ACZ负荷MR灌注成像对高血压患者脑血管储备功能的初步研究

目的 探讨MR灌注成像结合乙酰唑胺(ACZ)负荷试验,评估出现症状性脑梗死前高血压患者的脑血管储备功能. 资料与方法 对13例高血压患者和12例正常对照在口服ACZ前后进行2次MR PWI检查,选取双侧尾状核头部、豆状核、丘脑、额上回、颞上回及楔叶作为兴趣区(ROI),测量其局部脑血容量(rCBV)、平均通过时间(rMTT)并根据公式局部脑血流量(rCBF)= rCBV / rMTT、脑血管储备(%)= [(ACZ后rCBF ACZ前rCBF)/ ACZ前rCBF]×100%计算脑血管储备. 结果 (1)高血压组各ROI的rMTT、rCBV和rCBF在ACZ负荷前后无统计学意义(P＞0.05);对照组各ROI的rMTT在ACZ负荷后缩短(P＜0.05),rCBV和rCBF在ACZ后增加(P＜0.05);(2)高血压组各ROI的脑血管储备(5.5%～27.8%)较对照组相应ROI的脑血管储备(34.0%～56.1%)明显降低(P＜0.05). 结论 在出现症状性脑梗死之前,高血压患者的脑血管储备较同年龄组正常血压者下降,处于亚临床缺血的状态.     

慢性大脑中动脉狭窄与闭塞的MR灌注成像研究

目的:探讨单侧大脑中动脉(MCA)慢性重度狭窄、闭塞患者的MR脑灌注成像表现及其应用价值.方法:28例单侧MCA慢性重度狭窄或闭塞患者行MR脑灌注成像检查,得出有关脑灌注参数图,包括相对脑血流量(rCBF)、相对脑血容量(rCBV)、相对平均通过时间(rMTT)和达峰时间(TTP)图,对灌注成像表现进行定性和定量分析.结果:28例MCA慢性重度狭窄或闭塞患者,磁共振灌注加权成像(PWI)均发现病变侧灌注异常,病变侧rCBV、rMTT和TTP与对侧比较差异有显著性意义(P＜0.01),rCBF差异无显著性意义(P＞0.05).rMTT和TTP图显示病变侧较对侧明显延迟,24例仅累及MCA供血区,4例同时累及MCA和分水岭区.结论:PWI检查能够显示单侧MCA慢性重度狭窄或闭塞患者脑血流动力学受损情况,对临床诊断和治疗具有重要价值.     

磁共振弥散和灌注加权成像对短暂性脑缺血发作的评估

目的 探讨磁共振弥散(DWI)和灌注成像(PWI)结合,对短暂性脑缺血(TIA)分类及预后评估的价值.方法 41例TIA患者入选,第1次DWI及PWI均在发病后24 h内进行,DWI阳性或PWI异常者分别于7～14 d内、1～3月复查T2WI、FLAIR、DWI及PWI ;DWI阴性及PWI正常者7～14 d后复查,如无异常,则随访终止,反之,同上随访.症状侧脑血容量(CBV)和平均通过时间(MTT)值分别除以对侧对照正常半球的CBV和MTT值得到其相对值,即rCBV和rMTT,rCBF值由rCBV除以rMTT得到.根据随访后的DWI表现,TIA患者被分为预后好与差2组.结果 28例(68%)患者有DWI或PWI的异常.在这些患者中15例仅有DWI异常,6例仅有PWI异常,7例既有DWI异常又有PWI异常.预后差的TIA患者rCBF和rCBV均明显高于预后好的患者.结论 磁共振弥散和灌注结合有助于评价TIA患者缺血的程度,对于治疗及预后判断都非常有价值.     

