多期CT血管成像对急性缺血性卒中血管内治疗短期预后的价值

目的：探讨多期CT血管成像对急性缺血性卒中（AIS）血管内治疗短期预后的价值。方法：回顾性分析183例接受血管内治疗的AIS患者,按随访90 d改良Rankin量表（mRS）评分分为预后良好（mRS评分≤2）组和预后不良（mRS评分>2）组。通过改良Tan评分评估多期CT血管成像显示的侧支循环情况,侧支循环不良为闭塞大脑中动脉区域的侧支循环小于对侧1/2,侧支循环良好为闭塞大脑中动脉区域的侧支循环大于对侧1/2。采用多变量logistic回归,曲线下面积（AUC）评价模型性能,DeLong检验比较AUC间的差异。结果：Logistic回归显示,较低入院NIHSS评分和动脉晚期侧支循环良好是AIS患者短期预后良好的独立预测因素,AUC分别为0.72 (0.65～0.79)和0.75 (0.68～0.81)。两者联合时AUC可达0.79,显著高于单一预测因素（DeLong检验,均P<0.05）。结论：动脉晚期侧支循环良好和较低入院NIHSS评分是血管内治疗短期预后良好的独立预测因素。联合预测模型具有较高的诊断效能,可为临床治疗方案选择提供参考。     

软脑膜侧支吻合程度与预后相关性研究

目的探讨大脑中动脉M1段闭塞所致急性脑梗死患者软脑膜侧支吻合程度与临床预后的相关性。方法选取大脑中动脉M1段闭塞所致急性脑梗死患者82例,均于起病3 d内行头磁共振血管造影(MRA)检查,10 d内行头血管造影(DSA)或CT血管造影(CTA)检查。根据头DSA或CTA检查结果对患者软脑膜侧支吻合程度进行评分,再根据评分将患者分为两组,其中,侧支循环较好组(评分1~2分)患者35例,侧支循环较差组(评分3~5分)患者47例。电话随访3个月,分别记录并比较两组患者的改良兰金评分量表(mRS)评分。采用Logistic回归分析预后与mRS评分的影响因素,Spearman相关性分析软脑膜侧支吻合评分与mRS评分的相关性。结果侧支循环较好组的mRS评分为(0.92±0.83)分,侧支循环较差组mRS评分为(3.25±1.01)分,两组比较,差异有统计学意义(t=14.770,P<0.05)。美国国立卫生研究院卒中量表(NIHSS)评分与软脑膜侧支吻合评分是预后的影响因素(P<0.05);NIHSS评分、软脑膜侧支吻合评分、吸烟史及同型半胱氨酸是mRS评分的影响因素,其中,NIHSS评分与软脑膜侧支吻合评分是危险因素(P<0.05)。软脑膜侧支吻合评分与mRS评分存在正相关(r=0.868,P<0.05)。结论大脑中动脉M1段闭塞所致急性脑梗死患者的软脑膜侧支吻合评分越低,软脑膜侧支吻合程度越高,其临床预后越好。     

MRI高信号血管征不同评估系统与软脑膜侧支循环的相关性分析及效能评价

目的 探讨MRI高信号血管征(HVS)与急性脑梗死(ACI)区域软脑膜侧支评分(r LMC)的相关性及其评估效能。方法 分析发病3天内完成头颅MRI及CTA检查的71例ACI患者,对CTA行r LMC,对HVS行位置(HVS-position)、数量(HVS-count)、范围(HVS-area)评分,分析两者的相关性。ROC曲线检验HVS各评估系统单独及联合评估侧支循环的效能。结果 HVS-count、HVS-area与CTA r LMC呈正相关,且HVS-area(r=0.416,P=0.000)效能高于HVS-count(r=0.321,P=0.006); HVS-position与CTA r LMC呈正相关(r=0.180,P=0.133),但未达统计学意义。HVS-position、HVS-count、HVS-area联合评估侧支循环(AUC=0.904)的效能优于单项(AUC=0.622～0.834)或相互联合评估(AUC=0.820～0.885)。结论HVS-area评估软脑膜侧支循环的价值较高,HVS多评估系统的联合运用可提高量化软脑膜侧支循环的评估效能。     

