MR imaging of middle cerebral artery occlusion without cerebral infarction

Magnetic resonance (MR) images of 12 patients with angiographically proven middle cerebral artery (MCA) occlusion were analyzed, retrospectively. In three of the 12 patients, cerebral infarctions related to the MCA occlusions were not evident. Two of the three patients were cases of atherosclerotic occlusion and the remaining patient had an acute thromboembolism. In all of the occluded M1 portions of the MCA the flow void was absent and there were isointense linear structures, with or without a hyperintense component in the Sylvian vallecula, on T1-weighted images. For nine of the 12 patients, the absence of flow void in the ipsilateral Sylvian fissure was evident on the T2-weighted images. Therefore, even in cases with no evidence of a cerebral infarction, the presence of flow void in the Sylvian vallecula and Sylvian fissure must be searched for in routine reviews of MR images. If MR imaging can be obtained on an emergency basis, appropriate interventional therapy may be immediately initiated.     

急性脑静脉闭塞CT灌注成像的实验研究

目的观察脑静脉闭塞模型脑实质损害区CT灌注成像（CTP）变化规律,探讨该模型在该病研究中的价值。方法新西兰大白兔28只,随机分为2组（实验组24只,对照组4只）。一侧颈内静脉注入醋酸纤维素聚合物（CAP）合并双侧颈外静脉结扎术后1、3、6、12、24和48h行CTP检查对各组模型的脑血流动力学改变进行观察。结果实验组21只造模成功,其中3h及12h组各有1只在CTP上无明显异常表现,有19只CTP检查示脑血流灌注异常。术后1～3h,病变区脑血容量（CBV）轻度增加或正常,脑血流量（CBF）轻度降低,平均通过时间（MTT）稍延长;6～12h后病变中心区主要表现为CBV和CBF降低,MTT延长,而病变边缘区CBV增加或正常或轻度降低,CBF降低,MTT缩短;12～24h后病变中心区和边缘区CBV和CBF均明显降低,MTT明显延长。各时段病变中心区和边缘区的CBV%、CBF%、MTT%的差异均有统计学意义（P值均〈0.05）。对照组未见上述各种异常表现。结论 CT灌注成像可准确、敏感地反映急性脑静脉闭塞模型的血流动力学改变。     

Computed tomography in a primate stroke model using selective balloon catheter arterial occlusion.

Ten heparinized nonhuman primates (rhesus monkeys and Papio maryumaya baboons) were subjected to temporary occlusion of an insular branch of the middle cerebral artery with a balloon catheter. An infarct was created. The lesions were monitored in vivo by computed tomography performed at intervals for 1 year. Animals were sacrificed and the lesions examined histologically. The technique obviates the disadvantages of surgical reaction, intravascular thrombosis, and gross cerebral edema observed in prior animal stroke models.     

CT脑灌注与血管造影在急性脑梗死中的临床应用

目的:探讨64层螺旋CT脑灌注成像和脑血管造影技术在急性期脑梗死中的应用价值。方法:应用PhilipsBrilliance CT 64,对30例发病12h内急性脑缺血患者行CT平扫、CT脑灌注成像(CTP)和CT血管造影(CTA)检查。分析平扫及灌注成像表现,计算出缺血区脑血流参数,包括:脑血容量图(CBV)、血流量图(CBF)、对比剂平均通过时间(MTT)和对比剂峰值时间(TTP),与对侧相应区灌注参数进行比较,并重建颈段和脑内动脉CTA图像。所有病例在发病后3~14天复查CT平扫。结果:30例患者中16例头颅平扫发现早期脑梗死征象,14例常规平扫未发现异常,而CTP均发现灌注异常区。CTP表现为CBF及CBV减低、MTT及TTP延迟;患侧CBF、MTT、TTP与对侧差异有显著性意义(P<0.01),患侧CBV与对侧差异无显著性意义(P>0.01)。重建CTA图像显示16例一侧颈内动脉狭窄,8例一侧大脑中动脉狭窄(其中1例伴大脑后动脉狭窄、左侧后交通动脉闭塞);4例左侧大脑中动脉闭塞,2例左侧颈内动脉闭塞。结论:CTP能够早期、及时、准确地反映缺血部位及程度,预测半暗带;CTA可以显示病变血管的部位和程度;联合应用两者,对早期诊断急性脑缺血和指导治疗有重要价值。     

