单侧烟雾病大脑中动脉供血区血管情况与灌注状态的相关性研究

目的探讨单侧烟雾病(MMD)大脑中动脉(MCA)供血区血管情况与灌注状态的相关性,为更加个体化地评估血流动力学状态提供客观依据。方法回顾性分析2008年~2013年经天坛医院确诊的单一MCA受累的单侧MMD患者31例。分析MCA狭窄程度、侧支循环分级与MCA皮层的M1~M6区域CT灌注成像各灌注参数比值的相关性。统计学采用Spearman等级相关及多重线性回归检验。结果 1大脑中动脉狭窄程度和灌注参数图的相关性:除M3区域的rCBF及M4区域各灌注参数比值外,各区域的rCBF与MCA的狭窄程度呈负相关,而rMTT及rTTP与MCA狭窄程度呈正相关;2侧支循环分级与灌注参数图的相关性:侧支循环分级与M5区域的rCBV、M6区域的rCBF、rCBV呈负相关,与M1区域的rMTT、M6区域的rMTT及rTTP呈正相关;3其他影响因素:年龄是影响M3区域rCBF、rMTT及rTTP变化的独立因素。结论单侧MMD患者的MCA狭窄程度、侧支循环分级及年龄均是影响灌注参数比值变化的重要因素。     

MRA和MR灌注加权成像在不同类型烟雾病脑血流动力学中的研究

目的 探讨磁共振血管成像(MRA)在烟雾病分期、分类中的应用价值以及MR灌注加权成像(PWI)判断不同类型烟雾病脑血流动力学的情况.方法 搜集经DSA证实的28例烟雾病,按Suzuki分期(Ⅰ～Ⅵ期)方法分期,将尚未形成明显颅外至颅内侧支循环的Ⅰ、Ⅱ、Ⅲ期归第1类,将颅外向颅内侧支循环逐步明显的Ⅳ、Ⅴ、Ⅵ期归第2类.分别对DSA及MRA图像进行分期与分类,以DSA结果作为标准,比较MRA分期、分类结果的可靠性.运用MR PWI研究两类烟雾病患者脑血流动力学情况,测量患者拟手术侧及对侧大脑中动脉(MCA)分布区的灌注参数,包括脑血流量(CBF)、脑血容量(CBV)、平均通过时间(MTT)及延迟时间(DT),计算拟手术侧MCA分布区/对侧MCA分布区灌注参数相对比值(rCBF、rCBV、rMTT及rDT值).采用配对t检验比较不同类型烟雾病PWI灌注参数相对值的差异.结果 28例烟雾病患者DSA显示第1类16例,其中Ⅰ期0例,Ⅱ期5例,Ⅲ期11例;第2类12例,其中Ⅳ期9例,Ⅴ期2例,Ⅵ期1例.MRA显示第1类14例,其中Ⅰ期1例,Ⅱ期6例,Ⅲ期7例;第2类14例,其中Ⅳ期10例,Ⅴ期3例,Ⅵ期1例.MRA与DSA对比分期符合率仅为67.9％.PWI参数中MTT、DT两项参数对脑血流动力学变化敏感.第2类烟雾病患者拟手术侧MCA分布区/对侧镜像区的rMTT(2.35±0.49)及rDT(2.47±0.51)高于第1类rMTT(1.48±0.47)及rDT(1.51±0.56)(t值分别为4.46、4.87,P值均＜0.05),第2类烟雾病患者拟手术侧MCA分布区/对侧镜像区的rCBF(0.72±0.16)及rCBV(0.75±0.27)与第1类rCBF(0.89 ±0.25)及rCBV(1.01±0.32)差异无统计学意义(t值分别为-1.28、-1.79,P值均＞0.05).结论 MRA对烟雾病的分期有局限性,与DSA对比符合率低.PWI发现不同类型烟雾病的脑血流动力学参数rMTT和rDT存在差异.     

