Usefulness of triphasic perfusion computed tomography for intravenous thrombolysis with tissue-type plasminogen activator in acute ischemic stroke

BACKGROUND: Intravenous thrombolysis for acute ischemic stroke has been investigated in several clinical trials without enough information on collateral blood flow and perfusion deficit in the ischemic areas. The therapeutic time window varies from patient to patient depending on these factors. Triphasic perfusion computed tomography (TPCT) can provide this information as reliably as conventional angiography. OBJECTIVE: To assess the safety and efficacy of thrombolysis within 3 or 7 hours of stroke onset according to the extent of perfusion deficit on TPCT. METHODS: In 46 patients with acute middle cerebral artery (MCA) territory stroke, TPCT was performed with power injector-controlled, intravenous administration of contrast media after taking precontrast CT scans. Sequential scans of early, middle, and late phases were performed. The entire procedure took 5 minutes. Depending on collateral blood flow, the perfusion deficit on TPCT was graded as "severe perfusion deficit" or "moderate perfusion deficit." Twenty-nine patients were excluded based on clinical, laboratory, and TPCT findings. Seventeen patients were treated with an intravenous recombinant tissue-type plasminogen activator, 0.9 mg/kg. The 17 treated patients were divided into 2 groups: group 1 with small severe perfusion deficit (33% but 相似文献   

Triphasic perfusion computed tomography in acute middle cerebral artery stroke: a correlation with angiographic findings

OBJECTIVE: To evaluate the usefulness of triphasic perfusion computed tomography (TPCT) in diagnosing middle cerebral artery (MCA) occlusion and in assessing the perfusion deficit and collateral circulation in patients with acute ischemic stroke. BACKGROUND: Conventional angiography is the criterion standard for the diagnosis of MCA occlusion and for the assessment of perfusion deficit and collateral blood supply. The risk of hemorrhagic transformation after recanalization of occluded arteries by thrombolytic therapy is considered high when pretherapeutic residual flow is markedly reduced. PATIENTS AND METHODS: In 8 patients within 3 hours of onset of acute MCA stroke, precontrast computed tomographic scans were taken, and then TPCT was performed after power-injector controlled intravenous administration of contrast media. Sequential images of early, middle, and late phases were obtained. The whole procedure took 5 minutes. Perfusion deficit on TPCT was graded as "severe" or "moderate," depending on the state of collateral flow. Digital subtraction angiography (DSA) was performed in all patients within 6 hours of acute stroke. Direct intra-arterial urokinase infusion was begun immediately after the angiographic superselection of the MCA occlusion site in 6 of the 8 patients within 7 hours of onset (range, 4.3-6.2 hours). RESULTS: The DSA findings showed occlusion of the MCA stem (n = 1) and at the bifurcation (n = 4). The sites of proximal MCA occlusion could be identified on the early and middle images of TPCT in all 5 patients. On DSA findings, all 8 patients had a zone of perfusion deficit with markedly slow leptomeningeal collaterals and a zone of perfusion deficit with no collaterals. The zone of severe perfusion deficit on TPCT corresponded to the zone of perfusion deficit with no or few collaterals on angiography, and the zone of moderate perfusion deficit on TPCT corresponded to that of perfusion deficit with markedly slow leptomeningeal collaterals. Early parenchymal hypoattenuation on precontrast computed tomography was confined to the zone of severe perfusion deficit on TPCT. The initial National Institutes of Health Stroke Scale score correlated better with the total extent of severe perfusion deficit and moderate perfusion deficit on TPCT than that of severe perfusion deficit alone. After direct intra-arterial thrombolysis within 7 hours of onset, symptomatic hemorrhagic transformation did not develop in 4 patients with small severe perfusion deficit (33% or less of the presumed MCA territory). However, the remaining 2 patients with large severe perfusion deficit (more than 50% of the presumed MCA territory) deteriorated to death with hemorrhagic transformation. CONCLUSIONS: Triphasic perfusion computed tomography is useful for diagnosing proximal MCA occlusion and assessing perfusion deficit and collateral circulation as reliably as DSA. The zone of severe perfusion deficit on TPCT may be presumed to be the ischemic core, and that of moderate perfusion deficit, the penumbra zone. Triphasic perfusion computed tomography may be used as a rapid and noninvasive tool to make thrombolysis safer.     