CT脑灌注成像在超急性期脑梗死中的应用

CT脑灌注成像(CTP)可以显示脑血流动力学信息,早期即可显示缺血的梗死灶和缺血性半暗带,预测可以存活的脑组织,对早期诊断和治疗脑梗死及判断预后具有重要价值。随着64层螺旋CT的广泛应用,明显缩短了扫描时间,CT平扫、CTP和CT血管造影(CTangiography,CTA)联合扫描20min内即可完成,而且利用CTA和平扫图像获得三维脑灌注血容量(perfused blood volume,PBV)成像,可以全面显示病灶范围,避免小病灶的漏诊。     

Functional CT quantification of tumor perfusion after transhepatic arterial embolization in a rat model

PURPOSE: To quantify tumor perfusion after transcatheter arterial embolization (TAE) with functional computed tomography (CT) and to validate the reproducibility of quantification measurements. MATERIALS AND METHODS: This study was conducted in accordance with an institutional animal care and use committee-approved protocol. Sixteen rats with liver tumors underwent TAE with 1 mg (group 1) or 3 mg (group 2) of polyvinyl alcohol particles. In each group, four rats underwent functional CT immediately after TAE (day 0) and four others underwent functional CT 2 days after TAE (day 2). Another four rats served as control rats. Blood flow (BF), blood volume (BV), mean transit time (MTT), and permeability-surface area product were measured by using a functional CT software program. For evaluation of reproducibility, six additional rats with mammary tumors underwent functional CT twice, with examinations 2 hours apart. The mixed-effect model was used to assess the TAE treatment effect, and the Pearson correlation test was used to determine measurement reproducibility. RESULTS: With the exception of BF in group 1 on day 2 (P = .41), BF and BV values in both groups on both days were significantly lower than BF and BV values in the control rats (with P values ranging from .018 to <.001). BF was significantly lower in group 2 than in group 1 on days 0 and 2 (P = .043 and P = .02, respectively). BV was significantly lower on day 2 than on day 0 in group 2 (P = .016). MTT was generally inversely related to BF. MTTs in group 2 on days 0 and 2 were significantly longer than those in the control rats (P < .001 and P = .03, respectively), and MTT was shorter on day 2 than on day 0 in group 2 (P = .02). Permeability-surface area product changes were similar to BF changes. There were no significant differences (P values ranged from .2 to .5) between perfusion parameters in the reproducibility study. CONCLUSION: The results of this study validate the use of functional CT in the quantification of tumor perfusion after TAE and the reproducibility of such quantification measurements.     

16层螺旋CT脑灌注成像在急性脑梗死诊断中的应用价值

目的 探讨16层螺旋CT(MSCT)脑灌注成像对急性脑梗死的早期诊断价值.方法 对34例临床拟诊为急性脑梗死的患者行头颅CT平扫,脑CT灌注成像.评价脑CT灌注成像的达峰时间(TTP),脑血流量(CBF),脑血容量(CBV).全部病例3～7天内复查CT及临床随访.选取20名正常志愿者作为对照.结果 常规CT平扫显示:34例急性脑梗死患者在发病24h内,15例诊断为急性脑梗死,19例未见异常,后经复查CT及临床随访证实,2例为短暂性脑缺血发作(TIA),17例为急性脑梗死.脑CTP显示:34例急性脑梗死患者在发病24h内,32例脑CTP灌注异常,2例脑CTP灌注正常,脑CTP显示患者感兴趣区内脑血流量(rCBF)、脑血容量(rCBV)、对比剂达峰时间(rTTP)明显改变,病灶侧与对照侧、病灶中心区与周边区比较,差异有显著意义(P＜0.01).CT平扫的敏感度44.11％,特异度71.42％;CTP的敏感度94.11％,特异度100％.结论 脑CTP能够早期诊断急性脑梗死,定量分析可区分中心梗死区与缺血半暗带区,有助于临床医生早期选择治疗方案.     