磁共振灌注加权成像在肝豆状核变性诊断中的应用

目的 探讨MR灌注加权成像(perfnsion weighted imaging,PWI)在肝豆状核变性(hepatolenticular degener-ation,HLD)诊断中的应用价值.资料与方法 对30例临床诊断为HLD的患者及对照组25例行常规颅脑MRI,以及注射对比剂(Gd-DTPA)后采用自旋回波-回波平面成像(SE-EPI)序列MR PWI检查.通过工作站重组相对局部脑血容量(rCBV)图、局部脑血流量(rCBF)图及对比剂平均通过时间(rMTT)图.计算每例受试者的豆状核及丘脑等HID患者脑病变易发区域的rCBV、rCBF及rMTT相对值,比较HLD患者组和对照组之间的rCBV、rCBF及rMTT相对值差别.结果 常规MRI异常信号(多为长T1、长T2信号)最常见于HLD患者的豆状核及丘脑等部位.PWI显示HLD患者组的rCBV、ICBF均值较对照组低.结论 MR脑血流灌注图和半定量分析有助于观察HLD患者病变区的血流动力学改变,与常规MRI结合可同时反映HID患者脑病变的部位、形态和功能变化.     

单侧大脑中动脉狭窄程度与磁共振血流灌注相关性研究

目的:探讨大脑中动脉(MCA)狭窄程度与脑磁共振灌注加权成像(PWI)的相关性。方法:30例短暂性脑缺血发作(TIA)患者行高分辨力MRI检查并判断单侧MCA狭窄程度,同时行磁共振PWI检查,并对MCA不同狭窄状态下得出的患侧和镜像侧灌注参数,包括相对脑血容量(rCBV)、相对脑血流量(rBCF)、相对平均通过时间(rMTT)、相对达峰时间(rTTP)进行定量分析。结果:30例患者中,高分辨力MRI均可显示不同程度MCA狭窄,灌注均出现异常,患侧灌注参数rCBV、rCBF、rMTT、rTTP与镜像侧比较,差异均有统计学意义(P<0.05)。MCA狭窄率与rMTT延长百分率之间呈正相关性(r=0.45,P<0.05)。结论:高分辨力MRI对MCA狭窄程度的评估与PWI灌注参数之间存在正相关性,MCA狭窄程度与PWI相结合对于评价脑组织供血有一定的指导意义。     

后颅凹肿瘤的磁共振灌注成像

目的　评价磁共振灌注成像 (PWI)在后颅凹肿瘤的诊断和鉴别诊断中的价值。方法　本组 3 7例后颅凹肿瘤病人行双倍剂量PWI,求出肿瘤和脑白质的相对脑血流容积 (rCBV)和平均通过时间 (MTT) ,计算肿瘤与脑白质的rCBV之比QrCBV、肿瘤的MTT较白质的延长值rMTT。结果　血管母细胞瘤的血流灌注最高 ,明显高于其它肿瘤。转移瘤的QrCBV和rMTT变化范围较大 ,与其它肿瘤不易区别。髓母细胞瘤的QrCBV高于毛细胞型星形细胞瘤和室管膜瘤 ,但后两者间无显著统计学差异。脑膜瘤和神经源性肿瘤较脑内原发性肿瘤的rMTT明显延长。结论　PWI在后颅凹肿瘤的诊断和鉴别诊断中具有重要价值 ,可作为常规MRI检查的补充     