动脉自旋标记成像对轻中度急性脑梗死侧支代偿显示的临床应用价值

目的 :探讨MRI动脉自旋标记(ASL)成像对轻中度急性脑梗死侧支代偿状态及近期预后的临床评估价值。方法 :收集经临床和影像学证实且未经溶栓治疗的35例急性期轻中度缺血性脑卒中患者,采用GE 3.0 T超导MRI扫描仪行常规和三维伪连续式标记(3D-PCASL)序列检查,根据脑血流量伪彩图提示梗死核心区周围是否出现匍匐走行、条状高灌注信号,将35例分为侧支代偿组和对照组,分别对其入院当日与30 d行美国国立卫生研究院卒中量表(NIHSS)评分并分析比较。结果:2组入院当日NIHSS评分差异无统计学意义(P0.05),侧支代偿组入院当日及30 d临床NIHSS评分好转率、稳定率及进展率分别为76.47%(13/17)、17.65%(3/17)、5.88%(1/17);而对照组入院当日及30 d临床NIHSS评分好转率、稳定率及进展率分别为33.33%(6/18)、27.78%(5/18)、38.89%(7/18);2组近期预后NIHSS评分比较差异有统计学意义(P0.05)。结论 :通过ASL显示梗死核心区周围血液灌注信息反映侧支循环代偿状态,可为临床评估急性期缺血性脑卒中患者病情现状、近期预后及治疗方案的选择提供依据。     

一站式动态CTA结合CTP评估单侧大脑中动脉闭塞患者预后的价值

【摘要】目的：探讨第三代双源CT一站式全脑动态CT血管成像（dCTA）结合CT灌注成像（CTP）对单侧大脑中动脉（MCA）闭塞患者预后评估的价值。方法：搜集发病时间小于7天并行CTP检查的单侧MCA闭塞患者50例。根据出院时改良Rankin量表（mRS）分为预后良好组（mRS≤2分）和预后不良组（mRS＞2分）,分析软脑膜侧支循环、患侧/健侧灌注参数比值［相对脑血流量（rCBF）、相对脑血容量（rCBV）、相对平均通过时间（rMTT)、相对达峰时间（rTTP）］、入院美国国立卫生研究院卒中量表（NIHSS）评分及临床基线资料在预后评估中的价值。结果：预后良好组19例,预后不良组31例。dCTA软脑膜侧支循环与预后有显著相关性（τ＝0.616,P＜0.01）。预后良好与预后不良两组间各灌注参数比值、入院NIHSS评分、年龄、脑血管病史、房颤差异均有统计学意义（P值均＜0.05）。rCBF与rMTT、rTTP、年龄以及入院NIHSS评分与rCBV、rMTT、rTTP、年龄的ROC曲线下面积两两比较差异均有统计学意义（P值均＜0.05）。约登指数最高时rCBF最佳截断值为0.720,诊断敏感度100%,特异度80.6%,曲线下面积0.930。结论：一站式dCTA结合CTP能有效评估单侧MCA闭塞患者的侧支循环及脑血流灌注储备,软脑膜侧支循环代偿与预后呈正相关,rCBF对预后评估的诊断效能最佳。     

320排动态容积CT成像评估单侧大脑中动脉闭塞患者侧支循环的应用价值

目的 探讨320排动态容积CT全脑成像在评估单侧大脑中动脉(MCA)闭塞患者侧支循环中的应用价值及其对预后的评价作用.方法 纳入2011年3月至2015年9月在浙江省人民医院住院治疗的37例单侧症状性MCA闭塞患者.采用320排CT进行多参数全脑灌注扫描,获取常规CTA和4D-CTA图像,分析常规CTA、4D-CTA所示侧支循环状况和金标准DSA图像并作一致性检验,同时计算4D-CTA侧支循环评分与预后的相关性.结果 4D-CTA、常规CTA所示侧支循环良好患者分别为22例(59.4％)、14例(37.8％).以DSA为金标准,常规CTA、4D-CTA侧支循环评分Kappa值分别为0.58、0.78.4D-CTA所示侧支循环不良患者和侧支循环良好患者间治疗时间窗差异有统计学意义(t=2.27,P=0.029),两者侧支循环评分与随访90d改良Rankin量表评分呈负相关(r=-0.68,P＜0.001).结论 320排动态容积CT成像是评价单侧症状性MCA闭塞患者侧支循环建立情况的有效方法.4D-CTA比常规CTA能更好地评估侧支血流和预测预后,有助于血管内介入治疗决策.     