Prediction of clinical outcome with baseline and 24-hour perfusion CT in acute middle cerebral artery territory ischemic stroke treated with intravenous recanalization therapy

Introduction We sought to determine whether Alberta Stroke Program Early CT Scores (ASPECTS) derived from baseline noncontrast CT (NCCT) and perfusion CT (CTP) imaging maps can predict clinical outcome after recanalization therapy in acute ischemic stroke of the middle cerebral artery (MCA) territory and whether changes in the ASPECTS from baseline to 24 h after recanalization therapy can help predict clinical outcome. Methods We retrospectively studied consecutive patients with acute ischemic stroke of the MCA territory treated with intravenous tissue plasminogen activator (t-PA) or abciximab within 6 h of symptom onset. We performed NCCT and CTP before and 24 h after intravenous t-PA or abciximab treatment and determined the ASPECTS and the changes in the ASPECTS from baseline to 24 h. A favorable outcome was defined as a modified Rankin scale score of 0 or 1 at 3 months. Results During the 18-month study period 44 patients were studied. In multivariate logistic regression analysis, the cerebral blood volume (CBV) ASPECTS (OR 1.80, 95% CI 1.10 to 2.93) at baseline and the increase in cerebral blood flow (CBF) ASPECTS (OR 1.68, 95% CI 1.13 to 2.50) from baseline to 24 h were associated with a favorable outcome. The cutoff values for a favorable outcome using receiver operating characteristic curves were 8 and 1, respectively. When the CBV ASPECTS at baseline was 8 or more, its positive predictive value was only 58.1%. When the CBV ASPECTS at baseline was 8 or more and the increase in CBF ASPECTS from baseline to 24 h was 1 or more, the positive predictive value was 100% and the negative predictive value was 74.2%. Conclusion The CBV ASPECTS derived from baseline CTP maps was found to be predictive of a favorable outcome, but its positive predictive value was suboptimal. The change in the CBF ASPECTS from baseline to 24 h after treatment was helpful in predicting outcome.     

低剂量双源CT颅脑灌注成像在超急性期脑梗死中的诊断价值

目的探讨管电压为70 kV时不同管电流及采集频次对双源CT颅脑灌注成像(CTP)图像质量、辐射剂量的影响,及其在超急性期脑梗死患者中的诊断价值。方法前瞻性选取2017年12月至2019年2月浙江省丽水市中心医院临床可疑的超急性期脑梗死患者190例,按照数字表法随机分为4组,A、B、C组均50例,D组40例,均在发病6 h内行双源CT平扫及70 kV管电压颅脑灌注成像。A组管电流120 mA,B组和C组管电流均为100 mA,D组管电流80 mA。A、B、D组采集频次21次,C组采集频次17次。测量脑血流量(CBF)、脑血容量(CBV)、平均通过时间(MTT)、达峰时间(TTP)等,评价图像质量,记录有效剂量(ED)。各参数组间图像质量及辐射剂量的比较采用单因素方差分析。结果4组CTP伪彩图灰质和白质灌注参数(CBF、CBV、MTT及TTP)的差异均无统计学意义(P>0.05),所有图像均可满足诊断要求。A组颈内动脉、大脑中动脉血管管腔边缘锐利度、整体图像质量及颈内动脉图像噪声评级高于D组(P<0.05);A组颈内动脉血管管腔边缘锐利度高于B、C组(P<0.05);B、C组颈内动脉及大脑中动脉血管管腔边缘锐利度均高于D组(P<0.05)。CT平扫及A、B、C、D组的ED分别为1.10、2.11、1.76、1.42、1.40 mSv,差异有统计学意义(P<0.05)。与A组相比,B、C及D组的ED均有不同程度的降低,分别降低16.6%(0.35/2.11)、32.7%(0.69/2.11)及33.6%(0.71/2.11),差异均有统计学意义(P均<0.05)。对于超急性期脑梗死,低剂量双源CTP阳性率为93.5%(172/184),CT平扫阳性率为52.2%(96/184);对于超急性期腔隙性脑梗死,低剂量双源CTP阳性率为72.1%(31/43),CT平扫阳性率为16.3%(7/43)。结论70 kV管电压CTP,适当减低管电流(100 mA)及采集频次(17次)可降低辐射剂量且图像质量可满足诊断需求。相较于CT平扫,低剂量双源CTP对于超急性期脑梗死尤其是腔隙性脑梗死更为敏感。     

CT perfusion imaging in the early diagnosis of acute stroke

Early diagnosis of acute cerebral infarction is critical due to the time limit of thrombolytic treatment. Cerebral computed tomography (CT) perfusion imaging is a new technique, which appears to provide early diagnosis of major vessel occlusions in the brain. CT perfusion imaging also provides valuable information about the hemodynamic status of ischemic brain tissue. In this report, we present the CT perfusion findings in comparison to the non-contrast CT and diffusion-weighted (DW) magnetic resonance (MR) imaging findings in two cases of acute cerebral infarction. Non-contrast CT findings were non-specific in the first case and there was minimal hypoattenuation in the superior aspect of the lentiform nucleus in the second case. CT perfusion imaging demonstrated significant perfusion defects in the middle cerebral artery territory in both cases. DW-MR imaging confirmed acute infarctions, which were smaller than the perfusion defect areas in the CT perfusion imaging in both cases.     

