Hyperdense middle cerebral artery CT sign

Summary The early CT finding of an hyperdensity of a portion of the middle cerebral artery Hyperdense Middle Cerebral Artery Sign (HMCAS), in patients with supratentorial stroke, is often indicative of an embolic occlusion. Aim of this study was to verify the incidence and reliability of the HMCAS and its possible correlation with early CT findings and with the extent of late brain damage. We studied 36 patients presenting with symptoms of stroke in the MCA territory, by means of CT and angiography performed respectively within 4 and 6 hours. Follow-up CT scans were then obtained after one week and three months from the ischemic event. The HMCAS was present in 50% of our patients and in this group it always correlated positively with the angiographic finding of occlusion. The same group presented a high incidence of erly CT hypodensity (88%). Finally the presence of HMCAS might be considered a negative prognostic sign for the development of extensive brain damage.     

Proximal and distal hyperattenuating middle cerebral artery signs at CT: different prognostic implications

PURPOSE: To determine whether a proximal (M1-segment) or distal (M2- and/or M3-segment) hyperattenuating middle cerebral artery (MCA) sign in patients with ischemic infarction in the territory of the MCA indicates a worse short-term prognosis than that in patients without a hyperattenuating MCA sign. MATERIALS AND METHODS: We retrospectively reviewed the records of 352 patients who were diagnosed with ischemic brain infarction in the territory of the MCA. Of these patients, 186 patients met our final criteria and were included in this study. Nonenhanced computed tomography (CT) was performed for the entire brain, with a 5-mm section thickness in all patients, within 24 hours after symptom onset. The presence and location of a hyperattenuating MCA sign was correlated with neurologic deficit at discharge from the hospital (ie, short-term prognosis) by using the chi(2) test to detect differences between patient groups. RESULTS: Patients with a hyperattenuating MCA sign at CT have a worse short-term prognosis than do patients without a hyperattenuating MCA sign (P <.05). Patients with a proximal hyperattenuating MCA sign have a significantly (P <.01) worse short-term prognosis than do patients with a distal hyperattenuating MCA sign. CONCLUSION: A proximal hyperattenuating MCA sign is a reliable predictor of poor short-term prognosis in patients who experience acute stroke.     

Hyperdense middle cerebral artery sign on CT: efficacy in detecting middle cerebral artery thrombosis

The hyperdense middle cerebral artery sign is a CT predictor of the development of a large cerebral infarct. The limits of detectability were tested in a blinded, then unblinded analysis of CT scans from 25 acute stroke patients. In the initial blinded analysis, sign detection exhibited the following mean values: sensitivity, 78.5%; specificity, 93.4%; positive predictive value, 66%; negative predictive value, 96.4%; accuracy, 91.3%. Kappa statistics analysis indicated poor interobserver agreement (k = .38). Results of unblinded analysis were as follows: sensitivity, 69%; specificity, 94.4%; positive predictive value, 82.8%; negative predictive value, 88.7%; accuracy, 87.3%. There was fair unblinded interobserver agreement (k = .53). Unblinded analysis had a lower false-positive frequency and did not increase the number of true-positive determinations. We conclude that detection of the hyperdense middle cerebral artery sign on CT scans by multiple observers is a sensitive, accurate, and predictive indicator of middle cerebral artery thromboembolism.     

Loss of the insular ribbon: another early CT sign of acute middle cerebral artery infarction

Although computed tomography (CT) remains the most frequently used imaging examination in acute cerebral infarction, its sensitivity for early detection of strokes remains limited. In middle cerebral artery (MCA) strokes less than 6 hours old, loss of definition of the gray-white interface in the lateral margins of the insula ("insular ribbon") was observed. The acute and subacute CT findings in 11 retrospective and 16 prospective patients are presented. Loss of the insular ribbon was detected in 12 of the prospective cases and in all 11 retrospective cases. The insular ribbon is supplied by the insular segment of the MCA and its claustral branches. With cessation of MCA flow, the insular ribbon becomes the region most distal from the anterior and posterior cerebral collateral circulations. Consequently, the insular ribbon effectively becomes a watershed arterial zone. Loss of the insular ribbon is thus a reflection of acute edema due to infarction. Loss of the insular ribbon appears to be another frequent and reliable finding in acute MCA stroke.     