MR灌注成像在颈内动脉和大脑中动脉狭窄与闭塞的应用研究

目的 探讨单侧颈内动脉（ICA）／大脑中动脉（MCA）慢性重度狭窄、闭塞患者的MR脑灌注成像（PWI）表现及其应用价值，分析PWI表现与动脉狭窄程度的关系。资料与方法 90例单侧ICA／MCA慢性重度狭窄或闭塞患者行MRPWI检查，计算出有关脑灌注参数图，包括相对脑血流量（rCBF）、相对脑血容量（rCBV）、相对平均通过时间（rMTT）和达峰时间（TTP）图，对PWI表现进行定性和定量分析，并作病变侧与对侧对比。62例单侧ICA重度狭窄或闭塞、28例单侧MCA重度狭窄或闭塞患者分别为重度狭窄和闭塞两组，对脑灌注结果与动脉狭窄程度的关系进行分析。结果 90例ICA／MCA慢性重度狭窄或闭塞患者，PWI均发现灌注异常，表现分为3期：l期3l例，表现为TTP、rMTY延迟，rCBF和rCBV正常；2期41例，表现为TTP、rMTT延迟，rCBF正常．rCBV轻度增高；3期18例，表现为TTP、rMTY延迟，rCBF、rCBV轻度下降。病变区rCBV、rMTY和TTP与对侧比较有显著性差异（P〈0．01），PWI表现3期之间rCBF无显著差异（P〉0.05），rCBV、rMTT、TTP均有显著性差异（P〈0．01）。PWI表现分期与ICA／MCA狭窄程度无明显关联性；rMTT、TTP值与ICA／MCA狭窄程度有关联性，闭塞组的rMTT、TTP值高于重度狭窄组（P〈0.01）。结论PWI检查能够显示单侧ICA／MCA慢性重度狭窄或闭塞患者脑血流动力学受损情况，区分局部低灌注的程度，对临床的诊断和治疗具有重要价值，而ICA／MCA狭窄程度不能完全预测脑血流动力学改变。     

高分辨率MRI评价大脑中动脉狭窄程度与灌注加权成像评估脑供血的研究

目的 探讨高分辨率MRI(high-resolution MRI,HRMRI)判定大脑中动脉(middle cerebral artery,MCA)狭窄程度与脑MRI灌注加权成像(perfusion weighted imaging,PWI)评价脑供血的价值.方法 对30例短暂性脑缺血(TIA)患者行HRMRI以判定单侧MCA狭窄程度,并行MRI PWI检查,得出患侧和镜像侧灌注参数,包括相对脑血容量(relative cerebral blood volume,rCBV)、相对脑血流量(relative cerebral blood flow,rBCF)、相对平均通过时间(relative mean transit time,rMTT)、相对达峰时间(relative time to peak,rTTP),并对其进行定量分析.结果 30例患者中,HRMRI判定MCA轻度狭窄7例,中度狭窄9例,重度狭窄或闭塞14例;30例灌注均出现异常,rCBF、rMTT、rTTP灌注参数均具有统计学意义,其中MCA中度、重度狭窄或闭塞组狭窄率与rMTT延长百分率之间呈正相关(r=0.897、0.829,P<0.01).结论 HRMRI对MCA狭窄程度的评估具有重要价值,联合PWI评估脑供血对临床具有重要的指导意义.     

幕上脑梗死后对侧小脑半球低灌注的磁共振成像研究

目的 探讨磁共振灌注成像评价急性期单侧幕上大脑中动脉区脑梗死后对侧小脑半球灌注量改变的诊断价值.资料与方法 搜集 38 例幕上急性期脑梗死患者进行双侧小脑半球磁共振灌注成像(perfusion-weightedimaging,PWI),通过测量双侧小脑半球相对脑血容量(relalive cerebral blood volume,rCBV)、相对脑血流量(relalivecerebral blood flow,rCBF)和平均通过时间(relalive mean transit time,rMTT)及达峰时间(relalive time to peak,rTTP),判断幕上梗死病灶对侧小脑半球的灌注情况.结果 38 例中,16 例患者对侧小脑半球的 rTTP 延长,较健侧延长约(133.28±70.25)%;rMTT 值较健侧延长约(82.78±91.22)%,但无统计学意义(P=0.112,P>0.05);rCBF 较健侧降低约(53.74±41.56)%;rCBV 较健侧降低约(100.58±91.72)%.结论 部分幕上脑梗死患者可造成病变对侧小脑半球低灌注,并与梗死原发灶的体积相关,提示这些患者可能存在交叉性小脑机能联系不能(crossedcerebellar diaschisis,CCD).     