脑膜瘤瘤周水肿的64层螺旋CT灌注成像定量研究

目的:应用64层螺旋CT灌注成像定量估计脑膜瘤瘤周水肿的灌注状况.方法:对15例脑肿膜瘤伴瘤周水肿患者进行MSCT灌注成像,经灌注软件处理分别计算近瘤周水肿区及远瘤周水肿区局部脑血流量(rCBF)、局部脑血容量(rCBV)、表面通透性(PS),并与对侧脑白质灌注参数进行比较;测量并计算水肿指数EI[(V水肿+V肿瘤)/V肿瘤],并与rrCBV(rCBV水肿平均/rCBV对侧脑白质)的进行相关性分析.结果:脑膜瘤近瘤周水肿区、远瘤周水肿区的rCBF和rCBV明显低于对侧脑白质(rCBF:t=5.78和4.34,P=0.001,0.005; rCBV:t=6.46和8.46,P=0.001,0.003),近瘤周水肿区的rCBF和rCBV低于远瘤周水肿区(rCBF:t=3.49,P=0.013;rCBV:t=4.10,P=0.006),三组间PS值的差异均没有统计学意义(P值均＞0.05);水肿指数跟瘤周水肿区的rrCBV值呈负相关(r=-0.72,P＜0.01);2例恶性脑膜瘤近瘤周水肿区的rCBV、rCBF、PS值的均数明显高于良性脑膜瘤近瘤周水肿区.结论:脑膜瘤瘤周水肿区的灌注具有一定特征,有助于鉴别肿瘤良恶性,优化手术方案及相关辅助治疗、评价手术疗效、鉴别肿瘤复发和坏死.     

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.     

320排CT全脑动态容积成像联合颈部CTA在评估慢性缺血性脑血管病中的应用

目的利用320排CT全脑动态容积成像联合颈部CT血管成像(CTA)探讨慢性脑缺血患者脑血流动力学变化及其与脑供血动脉狭窄的关系。方法前瞻性连续纳入88例单侧颈内动脉(ICA)或大脑中动脉(MCA)狭窄或闭塞患者行CT灌注(CTP)及CTA检查,评估ICA/MCA狭窄程度和Willis环完整性,计算MCA供血区及前后分水岭区相对灌注值,分析ICA/MCA狭窄程度与Willis环完整性(分型)、脑组织血流灌注各参数值的相关性。结果 1)88例中轻度狭窄12例、中度狭窄25例、重度狭窄24例、闭塞27例,其中单侧单纯ICA狭窄或闭塞48例,单侧单纯MCA狭窄或闭塞(M1段)40例;2)MCA区、前后分水岭区的rCBV、rMTT、rTTP值四组间差异均有统计学意义(均P0.05),rCBF四组间比较差异无统计学意义(均P0.05);3)MCA区的rCBF与狭窄率呈负性弱相关(r=-0.254,P=0.017),前后分水岭区的rCBF与狭窄率相关性无统计学意义(分别为r=-0.131,P=0.13;r=-0.2,P=0.062);狭窄率与大脑中动脉供血区、前分水岭区及后分水岭区的rCBV(r值分别为0.497、0.316、0.29,均为P0.01),rTTP(r值分别为0.691、0.619、0.593,均为P=0.000),rMTT(r值分别为0.695、0.514、0.508,均为P=0.000)呈正相关;4)重度狭窄、闭塞组中,不同Willis环分型与MCA区脑灌注参数间无相关性。结论 320排CT全脑动态容积成像联合颈部CTA检查能显示脑血流灌注参数的变化及相应头颈部供血动脉狭窄程度和Willis环结构。随着相应动脉狭窄率的增加,CBV、TTP、MTT值较对侧增加越大。狭窄程度与rTTP相关程度最高。     

