TIA患者脑动态CT峰值时间灌注成像的初步研究

目的:探讨脑动态CT峰值时间（TTP）灌注成像对短暂性脑局部缺血发作（TIA）的诊断价值。材料和方法:对17例临床诊断为TIA的患者进行脑动态CT扫描TTP灌注成像检查。感兴趣区层厚10mm,扫描矩阵512×512,曝光电压和功率与常规扫描相同。动态CT检查为在启动高压注射器经肘静脉快速注入对比剂的同时对感兴趣层面进行连续快速扫描。曝光时间为1s,连续扫描40s,共40层。碘对比剂为300mg碘海醇,流量为8ml/s,总量为40ml。CT检查结束后,用自编软件进行动态增强CT数据处理。用手工画线方式将脑实质与颅骨、皮下组织、脑室和图像背景分割,最后仅留下脑实质的彩色TTP灌注图像。结果:17例常规CT检查（包括增强检查）和12例常规MR检查均未发现脑内有与TIA发作临床表现相符合的新鲜病灶。脑动态CT扫描TTP灌注成像显示脑内有与TIA发作临床表现相符合的病灶14例（82.35％）。其余3例脑TTP灌注成像未见异常。结论:虽然动态CT峰值时间脑灌注成像只能进行单一层面的检查,但其方法简单、易行,可显示常规CT和MR无法发现的早期脑缺血区的血流异常,对TIA的研究具有重要临床实用价值。该方法优于CBF和CBV灌注成像。     

CT灌注技术对脑血流分布的初探

目的 :改进灌注成像技术 ,对大脑不同区域血流分布的差异作初步探索。方法 :2 0例无运动系统或基底节区病变受检者行基底节层面灌注扫描。通过高压注射器团注对比剂 (30 0mg/ml浓度ultravist) ,流速 5ml/s,总量 4 0ml。在对比剂注射第 9s开始行灌注扫描。扫描条件 :12 0kV ,15 0mA ,速度 1层 /s ,层厚 5～ 8mm ,IOV 2 0 0mm× 2 0 0mm ,连续无间隔扫描 30s,图像重建时间 0 .5s。结果 :在开始注射对比剂第 9s行CT扫描 ,能获得较完整的动脉血管和脑实质内的灌注图像。灌注扫描数据用较小的间隔重建可获得较为平滑的γ 变量曲线。大脑两侧基底节区血流灌注量不等 ,上升值、峰值与上升斜率均左侧大于右侧 ,两者存在显著性差异。结论 :CT灌注技术是研究大脑血流分布的一个新的重要方法。大脑两侧基底节区血流灌注量的差异可能与人们的运动优势习惯有关。     

正常成人多层螺旋CT灌注成像的脑血流动力学研究

目的　探讨多层螺旋CT灌注成像 (MSCTPI)技术在正常人脑血流动力学中的应用。方法　选择 30例正常成年人行常规头颅CT平扫后 ,再行MSCTPI检查。在常规轴面CT扫描后选取基底节及其相邻层面 ,经肘静脉团注对比剂 ,同时开始连续 4 0s的双层动态扫描 ,重建的 80幅动态图像使用CT脑灌注软件包进行处理 ,获得灌注图像 ,测量所选脑内感兴趣区的血流量、血容量及达峰时间 ,并对其进行定量分析。结果　MSCTPI显示正常成年人脑灰质灌注高于脑白质 ,脑灰质的平均血流量、平均血容量、达峰时间分别为 (5 0 6± 9 0 )ml·min-1·10 0 g-1、(5 7 8± 9 1)ml·min-1·10 0 g-1、(10 6± 1 6 )s,脑白质分别为 (2 2 7± 8 6 )ml·min-1·10 0 g-1、(30 8± 9 8)ml·min-1·10 0g-1、(12 9± 2 6 )s。结论　MSCTPI技术为测量脑血流动力学指标提供了一种新的影像学方法。     