1.5T场强MR动脉自旋标记灌注成像在脑梗死中的初步应用

目的：探讨采用1.5T场强MR动脉自旋标记灌注成像（ASL-PWI）评价脑梗死的可行性。方法：对34例临床和MRI发现脑梗死的患者行常规MRI、扩散加权成像（DWI）及ASL-PWI扫描,根据Adamas分类将急性脑梗死分为大面积和小面积2组,比较DWI和ASL-PWI上病变的范围,比较病变区CBF值（CBF病变）与对侧正常区CBF值（CBF正常）。结果：20例大面积脑梗死中5例ASL-PWI显示病灶范围较DWI大,9例两者显示范围相当,5例前者小于后者,1例未见异常灌注区;14例小面积脑梗死中6例显示低灌注区,7例未能明确显示低灌注区,1例灌注增强;除1例灌注增强病例CBF病变大于CBF正常外,其它均小于后者。结论：在1.5T磁场强度上应用ASL-PWI技术能基本反映脑梗死区血流灌注的改变,其严格的相关性及临床意义有待于进一步探索。     

Neuronal damage after ischemic injury in the middle cerebral arterial territory: deep watershed versus territorial infarction at MR perfusion and spectroscopic imaging

PURPOSE: To determine the temporal patterns of neuronal injury between infarction subtypes and their possible association with changes in cerebral blood volume (CBV). MATERIALS AND METHODS: Twenty-five patients with ischemic injuries of middle cerebral arterial territories and receiving only conservative treatments were classified into territorial infarction (TI) (n = 16) and watershed infarction (WI) (n = 9) groups and were prospectively evaluated with longitudinal magnetic resonance (MR) examinations. Each patient underwent as many as five MR studies at various stroke stages following stroke symptom onset. Dynamic susceptibility-weighted contrast material-enhanced MR imaging was performed to yield the relative CBV (rCBV). Chemical shift imaging was used to measure the relative levels of N-acetylaspartate (NAA) and lactate of the ischemic brain tissue. Repeated-measures analysis of variance was used to examine the statistical significance in evolutional differences between TI and WI. RESULTS: For patients with TI, rCBV followed a progressively increasing pattern, from initial low values (0.46 +/- 0.28 [SD]) to peak high values (1.23 +/- 0.34) at early chronic stage. Relative NAA level decreased to 0.40 +/- 0.24 during acute stroke and was lost completely 4 days after ictus. Patients with WI showed consistently high rCBV throughout all stages, with residual relative NAA level (0.53 +/- 0.25) even at 1 month after symptom onset. Relative lactate level of patients with TI was significantly higher than that of patients with WI at the acute stage (P <.01). Differences in the temporal changes of both rCBV and brain metabolites between TI and WI were significant (P <.01). CONCLUSION: The different temporal patterns for stroke progression in TI and WI are associated with different evolutions of hemodynamics and neuronal injury.     

Time course of arterial hyperintensity with fast fluid-attenuated inversion-recovery imaging in acute and subacute middle cerebral arterial infarction

The purpose of this study was to evaluate the time course of arterial hyperintensity (AH) in acute and subacute cerebral infarctions of the middle cerebral artery (MCA) distribution by using fast fluid-attenuated inversion-recovery (FLAIR) imaging. A total of 40 FLAIR MR examinations were performed in 27 patients with MCA infarction within 13 days after ictus. Thirteen patients underwent two MR examinations during this period. Thrombotic or embolic infarctions were included in this study, but lacunar infarctions were excluded. The presence or absence of AH and the location of AH were analyzed. Overall, AH was found in 24 (60%) of 40 FLAIR examinations within 13 days after onset. AH was seen in 17 (100%) examinations less than 24 hours old, four (40%) of 10 examinations 1-4 days old, two (18%) of 11 examinations 5-9 days old, and one (50%) of two examinations 10-13 days old. AH was most frequently found at the sylvian fissure (87%), followed by the sulci (54%), and the horizontal segment of MCA (29%) in the affected MCA distribution. Although AH could be seen even at 13 days after ictus, the presence of AH declined over time. AH represented an early sign of acute embolic or thrombotic infarction. J. Magn. Reson. Imaging 2001;13:987-990.     