MR灌注成像在鉴别脑胶质瘤放疗后坏死与肿瘤复发中的应用

目的探讨MR灌注成像(PWI)在脑胶质瘤放疗后坏死和肿瘤复发鉴别诊断中的应用。资料与方法对术后行放疗的胶质瘤患者32例(肿瘤复发组18例;放射性坏死组14例),行MRPWI及常规MRI检查。由灌注数据获取脑血容积(CBV)图和脑血流量(CBF)图,计算出病灶及健侧脑皮质最大相对CBV(rCBV)值、最大相对CBF(rCBF)值。结果肿瘤复发组的rCBV值、rCBF值均升高,肿瘤复发的最大rCBV值及最大rCBF值分别为6.23±2.23、5.21±1.55,健侧分别为3.26±1.03(P<0.01)、2.41±1.15(P<0.01);放射性坏死组的rCBV值、rCBF值均降低,最大rCBV值及最大rCBF值分别为1.90±0.53、1.21±0.32,健侧分别为4.26±1.13(P<0.05)、3.36±1.24(P<0.05);两组间最大rCBV值和rCBF值差异均有统计学意义(t检验,P<0.01);非参数相关性分析表明最大rCBV值和最大rCBF值间存在显著的相关性(r=0.795,P<0.05)。结论MRPWI对脑胶质瘤放疗后坏死和肿瘤复发的鉴别有重要意义,最大rCBV值结合最大rCBF值可以更好地鉴别脑胶质瘤放疗后坏死和肿瘤复发。     

高CO2分压下大鼠神经胶质瘤肿瘤血管的MR灌注成像特点

目的 了解MR灌注成像显示肿瘤血管成熟度和变异度的可行性.方法 20只雄性SD大鼠,采用数字表法随机平分为肿瘤组和正常对照组.肿瘤组大鼠于右侧尾状核区种植C6胶质瘤细胞,复制大鼠脑胶质瘤模型.种植肿瘤细胞后4周,两组大鼠吸入高浓度CO2混合气体,吸入气体前后,分别行全脑灌注成像扫描,检测局部相对脑血容量(rCBV)、局部相对脑血流量(rCBF).扫描前测定大鼠血CO2分压、pH值等血气指标.检查后处死肿瘤组大鼠并取脑固定,全脑切片,分别行苏木精-伊红及鼠特异性平滑肌抗体反应素(SMA)抗体免疫组织化学染色.光学显微镜下观察肿瘤组织特征并进行SMA阳性血管计数.采用配对t检验比较两组大鼠脑组织MR灌注值、肿瘤组织微血管计数及血气指标的差异,并将免疫组织化学检查结果与MR检查结果进行Pearson相关性分析.结果胶质瘤的rCBV和rCBF呈明显的高灌注.所有大鼠在吸入含高浓度CO2的混合气体15 min后,血液CO2分压肿瘤组从(4.69±0.62)kPa升高至(7.62±0.81)kPa,对照组从(4.67±0.51)kPa升高至(7.63±0.78)kPa,差异具有统计学意义(t值分别为6.09,7.012,P值均＜0.05);pH值肿瘤组从(7.42±0.03)降至(7.10±0.05),对照组从(7.40±0.04)降至(7.08±0.02),差异具有统计学意义(t值分别为2.745,2.693,P值均＜0.05).肿瘤实质部分的rCBV和rCBF的增加率分别为(26±17)%和(26±18)%,低于肿瘤组健侧正常脑组织[分别为(90±32)%和(45±14)%],二者差异具有统计学意义(t值分别为5.05,2.355,P值均＜0.05).SMA染色部位在血管的平滑肌细胞,形态规则,肿瘤内SMA阳性血管较正常脑组织的阳性血管管壁薄,管腔直径宽;肿瘤内SMA阳性血管[(6.7±2.8)个/高倍视野]明显少于肿瘤组健侧脑组织[(12.7±2.8)个/高倍视野](t=1.86,P＜0.05).吸入高浓度CO2混合气体后,肿瘤实质区的rCBV和rCBF的变化率与免疫组织化学的SMA阳性血管计数之间均无显著的相关性(r值分别为0.504和0.607,P值均＞0.05).但正常脑组织的rCBV和rCBF变化率与其SMA阳性血管计数之间呈正相关(r值分别为0.721和0.525,P值均＜0.05).结论 MR灌注技术在改变血液CO2分压的条件下可以反映正常脑组织和肿瘤组织血流变化,进而间接判断肿瘤血管的成熟度.     