脑胶质瘤灌注成像与病理对照研究

目的运用磁共振灌注成像(PWI)获取对比剂首过期间的兴趣区图像,评价rCBV和rCBF在术前评估脑胶质瘤组织学分级中的价值.材料和方法本组共30例颅脑胶质瘤,均经病理证实.常规MRI扫描后行PWI,PWI序列为GRE-EPIRIT2*WI,由灌注资料获取rCBV、rCBF图像,计算最大rCBV和rCBF并与组织病理学分级对照.结果Ⅲ～Ⅳ级胶质瘤(18例)的rCBF、rCBV分别为1.8～7.4和2.67～10.48,均值分别为5.4±1.8和5.75±3.85.I～Ⅱ级胶质瘤(12例)rCBF、rCBV分别为0.5～1.7和1.36～3.16,均值分别为1.4±0.3和1.75±0.65.两组间rCBF和rCBV差别有显著性(P＜0.01,studentt检验).结论灌注成像对颅脑胶质瘤的术前分级有重要价值.     

Outcome of acute ischemic lesions evaluated by diffusion and perfusion MR imaging.

BACKGROUND AND PURPOSE: Diffusion and perfusion MR imaging have been reported to be valuable in the diagnosis of acute ischemia. Our purpose was to ascertain the value of these techniques in the prediction of ischemic injury and estimation of infarction size, as determined on follow-up examinations. METHODS: We studied 18 patients with acute ischemic stroke who underwent echo-planar perfusion and diffusion imaging within 72 hours of symptom onset. Quantitative volume measurements of ischemic lesions were derived from relative mean transit time (rMTT) maps, relative cerebral blood volume (rCBV) maps, and/or apparent diffusion coefficient (ADC) maps. Follow-up examinations were performed to verify clinical suspicion of infarction and to calculate the true infarction size. RESULTS: Twenty-five ischemic lesions were detected during the acute phase, and 14 of these were confirmed as infarcts on follow-up images. Both ADC and rMTT maps had a higher sensitivity (86%) than the rCBV map (79%), and the rCBV map had the highest specificity (91%) for detection of infarction as judged on follow-up images. The rMTT and ADC maps tended to overestimate infarction size (by 282% and 182%, respectively), whereas the rCBV map appeared to be more precise (117%). Significant differences were found between ADC and rMTT maps, and between rCBV and rMTT maps. CONCLUSION: Our data indicate that all three techniques are sensitive in detecting early ischemic injury within 72 hours of symptom onset but tend to overestimate the true infarction size. The best methods for detecting ischemic injury and for estimating infarction size appear to be the ADC map and the rCBV map, respectively, and the diffusion abnormality may indicate early changes of both reversible and irreversible ischemia.     

瘤周水肿的CT灌注成像与MR灌注成像初步比较研究

目的比较CT灌注成像和MR灌注成像瘤周水肿区相对脑血容量（rCBV）对鉴别高级别神经上皮肿瘤与转移瘤的价值。资料与方法选取同时行CT灌注成像和MR灌注成像检查的14例高级别神经上皮肿瘤（WHOⅢ、Ⅳ级）和8例转移瘤患者,比较瘤周水肿rCBV的鉴别诊断效果。结果CT灌注成像和MR灌注成像均显示高级别神经上皮肿瘤瘤周水肿区rCBV高于转移瘤者,差异有统计学意义（P〈0.05）。二者的受试者工作特性曲线（ROC）下面积分别为0.911和0.929。结论CT灌注成像和MR灌注成像瘤周水肿区rCBV对高级别神经上皮肿瘤与转移瘤的鉴别诊断均具有很高的价值,以MR灌注成像更佳。     

扩散和灌注加权成像对兔脑缺血半暗带的量化

目的:探讨磁共振扩散加权成像(DWI)和灌注加权成像(PWI)在对被挽救缺血半暗带(IP)评价中的价值。方法:将制作成功的58只兔大脑中动脉闭塞(MCAO)模型随机分为永久缺血组(A组)和缺血再灌注组(B组);A组再按缺血1、3、6、12、24、48 h分组(A_1～6组),B组再按缺血1h后再灌注0、2、5、11、23、47h分组(B_(1～6)组)。然后,对各组行I)WI和PWI检查。结果:缺血再灌注组DWI像上异常信号区面积明显小于永久缺血组;缺血24h,梗死范围基本稳定。缺血1h,当表观扩散系数(ADC)比值、相对脑血容量(rCBV)比值和相对平均通过时间(rMTT)比值分别为(73.40±4.33)%、(46.83±9.89)%、1.58±0.04时,该区可能为IP;当ADC比值和rCBV比值分别低于(58.83±6.06)%和(22.87±8.19)%、rMTT比值大于1.94±0.1时,缺血脑组织将会发生不可逆性坏死。结论:DWI结合PWI能够快速、有效地评价IP。     