高压注射器在磁共振灌注及血管成像中的应用

目的：通过压力注射器在磁共振灌注及血管成像中的应用体会,探讨其在磁共振检查中的临床意义,方法：30例脑肿瘤患者脑灌注成像,28例血管病变患者常规增强扫描及5例冠心病患者心肌灌注成像,使用Medrad Spectris MR injector注射器经上肢大静脉进行快速大剂量对比剂团注。造影前根据病变或血管的大小,首先预设置流速,流量及注射时间,对选定某一病变区域用动脉程序行短时扫描或延迟扫描,作为对照,另12例脑肿瘤患者脑灌注成像采用手推方式注射,并对脑灌注曲线做对比分析,结果：42例脑肿瘤中30例经手术病理确诊,6例外院手术,6例本院活检穿刺,28例血管病变经IADSA证实,所有检查均获成功。脑血流灌注曲线压力注射器组优于手推组,28例血管病变血管造影像及5例心肌灌注图像均达诊断标准。结论：压力注射器可保持稳定速度,确保对比剂浓度以完成准确灌注,江可根据灌注成像及血管造影成像程序调节速度和时间,更为精确地进行上述检查。     

低剂量与常规剂量对比剂双能量肺灌注图像质量对比分析

目的:探讨对比剂剂量对双源CT双能量肺灌注成像质量的影响.方法:疑肺动脉栓塞患者行双源CT双能量肺灌注扫描,30例使用低剂量(0.7ml/kg)对比剂,30例使用常规剂量对比剂(1.5ml/kg),注射速率均为4.5ml/s.扫描后同时获得肺动脉CTA及肺灌注图像.测量左、右叶肺动脉干及各肺叶动脉增强后的CT值,对比分析两组间增强后的CT值.判断肺灌注图像质量并分级,比较两组的肺灌注图像质量差异.结果:低剂量组与常规剂量组左、右叶肺动脉干及各肺叶动脉增强后的CT值无明显差异(P＞0.05).肺段及亚段肺动脉图像清晰显示.低剂量组肺灌注图像大部分信号均匀(26/30),常规剂量组肺灌注图像大部分信号均匀(24/30).常规剂量组上腔静脉、右心房高密度对比剂所致灌注伪影明显多于低剂量组(48:10).结论:低剂量与常规剂量双能量肺灌注成像的肺动脉图像质量无明显差异,降低对比剂剂量可以减少双能量肺灌注图像的伪影.     

64排螺旋CT血管成像显示Adamkiewicz动脉及其参数的优化

目的 探讨64排螺旋CT血管成像对Adamkiewicz动脉显示的最佳参数.方法 将84例受试者按检查序号分为4组,A组24例,对比剂流速为3 ml/s,开始注射对比剂后25 s,CT机自动开始扫描.B组20例,对比剂流速为4 ml/s,开始注射对比剂后25 s,CT机自动开始扫描.C组20例,对比剂流速为5 ml/s,开始注射对比剂后25 s,CT机自动开始扫描.D组20例,流速4 ml/s,应用自动阈值触发技术,当降主动脉内感兴趣区相对衰减值达到230 HU后,再延迟3 s,CT机自动触发进行扫描.将原始图像进行容积显示(volume rendering, VR)、多平面重建(multiplanar reformation, MPR)、曲面重建(curved planar reformation, CPR),观察和分析Adamkiewicz动脉的显示情况,对不同参数下的Adamkiewicz动脉显示效果进行比较.结果 总显示率为85.71%,对比剂流速4 ml/s的B组及对比剂流速5 ml/s的C组显示率高于3 ml/s的 A组,应用自动阈值触发技术的D组Adamkiewicz动脉显影效果优于A组、B组.结论 将对比剂流速控制在4 ml/s以上,以T9水平降主动脉感兴区相对衰减值达到230 HU作为阈值自动触发64排螺旋CT进行血管成像,可以成功地显示Adamkiewicz动脉.     

多层螺旋CT灌注成像在脑肿瘤中的应用研究

目的评价多层螺旋CT灌注扫描成像技术在脑肿瘤中的应用价值。资料与方法43例脑肿瘤患者于术前1周及术后出院时行常规CT扫描、CT灌注成像及增强扫描。数据应用CT工作站Perfusion3软件分析,获得脑血流量（CBF）图、血容量（CBV）图、对比剂平均通过时间（MTT）图和表面渗透性（PS）图。结果所有灌注图像均可清晰地显示肿瘤的大小与轮廓且能定量测定肿瘤组织的灌注状态。结论多层CT灌注成像为在体观察脑肿瘤血流状态及肿瘤血管功能提供了一种新的方法,对研究脑肿瘤的生物学特性,鉴别诊断及预后判断有一定的价值。     

