脑慢性缺血磁共振脑血流弥散成像和灌注成像诊断的比较

脑梗死无有效治疗方法，预防本病的发生十分重要，因此，对脑梗死前期病变——脑慢性缺血进行诊断和治疗有利于预防脑梗死。我们利用磁共振脑血流灌注成像（PWI）和弥散加权成像（DWI）对脑慢性缺血进行观察分析，旨在提高对本病的磁共振诊断率。     

灌注加权成像和扩散加权成像对兔早期后循环缺血的对比分析

目的 探讨磁共振灌注加权成像(perfusion weighted imaging,PWI)、扩散加权成像(diffusion weighted imaging,DWI)对兔后循环缺血的早期应用价值.方法 手术组采用三血管结扎法(即结扎右侧颈总动脉及双侧椎动脉)制备兔后循环缺血模型,假手术组仅暴露上述血管而不结扎.清洁级新西兰大白兔共72只,分为术后15 min 36只、30 min 36只.每组动物按性别、兔龄、体重配对,然后随机分到手术组(18只),假手术组(18只).各组于术后相应的时间进行PWI及DWI检查,检查完后,每组取4只动物迅速断头取脑,按MRI扫描层面切片,将脑片置于2%的TTC溶液中染色.再取8只动物,心脏灌注4% 的多聚甲醛后,其中4只取脑ROI做病理标本(HE染色),4只制备电镜标本(置于2.5%戊二醛中送检).结果 术后15 min手术组与配对的假手术组相比,脑血流量(cerebral blood flow, CBF)(15.37,27.15)下降, 平均通过时间(mean transit time, MTT)(25.50,14.12)延长,差异有统计学意义(P<0.001).脑血容量(cerebral blood volume, CBV)(6.56,6.44)、表观扩散系数(apparent diffusion coefficient, ADC) (0.77,0.76)差异无统计学意义(P>0.05).术后30 min,手术组与配对的假手术组相比CBF(15.21,28.83)、CBV(5.67,7.56)下降,MTT(22.35,16.07)延长,差异有统计学意义(P<0.001,P<0.01,P<0.001),ADC(0.78,0.75)差异无统计学意义(P>0.05).各组TTC染色、病理检查均无异常,电镜检查显示手术组动物细胞器异常改变.结论 和DWI的ADC值相比,PWI各参数值的定量分析可能有助于早期检出后循环缺血.     

灌注及弥散磁共振成像在急性缺血性脑卒中的应用

目的　评估磁共振 (MRI)弥散加权成像 (DWI)及灌注加权成像 (PWI)在急性缺血性卒中指导溶栓治疗的应用价值。方法　对 44例急性 (≤ 6h)缺血性卒中患者行DWI、PWI扫描 ,DWI及PWI的不匹配区为缺血半暗带 ,根据半暗带是否存在确定患者是否适合溶栓治疗。结果　脑梗死患者 33例 ,其中 2 3例 (52 3 % )有明显半暗带存在 (PWI >DWI) ;1 0例 (2 2 7% )无明显半暗带 (PWI=DWI)。临床表现为短暂性缺血发作 (TIA)者 1 1例 (2 5 0 % )。结论　PWI及DWI对照研究有助于发现超早期脑梗死半暗带 ,指导溶栓治疗 ;临床表现结合DWI有助于除外TIA     

早期脑梗死的临床与磁共振弥散加权成像

目的 从临床角度探讨磁共振弥散加权成像（diffusion weighted imagine,DWI)对早期脑梗死的诊断价值和确定DWI在区分常规MRI上所示的多发梗死灶中急性梗死方面的能力。方法 60例脑梗死均进行MRI常规程序及DWI（程度检查,并由4位经验丰富的医师在不了解患者临床体征的情况下进行阅片、记录出病变所在的详细的神经解剖部位,对同一层面所有的磁共振像进行比较,重点分析信号强度的病灶大小。数据经统计学分析。结果 DWI对超急性合肥市急性期脑梗死可显示T2加权像不能显示的病灶,并随时间延长显影范围逐渐增大,在T2加权像上可显示的病灶中,DWI可更清楚、更全面地显示病灶,大于T2病灶。在急性后期,常规MRI及DWI均有较清晰的影像学改变,恢复期及慢性期,DWI影像学逐渐改变变成等信号、杂信号,部分为囊性信号,且不易显示病灶。结论 DWI能非常可靠地显示超急性及急性脑梗死,而在急性后期及慢性期不如T2WI。其具有区分急性和非急性脑梗死的能力。     