Hemodynamic modifications in patients with symptomatic unilateral stenosis of the internal carotid artery: evaluation with MR imaging perfusion sequences

BACKGROUND AND PURPOSE: Risk of developing ischemia is higher in patients with reduced cerebrovascular reactivity than in those with preserved cerebrovascular reactivity. Therefore, we assessed cerebral hemodynamic modifications in patients with unilateral stenosis of the internal carotid artery by using perfusion-weighted MR imaging to determine if these modifications underlie or anticipate ischemic signs and symptoms. METHODS: Fifteen patients with unilateral 70-90% carotid artery stenosis were studied with digital subtraction angiography and perfusion-weighted MR imaging. Their findings were compared with those of 15 age- and sex-matched control subjects. Regional cerebral blood volume (rCBV) and mean transit time (MTT) values were calculated in the middle cerebral artery and border zone territories. RESULTS: No significant difference was noted in rCBV and MTT values between the hemispheres in the symptomatic patients. There was a significant difference in MTT values in the border zones between patients and control subjects. MR images in patients and control subjects did not reveal large territorial infarcts and did reveal similar white matter lesion burdens. CONCLUSION: There is adequate compensation of unilateral stenosis when the stenosis is less than 90%. The risk of stroke is higher in patients with stenoses exceeding 70%, mostly because of decreased collateral reserve when confronted with emboli.     

Postoperative evaluation of moyamoya disease with perfusion-weighted MR imaging: initial experience

BACKGROUND AND PURPOSE: Encephaloduroarteriosynangiosis (EDAS) has become the main treatment for moyamoya disease, a chronically progressive cerebrovascular occlusive disease in children. We aimed to assess the utility of perfusion-weighted MR imaging for evaluating hemodynamic changes before and after EDAS. METHODS: Thirteen patients with angiographically confirmed moyamoya disease who underwent EDAS were investigated, and results were compared with those of a control group (n = 5). Perfusion MR imaging was performed before and after EDAS by using a T2*-weighted contrast material-enhanced technique. Relative cerebral blood volume (rCBV) and time to peak enhancement (TTP) maps were calculated. Relative ratios of rCBV and TTP in the middle cerebral artery (MCA) and basal ganglia were measured and compared with those of the posterior cerebral artery (PCA). Changes in hemodynamic parameters between pre- and post-EDAS perfusion maps were investigated. RESULTS: The mean rCBV ratio of MCA to PCA in the patient group was slightly higher than that in the control group, without statistical significance. All 13 patients showed a delayed TTP in the MCA before EDAS compared with the control group (P =.0006), and the TTP after EDAS was significantly reduced (P =.0002). In the basal ganglia, shortening of the TTP was demonstrated before EDAS, but no significant change was observed after EDAS. CONCLUSION: Perfusion-weighted MR imaging can be applied for evaluating postoperative changes in cerebral blood flow in moyamoya disease. Shortening of the TTP in the MCA of the hemisphere operated on is a marker for the development of collateral circulation from the external carotid artery to the internal carotid artery.     

