CTP can monitor hemodynamic changes before and after thrombectomy,providing certain imaging basis for evaluating the recovery of cerebral blood perfusion after treatment.