大剂量对比剂团注在MRI检查中应用

目的：探讨大剂量对比剂注射器团注在脑转移瘤及其血管成像中的临床意义。方法：对35例脑转移瘤患者行MR平扫和增强扫描作为对照，其中26例脑转移瘤患者增强扫描分别采用单剂量手推方式注射(10ml和大剂量注射器团注，并对图像做对比分析。对22例体部血管病变患者和15例肝、肾移植患者及供体行常规扫描后的增强血管成像(enhancedMRA)。快速大剂量团注(20～40ml扫描以1．5～3ml／s流率经上肢大静脉注射造影，造影前根据病灶和血管大小，首先预设置流率、流量及注射时间，再对所选择的病变区域或血管行快速动态扫描和延迟扫描。结果：35例均已确诊有原发病灶的脑转移瘤忠者中23例经手术病理证实，12例经活检病理证实。19例体部血管病变经DSA证实。所有检查均获成功，且大剂量注射器团注组对病变显示优于小剂量手推组。结论：大剂量的注射冕团注能更清晰显示病灶数目和病灶大小、数目和病灶内钙化、坏死以及供给血管情况，为临床提供精确的诊断。     

64层螺旋CT使用低剂量对比剂在CTA中对脑动脉瘤的诊断价值

目的 研究64层螺旋CT使用低剂量对比剂联合生理盐水在CTA中对脑动脉瘤的应用价值.方法 对临床疑有脑动脉瘤51例患者分为三组:甲组90ml对比剂不用生理盐水冲洗；乙组、丙组分别使用70ml、50ml对比剂之后用相同流速生理盐水40ml冲洗.对比剂流速为5.0ml/s.当颈内静脉显影的一刹那开始扫描.利用工作站软件进行图像处理,评估三组血管图像质量及动脉瘤显示情况.结果 三组病例动脉瘤的灵敏度、特异性在统计学上没有明显差异,甲组动静脉均显示很好,CT值较高.丙组动脉显示良好,静脉少,污染轻,血管CT值略低.乙组居于二者之间.结论 使用低剂量对比剂50ml+40ml生理盐水以5.0ml/s流率注射,不仅可以得到理想的图像,还是一种安全、快速、经济的检查方法.     

多层CT灌注成像技术在脑肿瘤诊断中的应用

目的：探讨多层螺旋CT灌注扫描成像技术在脑肿瘤诊断中的应用价值。方法：收集2004．11—2006．1月辽宁医学院附属第一医院脑肿瘤住院患者43例，对所有患者行普通CT扫描、增强CT扫描及CT灌注成像。首先对患者行普通CT扫描及增强CT扫描，以平扫最大肿瘤层面为中心行灌注检查，应用“Toggling—table”技术行CT灌注扫描取得数据用Per-fusion3软件中的Brain tumor灌注分析软件进行分析。结果：本研究中普通CT、增强CT及CT灌注成像均能清晰地显示病变，但CT灌注成像能够获得更多的病变信息资料，获得的脑肿瘤区域的CBF、CBV、PS灌注图，PS图像可以清晰显示肿瘤区与水肿区及肿瘤的血管通透性。结论：多层CT灌注成像可以快速、简捷、清晰的显示出脑肿瘤的大小与轮廓，且灌注成像对在体观察脑肿瘤血流状态及肿瘤血管功能提供了一种新的方法。     

微机辅助CT脑灌注成像以及定量测量

目的：报告微机辅助CT脑灌注成像以及定量测量方法。方法：以PentiumⅡ300MHz微处理器，128MB内存，16MB显存，6G硬盘PC机和Windows98第2版为平台，用VissualC 为开发语言，根据中心容积定理，利用动态CT图像分析并计算脑血流动力学的有关参数，包括脑血流量（cerebral blood flow,CBF)，脑血容量（cerebral blood volume,CBV),平均通过时间（mean transit time,MTT)和峰值时间（time to peak,TTP)等。最后，将脑血流动力学数据根据色阶分别处理成脑血流量图（mapping of CBF)，脑血容量图（mapping of CBV)，平均通过时间图（mapping of MTT)和峰值时间图（mapping of TTP)。结果：动态增强CT图像经软件处理后可以在微机上显示脑组织的CBF，CBV，TTP和MTT灌注原始图像以及分割颅骨，皮下组织和脑室后的图像。急性脑缺血患者在MR T1加权像，T2加权像，平扫CT以及增强CT未显示的责任病灶，脑CT灌注图像可以清楚显示脑血流动力学的异常。结论：微机辅助CT脑灌注成像简单铁行，可显示常规CT和MR无法发现的早期脑缺血区的血流异常。与MR灌注成像相比更适用于急诊检查。     