Prognostic value of the hyperdense middle cerebral artery sign and stroke scale score before ultraearly thrombolytic therapy.

PURPOSETo determine the relationship between the hyperdense middle cerebral artery sign (HMCAS) and neurologic deficit, as evidenced by the National Institutes of Health (NIH) stroke scale score, and to determine the relationship of the HMCAS and the NIH stroke scale score to arteriographic findings after thrombolytic therapy.METHODSFifty-five patients with acute ischemic stroke were rated on the NIH stroke scale, were examined with CT, and were treated with intravenous alteplase within 90 minutes of symptom onset. Presence of the HMCAS was determined on the baseline CT scan by a neuroradiologist blinded to the patient''s neurologic deficit. Patients with the HMCAS were compared with those without HMCAS with regard to baseline NIH stroke scale score, 2-hour NIH stroke scale score, findings at posttreatment arteriography, 3-month residual neurologic deficit, and 3-month ischemia volumes as evidenced on CT scans.RESULTSEighteen patients (33%) had the HMCAS. These patients had a median baseline NIH stroke scale score of 19.5 compared with a median score of 10 for the patients lacking the HMCAS sign. At 3 months, one (6%) of the HMCAS-positive patients was completely improved neurologically compared with 17 (47%) of the HMCAS-negative patients. Restricting analysis to those patients with a stroke scale score of 10 or greater (n = 37), 18 HMCAS-positive patients showed less early neurologic improvement, were less likely to be completely improved at 3 months, and had larger infarcts compared with the 19 HMCAS-negative patients. Compared with the HMCAS-positive and HMCAS-negative patients with a stroke scale score of 10 or greater, patients with a stroke scale score of less than 10 had fewer occlusive changes of the internal carotid and middle cerebral arteries on posttreatment arteriograms and had a better neurologic recovery at 3 months.CONCLUSIONThe presence of the HMCAS on CT scans obtained within 90 minutes of stroke onset is associated with a major neurologic deficit, and in this study it predicted a poor clinical and radiologic outcome after intravenous thrombolytic therapy. However, a major neurologic deficit, defined as a stroke scale score of 10 or more, was better than a positive HMCAS as a predictor of poor neurologic outcome after thrombolytic therapy. Patients with a low stroke scale score (< 10) may benefit from ultraearly intravenous alteplase therapy.     

Hyperintense middle cerebral artery sign using MRI

AIM: To assess whether the presence of the hyperintense middle cerebral artery (MCA) sign, detected using magnetic resonance imaging (MRI), has any prognostic value in subacute infarction. The results were also compared with computed tomography (CT). MATERIALS AND METHODS: Twenty-five consecutive patients with suspected subacute ischaemic stroke (6-48 h after onset of symptoms) underwent MRI and CT assessment. The incidence of intraluminal thrombus demonstrated by conventional T1 and T2-weighted images was assessed. The results were correlated with National Institutes of Health Stroke Scale (NIHSS). RESULTS: Hyperintense MCA was identifiable on T1-weighted images in 77.8% patients, on T2-weighted images in 61.1% patients, and in 38.9% patients using CT. Patients with intraluminal thrombus identified by MRI had more severe stroke (mean NIHSS of 12.2+/-8.0 versus 4+/-3.2 respectively, p=0.003). CONCLUSIONS: The presence of hyperintense MCA by MRI is associated with higher NIHSS and may therefore have a prognostic value.     

An early CT sign of ischemic infarction: increased density in a cerebral artery

The diagnosis of ischemic cerebral infarction by CT usually is not possible for 12-24 hr after the event. A sign that allows earlier diagnosis is increased density of a cerebral vessel secondary to a thrombus or embolus. We report 19 cases of increased density in a middle cerebral artery or one of its major branches visible on the initial CT scan of patients subsequently clinically proven to have suffered a cerebrovascular accident. In three cases angiography confirmed the presence of embolus or thrombus as seen on the CT scans. In several cases subsequent CT scans showed the density to dissipate, thereby confirming its nature as thrombus or embolus. Recognition of this finding will allow earlier diagnosis of ischemic infarction, which may be important in instituting an appropriate therapeutic regimen.     