Pattern of Cortex and White Matter Involvement in Severe Middle Cerebral Artery Ischemia

BACKGROUND AND PURPOSE: In middle cerebral artery (MCA) stroke, ischemia usually is unevenly distributed within the MCA territory. We sought to investigate which brain structures are critical for the acute neurological deficit in severe MCA stroke. METHODS: We used magnetic resonance (MR) imaging and statistical parametric mapping in 64 consecutive stroke patients (64 +/-13 years) to study the pattern of the initial perfusion abnormality. RESULTS: Patients with lesion progression had more severe time-to-peak (TTP) abnormalities (P < .0001) in the inferior frontal gyrus, superior temporal gyrus, insula, and underlying hemispheric white matter than those with lesion regression. Also, patients with lesion progression had more severe T2 abnormalities on day 8 than those with lesion regression. In contrast, the changes of water diffusion were similar among the two groups resulting in a perfusion-diffusion mismatch in lesion progression. TTP-lesions were related to the neurological deficit score (r(s)=-0.563, P < .0001), T2-lesions (r= 0.686, P < .0001), and cerebral artery abnormalities assessed on MR-angiography (r(s)= 0.399, P < .01). CONCLUSIONS: In major MCA, stroke ischemia was most severe in the central portion of the MCA territory. It is suggested that involvement of hemispheric white matter accentuated the neurological deficit probably by affecting cortico-cortical and cortico-subcortical fibers.     

116例大脑中动脉病变患者脑梗死类型分布和脑灌注异常分析

目的 应用神经影像检查,分析大脑中动脉闭塞性疾病(MCAOD)患者梗死类型分布和脑灌注异常. 方法 对经CT血管造影(CTA)证实的116例MCAOD患者的CT平扫、CT灌注成像(CTP)和CTA的影像资料进行回顾性分析,确定其脑梗死类型分布和脑灌注改变. 结果 116例患者中,CTA共检出133条大脑中动脉(MCA)狭窄或闭塞,其中单侧者99例,双侧者17例.其中MCA闭塞25条,重度狭窄39条,中、轻度狭窄69条.CT或MRI显示腔隙性脑梗死(LIS)45例,各型分水岭脑梗死(CWSI)38例,流域性脑梗死26例,纹状体内囊梗死(SCI)10例,未检出梗死病灶14例.CTP显示MCA供血区内脑血流灌注异常96例,其中58例有MCA供血区的大范围血流灌注减低.未检出血流灌注异常者37例. 结论 由于MCA狭窄的部位、程度和发病机制的不同以及侧支循环的建立,MCAOD可造成不同类型的脑梗死和血流灌注异常.     