实验性脑血肿周围组织脑血流变化的CT灌注成像与病理学研究

目的探讨血肿周围组织病理发展进程及其与血肿周围局部脑血流变化的关系。方法采用自体血注射法制备大鼠脑出血模型,对70只大鼠于术后1h、3h、6h、12h、24h、48h和72h7个时间点,利用GELightspeed螺旋CT扫描机灌注成像及计算机辅助系统制作大鼠脑CT灌注参数图,对血肿周围局部脑血流量(rCBF)、局部脑血容量(rCBV)和对比剂平均通过时间(MTT)脑血液动力学参数进行定量测量,并与大鼠脑TTC染色、HE-染色以及超微结构改变进行比较。结果大鼠脑血肿周围可见明显的低灌注梯度,血肿周围rCBF和rCBV显著降低,MTT延长。TTC染色血肿周围未见白色梗死区。HE-染色可见血肿周围区星形细胞肿胀,神经细胞变性、坏死,出血灶周边毛细血管增生伴炎细胞浸润。电镜观察显示,注血早期血肿周围组织星形细胞肿胀,神经细胞改变不明显,髓鞘板层松散;随着注血后时间延长,血肿周围组织损伤呈渐进性加重,星形细胞肿胀明显,神经细胞出现变性,髓鞘板层发生局部断裂、崩解。结论大鼠脑注血早期血肿周围局部脑血流的显著降低引发了血肿周围及远隔区脑组织的缺血性损伤,注血后急性期血肿周围组织细胞损伤呈进行性加重,血肿周围存在涉及多种细胞损伤机制的半暗带。     

CT perfusion parameter values in regions of diffusion abnormalities

BACKGROUND AND PURPOSE: Dynamic CT perfusion imaging is a rapid and widely available method for assessing cerebral hemodynamics in the setting of ischemia. Nevertheless, little is known about perfusion parameters within regions of diffusion abnormality. Since MR diffusion-weighted (DW) imaging is widely considered the most sensitive and specific technique to examine the ischemic core, new knowledge about CT perfusion findings in areas of abnormal diffusion would likely provide valuable information. The purpose of our study was to measure the CT-derived perfusion values within acute ischemic lesions characterized by 1) increased signal intensity on DW images and 2) decreased apparent diffusion coefficient (ADC) and compare these values with those measured in contralateral, normal brain tissue. METHODS: Analysis was performed in 10 patients with acute middle cerebral artery territory stroke of symptom onset less than 8 hours before imaging who had undergone both CT perfusion and DW imaging within 2 hours. After registration of CT perfusion and DW images, measurements were made on a pixel-by-pixel basis in regions of abnormal hyperintensity on DW images and in areas of decreased ADC. RESULTS: Significant decreases in cerebral blood flow and cerebral blood volume with elevated mean transit times were observed in regions of infarct as defined by increased signal intensity on DW images and decreased ADC. Comparison of perfusion parameters in regions of core infarct differed significantly from those measured in contralateral normal brain. CONCLUSION: CT perfusion findings of decreased cerebral blood flow, mean transit time, and cerebrovascular volume correlate with areas of abnormal hyperintensity on DW images and regions of decreased ADC. These findings provide important information about perfusion changes in acute ischemia in areas of diffusion abnormality.     

Vascular reserve in chronic cerebral ischemia measured by the acetazolamide challenge test: comparison with positron emission tomography.

PURPOSETo determine the value of the acetazolamide challenge test with stable xenon-enhanced CT (Xe CT) for making therapeutic decisions in patients with chronic cerebrovascular disease.METHODSWe compared the Xe CT-measured acetazolamide response with various measures obtained by positron emission tomography. We performed both a positron emission tomographic scan and a Xe CT study in 11 patients with chronic cerebral ischemic diseases within a 1-week interval. An increase of cerebral blood flow after injection of acetazolamide was expressed as delta AT. Regional cerebral blood flow, cerebral oxygen metabolism, oxygen extraction fraction, and cerebral blood volume were measured with oxygen-15-labeled gases by positron emission tomography.RESULTSIn low-cerebral blood flow regions, decreased delta AT was accompanied by a significant elevation of oxygen extraction fraction and cerebral blood volume, compared with oxygen extraction fraction and cerebral blood volume in regions of normal delta AT. Plotting of regional data indicated that delta was significantly dependent on oxygen extraction fraction and cerebral blood volume. The area of decreased vascular reserve determined by the Xe CT image corresponded to the area of "misery perfusion" determined by positron emission tomography.CONCLUSIONThe acetazolamide challenge test with Xe CT may offer an alternative to positron-emission tomography in detecting lesions with elevated oxygen extraction fraction and cerebral blood volume (misery perfusion) that result from chronic hemodynamic stress.     