基于全脑灌注容积数据重建动态CTA对缺血性脑卒中侧支循环的评估价值分析

目的分析基于全脑灌注(CTP)容积数据重建动态CT血管成像(CTA)对缺血性脑卒中(AIS)侧支循环的评估价值。方法选取92例AIS患者(发病时间<6 h)的临床资料,均行全脑动态容积CTA-CTP检查。统计动态CTA下AIS侧支循环情况,分析侧支循环情况与梗死的相关性,并比较侧支循环良好与侧支循环不良组间灌注参数的差异情况。结果92例AIS患者均得到了良好的动态CTA图像,其中61例侧支循环良好(66.3%),31例侧支循环差(33.7%),每例患者头颅平扫及CTA-CTP检查的总辐射剂量范围为4.98~6.24 mSv,平均为5.87 mSv;CTA侧支循环评分与入院时基线梗死体积、低灌注区体积(Tmax>6 s)、严重低灌注区体积(Tmax>12 s)、核心梗死区不匹配比值及最终梗死体积呈负相关(r值分别为-0.469、-0.314、-0.429、-0.308、-0.445,P值分别为0.005、0.040、0.009、0.038、0.007);侧支循环不良组梗死核心体积(CVB<2 ml/100 g体积)、低灌注(Tmax>6 s)及严重低灌注区体积(Tmax>12 s)明显高于侧支循环良好组(均P<0.05),Tmax、HIR更大(均P<0.05),而侧支循环不良组核心梗死区与低灌注区不匹配比、rCBF、rCBV、rMTT值明显低于侧支循环良好组(均P<0.05)。结论基于全脑灌注容积数据重建动态CTA可较好地评估AIS患者侧支循环状态,可辅助预测临床预后。     

贝叶斯算法灌注参数对急性缺血性脑卒中患者侧支循环的评估价值

目的 评估贝叶斯算法灌注参数对急性缺血性脑卒中(AIS)患者侧支循环等级的预测效能，并进一步探索侧支循环等级与恶性水肿的相关性。方法 纳入75例前循环AIS患者资料，入院后行一站式CT检查，记录患者贝叶斯算法各灌注参数值。根据金标准DSA侧支循环评分分成良好侧支组和较差侧支组，比较两组间患者的临床基线及灌注各参数的特征。评估侧支循环等级与灌注参数之间的相关性，并确定灌注参数预测侧支循环的最佳截点；进一步探讨侧支循环等级预测患者脑恶性水肿的价值。采用Spearman相关分析评估各灌注参数与侧支等级的相关性；采用Kendall’s tau-b相关分析评估侧支循环与恶性水肿的相关性。通过受试者工作特征曲线分析确定最佳参数的阈值。结果 贝叶斯灌注参数DT在侧支循环良好组与较差组间具有显著差异(P<0.001),余参数与侧支循环等级无统计学差异。ROC分析显示延迟时间<2.098 s为最佳预测良好DSA侧支等级阈值。恶性水肿在侧支循环分组中差异具有统计学意义(P<0.05)。结论 贝叶斯灌注参数DT可作为预测患者侧支循环等级的生物学指标，延迟时间<2.098 s是预测良好...     

4D-CTA评估急性缺血性脑卒中静脉溶栓的价值

目的 探讨基于全脑灌注(CTP)模式下重建4D-CTA分型预测模型，评估急性缺血性脑卒中(AIS)实施静脉溶栓(IVT)及临床预后的价值。方法 连续性纳入AIS患者(发病1.5～48 h)170例，平扫CT后即行全脑CTP扫描并重建动脉早期至延迟期的4D-CTA图像，根据缺血区脑血管及相应期限脑实质密度动态变化将患者分为CT AI-IV型，并记录患者入院基线和出院的NIHSS评分。根据患者的治疗方式分为IVT组75例和双抗组95例，每组根据基线NIHSS评分和CTA分型进行建模，通过线性回归方法预测两组患者出院NIHSS评分和预后情况。结果 患者中IVT组75例，双抗组95例，线性回归发现两种治疗决策下的线性回归预测模型均显示基线NIHSS评分和CTA-Ⅱ、Ⅲ、Ⅳ型与出院的NIHSS评分存在显著线性差异。Ⅰ型仅可预测良好出院NIHSS评分结果。双抗组预测模型的相关系数明显优于IVT组(R2,0.925 vs 0.714,P<0.01)。结论 应用VHS模式下CTP扫描重建CTA分型可以预测AIS患者采取IVT和双抗治疗及临床预后。     

