Combined diffusion- and perfusion-weighted imaging: a new way for the assessment of hemispheric transient ischemic attack patients

Abnormalities in diffusion-weighted and perfusion-weighted magnetic resonance images not only occur in stroke patients but also in transient ischemic attack patients. We found magnetic resonance images were abnormal in 28 patients (68%): 15 had diffusion-weighted imaging abnormalities, 7 had both diffusion-weighted imaging and perfusion-weighted imaging defects and 6 had an isolated perfusion-weighted imaging abnormality. Patients with shorter onset to magnetic resonance imaging, large artery atherothrombosis, coronary artery disease, hyperlipidemia and hemiparesis were more likely to show perfusion-weighted imaging abnormalities. Compared with patients who had a good prognosis, in poor prognosis patients, the relative cerebral blood flow and relative cerebral blood volume was significantly higher. The data suggest that transient ischemic attack patients are more likely to have a poor prognosis when white matter of the symptomatic side shows hyperperfusion within 24 h of symptom onset; however, patients are more likely to have a good prognosis when white matter of the symptomatic side shows hypoperfusion.     

Artificial neural network prediction of ischemic tissue fate in acute stroke imaging

Multimodal magnetic resonance imaging of acute stroke provides predictive value that can be used to guide stroke therapy. A flexible artificial neural network (ANN) algorithm was developed and applied to predict ischemic tissue fate on three stroke groups: 30-, 60-minute, and permanent middle cerebral artery occlusion in rats. Cerebral blood flow (CBF), apparent diffusion coefficient (ADC), and spin–spin relaxation time constant (T2) were acquired during the acute phase up to 3 hours and again at 24 hours followed by histology. Infarct was predicted on a pixel-by-pixel basis using only acute (30-minute) stroke data. In addition, neighboring pixel information and infarction incidence were also incorporated into the ANN model to improve prediction accuracy. Receiver-operating characteristic analysis was used to quantify prediction accuracy. The major findings were the following: (1) CBF alone poorly predicted the final infarct across three experimental groups; (2) ADC alone adequately predicted the infarct; (3) CBF+ADC improved the prediction accuracy; (4) inclusion of neighboring pixel information and infarction incidence further improved the prediction accuracy; and (5) prediction was more accurate for permanent occlusion, followed by 60- and 30-minute occlusion. The ANN predictive model could thus provide a flexible and objective framework for clinicians to evaluate stroke treatment options on an individual patient basis.     

MRS及PWI对超急性脑梗死的诊断及疗效评估

目的:探讨MRS和PWI技术对超急性脑梗死诊断和治疗中的作用。方法:分别应用MRS和PWI技术对临床怀疑超急性脑梗死患者进行扫描,并对所获得图像进行分析。结果:在脑梗塞发作早期常规MRI无法检测到的低灌注区,而MRS和PWI技术最早可在发病1.5h发现病灶。结论:MRS和PWI技术的应用对监测脑部疾病的病理生理变化、早期诊断、疗效和预后判断均有十分重要的意义。     

MR弥散张量成像和灌注成像对鼠脑C6胶质瘤模型的量化分析

目的：探讨 MR 弥散张量成像和灌注成像在大鼠 C6脑胶质瘤模型诊断中的意义。方法：构建大鼠 C6脑胶质瘤模型,选择肿瘤最大层面分别获取 Ktrans、Kep、Ve、MD 和 FA 图。结果：Ktrans、Kep、Ve、MD 和 FA 值在肿瘤区域、坏死区域和正常脑组织均存在统计学差异（P〈0.001）。 Ktrans 值与 Kep 值呈高度正相关（肿瘤区域：0.932,P〈0.001;坏死区域：0.921,P〈0.001;正常组织：0.071,P ＝0.676）;扣除 Ktrans值的影响,Kep 值和 Ve 值呈负相关（肿瘤区域：-0.602,P〈0.001;坏死区域：-0.617,P〈0.001;正常组织：0.084,P＝0.626）;扣除 Kep 值的影响,Ktrans 值和 Ve 值呈正相关（肿瘤区域：0.406,P ＝0.014;坏死区域：0.582,P〈0.001;正常组织：0.275,P＝0.105）。 FA 值和 MD 值呈现负相关（肿瘤区域：-0.898,P〈0.001;坏死区域：-0.782,P〈0.001;正常组织：-0.478,P＝0.003）。结论：MR 弥散张量成像和灌注成像有助于胶质瘤模型中肿瘤区域、坏死区域和正常脑组织的鉴别。     