Venturi mask adjuvant oxygen therapy in severe acute ischemic stroke

BACKGROUND: The effect of oxygen therapy in acute ischemic stroke remains undetermined. OBJECTIVE: To investigate the feasibility of eubaric hyperoxia therapy by Venturi mask (VM) in a group of patients who experienced a severe acute ischemic stroke. DESIGN: Patients experiencing a first-ever large middle cerebral artery infarction were recruited within 48 hours after stroke. Patients were subdivided to undergo therapy with a VM with a fraction of inspired oxygen of 40% or with a nasal cannula. A large middle cerebral artery infarction was defined as a large low-attenuation area of more than one third of the middle cerebral artery territory on brain images. Stroke severity was evaluated by the National Institutes of Health Stroke Scale. RESULTS: Seventeen patients were enrolled in the VM group and 29 in the nasal cannula group. All the demographic and clinical characteristics were equally distributed initially. The mean initial National Institutes of Health Stroke Scale score was 20.5 and 18.9 in the VM and nasal cannula groups, respectively. Atrial fibrillation was found in 11 (65%) patients in the VM and 17 (59%) patients in the nasal cannula groups. The VM therapy was initiated within 13.7 (range, 3.0-41.5) hours after stroke and the duration was 132.9 (range, 48.0-168.5) hours. In-hospital mortality was 1 (6%) in the VM group and 7 (24%) in the nasal cannula group (P=.12). In the VM group, there were fewer incidences of fever (4 [24%] vs 15 [52%]; P=.06), pneumonia (1 [6%] vs 6 [21%]; P=.18), and respiratory failure (3 [18%] vs 8 [28%]; P=.45), but a higher incidence of bedsores (3 [18%] vs 2 [7%]; P=.29). CONCLUSIONS: By using VM therapy with a fraction of inspired oxygen of 40%, there might be less mortality and comorbidities in treated patients who experienced a severe acute ischemic stroke. Further randomized confirmatory studies should explore the decreased mortality in patients who experience a severe acute ischemic stroke, especially in those with a large middle cerebral artery infarction who undergo VM therapy with a fraction of inspired oxygen of 40%.     

Hemodynamic assessment of acute stroke using dynamic single-slice computed tomographic perfusion imaging

BACKGROUND: Stroke management would benefit from a broadly available imaging tool that detects perfusion deficits in patients with acute stroke. OBJECTIVE: To determine the role of dynamic, single-slice computed tomographic (CT) perfusion imaging (CTP) in the assessment of acute middle cerebral artery stroke. DESIGN AND PATIENTS: Imaging with CTP and CT within the first 6 hours of symptom onset and before the start of treatment in a consecutive clinical series of 22 patients (mean age, 68.3 years; 14 women; studied within 143 +/- 96 minutes of stroke onset). SETTING: A stroke unit in a university hospital. MAIN OUTCOME MEASURES: Area of the perfusion deficit (nAP(0)) from time-to-peak maps, hemispheric lesion area from follow-up CT (HLA(F)), final infarct volume, and stroke recovery (National Institutes of Health Stroke Scale scores). RESULTS: Eighteen patients had perfusion deficits in the middle cerebral artery territory and corresponding hypoattenuation in follow-up CT. Three patients with normal CTP findings showed lacunar infarctions or normal findings on follow-up CT. In 1 patient, CTP did not reveal a territorial deficit above the imaging slice. The overall sensitivity and specificity of CTP for the detection of perfusion deficits in patients with proven territorial infarction (n = 18) on follow-up CT were 95% and 100%, respectively. The nAP(0) was significantly correlated with the National Institutes of Health Stroke Scale score at admission (P<.003) and the HLA(F) (P<.001). Different stroke patterns were identified in patients with follow-up CTP (n = 10): (1) initial perfusion deficit and partial nutritional reperfusion (nAP(0)>HLA(F); n = 6), (2) initial perfusion deficit and nonnutritional reperfusion (nAP( 0)>/=HLA(F); n = 2), and (3) initial perfusion deficit without reperfusion (nAP(0)>/=HLA(F); n = 2). CONCLUSIONS: Computed tomographic perfusion imaging detects major perfusion deficits in the middle cerebral artery territory. Because CTP is broadly available, it may play a role in acute stroke management. Arch Neurol. 2000;57:1161-1166     