单期和多期CT血管造影评估缺血性脑卒中患者侧支状态与CT灌注参数的对比性研究

目的 对于急性缺血性脑卒中(AIS)大脑中动脉闭塞患者,比较单时相、多时相CT血管造影(sCTA、mC-TA)评估的侧支循环评分与定量灌注参数之间的关联性及在预测临床预后中的价值.方法 搜集2019年12月至2020年12月于急救中心行一站式CT检查的发病时间在24 h内的大脑中动脉闭塞患者的临床资料及影像学资料,从C...     

伴心房颤动急性脑梗死DWI分型与神经功能缺损程度的关系分析

目的 探讨伴心房颤动急性脑梗死扩散加权成像(DWI)分型和神经功能缺损程度的关系.方法 回顾性分析186例伴心房颤动急性脑梗死患者入院时早期DWI特征与其美国国立卫生研究院卒中量表(NIHSS)评分关系.结果 所有伴心房颤动急性脑梗死患者DWI均表现为高信号;其中前循环以单发皮层及皮层下梗死多见(94例,50.5%),后循环以多发梗死多见(18例,13.0%);左侧前循环皮层及皮层下梗死NIHSS评分(16.75±7.10)与右侧前循环皮层及皮层下梗死(13.50±5.70)差异有统计学意义(P<0.05);后循环多发梗死NIHSS评分(16.77±8.90)与较后循环皮层-皮层下梗死(6.38±2.03)差异有统计学意义(P<0.05).结论 伴心房颤动急性脑梗死DWI分型有助于脑梗死的病因诊断,结合NIHSS评分可以更好地评估疾病严重程度,为早期临床个体化治疗及预后判断提供依据.     

Angiographic assessment of pial collaterals as a prognostic indicator following intra-arterial thrombolysis for acute ischemic stroke

BACKGROUND AND PURPOSE: This study examines whether anatomic extent of pial collateral formation documented on angiography during acute thromboembolic stroke predicts clinical outcome and infarct volume following intra-arterial thrombolysis, compared with other predictive factors. METHODS: Angiograms, CT scans, and clinical information were retrospectively reviewed in 65 consecutive patients who underwent thrombolysis for acute ischemic stroke. Clinical data included age, sex, time to treatment, National Institutes of Health Stroke Scale (NIHSS) score on presentation of symptoms, NIHSS score at the time of hospital discharge, and modified Rankin scale score at time of hospital discharge. Site of occlusion, scoring of anatomic extent of pial collaterals before thrombolysis, and recanalization (complete, partial, or no recanalization) were determined on angiography. Infarct volume was measured on CT scans performed 24-48 hours after treatment. RESULTS: Fifty-three patients (82%) qualified for review. Both infarct volume and discharge modified Rankin scale scores were significantly lower for patients with better pial collateral scores than those with worse pial collateral scores, regardless of whether they had complete (P < .0001) or partial (P = .0095) recanalization. Adjusting for other factors, regression analysis models indicate that the infarct volume was significantly larger (P < .0001) and modified discharge Rankin scale score and discharge NIHSS score significantly higher for patients with worse pial collateral scores. Similarly, adjusting for other factors, the infarct volume was significantly lower (P = .0006) for patients with complete recanalization than patients with partial or no recanalization. CONCLUSIONS: Evaluation of pial collateral formation before thrombolytic treatment can predict infarct volume and clinical outcome for patients with acute stroke undergoing thrombolysis independent of other predictive factors. Thrombolytic treatment appears to have a greater clinical impact in those patients with better pial collateral formation.     

Assessment of Collateral Status by Dynamic CT Angiography in Acute MCA Stroke: Timing of Acquisition and Relationship with Final Infarct Volume

