MR imaging of middle cerebral artery stenosis and occlusion: value of MR angiography.

PURPOSETo investigate the effectiveness of MR angiography in conjunction with spin-echo imaging for evaluating vascular patency in patients with middle cerebral artery (MCA) stenosis or occlusion.METHODSSeven patients with MCA stenosis or occlusion, verified with contrast angiography in five and correlated with transcranial Doppler sonography in two, were examined using two-dimensional and/or three-dimensional time-of-flight MR angiographic techniques as well as conventional spin-echo imaging.RESULTSOf the seven patients, six demonstrated basal ganglionic and/or cortical infarct in the MCA territory. Except one case with minimal stenosis immediately distal to the MCA origin, all six cases with either severe stenosis or occlusion of the main trunk of the MCA showed the absence of normal flow voids using spin-echo imaging in the sylvian fissure on the affected side. However, it was not possible to discriminate between stenosis and occlusion. Although different mechanisms (ie, flow-induced spin dephasing for the 2-D technique and progressive spin saturation for the 3-D technique) were predominantly responsible for the loss of signal through the area of stenosis, both the 2-D and 3-D MR angiograms clearly depicted the compromised flow of the MCA: a focal discontinuity with decreased vessel caliber corresponded to stenosis, and nonvisualization of distal MCA branches represented occlusion.CONCLUSIONEither 2-D or 3-D time-of-flight MR angiography is a useful adjunct to conventional parenchymal spin-echo imaging for evaluating vascular patency in patients with MCA stenosis or occlusion, although it is important to recognize that each technique has a different basis for the loss of signal through the area of stenosis.     

MR血管壁成像对大脑中动脉深穿支梗死的初步研究

目的探讨大脑中动脉(MCA)深穿支梗死灶位置及数目与MCA动脉粥样硬化之间的关系。方法前瞻性收集2014年3月—2017年6月期间北京天坛医院脑血管病中心收治的急性脑梗死病人。经DWI证实,存在MCA深穿支供血区急性梗死灶的病人49例,其中男45例,女4例,年龄28~73岁,平均(55.5±10.6)岁。所有病人均于发病2周内行颅内大动脉3D高分辨MRI(HR-MRI)检查,即血管壁成像(VWI)。按照HR-MRI所示MCA有无斑块,将所有病人分为2组。采用Mann-Whitney U检验和χ~2检验分别比较2组之间脑梗死病灶位置和数目的差异。结果 2组间年龄、性别、高血压、糖尿病、高血脂等临床资料差异均无统计学意义(均P0.05)。HR-MRI显示MCA有斑块病人30例(61.2%),MCA无斑块病人19例(38.8%)。MCA有斑块组梗死灶最低层面为第2.5(1.0,3.3)层,MCA无斑块组梗死灶最低层面为第3.0(2.0,4.0)层,2组间梗死灶最低层面差异有统计学意义(Z=-2.084,P=0.037)。MCA有斑块组中,深穿支单发病灶者19例(63.3%),多发病灶者11例(36.7%);MCA斑无块组中,19例均为单发病灶(100%)。2组间单发病灶数目差异有统计学意义(P0.05)。结论 MCA动脉粥样硬化斑块与其深穿支供血区梗死灶的位置和数目有关,有助于进一步探讨深穿支区梗死的发病机制。     

MRI of middle cerebral artery occlusion

Magnetic resonance imagings (MRIs) of ten patients with angiographically proved middle cerebral artery (MCA) occlusion were retrospectively reviewed. Eight of the ten patients had cerebral infarcts, one had an intraventricular hemorrhage, and the remaining one had no significant abnormalities. All patients were examined by the 1.5 Tesla SIGNA (GE), using spin-echo pulse sequences. In all patients, occluded MCA could be detected by MRI. All occluded arteries showed absence of flow void and were demonstrated as iso- or hyperintense structures relative to gray matter on T1-weighted images, iso- or hypointense on T2-weighted images. In eight of the ten patients, absence of flow void in the sylvian fissure was observed on T2-weighted images. Thus, MRI was proved to be a pertinent diagnostic modality for evaluating MCA occlusions.     