110 mm容积螺旋穿梭扫描在全脑灌注及脑血管联合成像中应用的探讨

【摘要】
目的 探讨宝石能谱计算机断层扫描（computed tomography,CT）110 mm容积螺旋穿梭扫描在全脑灌注及脑血管联合成像中的应用价值。
方法 采用宝石能谱CT,注射造影剂后从颅底到头顶进行110 mm范围的容积螺旋穿梭扫描,重建56例受检者的全脑灌注及脑血管图像,同时期同机器常规扫描模式所得脑动脉重建检查100例,脑静脉三维重建检查25例,脑血流灌注检查80例分别建立数据库。容积螺旋穿梭扫描图像中,随机抽取脑灌注图像20例,44例非烟雾病患者中随机抽取脑动脉薄层最大密度投影（maximum intensity projection,MIP）像、脑动脉三维重建图像各20例,从17例进行脑静脉三维重建图像中随机抽取15例,与随机抽取相同例数的常规扫描模式下同类型图像,就图像质量进行评分后比较。
结果 宝石能谱CT 110 mm容积螺旋穿梭扫描所得脑灌注图像及脑静脉三维重建图像质量与常规扫描模式差异无显著性,容积螺旋穿梭扫描和常规扫描模式两组脑灌注图像得分分别为4.00（3.00,4.00） vs 4.00（3.00,4.00）,P=0.477,脑静脉三维重建图像得分分别为5.00（4.00,5.00） vs 4.00（4.00,5.00）,P=0.119。脑动脉薄层MIP图像质量优于常规扫描模式,其评分分别为4.00（4.00,5.00） vs 4.00（4.00,4.00）,P=0.016。脑动脉三维重建图像质量差于常规扫描模式,评分分别为3.00（3.00,4.00） vs 4.00（4.00,5.00）,P＜0.001。
结论 宝石能谱CT 110 mm容积螺旋穿梭扫描能够有效地对脑血管疾病患者进行影像学综合评估。     

大脑中动脉供血区大面积脑梗死患者出现致死性脑水肿的早期预测因素

目的 分析大脑中动脉供血区大面积脑梗死患者出现致死性脑水肿的早期预测因素.方法 回顾性研究大脑中动脉供血区大面积脑梗死患者发病24 h内的临床、实验室、影像学因素 病例组为死于致死性脑水肿的患者,对照组为其余存活者.结果 共有72例患者入院,病例组26例,对照组46例 多变量logistic回归分析显示,2组的发病24 h内NIHSS评分（P=0.017）和脑梗死类型（P=0.001）2个因素有显著差异.结论 发病24 h内NIHSS评分≥24、脑梗死范围＞大脑中动脉供血区可能是大脑中动脉供血区大面积脑梗死患者出现致死性脑水肿的早期独立预测因素.     

Tissue at risk concept for endovascular treatment of severe vasospasm after aneurysmal subarachnoid haemorrhage

OBJECTIVE: To report a case of severe vasospasm after subarachnoid haemorrhage (SAH) where "tissue at risk" was identified by magnetic resonance imaging (MRI), and to demonstrate the haemodynamic consequences with either resolution of the perfusion-diffusion mismatch by balloon angioplasty or evolution of an infarct. METHODS: A 45 year old women with SAH underwent surgical treatment of a ruptured middle cerebral artery (MCA) aneurysm. On day 3 she became obtunded and developed a right hemiparesis. Diffusion weighted (DWI) and perfusion weighted (PWI) imaging were done before and after transluminal balloon angioplasty (TBA) of multifocal proximal vasospasm. RESULTS: The initial MRI revealed no DWI lesion but PWI showed a severe perfusion deficit of 6.7 to 16.4 seconds in the complete left MCA territory. Digital subtraction angiography confirmed severe segmental narrowing of left C1 and M1. The spastic segments were successfully dilated by TBA. Follow up MRI showed that the PWI-DWI mismatch resolved in the anterior and middle MCA territory with no tissue infarction, whereas in the terminal dorsal MCA territory a severe mismatch remained and cerebral infarction evolved. CONCLUSIONS: PWI/DWI can identify tissue at risk for infarction in severe vasospasm following SAH. This may allow selection of patients for angioplasty and the monitoring of treatment effects.     