可控性大鼠急性脑局部缺血模型的建立及CT灌注成像与病理学评价

目的 建立稳定、可控的脑局部缺血动物模型，并通过CT灌注成像和病理学方法对其进行评价。方法 雄性Wistar大鼠28只，随机分为4组(假手术组、脑梗死15min组、脑梗死30min、再灌注1h组及低灌注6h组)，每组7只鼠。在激光多普勒血流仪监测下采用改良的线栓法制作可控性脑局部缺血动物模型。利用CT灌注成像对各组动物模型的缺血状态进行观察，并与光学显微镜、电子显微镜结果以及红四氮唑(TTC)染色标本对照。结果 脑梗死15min组在激光多普勒血流仪监测下将局部脑血流量(rCBF)控制为5％～22％，CT灌注成像显示7只大鼠局部脑血流量均下降，TIC染色呈浅红色，未见明确梗死病灶，病理学检查显示部分神经元变性和星形细胞肿胀。脑梗死30min再灌注1h组在激光多普勒血流仪监测下将rCBF控制为4％～23％，病理学检查显示7只大鼠脑缺血灶内星形细胞肿胀明显，可见大量神经元变性，标本TTC染色所示的白色梗死区与CT灌注成像异常区域一致。在低灌注6h组，由于rCBF下降程度较小(为38％～55％)，病理学显示7只大鼠星形细胞肿胀明显而神经元变性轻微，TTC染色未见明确梗死病灶。假手术组7只大鼠均未见上述各种异常表现。结论 可控性大鼠急性脑局部缺血模型稳定可靠，能模拟出不同灌注程度的缺血状态，除了可用于脑梗死的研究外，更适用于脑梗死前期的急性脑局部缺血的研究。功能CT灌注成像是评价急性脑局部缺血模型的1种准确、敏感的方法。     

磁共振脑血流灌注的影像及定量分析

目的 应用对比增强磁共振脑血流灌注成像,研究不同病理状态下脑组织的血液动力学变化。方法 采用对Ｔ２＾＊敏感的平面回波自由衰减序列（ＥＰＩ－ＦＩＤ）,对４５例因性因管病、１１例其他脑血管病、４例脑肿瘤和４例脑炎患者进行了注射对比剂后的血流灌注加权成像（ＰＷＩ）,分析脑血流灌注图,并定量地研究脑组织的血液动力学变化。结果 磁共振脑血流灌注图和定量分析发现５４个病例的脑组织有异常的血液动力学变化;ＰＷＩ     

Multiphasic perfusion computed tomography in hyperacute ischemic stroke: comparison with diffusion and perfusion magnetic resonance imaging

PURPOSE: The purpose of this study was to compare multiphasic perfusion computed tomography (CT) with diffusion and perfusion magnetic resonance imaging (MRI) in predicting final infarct volume, infarct growth, and clinical severity in patients with hyperacute ischemia untreated by thrombolytic therapy. METHOD: Multiphasic perfusion CT was performed in 19 patients with ischemic stroke within 6 hours of symptom onset. Two CT maps of peak and total perfusion were generated from CT data. Diffusion-weighted imaging (DWI) and perfusion MRI were obtained within 150 minutes after CT. Lesion volumes on CT and MRI were compared with final infarct volume and clinical scores, and mismatch on CT or MRI was compared with infarct growth. RESULTS: The lesion volume on the CT total perfusion map strongly correlated with MRI relative cerebral blood volume (rCBV), and that on the CT peak perfusion map strongly correlated with MRI relative cerebral blood flow (rCBF) and rCBV (P < 0.001). The lesion volume on unenhanced CT or DWI moderately correlated with final infarct volume, but only lesion volume on unenhanced CT weakly correlated with baseline clinical scores (P = 0.024). The lesion volumes on the CT peak perfusion map and MRI rCBF similarly correlated with final infarct volume and clinical scores and more strongly than those on mean transit time (MTT) or time to peak (TTP). DWI-rCBF or CT mismatch was more predictive of infarct growth than DWI-MTT or DWI-TTP mismatch. CONCLUSION: Multiphasic perfusion CT is useful and of comparable utility to diffusion and perfusion MRI for predicting final infarct volume, infarct growth, and clinical severity in acute ischemic stroke.     