MR imaging of basilar artery occlusion

We studied six patients with basilar artery occlusion using magnetic resonance imaging. Two patients also had arteriography. All had signs consistent with pontine infarction; three had a "locked in" syndrome. Magnetic resonance imaging (five done within 24 h of onset of progression of neurologic symptoms) revealed a linear structure of increased signal intensity in the pontine cistern on T1-weighted parasagittal images and absence of flow void phenomena. Hyperintense signals at various brain stem levels corresponding to the course of the basilar artery were noted on T2-weighted images. Multiple parenchymal abnormalities were noted in the brain stem (six), cerebellum (four), occipital lobes (two), and thalamus (two). Magnetic resonance performed early in the course of basilar artery occlusion is a high-yield, safe procedure and might eliminate the need for arteriography.     

Rodent stroke induced by photochemical occlusion of proximal middle cerebral artery: evolution monitored with MR imaging and histopathology

PURPOSE: To longitudinally investigate stroke in rats after photothrombotic occlusion of proximal middle cerebral artery (MCA) with magnetic resonance imaging (MRI) in correlation with histopathology. MATERIALS AND METHODS: Forty-two rats were subjected to photochemical MCA occlusion and MRI at 1.5T, and sacrificed in seven groups (n=6 each) at the following time points: 1, 3, 6 and 12h, and at day 1, 3 and 9. T2-weighted (T2WI) and diffusion-weighted imaging (DWI) with apparent diffusion coefficient (ADC) map was performed in all rats. Contrast-enhanced T1-weighted imaging (CE-T1WI) was compared to intravital staining with Evans blue in one group for assessing blood-brain barrier (BBB) integrity. The brain was stained histochemically with triphenyl tetrazolium chloride (TTC) and processed for pathological assessment. The evolutional changes of relative lesion volume, signal intensity (SI), and the BBB integrity on MRI with corresponding histopathology were evaluated. RESULTS: The ischemic lesion volume reached a maximum around 12h to day 1 as visualized successively by DWI, ADC map and T2WI, implicating the evolving pathology from cytotoxic edema through vasogenic edema to tissue death. The ADC of brain infarction underwent a significant reversion after 12h, reflecting the colliquative necrosis. On CE-T1WI, BBB leakage peaked at 6h and at day 3 with a transitional partial recovery around 24h. The infarct volume on T2WI, DWI and ADC map matched well with that on TTC staining at 12h and at day 1 (p>0.05). CONCLUSION: The evolution of the present photothrombotic stroke model in rats could be characterized by MRI. The obtained information may help longitudinal studies of cerebral ischemia and anti-stroke agents using the same model.     

MR imaging of intracranial vertebral artery occlusion

Summary Magnetic resonance (MR) images of nine patients with intracranial vertebral artery occlusion (five proved, four presumed) have been reviewed. In two of nine, both vertebral arteries were occluded and in five of the nine, the basilar artery was also blocked. All occluded arteries showed absence of flow void and were clearly demonstrated as mildly hypo-mildly hyperintense structures to brainstem parenchyma on the T1-weighted images. In two of five patients with basilar artery occlusion, retrograde filling of the distal basilar artery was detected. Thus, MR imaging, in particular the T1-weighted image, is a pertinent diagnostic modality for evaluating intracranial vertebral artery occlusion. Angiography does not seem to be required for confirmation.     

High resolution MR imaging in patients with symptomatic middle cerebral artery stenosis

Purpose

High resolution magnetic resonance imaging (HRMRI) has been used as an imaging modality to depict the intracranial artery wall. The aim of this study was to compare images of the vessel wall between symptomatic and asymptomatic atherosclerotic plaques of the middle cerebral artery (MCA) using HRMRI.

Materials and methods

From September 2009 to August 2010 we prospectively screened consecutive patients for MCA stenosis using time-of-flight (TOF) MR angiography. We studied 14 patients with symptomatic MCA stenosis and 16 patients with asymptomatic MCA stenosis. The HRMRI protocol included three different scans: T1-, T2-, and proton density (PD)-weighted black blood MRI. The cross-sectional images of the MCA wall on HRMRI were compared between the two groups based on the degree of stenosis, remodeling ratio, outward or inward remodeling, plaque signal intensity, plaque surface irregularity, and presence of an intact inner wall.

Results

The degree of MCA stenosis and the ratio of plaque thickening to patent lumen in the symptomatic group were significantly higher than in the asymptomatic group. Outward remodeling of the stenotic area in symptomatic group was significantly higher than that seen in the asymptomatic group, and the reverse was true for inward remodeling of the stenotic area (it was significantly higher in the asymptomatic group compared to the symptomatic group). T2- and PD-weighted high signal foci, eccentric wall thickening, and plaque volume in the stenotic area were all similar between the two groups.