BACKGROUND AND PURPOSE:Dynamic CTA is a promising technique for visualization of collateral filling in patients with acute ischemic stroke. Our aim was to describe collateral filling with dynamic CTA and assess the relationship with infarct volume at follow-up.MATERIALS AND METHODS:We selected patients with acute ischemic stroke due to proximal MCA occlusion. Patients underwent NCCT, single-phase CTA, and whole-brain CT perfusion/dynamic CTA within 9 hours after stroke onset. For each patient, a detailed assessment of the extent and velocity of arterial filling was obtained. Poor radiologic outcome was defined as an infarct volume of ≥70 mL. The association between collateral score and follow-up infarct volume was analyzed with Poisson regression.RESULTS:Sixty-one patients with a mean age of 67 years were included. For all patients combined, the interval that contained the peak of arterial filling in both hemispheres was between 11 and 21 seconds after ICA contrast entry. Poor collateral status as assessed with dynamic CTA was more strongly associated with infarct volume of ≥70 mL (risk ratio, 1.9; 95% CI, 1.3–2.9) than with single-phase CTA (risk ratio, 1.4; 95% CI, 0.8–2.5). Four subgroups (good-versus-poor and fast-versus-slow collaterals) were analyzed separately; the results showed that compared with good and fast collaterals, a similar risk ratio was found for patients with good-but-slow collaterals (risk ratio, 1.3; 95% CI, 0.7–2.4).CONCLUSIONS:Dynamic CTA provides a more detailed assessment of collaterals than single-phase CTA and has a stronger relationship with infarct volume at follow-up. The extent of collateral flow is more important in determining tissue fate than the velocity of collateral filling. The timing of dynamic CTA acquisition in relation to intravenous contrast administration is critical for the optimal assessment of the extent of collaterals.

Collateral vessel status is an important predictor of final infarct size and clinical outcome in patients with a stroke due to acute proximal anterior circulation occlusions.^1,2 Leptomeningeal collaterals can provide a detour for blood to reach the ischemic territory of an occluded artery, thereby sustaining tissue at risk for a longer time.^1,3,4 DSA is considered the criterion standard for visualization of the collateral circulation. However, DSA is currently reserved for part of the thrombectomy procedures and has no role in the diagnostic work-up of patients with acute ischemic stroke.In clinical practice, imaging of collaterals is often performed with single-phase CTA. Single-phase CTA visualizes the cerebral circulation at only a single moment in time. The information captured in this snapshot depends on the timing of the CTA acquisition after contrast injection, which may lead to inaccurate estimation of the collateral circulation.^1,5,6 Dynamic CTA is increasingly investigated for the visualization of collaterals in acute ischemic stroke.^7–9 Dynamic CTA can be derived from CT perfusion datasets and provides time-resolved images of the arterial, parenchymal, and venous phases. Not only the extent but also the velocity of collateral filling can be evaluated with dynamic CTA.The aim of this study was to assess dynamic CTA as a method for imaging the collateral circulation in patients with acute ischemic stroke. We devised a grading system that gives information on the extent and velocity of pial arterial filling in a time-resolved manner. We compared this new method with collateral assessment on single-phase CTA in relation to infarct volume at follow-up.     

Effect of Collaterals on Clinical Presentation,Baseline Imaging,Complications, and Outcome in Acute Stroke

BACKGROUND AND PURPOSE:Good CTA collaterals independently predict good outcome in acute ischemic stroke. Our aim was to evaluate the role of collateral circulation and its added benefit over CTP-derived total ischemic volume as a predictor of baseline NIHSS score, total ischemic volume, hemorrhagic transformation, final infarct size, and a modified Rankin Scale score >2.MATERIALS AND METHODS:This was a retrospective study of 395 patients with stroke dichotomized by recanalization (recanalization positive/recanalization negative) and collateral status. Clot burden score was quantified on baseline CTA. Total ischemic volumes were derived from thresholded CTP maps. Final infarct size was assessed on follow-up CT/MRI. We performed uni-/multivariate analyses for each outcome, adjusting for rtPA status, using general linear (continuous variables) and logistic (binary variables) regression. Model comparison with collateral score and total ischemic volume was performed using the F or likelihood ratio test.RESULTS:Collateral presence independently and inversely predicted all outcomes except hemorrhagic transformation in patients who were recanalization negative and mRS >2 in patients who were recanalization positive. The greatest collateral benefit occurred in patients who were recanalization negative, contributing 16.5% and 19.2% of the variability for final infarct size and mRS >2. The collateral score model is superior to the total ischemic volume for mRS >2 prediction, but a combination of total ischemic volume and collateral score is superior for mRS >2 and final infarct prediction (24% and 28% variability, respectively). In patients who were recanalization positive, a model including collateral score and total ischemic volume was superior to that of total ischemic volume for hemorrhagic transformation and final infarct prediction but was muted compared with patients who were recanalization negative (11.3% and 16.9% variability).CONCLUSIONS:Collateral circulation is an independent predictor of all outcomes, but the magnitude of significance varies, greater in patients who were recanalization negative versus recanalization positive. Total ischemic volume assessment is complementary to collateral score in many cases.