磁共振弥散加权成像与短暂性脑缺血发作预后的相关性研究

短暂性脑缺血发作(transient isclneroic attack,TIA)是临床常见的脑血管病,也是一种可以控制的脑血管病.磁共振弥散加权成像(diffusion weight imaging,DWI)是利用水分子弥散运动的特件进行弥散测量和成像,对急性腩缺血的榆测较传统MRI检查更为敏感.近年来随着DWI的广泛应用,对TIA的定义、诊断及预后的评价取得了较人的进展.本文主要对DWI异常与TIA患者的预后的相关性进行概括综述.     

Balo同心圆性硬化磁共振成像与弥散加权成像特点及其机制

目的 总结同心圆硬化的MRl及弥散加权成像(DWI)特点,并探讨其影像学变化与可能发生机制的相关性.方法 总结临床确诊的同心圆硬化患者3例,均行头颅MRI及DWI检查,其中1例患者行氢质子波谱成像(1H-MRS).结果 3例患者均为多发病灶,病灶多位于中央白质区,均可见特征性的"同心圆样"或"洋葱皮样"改变,增强扫描旱环形或半环形强化.DWI见病灶呈高、低交替环形信号,表观扩散系数(ADC)值随同心圆病理的脱髓鞘区与髓鞘保留区相问存在而出现高低相间变化.结论 Balo同心圆硬化MRI和DWI表现具有特征性,可与病理改变对应,为加深该病发生机制认识提供影像学证据.     

磁共振弥散加权成像早期未见异常的急性脑梗死1例

1病例介绍 患者,男性,54岁,因＂右侧面部麻木、行走不稳3 h＂于2013年6月3日入院。3 h前患者无明显诱因下出现右面部麻木、行走不稳,行走时向右侧倾斜,伴头晕,言语稍欠流利,无肢体无力,无恶心、呕吐,无视物旋转、视力改变,无耳鸣及听力改变,无饮水呛咳,无胸闷气短,无畏寒发热。急来我院就诊,为进一步治疗急诊入院。     

大鼠局灶性脑缺血再灌注TTC染色与MRI弥散加权成像的相关性研究

目的 研究大鼠局灶性脑缺血再灌注MRI弥散加权成像(DWI)的变化,探讨其与TIC染色变化的关系. 方法 44只雄性SD大鼠按随机数字表法分为假手术组和脑缺血2h、脑缺血6h再灌注不同时间组(0 h、0.5h、2h、6h、24 h),每组各4只.脑缺血2h组、脑缺血6h组采用线栓法制作成大脑中动脉栓塞模型.各组大鼠于不同再灌注时间点行MRI DWI扫描,结束后立即处死,取相应部位脑组织行TTC染色,观察分析其与DWI成像的关系. 结果 脑缺血2h组、脑缺血6h组再灌注0h均可见部分右侧大脑半球DWI呈高信号,表观扩散系数(ADC)值降低,TTC染色可见部分右侧大脑半球失染呈白色.缺血2h组再灌注24 h后DWI异常信号区相对面积明显变小,ADC值增大,TTC失染相对面积变小,较再灌注0h差异有统计学意义(P＜0.05),而脑缺血6h组则差异无统计学意义(P＞0.05).脑缺血6h组再灌注不同时间点较脑缺血2h组再灌注相应时间点DWI异常信号区相对面积大,ADC值低,TTC失染相对面积大,差异有统计学意义(P＜0.05).脑缺血2h组、脑缺血6h组再灌注相对应时间点DWI异常信号区面积与TTC染色失染区面积比较差异无统计学意义(P＞0.05). 结论 脑缺血再灌注后可用MRI DWI成像评价脑缺血面积.     