Conclusions

HRMRI has the potential to distinguish between atherosclerotic plaques in symptomatic and asymptomatic MCA stenoses.     

Prominent laterality of the posterior cerebral artery at three-dimensional time-of-flight MR angiography in M1-segment middle cerebral artery occlusion

BACKGROUND AND PURPOSE: Three-dimensional time-of-flight MR angiography (3D TOF MRA) often discloses prominent posterior cerebral artery (PCA) laterality in the setting of M1-segment middle cerebral artery (MCA) occlusion. We sought to analyze the implications of prominent PCA laterality at 3D TOF MRA. METHODS: We retrospectively reviewed 3D TOF MRA and digital subtraction angiography (DSA) findings in 25 patients (12 male, 13 female; mean age, 68.8 years [age range, 29-94 years]) with M1-segment occlusion. The observable laterality of the PCA, determined on the basis of 3D TOF MRA findings, was scored according to distal signal extent and compared with findings of collateral flow from the ipsilateral PCA via the leptomeningeal anastomosis (LMA) at DSA. Frequency of PCA laterality at 3D TOF MRA in patients and that in 56 healthy control subjects was also compared. RESULTS: The positive predictive value of PCA laterality for the existence of collateral flow was 99.9% and the negative predictive value 30.7%. The distal extent of ipsilateral PCA signal at 3D TOF MRA positively correlated with the grade of collateral flow from the PCA via the LMA (r = 0.802; P <.01). PCA laterality was significantly less common in control subjects (P <.01). CONCLUSION: Prominent PCA laterality at 3D TOF MRA in patients with M1-segment occlusion represents the existence of collateral flow from the PCA via the LMA.     

MR angiography and imaging for the evaluation of middle cerebral artery atherosclerotic disease

Intracranial atherosclerotic disease may constitute the most common cause of ischemic stroke worldwide; yet, in the developed world, imaging research has largely focused on extracranial atherosclerosis. Many studies in populations of Asian, African, and Hispanic descent demonstrate the preponderance of intracranial stenosis compared with carotid stenosis. This review examines the clinical presentations of MCA atherosclerosis and stenosis and the use of noninvasive MR imaging in the assessment of intracranial vasculature. MRA is a well-validated technique that offers great advantage over traditional angiography. Advances in high-resolution MR imaging of MCA stenosis have the potential to yield excellent visualization of plaque. Future developments in high-resolution MR imaging to depict intracranial atherosclerosis are explored in this review; these advances will guide endovascular therapy and the comparison of novel interventions.     

Quantification of blood flow in the middle cerebral artery with phase-contrast MR imaging

The aim of this study was to assess blood flow in the middle cerebral artery (MCA) according to age, gender, and side. Eighty-eight subjects without carotid obstruction were measured for mean velocity, vessel area, and volume flow rates of both MCA with phase-contrast MR. A high-resolution sequence with a matrix of 300 × 512 and a double oblique localizing strategy was used for measurement. A mean velocity of 33 ± 6.8 cm/s, a mean vessel area of 6.2 ± 1.2 mm² and a mean flow rate of 121 ± 28 ml/min were measured in the MCA. Lower volume flow rates were seen in subjects aged over 50 years (p < 0.01). When comparing women with men, a lower vessel area (p < 0.05) of the MCA was counterbalanced by a higher velocity, resulting in no significant difference of the volume flow rate. No difference occurred between the right and the left side. Flow reduction occurs in the elderly. A lower vessel area of the MCA in women is compensated by a higher velocity. Received: 3 September 1999; Revised: 17 January 2000; Accepted: 23 February 2000     

静脉性脑梗死MR影像特点

目的回顾总结静脉性脑梗死MRI及MRV影像表现,旨在提高影像诊断水平。方法对15例静脉性脑梗死的MR表现进行了回顾性分析,其中9例临床治疗后复查MR表现明显好转,临床症状明显改善。15例均行常规MRI平扫,其中9例同时进行MR增强及3DCE-MRV,6例行2DTOF MRV。结果 15例脑内多发病灶9例,单发病灶6例,其中2例脑梗死伴出血改变。15例中发生于额叶4例,顶叶6例,颞叶3例,枕叶1例,小脑1例。静脉栓塞部位11例为上矢状窦,1例直窦及左横窦,1例右侧横窦及乙状窦,2例皮层大脑浅静脉。9例行增强扫描,5例病灶内不规则强化,2例脑膜强化,3例无强化.7例MRV均显示栓塞的静脉血流信号丢失或缺损,3例出现异常静脉侧支或引流静脉异常扩张。结论静脉性脑梗死MR影像表现具有特征性,MRI结合MRV可以作为首选的无创检查方法,对静脉栓塞早期诊断和治疗有重要作用。     