Malignant middle cerebral artery infarction in hyperacute ischemic stroke: evaluation with multiphasic perfusion computed tomography maps

OBJECTIVE: The purpose of this study was to compare the incidence of large hypoperfusion (greater than two-thirds of MCA territory) on computed tomography (CT) perfusion maps between hyperacute middle cerebral artery (MCA) stroke patients without or with malignant cerebral edema. METHODS: Twenty-seven patients diagnosed with a hyperacute MCA stroke who had an initial National Institutes of Health Stroke Scale (NIHSS) score greater than 10 were included. Multiphasic perfusion CT was performed within 6 hours of symptom onset. Patients were divided into 2 groups: the malignant group (n = 11), composed of patients who died within 7 days, and the nonmalignant group, which included all other patients (n = 16). Unenhanced CT and CT perfusion maps were assessed and compared between the 2 groups with special emphasis on examining the CT findings, including hyperdense MCA sign, large (greater than two-thirds) hypoattenuation and hypoperfusion in the MCA territory, and hypoattenuation in the basal ganglia and other vascular territories. RESULTS: The incidence of large hypoattenuation (greater than two-thirds of MCA territory) on unenhanced CT and large hypoperfusion on CT perfusion maps differed significantly between the 2 groups (P < 0.05). Large hypoperfusion on the CT total perfusion map was most accurate (93%) among various CT findings for the prediction of malignant MCA infarction with high sensitivity (91%), specificity (94%), and positive predictive value (91%). CONCLUSIONS: The incidence of large hypoperfusion on a CT perfusion map was higher in the malignant group than the nonmalignant group. CT perfusion maps may provide added information about cerebral perfusion and could be a useful predictor of malignant MCA infarction.     

Correlation of early CT signs in the deep middle cerebral artery territories with angiographically confirmed site of arterial occlusion

BACKGROUND AND PURPOSE: Early CT signs in the deep middle cerebral artery (MCA) territories have been reported to be seen at the initial period of ischemia. We attempted to investigate the incidence of parenchymal hypodensity within 3 hours after ischemic onset among patients with angiographically proved embolic MCA occlusion and to assess the correlation of subtle hypodensity in the deep MCA territories with involvement of the lenticulostriate arteries in the presence of ischemia. METHODS: Fifty CT images obtained within 3 hours after onset of embolic MCA occlusion were retrospectively reviewed by three neurosurgeons who were aware of clinical features. Early CT signs in the deep MCA territories were divided into three grades according to their anatomic location: grade I, normal basal ganglia with hypodensity localized to the insula; grade II, partial obscuration of the posterolateral part of the putamen; and grade III, hypodensity of the entire lentiform nucleus. A grade I CT sign was considered to be a negative finding for lenticulostriate artery involvement, whereas grade II and III CT signs were considered to be positive findings. Site of occlusion and involvement of the lenticulostriate arteries were confirmed by angiography. RESULTS: Thirty-eight (76%) of 50 patients had early CT signs in the deep MCA territories. Sensitivity and specificity of a grade I CT sign indicating absence of lenticulostriate artery involvement in ischemia were 65% and 87%, respectively. On the other hand, sensitivity and specificity of grade II and grade III CT signs for presence of lenticulostriate artery involvement in ischemia were 77% and 100%, respectively. Grade II CT signs resulted from various sites of occlusion, whereas grade III was unequivocally predictive of proximal occlusion to all of the lenticulostriate arteries. CONCLUSION: Involvement of the lenticulostriate arteries may be presumed by precise evaluation of subtle, CT-revealed hypodensity in the deep MCA territories, even within 3 hours of ischemic onset.     

Ultra-low-dose multiphase CT angiography derived from CT perfusion data in patients with middle cerebral artery stenosis

Neuroradiology - Computed tomography (CT) perfusion (CTP) source images contain both brain perfusion and cerebrovascular information, and may allow a dynamic assessment of collaterals. The purpose...     