In the setting of acute ischemic stroke, revascularization therapies are administered with the intent of salvaging ischemic penumbra by restoring antegrade flow.¹ Even though conventional angiography is considered the gold standard for collateral circulation assessment, CT angiography is increasingly used in triaging patients with acute stroke.²Growing evidence underscores the importance of the collateral circulation in maintaining the penumbra and predicting radiological and clinical response to revascularization.^3,4 Good CTA collaterals independently predict good outcome in acute ischemic stroke^1,2 and correlate with smaller admission infarct size.⁵ CTA collateral scoring demonstrates good interrater reliability^2,6–8; is widely available, including after-hours; and has the advantage of not requiring advanced postprocessing, which is subject to a host of technical differences.⁹ The best means of accurate collateral assessment is debated^1,10–13; however, irrespective of the method of assessment, collateral status significantly predicts clinical outcome and risk of infarct.^2,14,15 Limitations of collateral evaluation are that vessel opacification is time- and acquisition speed–dependent, indicating the need for time-invariant CTA imaging.^10,11 Additionally, the tissue perfusion status is not directly imaged in contradistinction to CT perfusion, in which penumbral prediction is well-studied.¹⁶A recent study suggested that a good clinical outcome could only be achieved in the presence of recanalization and good-to-intermediate collateral status. No effect was seen in patients without recanalization. Furthermore, the effect of other comorbid clinical (blood pressure, glycemic status, presence of vascular risk factors, and so forth) or radiological features (clot burden score [CBS], clot location, hemorrhagic transformation [HT]) was not considered in outcome determination.¹³ The relationship of collateral status and these other imaging and clinical stroke predictors, independent of recanalization status, for major outcomes is also not well-established in large acute stroke populations. Emphasis on collateral status has increased due to its recent inclusion in patient selection for endovascular treatment¹⁷; however, the added predictive value of collateral score (CS) over perfusion imaging assessment of total ischemia is not well-studied. We hypothesized that for a given recanalization status in the absence of perfusion availability, collateral determination significantly predicts baseline stroke severity (quantified by the baseline National Institutes of Health Stroke Scale score [bNIHSS]) and clinical (hemorrhagic transformation, 90-day modified Rankin Scale score of > 2) and radiological outcomes (final infarct volume). In the present study, we also sought to quantify the added value of a CS over CTP-estimated total ischemic volume (TIV). The added contribution was assessed independent of recanalization status and accounted for additional important clinical and imaging covariates in multivariate models.     

Intra-arterial thrombolysis using rt-PA in patients with acute stroke due to vessel occlusion of anterior and/or posterior cerebral circulation

Introduction The aim of our study was to evaluate the safety and efficacy of intra-arterial (IA) thrombolysis using recombinant tissue plasminogen activator (rt-PA) in patients with acute stroke due to occlusion in the anterior or posterior circulation. Methods We retrospectively analyzed the clinical and radiological data of 88 consecutive patients with acute ischemic stroke who underwent emergency cerebral angiography for the purpose of subsequent IA thrombolysis. The neurological deficit on admission and discharge was graded using the National Institutes of Health Stroke Scale (NIHSS) score. Baseline computer tomography (CT) scans were examined for any signs indicative of cerebral ischemia. The angiographic findings were classified according to the Thrombolysis in Myocardial Infarction (TIMI) score for myocardial infarction. Follow-up CT scans were examined for hemorrhagic complication. Results Of the 88 patients who underwent IA thrombolysis, 63 presented with complete or partial arterial occlusion in the suspected perfusion area. In these 63 patients, the median NIHSS score dropped from 15 points on admission to 10 points at discharge. The recanalization rate was 52.6% for partial and complete reperfusion. In-hospital mortality was 20.6% (9.1% for carotid, 44.4% for basilar territory occlusion). Intracerebral bleeding (ICB) occurred in 38.6% of the patients with occlusion in the anterior circulation, resulting in these patients presenting a worse clinical outcome than those without ICB. Only minor extracranial bleedings occurred in 20.6% of patients. Patients with ICB had a significantly higher frequency of ischemic signs on the baseline CT scan. Conclusion Occlusion of a cerebral artery is present in about 75% of the patients eligible for thrombolytic therapy. Intra-arterial thrombolysis using rt-PA in patients with acute ischemic stroke can achieve re-vascularization, although ICB remains the major risk factor affecting its efficacy.     