不同溶栓方法治疗急性大脑中动脉闭塞性脑梗死疗效探讨

目的 探讨不同溶栓治疗方法对急性大脑中动脉闭塞所致急性脑梗死的疗效及安全性.方法 132例大脑中动脉闭塞急性脑梗死患者按就诊顺序采用抽签的方法随机分成3组,分别为静脉溶栓组(48例)、颈内动脉溶栓组(43例)及局部血栓内接触性溶栓组(41例),3组患者均给予阿替普酶治疗.对3组患者治疗前后神经功能缺失情况、疗效、并发症及病死率进行记录并进行统计学分析,符合正态分布的计量资料组间比较采用方差分析,计数资料比较采用x2检验,以P＜0.05为差异具有统计学意义.结果 静脉溶栓组治疗后2、24h及2周有效率分别为18.8％ (9/48)、39.6％(19/48)、45.8％( 22/48),颈内动脉溶栓组治疗后2、24h及2周有效率分别为39.5％( 17/43)、53.5％ (23/43)、58.1％ (25/43),血栓内接触性溶栓组治疗后2、24h及2周有效率分别为78.0％(32/41)、85.4％ (35/41)、87.8％(36/41),血栓内接触性溶栓组2、24h及2周有效率明显高于颈内动脉溶栓组(x2值分别为12.809、9.979、9.289,P值均＜0.01)与静脉溶栓组(x2值分别为31.295、19.425、17.161,P值均＜0.01),差异具有统计学意义.颈内动脉溶栓组治疗后2h有效率高于静脉溶栓组,差异具有统计学意义(x2 =4.801,P＜0.05),24h、2周有效率与静脉溶栓组差异无统计学意义(x2值分别为1.765、1.375,P值均＞0.05).静脉溶栓组、颈内动脉溶栓组、血栓内接触性溶栓组术后2周出血率分别为14.6％( 7/48)、14.0％( 6/43)、7.3％ (3/41),病死率分别为6.2％( 3/48)、4.6％( 2/43)、2.4％( 1/41),各组间差异均无统计学意义(x2值分别为1.328、0.786,P值均＞0.05).结论 血栓内接触性溶栓治疗急性大脑中动脉闭塞性脑梗死起效快,效果好,值得推广.     

Schizencephaly with occlusion or absence of middle cerebral artery

In a study of 160 infants with prenatal and/or perinatal risk factors for brain damage, we observed three cases of schizencephaly. All cases were unilateral, and the clefts had open lips. In two cases, magnetic resonance angiography showed occlusion or absence of the middle cerebral artery (MCA) on the affected side. Two of the patients, including one with absent flow in the MCA of the affected side, had ipsilateral cerebellar atrophy.     

Hyperacute ischemic stroke: middle cerebral artery susceptibility sign at echo-planar gradient-echo MR imaging

PURPOSE: To evaluate the accuracy of echo-planar T2*-weighted magnetic resonance (MR) sequences in detection of acute middle cerebral artery (MCA) or internal carotid artery (ICA) thrombotic occlusion. MATERIALS AND METHODS: Forty-two consecutive patients with stroke involving the MCA territory underwent MR imaging within 6 hours after clinical onset. MR examination included echo-planar T2*-weighted, diffusion-weighted (DW), and perfusion-weighted (PW) imaging and MR angiography. Presence or absence of the susceptibility sign on echo-planar T2*-weighted images, which is indicative of acute thrombotic occlusion involving MCA or ICA, was assessed in consensus by two observers blinded to clinical information and other MR imaging data. Differences in lesion volume on DW and PW images between patients with and those without the susceptibility sign were evaluated with the Mann-Whitney test. P <.05 was considered to indicate a significant difference. RESULTS: Thirty patients (71%) had a positive susceptibility sign that correlated with MCA or ICA occlusion at MR angiography in all cases (sensitivity, 83%; specificity, 100%). Mean lesion volume on PW images was higher in patients with a positive susceptibility sign (P =.01), but no significant differences were found in mean lesion volume on DW images. Cases in which the susceptibility sign was identified proximal to MCA divisional bifurcation (27 patients) showed a mean perfusion deficit of 83.9% of the total MCA territory (range, 50%-100%). CONCLUSION: Presence of the susceptibility sign proximal to MCA bifurcation provides fast and accurate detection of acute proximal MCA or ICA thrombotic occlusion.     