Temporal changes in reversible cerebral ischemia on perfusion- and diffusion-weighted magnetic resonance imaging: the value of relative cerebral blood volume maps

Using a transorbital approach we induced the temporal occlusion and reperfusion model in 18 cats. A vascular clamp was placed on the main trunk of the left middle cerebral artery (MCA) for 1 h. Diffusion- and perfusion-weighted MR images were obtained at 1, 3, 6 and 24 h after the clip was released. The cats were killed 24 h after reperfusion, and triphenyl tetrazolium chloride (TTC) staining was performed. After the relative cerebral blood volume (rCBV), time to peak enhancement (TTP) and apparent diffusion coefficient (ADC) maps had been acquired, ROIs were drawn on (1) the area of the infarct produced, (2) the area of high signal intensity on initial diffusion-weighted magnetic resonance imaging (DWI) but normal on TTC staining, e.g., salvaged parenchyma. The ratios of these areas to the normal contralateral cortex were calculated and compared with those of the areas of the final infarct and the salvaged parenchyma. Areas of final infarct showed a temporal increase of rCBV on 3 and 6-h imaging and a final depletion on 24-h imaging. A persistent decrease of ADC value and delayed TTP were observed. Salvaged parenchyma also showed increased rCBV after reperfusion until the last imaging comparing it to the final area of infarct (P < 0.05, 24-h rCBV). The initial decrease in the ADC and delayed TTP normalized on 24-h imaging. In conclusion, rCBV of 24-h imaging was the reliable parameter to predict final infarct. A combination of serial changes on DWI and perfusion-weighted imaging (PWI) can predict ischemic penumbra and outcome.     

CT灌注成像对烟雾病术后桥血管再通及手术前后脑血流变化的评价

目的 探讨CT灌注成像技术（CTP）在烟雾病颞浅-大脑中动脉塔桥术（STA-MCA）术后桥血管再通及手术前后脑血流变化的价值.方法 22例烟雾病患者在实施STA-MCA手术前、术后行CTP及CTA检查,对患者手术前后脑血流量（CBF）、脑血容量（CBV）、平均通过时间（MTT）和达峰时间（TTP）进行定量、定性分析,计算术侧/对侧相对比值（rCBF、rCBV、rTTP及rMTT值）.采用配对t检验或配对序符号检验比较手术前后CT灌注参数值及相对值的差异.结果 22例患者术后CTA检查显示桥血管均通畅.22例患者术前手术侧与对比侧CTP参数值比较,患侧大脑中动脉分布区的CBF降低,CBV增加,MTT延长;烟雾病患者血管搭桥术后手术侧与手术前比较发现,大脑中动脉分布区的rCBF增加,rCBV不变,rMTT降低.差异有统计学意义（P＜0.05）.结论 CTP联合CTA技术,可显示烟雾病患者脑部血管形态和血容量改变.对烟雾病STA-MCA搭桥术后桥血管再通情况及脑血流动力学变化同时进行评价,具有极高的临床应用价值.     

动态磁敏感对比增强磁共振成像在脑肿瘤术前评估中的应用

目的 评价动态磁敏感对比增强(DSC)磁共振成像技术在脑肿瘤术前评估中的应用价值.方法经病理证实的41例脑肿瘤患者,其中,高级别胶质瘤8例,低级别胶质瘤16例,转移瘤7例,脑膜瘤10例,使用3.0T MR扫描仪进行静脉团注钆喷替酸葡甲胺(Gd-DTPA)的DSC灌注检查,原始图像分析处理后分别获取肿瘤实性区域、瘤周1 cm及2 cm区域血流灌注指标平均rCBVmax比值及平均rCBFmax比值.所得数据经统计学处理,并用Pearson相关分析法来分析两灌注指标的相关性.结果在肿瘤实性区域,低级别胶质瘤组与其他各组间差异均有统计学意义(P<0.05);在瘤旁1 cm区域,高级别胶质瘤组与其他各组间差异均有统计学意义(P<0.05),低级别胶质瘤组与转移瘤组间差异有统计学意义(P<0.05).各组脑肿瘤瘤区实性区域与瘤旁1 cm及2 cm区域差异均有统计学意义(P<0.05),其中高级别胶质瘤组及转移瘤组瘤旁1 cm与2 cm区域间差异有统计学意义(P<0.05).Pearson相关分析结果显示同组肿瘤相同区域两指标均显著正相关.结论 DSC技术在脑肿瘤术前病理学级别评估及鉴别诊断中具有重要的应用价值.