脑梗死磁共振弥散加权成像信号改变和近似弥散系数的时间演变规律

目的 :确定脑梗死磁共振弥散加权成像 (DWI)信号改变和近似弥散系数 (ADC)的时间演变规律。方法 :分析 10 1例脑梗死患者的 13 5次DWI资料。结果 :超急性、急性和亚急性期脑梗死DWI为高信号 ,慢性早期多数病灶仍为高信号 ,慢性晚期绝大部分病灶为等或低信号。超急性期、急性期和亚急性期脑梗死ADC下降 ,慢性早期多数病灶接近或高于正常 ,慢性晚期明显升高。结论 :脑梗死的DWI信号和ADC变化具有特征性的时间演变规律 ,结合常规MRI ,DWI可以推断脑梗死所处的时期     

MR灌注与弥散加权成像不同匹配与急性脑梗死降纤治疗效果的关系

目的 探讨MR灌注加权成像(PWI)与弥散加权成像(DWI)(PWI/DWI)不同匹配与急性脑梗死降纤治疗效果的关系.方法 给38例急性脑梗死患者行巴曲酶降纤治疗,在治疗前予以MR PWI及DWI检查,在治疗前和治疗后进行美国国立卫生研究院卒中量表(NIHSS)评分并评定疗效.比较PWI/DWI不同匹配患者治疗前后的N...     

Dynamics of regional distribution of ischemic lesions in middle cerebral artery trunk occlusion relates to collateral circulation

We describe the regional distribution of acute perfusion, diffusion, and final infarct lesions in middle cerebral artery (MCA) trunk occlusion. A total of 31 patients with acute ischemic stroke and MCA trunk occlusion were studied by multiparametric magnetic resonance imaging. Probabilistic maps of lesion distribution were generated. The probability of initial and final infarcts was highest in the central MCA region with decreasing probability toward the periphery where the probability of the tissue at risk of infarction to be saved was highest. The probability of brain regions being involved in acute diffusion lesions and evolving into or escaping from the final infarct relates to the anatomy of arterial blood supply.     

早期腔隙性脑梗死的临床与磁共振弥散加权成像

目的:从临床角度探讨磁共振弥散加权成像(diffusion weighted i maging,DWI)对早期腔隙性脑梗死(lacu-na cerebral infarction,LI)的诊断价值。方法:分析60例早期腔隙性脑梗死患者的临床资料,同时进行MRI常规序列及DWI序列检查,并由4位经验丰富的医师在不了解患者临床体征的情况下进行阅片,记录出病变所在的详细的神经解剖部位,对同一层面所有的磁共振像进行比较,重点分析信号强度和病灶大小。数据经统计学分析。结果:60例患者中高血压病45例(75%)、高脂血症21例(35%)、糖尿病18例(30%);常见临床类型为纯运动性轻偏瘫(PMH)及变异型20例,腔隙状态(LS)12例,无症状腔隙性梗死(ALI)10例,感觉运动性卒中(SMS)8例。病灶部位主要为尾状核(29.1%)、豆状核(23.3%)、放射冠(15.1%)、丘脑(10.5%)、内囊(7.0%)。60例患者中超急性期(≤6小时)20例,DWI扫描均检出病灶,常规MRI扫描均未检出病灶;急性期(7~24小时)患者22例,DWI扫描均检出病灶,DWI检出率为100%,而常规MRI共检出12例,检出率为55%(P<0.05)。DWI在超早期及急性期可显示T2加权像不能显示的病灶,并随时间延长显影范围逐渐增大。在T2加权像上可显示的病灶中,DWI可更清楚、更全面地显示病灶,大于T2病灶。结论:高血压病是LI的直接原因;腔隙病灶主要位于基底节,LS及ALI的检出率有上升趋势,DWI对早期LI的诊断显著优于常规MRI。DWI应作为早期LI的首选检查方法。     

T2-weighted magnetic resonance imaging of cerebrovascular reactivity in rat reversible focal cerebral ischemia