大脑中动脉分布区脑梗死模式的分析研究

目的：探索影像学梗死模式在判定动脉粥样硬化性大脑中动脉分布区梗死的责任血管及发生机制中的临床价值。 方法：选取2015年1月—2016年12月在我院神经内科住院的缺血性脑卒中患者105例,分为颈内动脉（ICA）梗死组68例,大脑中动脉（MCA）梗死组37例,比较两组患者的临床资料及病变血管的狭窄程度,并对不同狭窄程度下的脑梗死模式进行统计分析。 结果：ICA梗死组的低密度脂蛋白水平高于MCA梗死组,差异具有统计学意义[（2.34±0.70）mmol/L vs.（2.08±0.49）mmol/L,t=2.00,P<0.05];两组间的临床病史、侧支循环情况、单双侧梗死、单发及多发梗死、三酰甘油、高密度脂蛋白、同型半胱氨酸、血压的差异均无统计学意义。105例脑梗死患者共累及108支血管。其中37支为MCA病变所致,71支为ICA病变所致。ICA组中轻度狭窄血管的比例高于MCA组,差异有统计学意义（42.3% vs. 8.1%,P<0.05）;两组中、重度狭窄和闭塞血管的比例差异无统计学意义。ICA梗死组和MCA梗死组发生大面积梗死分别为1/0例,散在皮层梗死2/2例,单独内分水岭梗死3/13例,单独外分水岭梗死7/9例,单独穿动脉梗死7/13例,散在皮层及内分水混合梗死4/16例,穿动脉及内分水岭混合梗死4/8例,穿动脉、散在皮层及内分水岭混合梗死9/10例;轻度、中度及重度狭窄程度的ICA与MCA两组间梗死模式差异无统计学意义;闭塞的MCA组中发生穿动脉梗死的比例高于闭塞的ICA组（4/13 vs. 0/16,P=0.03）,差异有统计学意义。 结论：影像学梗死模式在临床判定责任血管的价值依赖于后期更严谨的研究设计,此类依靠管腔狭窄程度作为分组指标的方法可能是影响研究结果的重要因素。     

Occipital-vertebral anastomosis in a case of middle cerebral artery occlusion

Summary The collateral circulation between the occipital artery, a branch of the external carotid and the vertebral artery, represents an anastomotic pathway which is relatively rare and not very efficient from the functional point of view. Its angiographic demonstration has been described only in cases of occlusion of the cervical internal carotid or the proximal portion of the vertebral artery. The observation described here corresponds to an occipital-vertebral anastomosis in a patient with obstruction of the middle cerebral artery. Its pathogenesis is discussed as well as its efficiency as anastomotic collateral circulation in the presence of a meningeal anstomosis which by a retrograde pathway effects the revascularization of the occluded Sylvian territory.

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Anastomose zwischen der A. vertebralis und der A. occipitalis bei einem Verschluß der A. cerebri media

Zusammenfassung Der Collateral-Kreislauf zwischen der A. occipitalis, von der A. carotis externa ausgehend, und der A. vertebralis ist relativ selten. Auch erscheint er funktionell unzureichend. Die angiographische Darstellung dieses Collateral-Kreislaufs wurde nur bei Kranken beschrieben, bei denen ein Verschluß der A. carotis interna (Halsteil) oder des proximalen Abschnittes der A. vertebralis vorlag. Die Verfasser berichten nun über einen 17jährigen Mann, bei dem arteriographisch eine Anastomose zwischen der A. occipitalis und der A. vertebralis nachgewiesen werden konnte. Bei dem Patienten lag ein Verschluß der A. cerebri media vor. Durch diesen Collateral-Kreislauf kam es zu einer ausgezeichneten Füllung der intracraniellen Gefäßabschnitte.

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Anastomose occipito-vertébrale dans un cas d'occlusion de l'artère cérébrale moyenne

Résumé Circulation collatérale entre l'artère occipitale, branche de la carotide externe et l'artère vertébrale. L'observation décrite concerne un cas de thrombose de l'artère sylvienne. L'anastomose occipito-vertébrale est peu fonctionnelle.