星形细胞瘤与脑转移瘤微循环状态的DSC-PWI研究

目的 探讨MR动态磁敏感灌注加权成像(DSC-PWI)在星形细胞瘤分级及与单发脑转移瘤鉴别诊断中的价值.方法 对病理证实的18例星形细胞瘤、14例脑转移瘤患者行常规MRI及DSC-PWI检查.分别测量脑肿瘤实质及瘤周区的平均局部脑血容量(rCBV)值、局部脑血流量(rCBF)值、局部平均通过时间(rMTT)和局部达峰时间(rTTP).肿瘤不同区域之间、星形细胞瘤不同级别之间、星形细胞瘤与转移瘤之间的灌注参数差异采用单因素方差分析.对于肿瘤间有统计学差异的参数,采用受试者工作特征曲线(ROC)分析其诊断效能.结果 高级别星形细胞瘤实质、近侧瘤周区和远侧瘤周区rCBV值具有显著性差异;瘤内实质rCBF值明显高于近瘤区.高级别星形细胞实质rCBV值和rCBF值均明显高于低级别星形细胞瘤,rTTP值明显低于低级别星形细胞瘤.以rCBV值1.45为阈值鉴别高、低级别星形细胞瘤,ROC曲线下面积(AUC)为0.792.转移瘤实质的rTTP高于星形细胞瘤;高级别星形细胞瘤的近瘤区rTTP、远瘤区rCBF低于转移瘤;低级别星形细胞瘤实质rTTP低于转移瘤.结论 DSCPWI能够定量评估肿瘤实质和瘤周微循环状态.     

CT灌注成像在急性自发性高血压性脑出血中的应用

目的 应用CT灌注成像(CT perfusion,CTP)对急性自发性高血压出血性脑卒中(acute spontaneously hypertensive intracerebral hemorrhage,shICH)血肿周围脑血液动力学变化进行定量研究,验证血肿周围是否存在缺血半暗带.方法 对26例(男22例,女4例,年龄33～74岁,平均55.08岁)临床及CT确诊为幕上shICH患者行CTP检查,自发病到灌注扫描的时间为8～19h,平均14.88h.以血肿最大层面为参照,测量血肿内部、血肿周围、远隔区及对侧镜像区脑血流量(CBF)、脑血容量(CBV)、平均通过时间(MTT),并计算相对灌注参数值rCBF、rCBV、rMTT(患侧/健侧).结果 shICH血肿灌注参数伪彩图从血肿中心到外周色差呈阶梯样分布.血肿周围组CBV值为(1.61±1.53)ml·100g-1、CBF值为(16.48±17.38)ml·100g-1·min-1),低于对侧镜像区(ZCBV=-2.603、ZCBF=-4.178,P＜0.05);MTT值为(9.12±2.57)s,较对侧镜像区延长(t=4.747,P＜0.05).方差分析显示血肿内部、血肿周围组及远隔区组灌注参数MTT及相对值rCBF、rCBV、rMTT均数间差异有统计学意义(FMTT=9.043、FrCBV=38.031、FrCBF=25.023、FrMTT=12.486,P＜0.05),进一步LSD分析,血肿周围组与远隔区组MTT、rMTT、rCBF差异有统计学意义(P＜0.05),但两组间rCBV值无统计学差异(P＞0.05).且秩和检验显示血肿周围组CBF明显低于远隔区组(Z=2.288,P＜0.05),但两组间CBV均值差异无显著性(Z=-0.357,P＞0.05).结论 CTP可反应shICH血肿周围低灌注状态,但没有证据显示存在缺血半暗带.     

CT灌注对急性缺血性脑卒中溶栓治疗后出血转化的评价性研究

目的 探讨CT灌注对急性缺血性脑卒中(AIS)溶栓治疗后出血转化(HT)的评价性.方法 选取56例于2015年5月-2017年2月接收的AIS患者,根据CT平扫图像出血与否分为出血组(n=20)和未出血组(n=36),每个病例均测患侧和健侧CTP参数,计算相对参数值.结果 出血组患者rCBF值、rCBV值均显著低于未出血组(P<0.05),而两组rMTT比较均无明显差异性(P>0.05);rCBV、rCBF与HT均呈负相关性(P<0.05).结论 CTP对称部位相对参数值对于AIS溶栓治疗HT的预测有重要意义.     