氙CT测定合并脑血管狭窄的缺血性脑血管病患者局部脑血流量的研究

目的 通过氙CT（Xenon computer tomography,Xe-CT）检查,研究合并有脑血管狭窄的缺血性脑血管病患者局部脑血流量（regional cerebral blood flow,rCBF）特点。方法 正常对照组10例,病例组22例。对所有入组对象进行Xe-CT检查,通过手工划分和皮层6分法分别测定全脑、半球、各血管分布区及各血管分布区皮层rCBF,并进行如下数据分析：①对照组各划分区域自身rCBF对比分析;②病例组各划分区域自身rCBF对比分析;③病例组与对照组各划分区域rCBF对比分析。结果 正常对照组两侧大脑半球rCBF相当,分布较为平衡。用各划分方法测定并比较两侧各大血管供应区rCBF,结果差异无统计学意义。病例组与对照组进行对比发现：①病例组全脑静息rCBF与正常对照组差异无统计学意义（38.9±10.3 ml·100 g-1·min-1 vs 44.7±7.1 ml·100 g-1·min-1,P >0.05）。②病例组两侧大脑半球rCBF差异度高于对照组（7.2±5.6 ml·100 g-1·min-1 vs 3.2±2.5ml·100 g-1·min-1,P =0.008)。③手工法与皮层6分法均显示病例组责任大脑中动脉（middle cerebral artery,MCA）支配区静息rCBF低于对照组相应区域。左侧责任MCA与对照组左侧MCA支配区域比较有统计学差异（34.3±11.2 ml·100 g-1·min-1 vs 48.1±6.4 ml·100 g-1·min-1,P =0.03)。病例组自身rCBF对比后发现：皮层6分法所测得责任侧MCA皮层区域rCBF显著低于对侧相应区域（45.8±15.2 ml·100 g-1·min-1 vs 55.4±14.5 ml·100 g-1·min-1,P =0.039)。结论 使用Xe-CT测量脑血流量,并通过手工划分全脑、半球、责任血管区域,联合软件自带6分法分析图像,反映出脑血流灌注下降是合并脑血管狭窄的缺血性脑血管病患者的重要特点,它与脑血管狭窄存在一定联系。     

Aphasia in hyperacute stroke: language follows brain penumbra dynamics

During the first few hours after onset, stroke symptoms may evolve rapidly. We studied the correlation between brain perfusion and aphasia changes during the hyperacute phase of stroke using a new technique of perfusion computed tomography (P-CT). Using an aphasia score developed for each language modality, language was evaluated within 6 hours after onset, then sequentially during the first week. Maps of the penumbra and infarct obtained from P-CT images and definite infarct size evaluated using T2 and diffusion-weighted MRI (DWI) on day 3 were rated by a neuroradiologist, blinded to the clinical deficit. Within 6 hours, deficits in all language modalities were present in 13 out of 24 consecutive patients, corresponding to large anterior-posterior perfusion deficits of the left middle cerebral artery (MCA) territory. The aphasia score correlated with a corresponding perfusion deficit in specific areas of the MCA territory, and showed significantly less improvement when the penumbra evolved toward infarction than when at least part of the penumbra was rescued. Our findings suggest a particularly good correlation between the evolution of aphasic symptoms and penumbra dynamics. Further studies on the relevance of penumbra dynamics in function-specific brain areas to decision taking in hyperacute stroke management are required.     

Identification of major ischemic change. Diffusion-weighted imaging versus computed tomography.