Role of recanalization in acute stroke outcome: rationale for a CT angiogram-based "benefit of recanalization" model

BACKGROUND AND PURPOSE: In acute middle cerebral artery (MCA) stroke, CT angiographic (CTA) source images (CTA-SI) identify tissue likely to infarct despite early recanalization. This pilot study evaluated the impact of recanalization status on clinical and radiologic predictors of patient outcomes.MATERIALS AND METHODS: Of 44 patients undergoing CT/CTA within 6 hours of developing symptoms of proximal MCA ischemia, 19 patients achieved complete proximal MCA (MCA M1) recanalization. Admission National Institutes of Health Stroke Scale (NIHSS) score, onset-to-imaging time, CTA-SI Alberta Stroke Program Early CT Score, MCA M1 occlusion, cerebrovascular collaterals score, and CTA-SI lesion volume were correlated with 3- to 6-month follow-up modified Rankin Scale (mRS). We developed 2 stepwise regression models: one for patients with complete MCA M1 recanalization and one for patients without complete recanalization.RESULTS: Complete and incomplete recanalization groups had similar median admission NIHSS scores (19 versus 19) and mean onset-to-imaging times (2.3 versus 1.9 hours) but different proportions of patients achieving mRS scores 0–2 (74% versus 40%; P = .04). The only independent predictors of clinical outcome in patients with complete recanalization were onset-to-imaging time and admission CTA-SI lesion volume (total model R² = 0.75; P = .01). The only independent predictors of outcome in patients with incomplete recanalization were admission CTA-SI lesion volume and NIHSS score (total model R² = 0.66; P = .007).CONCLUSION: Regardless of recanalization status, admission CTA-SI lesion volume was associated with clinical outcome. Recanalization status did, however, affect which variables in addition to CTA-SI volume significantly impacted clinical outcome: time with complete recanalization and NIHSS with incomplete recanalization. This finding may support the development of a model predicting the potential clinical benefit expected with early successful recanalization.

Identifying predictors of clinical outcome after thrombolytic therapy for acute ischemic stroke may improve patient selection. However, clinical examination and unenhanced CT, the current standards for admission evaluation, are limited in predicting which patients are likely to improve with or worsen without recanalization.^1–8 Although the predictive capabilities of imaging techniques, such as diffusion-weighted imaging (DWI), CT cerebral blood volume, xenon CT cerebral blood flow, positron-emission tomography, or transcranial Doppler sonography have been demonstrated,^9–14 patient and site-specific factors limit the widespread application of these technologies in the acute setting.Because CT is faster, less expensive, and more universally available than MR imaging, evidence supporting the accurate characterization of stroke physiology with advanced CT imaging could widely impact the management of patients with ischemic stroke.^15–18 The source images from the CT angiography (CTA) vascular acquisition provide clinically relevant data concerning tissue perfusion level. Theoretically, under an approximately steady-state level of contrast in the arterial and capillary vascular bed, CTA source images (CTA-SI) are weighted predominantly by blood volume rather than blood flow.^19–21 These CTA-SI, like DWI on MR imaging, have been shown to correlate with final infarct volume.²²We sought to characterize the role of admission CTA-SI and other relevant clinical variables in determining clinical outcome among acute stroke patients who undergo attempted recanalization. Because the success of recanalization is unknown at presentation and can impact clinical outcome, we divided patients a priori into 2 cohorts based on the degree of recanalization later achieved.     

The Impact of Arterial Collateralization on Outcome after Intra-Arterial Therapy for Acute Ischemic Stroke