Cerebrovascular carbon dioxide (CO₂) reactivity is an important hemodynamic index in cerebrovascular disease. In the present study T2^*-weighted magnetic resonance image (T2^*WI) was evaluated as a non-invasive method to investigate changes in CO₂ reactivity. Fourteen rats were subjected to permanent or, 30 and 90 min of temporary middle cerebral artery occlusion. A series of T2^*WIs and diffusion-weighted magnetic resonance images (DWI) was performed hourly under normo- and hypercapnic conditions. Triphenyltetrazolium chloride (TTC) staining of brain sections was obtained at the end of experiment to evaluate ischemic damage. During ischemia, a 4–6% signal increase upon hypercapnia was observed on T2^*WI in the non-ischemic hemisphere, while no such reactivity was seen in the putamen and cortex ipsilateral to the MCA occlusion. After reperfusion, CO₂ reactivity recovered in the putamen and cortex in the 30 min ischemia group and in the cortex alone of the 90 min ischemia groups. The areas with irreversible CO₂ reactivity dysfunction coincidentally revealed no recovery on DWI and lack of TTC staining. The results indicate that T2^*WI can be used to monitor changes in CO₂ reactivity after various ischemic insults that may indicate tissue viability.     

Rapamycin protects against middle cerebral artery occlusion induced focal cerebral ischemia in rats

Stroke is a major cause of mortality and disability. The management with thrombolytic therapy has to be initiated within 3-4 h and is associated with limitations like increased risk of intracranial hemorrhage and progression of cerebral injury. Immunophilin inhibitors such as cyclosporine A and tacrolimus have been shown to afford neuroprotection by improving neurological functions and infarct volume in models of ischemic stroke. In the present study, the effect of rapamycin in middle cerebral artery occlusion (MCAo) model of ischemic stroke was evaluated.Ischemic stroke was induced in rats by occluding the MCA using the intraluminal thread. After 1 h of MCAo, animals were administered rapamycin (50, 150, 250 μg/kg, i.p.). After 2 h of occlusion, reperfusion was done. Thirty minutes after reperfusion, animals were subjected to diffusion-weighted magnetic resonance imaging for assessment of protective effect of rapamycin. Twenty-four hours after MCAo, motor performance was assessed, the animals were euthanized and the brains were removed for estimation of malondialdehyde, glutathione, nitric oxide and myeloperoxidase.Significant improvement was observed with rapamycin 150 and 250 μg/kg in percent infarct area, apparent diffusion coefficient and signal intensity as compared to vehicle treated group. Rapamycin treatment ameliorated motor impairment associated with MCAo and significantly reversed the changes in levels of malondialdehyde, glutathione, nitric oxide and myeloperoxidase.The results of the present study indicate neuroprotective effect of rapamycin in MCAo model of stroke. Therefore, rapamycin might be considered as a therapeutic strategy for stroke management.     

颅内原发性淋巴瘤DWI及PWI表现

目的 探讨颅内原发性淋巴瘤扩散加权成像(DWI)和灌注加权成像(PWI)特点.方法 回顾性分析10例颅内原发性淋巴瘤的DWI表现和9例颅内原发性淋巴瘤的PWI特征,所有病例均经病理证实,并结合其病理特征与高级别(Ⅲ、Ⅳ级)星形细胞瘤作对照.结果 颅内原发性淋巴瘤DWI多呈均匀高信号,肿瘤实质ADC值为(79.73±10.21)×10-5mm2/s,明显低于高级别星形细胞瘤ADC值(99.81±19.57)×10-5mm2/s(P=0.002).9例行PWI检查,颅内原发性淋巴瘤肿瘤实质最大rCBV比值为1.71±0.59,而14例高级别星形细胞瘤肿瘤实质最大rCBV比值为5.17±1.73,与高级别旱形细胞瘤比较,颅内原发性淋巴瘤呈低灌注趋势(P=0.001).结论 颅内原发性淋巴瘤DWI、PWI具有一定的特征,术前行DWI、PWI有助于提高MRI对颅内原发性淋巴瘤的诊断水平.     

磁共振多扫描技术对短暂性脑缺血病变的诊断价值

目的 总结并分析短暂性脑缺血病变的三维动脉自旋标记(3D-ASL)、三维时间飞跃法(3D-TOF)及弥散加权成像(DWI)的影像特点.方法 回顾性分析昆明医科大学附属延安医院神经内科门诊及住院部2018-08—2020-06收治的短暂性脑缺血发作(TIA)患者43例,所有患者行MRI常规序列检查、DWI、MRA、3D-...     