PWI对胶质瘤术后复发与放射性脑损伤的鉴别诊断价值

脑胶质瘤术后放疗后的病人,一旦脑内出现新的异常强化灶时常需要考虑肿瘤复发或放射性脑损伤,常规磁共振检查较难鉴别。磁共振灌注加权成像（PWI）是反映组织微观血流动力学信息的一项新技术,可对二者鉴别提供更多信息,本文就近年PWI在诊断肿瘤复发及放射性脑损伤中的应用加以综述。     

磁共振弥散及灌注成像在脑梗死缺血半暗带测量及预后判定的应用

目的应用磁共振弥散(DWI)及灌注成像(PWI)对脑梗死缺血半暗带(IP)判定及其在预后评估的价值。方法对41例符合入组标准的脑梗死患者进行磁共振扫描,分别于入院、发病一、三个月对患者进行神经运动功能评分(NIHSS)。应用DWI及PWI面积值计算IP,结合NIHSS评估IP在脑梗死预后价值。结果 39例患者存在IP,对IP/PWI与NIHSS差值进行相关性分析,两者呈正相关关系,IP/PWI比值越大患者预后越好。结论应用DWI与PWI测量IP及评估脑梗死预后具有一定价值。     

急性脑缺血及再灌注的DWI与PWI实验研究

目的利用DWI及PWI研究大鼠(MCAO)急性脑缺血再灌注模型,观察脑缺血再灌注的动态变化规律,探讨急性脑缺血的发病机理。方法建立大鼠急性脑缺血再灌注模型,45只雄性SD大鼠(280～320g),随机分成3组(A、B、C组,n=15)。单丝尼龙线置入颈内动脉,阻闭右侧大脑中动脉。分别于阻闭30min、1h、2h后抽出尼龙线,恢复再灌注。于再通前,再通后1h、2h、3h、6h、12h及24h行功能及常规磁共振扫描。对3组结果进行比较分析。结果(1)A组再通后较再通前DWI所示高信号区明显缩小,B组再通后较再通前不同程度缩小,C组再通后均较前略有扩大。3组间差异显著(P<0.01)。(2)急性期病灶中心血流灌注减少程度A与C组间差异有统计学意义(P<0.05)。结论DWI及PWI对于急性脑缺血及缺血再灌注后缺血灶的动态变化、发病机理、尤其是判定缺血半暗带的存在具有一定的价值。     

DWI／PWI在脑梗死缺血半暗带量化评定中的应用

目的评价磁共振弥散加权成像（DWI）和灌注加权成像（PWI）在界定超早期脑梗死缺血半暗带中的应用。方法25例发病时间在6h以内的超早期脑梗死患者行MRI检查,包括DWI和PWI,测量分析梗死中心区、缺血半暗带（IP）及对侧镜像区扩张变化和血流灌注。计算ADC值。结果超早期大面积脑梗死患者PWI上显示的脑灌注延长区域与DWI上显示的高信号急性脑梗死区域不匹配,PWI显示的病灶范围大于DWI显示;DWI定量分析显示,与梗死中心区比较,IP、梗死中心对侧镜像区ADC值均明显增高,有显著性差异（P〈0．01）;IP区fADe值高于梗死中心区,两者比较有显著性差异（P〈0．05）;PWI显示大面积梗死患者脑组织血流灌注明显减低,腔隙性脑梗死患者未见明显的灌注减低区。结论DWI与PWI的联合检查可准确诊断超早期脑梗死并预测IP。     

弥散加权和灌注加权在缺血性中风的应用

目的　观察缺血性中风早期病灶的部位及程度,评价病灶的微循环状态。方法　ＤＷＩ和ＰＷＩ是一 种新的磁共振成像技术,ＤＷＩ通过测定水分子的布朗运动而获得;ＰＷＩ通过静脉团注造影剂而得到。结果　ＤＷＩ 能明确早期急性缺血性病灶的部位,ＰＷＩ证实病灶区微循环不良的范围。结论　有助于对缺血性中风患者治疗方 法的选择,并提供了一种高度敏感的评价治疗效果的方法。     

前列地尔注射液对急性脑梗死患者MR脑灌注水平的影响

目的 观察前列地尔注射液对急性脑梗死(acute cerebral infarction,ACI)患者的临床疗效及对患者脑灌注水平的影响.方法 83例ACI患者随机分为前列地尔组(n=43)和常规治疗组(n=40)及健康对照组(n=40).采用全脑磁共振灌注成像(PWI),观察患者在治疗后48 h,7d的脑灌注水平,并在治疗后7d进行临床疗效的判定.结果 两组患者治疗7d后,前列地尔组在相对脑血流量(rCBF),相对脑血容积(rcBV),均较常规治疗组显著增加(P＜0.01).结论 前列地尔注射液可能通过改善脑灌注水平发挥治疗ACI的有效性.