Interobserver agreement in assessing early CT signs of middle cerebral artery infarction.

PURPOSETo assess the reliability of detecting signs of hemispheric infarction on CT scans obtained within 6 hours of the onset of symptoms.METHODSA neuroradiologist selected 12 normal and 33 abnormal CT studies showing the hyperdense middle cerebral artery sign (HMCAS) (n = 10), brain swelling (n = 22), and parenchymal hypodensity (n = 33) from two series of 750 patients with recent onset of middle cerebral artery stroke. These selections served as the reference source for a nonblinded analysis of the initial and follow-up CT scans. Six neuroradiologists then reviewed the CT scans twice, first blinded then not blinded to clinical symptoms. They assessed the signs of infarction for each hemisphere separately and estimated the volume of abnormal parenchymal hypodensity in increments of 20% within the territory of the middle cerebral artery.RESULTSUnblinding the reviewers did not change interobserver agreement significantly. The chance adjusted agreement was moderate to substantial: kappa = .62 (95% confidence interval [CI], .46 to .78) and kappa = .57 (95% CI, .33 to .81) for the HMCAS of the right and left hemisphere, respectively; kappa = .59 (95% CI, .47 to .71) and kappa = .56 (95% CI, .38 to .74) for focal brain swelling of the right and left hemisphere, respectively; and kappa = .58 (95% CI, .50 to .66) and kappa = .55 (95% CI, .32 to .67) for parenchymal hypodensity of the right and left hemisphere, respectively. Weighted kappa was .65 and .57 for the estimation of the hypodense tissue volume in the right and left hemisphere, respectively. Agreement with the reference source ranged from 73% to 93% for all variables and both hemispheres.CONCLUSIONEven with no clinical information, neuroradiologists can assess subtle CT signs of cerebral infarction within the first 6 hours of symptom onset with moderate to substantial interobserver agreement.     

Prognostic value of subacute crossed cerebellar diaschisis: single-photon emission CT study in patients with middle cerebral artery territory infarct

BACKGROUND AND PURPOSE: Although chronic-stage crossed cerebellar diaschisis (CCD) is reported to be associated with the neurologic state or clinical improvement after infarct, the prognostic value of early-stage CCD remains controversial. Our aim was to determine whether measurements of CCD in the acute and subacute stages obtained at single-photon emission CT (SPECT) facilitate the prediction of stroke outcome. METHODS: The pattern of cerebral blood flow changes after the occurrence of acute middle cerebral artery ischemia with severe cortical symptoms was examined by using technetium 99m-hexamethylpropyleneamine oxime ((99m)Tc-HMPAO) SPECT. Fifteen patients (mean age, 73 years +/- 8 [SD]) with unilateral ischemia were examined in the early subacute stage (10 days +/- 5). In 11 patients, SPECT was performed in both the acute (16 hours +/- 10) and subacute stages. From the total counts obtained from each cerebellar hemisphere, the asymmetry index (AI) was calculated as follows: [(value in unaffected hemisphere--value in affected hemisphere)/value in unaffected hemisphere] x 100. Clinical outcome (at 60 days) was assessed by means of the Scandinavian Stroke Scale (SSS) and Barthel Index (BI). RESULTS: AIs in the acute stage and clinical outcome (ie, SSS and BI scores) showed no significant correlation, but the severity of AI in the early subacute stage correlated significantly with both the final SSS (r = -0.69; P <.01) and BI scores (r = -0.82; P <.01). CONCLUSION: Cerebellar hypoperfusion detected at (99m)Tc-HMPAO SPECT in the early subacute stage in patients with supratentorial infarct indicates a worse clinical outcome.     

