【作者】 陈涓；

【导师】 陈敏；

【作者基本信息】 北京协和医学院 ， 影像医学与核医学， 2013， 博士

【摘要】 目的本研究试图运用全脑覆盖的动态容积4D CT血管造影及CT灌注(4DCTP-CTA)技术及磁共振动脉自旋标记(Arterial Spin Labeling, ASL)技术,对不同时期不同程度的缺血性脑卒中患者的脑灌注状态、侧支循环情况做出评价,并结合随访的影像学检查及临床评分对其预后进行预测；同时对两种检查方法进行比较。方法对63例临床拟诊缺血性脑血管病的患者,在发病的不同阶段(超急性期～亚急性期)进行CT平扫及动态容积4D CTP-CTA检查。以20%为阈值,根据rCBF或rCBV的程度将患者分为3组,高灌注(患侧与健侧rCBF或rCBV比值>120%),正常灌注(患侧与健侧rCBF或rCBV比值在80%～120%)和低灌注组(患侧与健侧rCBF或rCBV匕值<80%)。45例患者在4D CTP-CTA检前后的0.5小时～3天进行了磁共振成像(包括磁共振常规成像序列、磁共振扩散加权成像及磁共振血管成像),其中15例行ASL灌注成像。40例患者在最初检查后的14-30天进行CT或MRI影像学随诊,其中28例行头颅CT平扫,12例行头颅MRI平扫。41例患者在初诊时由有经验的神经科医师进行NIHSS评分。分析不同程度的灌注结果,并与NIHSS评分进行相关性检验,结合临床对其预后进行分析。结果(1)本组4D CTP-CTA诊断缺血性病变的敏感性93.44%,特异性100%；(2)4D CTP-CTA可以有效地显示全脑病变,包括幕下病变及侧脑室体部以上平面的病变及腔隙性缺血灶；(3)患侧与健侧rCBF比值<56%时,均发生脑梗死；患侧与健侧rCBV比值>80%者,临床预后较好,梗死灶面积较小；一侧半球大面积缺血时,NIHSS评分明显高于其他组(P<0.01),且预后较差；(4)缺血范围较大累及一侧半球多个解剖层面时,CTA常可发现责任血管狭窄/闭塞,达到96.4%(27/28例)；(5)侧枝循环良好的患者,梗死面积小,临床预后较好；(6)本组15例患者接受了ASL检查,其中1例4D CTA-CTP发现血管发育异常, CTP表现为双侧大脑中动脉供血区TTP延长,ASL未见异常；2例TIA患者,CTP-CTA阴性,ASL灌注阴性。其余12例为缺血性卒中患者。本组数据显示延迟时间1500ms为最佳采集时间点,13/15例(86.67%)患者在这个时间点CBF图像质量及分辨率最好,2/15例(13.33%)患者在2000ms时间点CBF图像质量及分辨率最好。12例中1例桥脑梗塞CTP灌注阴性,ASL灌注阴性；1例右侧脑室旁腔隙梗塞灶,CTP阴性,ASL阴性；另外10例中4例为大面积缺血累及2个以上解剖层面,CTP及ASL均为阳性；另外6例患者缺血灶面积较小,仅累及1个解剖层面,CTP阳性,ASL阴性。4例ASL阳性患者中,3例ASL图显示CBF减低,1例CBF升高,检查的敏感性仅为33.33%,特异性为100%。4例ASL阳性患者的CTP-CBF值与ASL-CBF值无统计学差异(P=0.025)。结论(1)4D CTP-CTA灌注对缺血性脑血管病诊断的敏感性及特异性较高,可作为急诊的常规检查。(2)一站式全脑动态容积CTP-CTA成像使得CT第一次实现全脑动态成像,准确判断缺血后脑组织各期的血液动力学变化,结合动态CTA,提高了显示脑血液动力学病理变化的能力,是一种可靠的脑血管病影像学检查方法,可以为临床制定有针对性的个体治疗方案,提供更准确、全面的影像学依据。相对于以往其他CT灌注的主要优势在于：(a)覆盖范围增大,达到全脑覆盖；(b)CTP扫描的同时得到CTA的信息,缩短了扫描时间,且无需注射额外的对比剂；(c)CTA可以动态三维显示从纯动脉期到纯静脉期及期间任意时相的血流状况；(d)一站式扫描大大降低了患者所受的辐射剂量。(3)4D CTP-CTA技术,时间分辨率大大提高,可以显示各个时项的血流状态,有望成为替代DSA显示侧枝血管的新型影像手段,是评价侧枝循环及脑灌注状态的切实可行的,可靠的和有效的方法,提高人们对侧枝循环病理生理特征的理解。(4)关于静脉窦血栓及血管畸形的CTP表现,有待大样本量的进一步研究。(5)本组试验由于客观条件限制,采用大孔径1.5T MR扫描仪获得的ASL图像分辨率不及CTP图像,且扫描时间较长。但是对于面积较大的病变,且患者存在碘过敏等禁忌症及肾功能不良者,ASL技术仍然是个不错的选择。更多还原