采用256层CT全脑灌注研究烟雾病术后桥血管再通及手术前后脑血流动力学的变化

目的 研究256层CT全脑灌注同时评价烟雾病术后桥血管再通及手术前后脑血流动力学变化的可行性.方法 选取25例烟雾病患者在手术前后均行全脑CTP检查.容积CTA图像通过CTP动脉期原始图像获得,并与术后的常规CTA图像进行比较.测量患者手术侧及对侧的大脑中动脉分布区的灌注参数,包括脑血流量(CBF)、脑血容量(CBV)、平均通过时间(MMT)和达峰时间(TTP),计算术侧/对侧相对比值(rCBF、rCBV、rTTP及rMTT值).采用配对t检验或配对秩符号检验比较手术前后CT灌注参数值及相对值的差异.正态分布数据以x±s表示,非正态分布数据以M(P25～P75)表示.结果 25例患者术后桥血管均显示通畅.容积CTA图像与传统CTA图像显示桥血管情况的结果一致.烟雾病患者血管搭桥术后手术侧大脑中动脉分布区的CBF[72.86(55.54～112.19)ml·100g-1·min-1]、rCBF[1.31(1.05～1.73)]及rCBV(1.45±0.62)明显高于术前的CBF[46.72(28.57～57.67)ml·100g-1·min-1]、rCBF[0.53(0.33～0.82)]及rCBV(1.01±0.36)(Z值分别为-2.72、-2.98,t=-2.85,P值均＜0.05);术后患侧大脑中动脉分布区的MTT[(3.98±2.36)s]、TTP[(17.56±4.38)s]及rTTP(1.01±0.09)明显低于术前的MTT[(5.43±2.07)s]、TTP[(19.40±3.87)s]及rTTP(1.14±0.28)(t值分别为2.41、2.17、2.17,P值均＜0.05).结论 256层CT经单次注射对比剂、单次扫描可同时获得CTA图像及全脑CTP参数图,可对烟雾病术后桥血管再通情况及脑血流动力学变化同时进行评价.     

Changes in cerebral hemodynamics after carotid stenting of symptomatic carotid artery

Purpose

To evaluate changes in cerebral hemodynamics after carotid stenting of symptomatic carotid artery in the patients who underwent ischemic stroke caused by carotid artery stenosis.

Methods

Twenty patients with unilateral symptomatic carotid artery stenosis received brain computer tomography perfusion (CTP) scan a week before and a week after carotid artery stenting. Three absolute values including mean transit time (MTT), cerebral blood volume (CBV), and cerebral blood flow (CBF) were acquired and analyzed by use of the post-processing software. Six vascular territories such as ACA territory, MCA territory, PCA territory, basal ganglia, watershed between ACA and MCA territory (frontal watershed), watershed between MCA and PCA territory (posterior watershed) were chosen for comparison. Relative parameter values were defined as rCBF (relative CBF), rCBV (relative CBV), rMTT (relative MTT) through comparing absolute values in symptomatic hemispheres to absolute values in asymptomatic hemispheres. The relative perfusion parameter values before treatment were compared with post-treatment values. These analyses were performed by using the paired t test.

Results

The mean rMTT decreased significantly in ACA territory, MCA territory and two watershed after treatment, while the mean rCBF increased significantly in those areas after treatment. But the mean rCBV had no significant changes in all six vascular territories. In PCA territory, all the parameters had no significant changes.

Conclusion

Carotid artery stenting yields satisfactory cerebral perfusion in ACA territory, MCA territory, basal ganglia and two watersheds.     

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.     

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.     

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.     