Large middle cerebral artery infarctions and the hyperdense middle cerebral artery sign in patients with atrial fibrillation

PURPOSE: Strokes in patients with atrial fibrillation are often due to large middle cerebral artery (MCA) infarctions, caused by cardiogenic emboli. The purpose of this study was to characterise the large MCA infarctions and to describe the prevalence and prognostic value of the hyperdense middle cerebral artery sign (HMCAS) in patients with atrial fibrillation. MATERIAL AND METHODS: The patient material comprised all 449 patients included in a randomised clinical trial of low molecular-weight heparin versus aspirin in patients with acute ischaemic stroke and atrial fibrillation. Patients with Scandinavian Stroke Scale score <8 were excluded. CT was performed on admission and at day 7, and was evaluated blinded to clinical data. The CT findings on admission were related to functional outcome at 14 days and 3 months, and incidence of cerebral haemorrhage within 7 days. RESULTS: Altogether 66/449 (15%) of the patients had large MCA infarctions. These patients had poorer clinical outcomes, and a higher frequency of haemorrhage on control CT within 7 days (15/59, 26% vs. 43/368, 12%). The HMCAS was found in 32/449 (7%) of the patients. It was significantly more frequent in patients with large MCA infarctions (17/66, 26% vs. 15/383, 4%), and was found most frequently within the first few hours following stroke onset. The HMCAS was associated with poor clinical outcomes and a higher frequency of cerebral haemorrhage, but these effects were partially explained by a preponderance of other risk factors in the HMCAS group. CONCLUSION: Large MCA infarction is a frequent finding in patients with atrial fibrillation. These patients have a high prevalence of the HMCAS, which is an early infarction sign and a marker of a poor prognosis.     

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。     

MR imaging of middle cerebral artery occlusion without cerebral infarction

Magnetic resonance (MR) images of 12 patients with angiographically proven middle cerebral artery (MCA) occlusion were analyzed, retrospectively. In three of the 12 patients, cerebral infarctions related to the MCA occlusions were not evident. Two of the three patients were cases of atherosclerotic occlusion and the remaining patient had an acute thromboembolism. In all of the occluded M1 portions of the MCA the flow void was absent and there were isointense linear structures, with or without a hyperintense component in the Sylvian vallecula, on T1-weighted images. For nine of the 12 patients, the absence of flow void in the ipsilateral Sylvian fissure was evident on the T2-weighted images. Therefore, even in cases with no evidence of a cerebral infarction, the presence of flow void in the Sylvian vallecula and Sylvian fissure must be searched for in routine reviews of MR images. If MR imaging can be obtained on an emergency basis, appropriate interventional therapy may be immediately initiated.     

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.     

Post-traumatic cerebral infarction caused by thrombus in the middle cerebral artery

A woman in her 80s was found unconscious after being hit by a car while crossing a road. After admission to hospitals, computed tomography (CT) scans revealed traumatic brain injury (TBI), and the patient was treated symptomatically. However, despite improvement of TBI in CT images, she died unexpectedly. Postmortem CT demonstrated cerebral infarction in the territory of the right middle cerebral artery (MCA). Histopathological examination revealed lumen-obstructing thrombosis and intimal injury upstream of the thrombosis in the right MCA. These findings suggested that the intimal injury in the MCA had led to thrombus formation, and thromboembolism in the region distal to the injury leading to post-traumatic cerebral infarction (PTCI). Both postmortem CT and autopsy were able to reveal the final condition of the deceased, which had not been fully anticipated by the clinicians who had treated her after the accident. The longitudinal antemortem to postmortem course revealed by multiple CT images and the histopathological examination provided crucial clues to the pathogenesis of PTCI in this case.     

Early serial SPET in acute middle cerebral artery infarction

The size and severity of perfusion defects in acute cerebral ischaemia on single photon emission tomographic (SPET) images may provide useful information regarding long-term (> 3 month) stroke outcome. A decreased predictive value has been reported with delayed SPET more than 24 h after stroke onset. We examined 20 patients with acute middle cerebral artery (MCA) infarctions using serial 99Tcm-ECD or 99Tcm-HMPAO SPET (SPET 1 one day and SPET 2 three days after stroke onset). Neurological (NIH, SSS) and functional (Barthel, Rankin) scores were calculated simultaneously and 3 months poststroke. The two SPET scans correlated equally well with the severity of functional and neurological deficits evaluated 3 months after stroke onset. In comparison to clinical assessment, the prognostic value of SPET was relatively better on the first day than the third day. Crossed cerebellar diaschisis correlated with early SPET deficits, but did not predict functional outcome. Our results suggest that SPET, either with 99Tcm-ECD or 99Tcm-HMPAO, can be used to predict stroke outcome in acute MCA infarction up to 72 h poststroke without significant interference from luxury perfusion.     