BACKGROUND AND PURPOSE:Although intra-arterial therapy for acute ischemic stroke is associated with superior recanalization rates, improved clinical outcomes are inconsistently observed following successful recanalization. There is emerging concern that unfavorable arterial collateralization, though unproven, predetermines poor outcome. We hypothesized that poor leptomeningeal collateralization, assessed by preprocedural CTA, is associated with poor outcome in patients with acute ischemic stroke undergoing intra-arterial therapy.MATERIALS AND METHODS:We retrospectively analyzed patients with acute ischemic stroke with intracranial ICA and/or MCA occlusions who received intra-arterial therapy. The collaterals were graded on CTA. Univariate and multivariate analyses were used to investigate the association between the dichotomized leptomeningeal collateral score and functional outcomes at 3-months mRS ≤2, mortality, and intracranial hemorrhages.RESULTS:Eighty-seven patients were included. The median age was 66 years (interquartile range, 54–76 years) and the median NIHSS score at admission was 18 (interquartile range, 14–20). The leptomeningeal collateral score 3 was found to have significant association with the good functional outcome at 3 months: OR = 3.13; 95% CI, 1.25–7.825; P = .016. This association remained significant when adjusted for the use of IV tissue plasminogen activator: alone, OR = 2.998; 95% CI, 1.154–7.786; P = .024; and for IV tissue plasminogen activator and other confounders (age, baseline NIHSS score, and Thrombolysis in Cerebral Infarction grades), OR = 2.985; 95% CI, 1.027–8.673; P = .045.CONCLUSIONS:We found that poor arterial collateralization, defined as a collateral score of <3, was associated with poor outcome, after adjustment for recanalization success. We recommend that future studies include collateral scores as one of the predictors of functional outcome.

Intravenous tissue plasminogen activator is the only proved reperfusion therapy for acute ischemic stroke. However, a narrow therapeutic time window (<4.5 hours) limits its use because the clinical effectiveness is critically time-dependent.^1–3 In addition, recanalization rates with IV-tPA are low in the setting of large-artery occlusion, (eg, ICA occlusion <10%).^4–6 Intra-arterial therapy (IAT) has higher recanalization rates than intravenous thrombolysis, but this result has not been matched by concordant improvement in clinical outcomes.^7–9 Two recent randomized trials comparing IAT with IV-tPA, the Interventional Management of Stroke III trial and the Local versus Systemic Thrombolysis for Acute Ischemic Stroke trial, did not demonstrate superiority.^10,11Inadequate arterial collateralization is a possible mechanism to explain the mismatch between recanalization success and clinical outcome, apart from the presence of an already infarcted ischemic core and an incomplete microcirculatory reperfusion after focal cerebral ischemia.^12,13 A favorable arterial collateralization as determined by a robust leptomeningeal anastomoses profile may enhance recanalization, improve downstream reperfusion, reduce the extent of infarct core and ischemic lesion growth, decrease hemorrhagic transformation, and improve outcome postrevascularization.^14–16The leptomeningeal collateral scoring system based on CTA correlates with clinical outcome.^17–21 However, its role in IAT is unclear. We hypothesized that a poor leptomeningeal CTA score predicts clinical futility in patients undergoing IAT independent of recanalization status.     

Comparison of perfusion computed tomography with diffusion-weighted magnetic resonance imaging in hyperacute ischemic stroke

OBJECTIVE: In this study, perfusion CT and diffusion-weighted magnetic resonance imaging (DWI) were compared as means of assessing the ischemic brain in hyperacute stroke. METHODS: Twenty patients with ischemic stroke underwent perfusion computed tomography (CT) and magnetic resonance imaging (MRI) studies <3 hours after stroke onset. Cerebral blood flow thresholds were used to delineate the ischemic lesion, penumbra, and infarct. Correlations between the volume of the hypoperfused areas, the abnormality volume in admission DWI and follow-up CT/MRI studies, and the clinical National Institutes of Health Stroke Scale (NIHSS) scores were performed. RESULTS: The volume of the ischemic (core and penumbra) lesion on admission perfusion CT was correlated with the volume of admission DWI abnormalities (r=0.89, P=0.001). The infarcted core tissue volume (on admission CT) correlated more strongly (r=0.77, P=0.0001) than the admission DWI abnormality volume (r=0.69, P=0.002) with the follow-up infarct volume on fluid-attenuated inversion recovery images. A correlation was demonstrated between infarct volume in perfusion CT and follow-up DWI abnormality volume (r=0.89, r=0.77, P=0.002). Significant correlations were found between ischemic and infarct region volumes in perfusion CT and NIHSS admission and follow-up scores (P < or = 0.01). CONCLUSIONS: Both imaging modalities provide a sufficient assessment of the hyperacute brain infarct, with significant correlation between them and the clinical condition at admission. Perfusion CT allows differentiation of the penumbra and infarct core region with significant predictive value of follow-up infarct volume and clinical outcome.