猴大脑中动脉闭塞模型脑缺血半暗带的面积演变

目的 研究不同时间点猴脑缺血半暗带(IP)面积的演变规律.方法 成年猴7只,采用自体血栓介入法制作猴大脑中动脉闭塞模型.于导丝到位后1、5、10、15、20、24 h分别行CT灌注成像、DWI、PWI和T2WI.取4点ROI,1点为中心区,3点为边缘区,2点为1、3点的中点,4点为邻近的正常信号区.测量脑血流量(CBF)、脑血容量(CBV)、平均通过时间(MTT)、ADC和负性强化积分(NEI),计算时采用与正常对侧的比值(rCBF、rCBV、rMTr、rADC、rNEI).采用PWI(MIT)-DWI和计算机图像处理软件结合IP阈值两种方法计算IP面积.采用单因素方差分析计算不同时间点缺血灶内不同部位的差异,采用ROC曲线分析不同影像参数的IP阈值及其敏感度和特异度.结果 7只猴中5只造模成功.1、2、3点间20 h内rCBF、20 h内rNEI、15 h内rCBV、10 h内rADC、24 h时rMTT差异有统计学意义(P＜0.05).1、2、3点ROI值分别为:rCBF:1 h(0.160 ±0.034、0.310±0.037、0.540±0.107),5 h(0.098±0.029、0.157±0.052、0.427±0.116),10 h(0.072±0.023、0.097 ±0.028、0.209 ±0.070),15 h(0.054 ±0.017、0.069±0.015、0.166 ±0.049),20 h(0.038±0.011、0.026 ±0.007、0.092±0.013);rNEI:1 h(0.219 ±0.085、0.303 ±0.099、0.463 ±0.132).5 h(0.143 ±0.057、0.195 ±0.055、0.348 ±0.127),10 h(0.127 ±0.029、0.171 ±0.058、0.259 ±0.079).15 h(O.128 ±0.024、0.164 ±0.031、0.217 ±0.030),20 h(0.075 ±0.019、0.147 ±0.058、0.129 ±0.045):rCBV:1 h(0.594 ±0.199、0.804 ±0.099、1.021 ±0.169),5 h(0.457±0.103、0.462 ±0.145、0.815 ±0.201),10 h(0.222 ±0.046、0.249 ±0.065、0.529 ±0.135),15 h(0.201 ±0.047、0.187 ±0.055、0.361±0.083);rADC:1 h(0.515±0.115、0.667 ±0.097、0.761±0.106),5 h(0.488 ±0.100、0.539 ±0.107、0.674 ±0.099),10 h(0.456±0.057、0.549 ±0.049、0.590±0.081);24 h rMTT(4.163 ±1.179、4.192±1.607、2.397 ±0.909).IP阈值分别 rCBF＞0.203、rCBV＞0.483、rADC＞0.571、rNEI＞0.250.rCBF阈值法所得IP面积15 h前大于PWI-DWI法,20、24 h rCBF阈值法所得IP面积小于PWI-DWI法.不同时间点猴脑IP面积演变:1 h 20%～38%,5 h 15%～36%,10 h 15%～35%.15 h13%～25%,20 h 9%～15%,24 h 3%～12%.结论猴脑IP存在的时间窗为15～20 h.缺血早期DWI高信号内存在IP,PWI-DWI不能准确显示IP,CT灌注与DWI相匹配更为准确.     

Toward normal perfusion after radiosurgery: perfusion MR Imaging with independent component analysis of brain arteriovenous malformations

BACKGROUND AND PURPOSE: Brain perfusion is disturbed by cerebral arteriovenous malformations (AVMs). Our study was conducted to determine the radiosurgical effects on this disturbed perfusion. METHODS: MR perfusion imaging with independent component analysis was performed in five healthy subjects and 19 patients with AVM before and after radiosurgery (every 6 months up to 2 years). Perfusion map relative cerebral blood volume (rCBV), cerebral blood flow (rCBF), and mean transient time (rMTT) were assessed. Regions of interest (ROIs) on AVM target sections were defined as follows: N, AVM nidus; H, the rest of the ipsilateral hemisphere; P, immediately posterior to the nidus; A, immediately anterior to the nidus; Ar, anterior remote; Pr, posterior remote. Similar ROIs in the contralateral hemisphere (N1, H1, P1, A1, Pr1, and Ar1) served as internal references. Perfusion ratios of ROI-ROI1 were defined. Nonparameteric Mann-Whitney U tests and generalized linear models were used for statistical analysis. RESULTS: Before radiosurgery, patients' H/H1 rCBV and rCBF ratios were significantly higher than those of healthy subjects (P < .005), indicating AVM steal. Three types of perilesional perfusion disturbance were observed. From the first postradiosurgical follow-up at 6 months, N/N1 rCBV and rCBF ratios gradually decreased to 1.0 (both P < .001), whereas rMTT ratios gradually increased to 1.0 (P < .015); H/H1, A/A1, and P/P1 rCBV and rCBF ratios decreased after radiosurgery (P < .005), indicating reversal of steal toward normal perfusion. CONCLUSION: Initial high transnidal flow and perinidal perfusion disturbances were demonstrated. They gradually changed toward normal perfusion after radiosurgery. This explains, in part, the pathophysiologic factors of AVM and therapeutic effects.     