Dynamic CT Perfusion Imaging for the Detection of Crossed Cerebellar Diaschisis in Acute Ischemic Stroke

Objective

Although the detection of crossed cerebellar diaschisis (CCD) by means of different imaging modalities is well described, little is known about its diagnosis by computed tomography perfusion (CTP) imaging. We investigated the detection rate of CCD by CTP imaging and the factors related to CCD on CTP images in patients with acute ischemic stroke.

Materials and Methods

CT perfusion maps of cerebral blood volume (CBV), cerebral blood flow (CBF), mean transit time (MTT), and time-to-peak (TTP) obtained from 81 consecutive patients affected by an acute ischemic stroke were retrospectively reviewed. Whole-brain perfusion maps were obtained with a multichannel CT scanner using the toggling-table technique. The criteria for CCD was a unilateral supratentorial ischemic lesion and an accompanying decrease in perfusion of the contralateral cerebellar hemisphere on the basis of CTP maps by visual inspection without a set threshold. Maps were quantitatively analyzed in CCD positive cases.

Results

The criteria for CCD were fulfilled in 25 of the 81 cases (31%). Detection rates per CTP map were as follows: MTT (31%) > TTP (21%) > CBF (9%) > CBV (6%). Supratentorial ischemic volume, degree of perfusion reduction, and infratentorial asymmetry index correlated strongly (R, 0.555-0.870) and significantly (p < 0.05) with each other in CCD-positive cases.

Conclusion

It is possible to detect CCD on all four of the CTP-based maps. Of these maps, MTT is most sensitive in detecting CCD. Our data indicate that CTP imaging is a valid tool for the diagnosis of CCD in patients affected by an acute hemispheric stroke.     

320排动态容积CT全脑灌注成像在脑梗死缺血半暗带分期中的应用

目的 应用320排动态容积CT全脑灌注成像探讨脑梗死缺血半暗带分期的可行性.资料与方法 测量18例存在缺血半暗带脑梗死患者的梗死核心区、缺血半暗带区及其镜像对侧脑血容量(CBV)、脑血流量(CBF)、平均通过时间(MTT)及达峰时间(TTP),按脑梗死前期分期标准对缺血半暗带进行分期.结果 18例缺血半暗带区表现为MTT、TTP延长,CBF降低,CBV轻度升高、正常或轻度降低.与梗死核心区比较,缺血半暗带区CBV、CBF升高,MTT延长,TTP缩短(P＜0.05);与健侧对应区比较,CBF降低,MTT及TTP延长(P＜0.05),而CBV无显著差异(P＞0.05).缺血半暗带分期:Ⅰ2期3例,Ⅱ1期9例,Ⅱ2期6例.结论 应用320排动态容积CT全脑灌注成像可明确脑梗死患者的病变部位、范围以及有无缺血半暗带存在,并可对缺血半暗带进行分期.     

CT perfusion scanning with deconvolution analysis: pilot study in patients with acute middle cerebral artery stroke.

PURPOSE: To measure mean cerebral blood flow (CBF) in ischemic and nonischemic territories and in low-attenuation regions in patients with acute stroke by using deconvolution-derived hemodynamic imaging. MATERIALS AND METHODS: Twelve patients with acute middle cerebral artery stroke and 12 control patients were examined by using single-section computed tomography (CT) perfusion scanning. Analysis was performed with a deconvolution-based algorithm. Comparisons of mean CBF, cerebral blood volume (CBV), and mean transit time (MTT) were determined between hemispheres in all patients and between low- and normal-attenuation regions in patients with acute stroke. Two independent readers examined the images for extent of visually apparent regional perfusion abnormalities. The data were compared with extent of final infarct in seven patients with acute stroke who underwent follow-up CT or magnetic resonance imaging. RESULTS: Significant decreases in CBF (-50%, P =.001) were found in the affected hemispheres of patients with acute stroke. Significant changes in CBV (-26%, P =.03) and MTT (+111%, P =.004) were also seen. Significant alterations in perfusion were also seen in low- compared with normal-attenuation areas. Pearson correlation between readers for extent of CBF abnormality was 0.94 (P =.001). Intraobserver variation was 8.9% for CBF abnormalities. CONCLUSION: Deconvolution analysis of CT perfusion data is a promising method for evaluation of cerebral hemodynamics in patients with acute stroke.