Dynamic susceptibility contrast perfusion magnetic resonance imaging in patients with symptomatic unilateral middle cerebral artery stenosis or occlusion

PURPOSE: To evaluate cerebral hemodynamic disturbance in patients with symptomatic unilateral middle cerebral artery (MCA) high-grade stenosis or occlusion using dynamic susceptibility contrast perfusion magnetic resonance imaging (DSC-pMRI). MATERIAL AND METHODS: DSC-pMRI was performed in 28 patients with symptomatic unilateral MCA high-grade stenosis or occlusion. Hemodynamic parameters including relative cerebral blood flow (rCBF), relative cerebral blood volume (rCBV), relative mean transit time (rMTT), and time to peak (TTP) were calculated and compared between the stenosed or occluded side and contralateral side. Seven of the 28 patients underwent surgery or interventional therapy, and hemodynamic changes between pre- and post-therapy were investigated. RESULTS: Prolonged rMTT and TTP were found in the stenosed or occluded MCA territories in all 28 patients. Significant differences were found in rCBV (P<0.05), rMTT (P<0.001), and TTP (P<0.001) between the stenosed or occluded side and the contralateral side. However, no significant difference was observed in rCBF (P>0.05). In the seven patients with surgical or interventional therapy, the values of rMTT and TTP significantly decreased after surgery or interventional therapy (P<0.001). CONCLUSION: DSC-pMRI may be a useful tool for evaluating and monitoring cerebral hemodynamic disturbance in patients with symptomatic unilateral MCA high-grade stenosis or occlusion.     

Practical injection-rate CT perfusion imaging: deconvolution-derived hemodynamics in a case of stroke

Previously reported methods of dynamic, contrast-enhanced, CT perfusion imaging in acute stroke have been promising but substantially limited by their dependence on very rapid rates of injection (typically 10–20 ml/s in an arm vein). Newly available deconvolution software permits the use of lower rates of injection (e. g., 3–4 ml/s), and rapidly provides maps of cerebral blood flow, cerebral blood volume and mean transit time. We report the potential of CT perfusion imaging performed with an injection rate of 4 ml/s to provide information on the extent of hemodynamic abnormality, and to help distinguish viable from nonviable ischemic tissue. The slower injection rates permitted by deconvolution analysis substantially enhance the practicality of CT perfusion imaging for studying stroke. Received: 22 May 2000 Accepted: 1 August 2000     

Measuring elevated microvascular permeability and predicting hemorrhagic transformation in acute ischemic stroke using first-pass dynamic perfusion CT imaging

BACKGROUND AND PURPOSE: Hemorrhagic transformation (HT) can be a devastating complication of acute ischemic stroke (AIS). The purpose of this study was to determine whether increased microvascular permeability (PS) of the blood-brain barrier was detected in early AIS by using first-pass dynamic perfusion CT (PCT) and whether PS was significantly higher in infarcts destined for HT. MATERIALS AND METHODS: Fifty patients with AIS less than 3 hours old and evaluated by PCT were included. PS color maps were retrospectively generated from PCT data using the Patlak model. One reader analyzed each PS map by drawing 4 circular 10-mm regions of interest on any focal abnormality. The mean of these 4 regions of interest represented the PS of the infarct (PSinfarct). The mean of 4 mirror regions of interest on the nonischemic contralateral hemisphere was also obtained (PScontrol). PSinfarct and PScontrol were compared by using an exact Wilcoxon test. PSinfarct for infarcts that developed HT on follow-up (PSHT) was compared with all of the others (PSNo-HT) using an exact Mann-Whitney test. RESULTS: Forty-four infarcts (88%) showed focal PS elevation in the region of infarct. In units of milliliters per 100 milliliters per minute, PSinfarct ranged from 0 to 13 (mean: 3.5+/-3.1) versus PScontrol of 0-0.8 (mean: 0.28+/-0.27; P<.0001). Six infarcts (12%) developed HT, all of which were within the region of PS elevation. PSHT ranged from 5.2 to 13 (mean: 9.8+/-2.9) versus PSNo-HT of 0-5.9 (mean: 2.7+/-2.0; P<.0001). Eighteen infarcts (36%) were treated with recombinant tissue plasminogen activator (rtPA). A significant difference between PSHT and PSNo-HT persisted irrespective of rtPA treatment. CONCLUSIONS: Elevated permeability was detectable in AIS by using first-pass PCT and it predicted subsequent HT.