【Abstract】 Object This study attempts to evaluate varying degrees of cerebral perfusion status and collateral circulation perfusion situation in different periods of patients with ischemic stroke by using dynamic volume of the whole brain coverage4D CT angiography and CT perfusion (4D CTP-CTA) technology and magnetic resonance arterial spin labeling (Arterial Spin Labeling, ASL) technology. We also tried to predict clinical prognosis by using4D CTP-CTA and ASL when combining with follow-up imaging studies and clinical score. The correlation of these two methods was also analyzed.Methods63patients of clinical diagnosis of ischemic cerebrovascular disease in different stages of the onset (hyperacute to subacute) undertook CT scan and dynamic volumetric4D CTP-CTA. By using threshold of20%, the patients were divided into3groups according to the degree of rCBF, hyperperfusion (ipsilateral and contralateral the rCBF ratio>120%), and iso-perfusion (ipsilateral and contralateral rCBF ratio in the80%to120%) and lower perfusion group (ipsilateral and contralateral rCBF ratio <80%).45patients undertook magnetic resonance imaging (including conventional magnetic resonance imaging sequences, magnetic resonance diffusion weighted imaging and magnetic resonance angiography) before and after the0.5hours to3days of4D CTP-CTA.15of them undertook ASL perfusion imaging as well. CT or MRI imaging followed up40patients14to30days after the initial examination.28of them had routine head CT scan, and12of them had cranial MRI scan.41patients had initial NIHSS score by an experienced neurologist. Analysis of the results of different degree of perfusion, and clinical situation were analyzed.Results (1) Sensitivity of4D CTP-CTA was93.44%, with specificity of100%;(2)4D CTP-CTA can effectively show the whole brain lesions, including the infratentorial lesion and the lesions above the ventricle, even for lacunar ischemic lesions;(3) Brain tissue is likely to infarct when rCBF<56%; and it is likely to survive when rCBV>80%, and with small infarct and good prognosis. When large area of ischemia involved unilateral hemisphere, patients with high NIHSS and bad prognosis (P<0.01);(4) When large area of ischemia involved multiple level of unilateral hemisphere, the corresponding arteries were usually stenosis or occlusion, 96.4%(27/28) in our study;(5) Patients with good collateral circulation infarct size and better clinical outcomes;(6) In this study,15patients undertook ASL imaging. One of them showed vascular dysplasia on4D CTA with prolonged TTP on CTP but normal on ASL. Two cases of TIA showed normal on both4D CTP-CTA and ASL. The remaining12cases were ischemic stroke patients. For three delay time points,1500ms was the best for images acquisition and showed better CBF image quality in13/15patients (86.67%).2000ms was the best for2/15patients (13.33%). ASL was negative in8patients with1of pontine infarct,7of lacunar infarct. Four cases were positive finding with3showed reduction of CBF1showed increased CBF. The sensitivity was33.33%and specificity was100%. The CTP-CBF value was no significant different with that of ASL.Conclusion (1)4D CTP-CTA of ischemic cerebrovascular disease diagnostic is sensitive and specific, which can be used as emergency routine examination.(2) a one-stop whole cerebral dynamic volume CT dynamic imaging accurately determine the ischemic brain tissue of hemodynamic changes, combined with the dynamic the CTA, displays cerebral hemodynamic changes. It is a reliable and helpful imaging examination method in clinical individual treatment program, providing more accurate and comprehensive imaging evidence. The advantage of4D CTP-CTA were:(a) the coverage was enlarged when compared with other previous CT perfusion increases, reaches the whole brain coverage;(b) the CTP scanned while shortening the scanning time, and without additional injection of contrast agent;(c)4D CTP-CTA technology, with great time resolution, can display blood flow from pure arterial phase to the pure venous phase and any phase between them;(d) a one-stop scanning greatly reduce patient radiation dose.(3)4D CTA can be used to display collateral vessels, which is expected to be a new image means to replace DSA to evaluate collateral circulation, and to improve people’s understanding of the pathophysiological characteristics of the collateral circulation.(4) As for CTP manifestations of venous sinus thrombosis or vascular malformations, pending further study of larger sample is needed.(5) In this study,1.5T MR scanners was used to acquire ASL image, results in low resolution compared with CTP. But for the patients with larger lesions and patients with iodine allergy the contraindication and renal dysfunction, ASL still is a good choice.更多还原