BACKGROUND AND PURPOSE: Thrombolytic therapy is not recommended in patients with CT changes of recent major infarction, which has been defined as reduced attenuation or cerebral edema involving >33% of the middle cerebral artery territory (European Cooperative Acute Stroke Study [ECASS] criteria). Diffusion-weighted imaging (DWI) is more sensitive than CT in detecting acute ischemia, and the combination of DWI, MR perfusion imaging, and MR angiography provides additional information from a single examination. We sought to determine whether DWI could identify the presence and extent of major ischemia as well as CT in hyperacute stroke patients. METHODS: Seventeen suspected hemispheric stroke patients were studied with both CT and DWI within 6 hours of symptom onset. None received thrombolytic therapy. The scans were examined separately by 2 neuroradiologists in a blinded fashion for ischemic change and cerebral edema, graded as normal, <33%, or >33% of the MCA territory. Final diagnosis of stroke was determined with the use of standard clinical criteria and T2-weighted imaging at day 90. RESULTS: Sixteen of 17 patients had a final diagnosis of stroke. Acute ischemic changes were seen in all 16 on DWI (100% sensitivity) and in 12 of 16 on CT (75% sensitivity). DWI identified all 6 patients with major ischemia on CT, with excellent agreement between the 2 imaging techniques (kappa=0.88). One patient eligible for thrombolysis on the ECASS CT criteria had major ischemia on DWI. CONCLUSIONS: DWI is more sensitive than CT in the identification of acute ischemia and can visualize major ischemia more easily than CT.     

Massive Cerebral Edema After Recanalization Post-Thrombolysis

BACKGROUND: Intravenous thrombolysis with tissue plasminogen activator is an approved and effective therapy for acute ischemic stroke within the first 3 hours from onset. In addition to the risk of hemorrhage, there is a risk of postrecanalization cerebral edema. The authors present the case of a patient with an ischemic stroke treated successfully with intra-arterial thrombolysis who subsequently developed massive brain edema in the face of clinical improvement. CASE: An 81-year-old man presented within 1 hour of developing a full right middle cerebral artery (MCA) syndrome. Computed tomography (CT) was normal. A cerebral angiogram demonstrated an occlusion of the M1 segment of the right MCA. The patient was treated with intra-arterial urokinase 750,000 units. He recovered during the procedure. Serial CT scans demonstrated progressive edema with mass effect in the right MCA distribution. The patient remained asymptomatic except for a mild sensory deficit. DISCUSSION: Postrecanalization cerebral edema is an uncommon but potentially lethal complication of thrombolysis. It is postulated that the edema is due to ischemic injury aggravated by reperfusion with vasogenic edema. The presence of this massive edema is usually associated with clinical worsening. The present case illustrates that this disorder can be associated with good outcome.     

Ultrasonic evaluation of pathological brain perfusion in acute stroke using second harmonic imaging

OBJECTIVE: To evaluate the use of transient response second harmonic imaging (HI) by means of ultrasound to assess abnormalities of cerebral echo contrast agent enhancement in patients with acute stroke. METHODS: The study comprised 25 patients with acute onset of hemispheric stroke (<24 h) with sufficient insonation conditions and 14 control subjects without cerebrovascular disease. All stroke patients had HI, extracranial and transcranial colour coded duplex examinations of the arteries supplying the brain, and clinical examinations (European stroke scale) performed in the acute phase, on day 2, and within 1 week. Acute CT was repeated within 1 week and facultatively accompanied by angiography. Examinations using HI were performed in an axial diencephalic plane of section using the transtemporal acoustic bone window. After bolus application of galactose based microbubbles, 61 ultrasound images with a cardiac cycling triggering frequency of once every 2 seconds were recorded and evaluated off line. Focal perfusion deficit was identified if no contrast enhancement was visualised in a circumscribed region of interest and insufficient temporal bone window was excluded. In cases of reappearance of contrast enhancement reperfusion was assessed. RESULTS: Adequate cerebral contrast enhancement could be seen in 21 subjects. In seven, a large hemispheric deficit of contrast enhancement affecting the entire middle cerebral artery (MCA) territory was detectable; the lentiform nucleus was affected in three subjects. Assessment of cerebral contrast abnormalities was possible in two patients with superficial MCA infarctions but in none of the patients with lacunar ischaemias. None of the control persons had focal deficits of cerebral echo contrast enhancement. In all patients with complete MCA infarction and striatocapsular infarction, presumed ischaemic areas in HI examinations correlated with final CT findings. Overall sensitivity and specifity of HI examinations for predicting size and localisation of the infarction were 75 and 100%, respectively. During follow up, reappearance of contrast enhancement was determined in three patients, in two patients circulatory arrest due to malignant brain oedema with missing contrast enhancement in the entire cerebral hemisphere could be seen. Extent of contrast enhancement deficits significantly correlated with the clinical status on admission and after 1 week (p<0.01). CONCLUSIONS: Second harmonic imaging is the first ultrasonic technique that enables visualisation of pathological cerebral echo contrast enhancement. Because this method identifies deficits of focal contrast enhancement in patients with acute stroke and allows estimation of the final infarct size and clinical prognosis, it may help to select and monitor patients for invasive therapies.     