Feasibility of establishing cerebral ischemia models by using aerocyst-blocking bilateral ascending pharyngeal artery of piglets Imaging assessment

BACKGROUND: The cerebral ischemia and ischemia/reperfusion animal models are used to simulate the human cerebrovascular diseases is one of the popular topics of neurological science recently. To study the pathophysiology, pathogenesis, prophylaxis and treatment of ischemic cerebrovascular diseases and to establish the ideal animal model that is the most similar to the human cerebral ischemia, are the topics that the people generally cared about. OBJECTIVE: To evaluate the effects of aerocyst-blocking bilateral ascending pharyngeal artery on the establishment of cerebral ischemia models by using digital subtraction angiography (DSA), magnetic resonance diffusion-weighted imaging (DWI) and magnetic resonance perfusion-weighted imaging (PWI). DESIGN: Repetitive measure animal experiment. SETTING: Zhongshan Hospital Affiliated to Dalian University. MATERIALS: The experiment was carried out in the Animal Laboratory (Provincial Laboratory), Zhongshan Hospital of Dalian Univeristy from January to May 2006. A total of 14 domestic piglets, of 6 months old, weighing 12–15 kg, of either gender, were selected from Animal Experimental Center, Dalian University. Multistar T.O.P digital subtraction angiography machine was provided by Siemens Company, German. METHODS: Aerocyst-blocking bilateral ascending pharyngeal artery was used to establish cerebral ischemia models. And then, Multistar T.O.P. DSA was used for imaging of cerebral vessels before blocking, during blocking and at 0.5 and 2 hours after ischemia perfusion. GE Signa 1.5 T supraconduction magnetic resonance imaging was used for DWI examination; in addition, PWI was used based on focal sites and areas. Otherwise, magnetic resonance imaging (MRI) was used to detect signal changes of T1WI and T2WI in ischemic areas. MAIN OUTCOME MEASURES: Analytic results of DSA, DWI, PWI and MRI. RESULTS: All 14 experimental piglets were involved in the final analysis. ① DSA: The blood flow of bilateral ascending pharyngeal arteries and its branch were blocked at blocking phase, which restored 0.5 and 2 hours after reperfusion. ② DWI and PWI: There were no observable abnormalities in PWI and DWI at pre-blocking. Abnormal increased signals were found on both DWI and PWI at during and post-blocking. There were reduction in ADC and rCBF and delay in rTTP at all time points except pre-blocking. ③ MRI: There were no abnormal signals observable at any time of pre- and post-blocking in T1WI and T2WI. CONCLUSION: It is feasible to establish this kind of animal experimental models, and it can simulate the ischemic state; meanwhile, the existence and extent can be showed directly by DSA, DWI, and PWI.     

Diffusion- and perfusion-weighted magnetic resonance imaging of focal cerebral ischemia and cortical spreading depression under conditions of mild hypothermia

In a model of experimental stroke, we characterize the effects of mild hypothermia, an effective neuroprotectant, on fluid shifts, cerebral perfusion and spreading depression (SD) using diffusion- (DWI) and perfusion-weighted MRI (PWI). Twenty-two rats underwent 2 h of middle cerebral artery (MCA) occlusion and were either kept normothermic or rendered mildly hypothermic shortly after MCA occlusion for 2 h. DWI images were obtained 0.5, 2 and 24 h after MCA occlusion, and maps of the apparent diffusion coefficient (ADC) were generated. SD-like transient ADC decreases were also detected using DWI in animals subjected to topical KCl application (n=4) and ischemia (n=6). Mild hypothermia significantly inhibited DWI lesion growth early after the onset of ischemia as well as 24 h later, and improved recovery of striatal ADC by 24 h. Mild hypothermia prolonged SD-like ADC transients and further decreased the ADC following KCl application and immediately after MCA occlusion. Cerebral perfusion, however, was not affected by temperature changes. We conclude that mild hypothermia is neuroprotective and suppresses infarct growth early after the onset of ischemia, with better ADC recovery. The ADC decrease during SD was greater during mild hypothermia, and suggests that the source of the ADC is more complex than previously believed.