Haemodynamic assessment in patients with dural arteriovenous fistulae: dynamic susceptibility contrast-enhanced MRI

Cerebral haemodynamics in patients with dural arteriovenous fistulae (DAVF) have not been fully investigated and their effects are not clear. Our purpose was to assess impaired haemodynamics in patients with DAVF using dynamic susceptibility contrast-enhanced MRI (DSC-MRI). We used this technique in eight control subjects (group I) and 17 patients with DAVF who were scheduled to undergo or had already undergone endovascular embolisation and/or surgical excision. There were seven patients with cavernous sinus DAVF (CSDAVF) and the other ten had unilateral transverse/sigmoid sinus DAVF. All patients with CSDAVF underwent DSC-MRI preoperatively (group II) and those with transverse/sigmoid sinus DAVF underwent preoperative DSC-MRI (group III) and postoperative (group IV) assessment. The ratios of relative cerebral blood volume (rCBV), cerebral blood flow (rCBF) and mean transit time (rMTT) were calculated relative to contralateral values. Patients in group II had no significant haemodynamic impairment in grey (GM) or white matter (WM), but cerebellar rMTT were significantly prolonged ( P<0.05). Group III showed haemodynamic impairment characterised by significant increase in rCBV, prolongation of rMTT and decrease in rCBF in GM ( P<0.05). Significantly increased rCBV and prolonged rMTT in the GM ( P<0.05) were obvious in group III patients irrespective of retrograde leptomeningeal venous drainage (RLVD). In group IV, rCBV and rCBF returned to normal values, whereas rMTT was still significantly prolonged in GM ( P<0.05). Our study indicates that patients with CSDAVF may have impaired cerebellar perfusion, and that those with transverse/sigmoid sinus DVAF can have disturbed cerebral haemodynamics, even in the absence of RLVD.     

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。     

Perfusion-weighted MRI to evaluate cerebral autoregulation in aneurysmal subarachnoid haemorrhage

Introduction  The aim of this study was to evaluate autoregulatory mechanisms in different vascular territories within the first week after aneurysmal subarachnoid haemorrhage (SAH) by perfusion-weighted magnetic resonance imaging (PW-MRI). For this purpose, regional cerebral blood flow and volume (rCVF and rCBV) were measured in relation to different degrees of angiographically visible cerebral vasospasm (CVS). Materials and methods  In 51 SAH patients, PW-MRI and digital subtraction angiography were performed about 5 days after onset of SAH. Regional CBF and rCBV were analysed in the territories of the anterior cerebral artery (ACA), the middle cerebral artery (MCA) and the basal ganglia of each hemisphere in relationship to the degree of CVS in the particular territory. Correlations between rCBF, rCBV and CVS were analysed. Results  CVS was found in 22 out of 51 patients in at least one territory. In all territories, rCBV decreased with increasing degree of CVS, correlated with a decrease of rCBF. In the ACA territories, SAH patients with severe CVS had significantly lower rCBF compared to healthy subjects and to SAH patients without CVS. In the basal ganglia, rCBF and rCBV of the control group were significantly higher compared to the patients without and with moderate vasospasms. Conclusion  PW-MRI showed simultaneous decrease of rCBF and rCBV in patients with SAH. The fact that rCBV did not increase in territories with CVS to maintain rCBF reveals dysfunctional vascular autoregulation. Vasospasms in the microvasculature are most evident in the basal ganglia, showing decreased rCBV and rCBF even in SAH patients without CVS.