Neurovascular territory involved in different etiological subtypes of ischemic stroke in the Perugia Stroke Registry

We studied the correlation between the potential causes of stroke (TOAST etiological groups) and the involvement of different vascular territories seen on computed tomography (CT) scans in patients with ischemic stroke. Information from consecutive patients with a first-ever stroke have been prospectively coded and entered into a computerized data bank (Perugia Stroke Registry). A population of 1,719 patients were evaluated: 1,284 patients (74.7%) had ischemic stroke. Large artery disease was the main cause of entire middle cerebral artery (MCA) territory infarcts (40.9%), superficial MCA territory infarcts (35.7%), and watershed infarcts (68.2%). The highest presence of emboligenic heart disease was found in the entire MCA territory infarcts (28.8%) or superficial (29.4%) supratentorial infarcts and in cerebellar infarcts (36.8%). Small artery disease was the most common presumed cause of deep MCA infarcts (75.0%) and posterior cerebral artery (PCA) territory infarcts (52.1%). In conclusion: stroke location could depend on its etiology. Lacunar infarcts are the most prevalent (36.7%), being mostly localized in the deep MCA territory; large artery disease includes more than two-thirds of watershed infarcts; the most prevalent territories involved in cardioembolic stroke are the entire MCA and posterior fossa.     

The probability of middle cerebral artery MRA flow signal abnormality with quantified CT ischaemic change: targets for future therapeutic studies

OBJECTIVES: In this study we define the probability of vascular abnormality in the middle cerebral artery (MCA) territory according to the extent of ischaemic change seen using computed tomography (CT). We assessed the sensitivity and specificity of the hyperdense middle cerebral artery (HMCA) and the "dot" sign using magnetic resonance angiography (MRA). METHODS: Patients presenting with ischaemic stroke had a CT scan (<6 h) prior to MRI (<7 h). A quantitative CT scoring system (ASPECTS) was applied to CT and diffusion weighted images (DWI) at baseline and follow up (24 h) by five independent observers. The presence of HMCA and the MCA "dot" sign was also evaluated. An expert reader assessed the 3D time of flight (TOF) MRA in the anterior circulation for areas of decreased vascular signal in the MCA territory, with an absent signal taken to represent severely reduced or absent flow. RESULTS: A total of 100 consecutive patients had baseline CT and MR scans. The median NIHSS was 9. The median CT ASPECTS was 8 and equalled the median DWI ASPECTS. There were a total of 10 HMCA and 19 MCA "dot" signs, with four patients having both HMCA and "dot" signs. A total of 47 MRA flow signal abnormalities were observed in the anterior circulation. CONCLUSIONS: In the absence of accessible neurovascular imaging, the extent of CT ischaemia (ASPECTS) is a strong predictor of vascular occlusion. The CT hyperdense artery signs have a high positive predictive value but low negative predictive value.     

Experimental thromboembolic stroke in cynomolgus monkey

To develop an experimental model of thromboembolic stroke without intracranial surgery, an autologous blood clot was delivered to the middle cerebral artery (MCA) via the internal carotid artery in cynomolgus monkeys. Male cynomolgus monkeys, in which a chronic catheter had been earlier implanted in the left internal carotid artery, were used. The clot was flushed into the internal carotid artery under sevofluorane anesthesia. A neurologic deficit score was assigned after MCA embolization. After 24 h, cerebral infarct size and location were determined by the TTC staining method. Cerebral blood flow (CBF) was measured prior to and after MCA embolization, using positron emission tomography (PET). After embolization, long-lasting and profound extensor hypotonia of the contralateral upper and lower limbs, and mild to severe incoordination were observed. Contralateral hemiplegia was observed over the following 24 h. In gross morphologic observation of the brain, the lesions involved mostly the caudate nucleus, putamen, globus pallidus and insular cortex. CBF was maximally reduced in the left MCA territory, but not in the right MCA territory. This model is relevant to thromboembolic stroke in human in neurologic dysfunction and histopathologic brain damage.     

Posterior cerebral artery infarction from middle cerebral artery infarction

BACKGROUND: While it is known that posterior cerebral artery (PCA) infarction may simulate middle cerebral artery (MCA) infarction, the frequency and localization of this occurrence are unknown. OBJECTIVE: To determine the frequency of PCA infarction mimicking MCA infarction and the territory of the PCA most commonly involved in this simulation. DESIGN: We studied 202 patients with isolated infarction in the PCA admitted to our stroke center to determine the frequency of PCA infarction simulating MCA infarction, the involved PCA territory, and the patterns of clinical presentation. RESULTS: We found 36 patients (17.8%) with PCA ischemic stroke who had clinical features suggesting MCA stroke. The PCA territory most commonly involved was the superficial PCA territory (66.7%), followed by the proximal PCA territory (16.7%) and both the proximal and the superficial PCA territories (16.7%). The principal stroke mechanism was cardioembolic (54.1%) in the superficial PCA territory, lacunar (46.2%) in the proximal PCA territory, and undetermined (40.2%) in both the proximal and the superficial territories. Among the 36 patients, the most common clinical associations were aphasia (13 patients), visuospatial neglect (13 patients), and severe hemiparesis (7 patients). CONCLUSIONS: Posterior cerebral artery infarction simulating MCA infarction is more common than previously thought. Early recognition of the different stroke subtypes in these 2 arteries may allow specific management.     

Pathophysiological topography of acute ischemia by combined diffusion-weighted and perfusion MRI.

BACKGROUND AND PURPOSE: Combined echoplanar MRI diffusion-weighted imaging (DWI), perfusion imaging (PI), and magnetic resonance angiography (MRA) can be used to visualize acute brain ischemia and predict lesion evolution and functional outcome. The appearance of a larger lesion by PI than by DWI quantitatively defines a mismatch of potential clinical importance. Qualitative lesion variations exist in the topographic concordance of this mismatch. We examined both the topographic heterogeneity and relative frequency of mismatched patterns in acute stroke using these MRI techniques. METHODS: Acute DWI, PI, and MRA studies of 34 prospectively recruited patients with supratentorial ischemic lesions scanned within 24 hours of stroke onset (range 2.5 to 23.3 hours, 12 patients <6 hours) were analyzed. RESULTS: Ischemic lesions were predominantly in the middle cerebral artery (MCA) territory (94%), with DWI lesions most commonly affecting the insular region. Mismatched patterns with PI lesion larger than DWI lesion occurred in 21 patients (62% overall), in all 4 patients imaged within 3 hours, and in 44% of patients imaged after 18 hours. A patient with a large PI but no DWI lesion and severe clinical deficit at 2.5 hours after stroke onset recovered completely. Regional variations in DWI and PI lesion loci were found, inferring site of proximal MCA occlusion, embolic pathogenesis, and regional arterial reperfusion. CONCLUSIONS: Analysis of the topographic concordance of PI and DWI lesions in acute stroke reveals regional PI lesions without concomitant DWI lesions, which do not necessarily progress to infarction but may suggest stroke pathogenesis and site of current arterial occlusion. Location of DWI lesions may suggest an earlier site of arterial occlusion and regions of maximal perfusion deficit.