高信号血管征评估急性大脑中动脉脑梗死的 现状与展望

液体衰减反转恢复（FLAIR）序列上的高信号血管征（HVS）是急性脑梗死的重要影像征象,反映脑血流灌注不足,可用于评估侧支循环、缺血半暗带和预测预后。急性大脑中动脉（MCA）脑梗死的多种HVS评价方法主要包括总体HVS、远端HVS、HVS/扩散加权成像（DWI）不匹配等,这些评价方法各有侧重,临床价值不同。总体HVS主要反映脑血流灌注不足及超急性期脑梗死,而远端HVS有助于判断侧支循环及缺血半暗带,HVS/DWI不匹配有可能替代灌注加权成像（PWI）/DWI不匹配,用于评估缺血半暗带。对MCA脑梗死HVS的多种评价方法及其临床应用价值进行综述。     

Sensitivity and prognostic value of early CT in occlusion of the middle cerebral artery trunk.

PURPOSETo investigate the incidence and prognostic value of local brain swelling, the extent of parenchymal hypodensity, and the hyperdense middle cerebral artery sign as shown by CT within the first 5 hours after the onset of symptoms in patients with angiographically proved middle cerebral artery trunk occlusions.METHODSFifty-three patients were studied prospectively with CT 46 to 292 minutes (median, 120; mean, 134 +/- 59) after symptom onset and scored clinically at admission and 4 weeks later. All patients were treated with recombinant tissue plasminogen activator (30 to 100 mg).RESULTSEarly CT showed parenchymal hypodensity in 43 patients (81%), local brain swelling in 20 patients (38%), and hyperdensity of the middle cerebral artery trunk in 25 patients (47%). Hypodensity covering more than 50% of the middle cerebral artery territory had an 85%, local brain swelling a 70%, and the hyperdense middle cerebral artery sign a 32% positive predictive value for fatal clinical outcome. Specificity of these findings for fatal outcome was 94%, 83%, and 51%, respectively, and sensitivity was 61%, 78% and 44%, respectively.CONCLUSIONSEarly CT in acute middle cerebral artery trunk occlusion is highly predictive for fatal clinical outcome if there is extended hypodensity or local brain swelling despite aggressive therapeutic attempts such as thrombolysis or decompressive surgery.     

Early diagnosis of cerebral infarct. Hyperdensity of the middle cerebral artery as the first CT sign of an ischemic lesion

An early CT sign of cerebral infarction in the sylvian area is described: the normal density value of the middle homolateral cerebral artery is increased, because of thrombotic or embolic deposits inside.     

FLAIR序列大脑中动脉高信号征与急性期脑梗死关系的探讨

目的:探讨FLAIR序列大脑中动脉高信号征(HSMCA)诊断急性期脑梗死的价值.方法:对55例大脑中动脉供血区急性脑梗死患者进行常规MRI检查及DWI、MRA检查,并将FLAIR序列大脑中动脉高信号征与TOF-MRA、DWI序列高信号病灶及随访检查进行对比.结果:FLAIR序列17例(30.9%)患者发现大脑中动脉M1段高信号征,其中左侧大脑中动脉11例,右侧大脑中动脉6例;合并M2、M3、M4和M5段高信号7例.患者自出现严重自觉症状到进行MRI检查,间隔时间1h到15h不等,平均3.6h.17例HSMCA患者中,8例相应节段大脑中动脉均有严重狭窄或闭塞;38例无HSMCA患者中,12例双侧大脑中动脉有节段性狭窄,严重狭窄或闭塞7例, HSMCA患者较无HSMCA患者病变侧大脑中动脉严重狭窄的数量明显增多,二者之间存在显著性差异(P＜0.003).结论:FLAIR序列上大脑中动脉高信号征可作为诊断急性期脑梗死的早期参考征象.     

早期急性大脑中动脉梗塞58例CT评价

ＣＴ随访 1993年 10月～ 1999年 9月证实的早期急性大脑中动脉梗塞 5 8例 ,对比研究首检ＣＴ资料片与复查ＣＴ资料片 ,回顾性分析首次ＣＴ表现特征 ,以探讨早期急性大脑中动脉梗塞的ＣＴ诊断价值 ,进一步指导临床。1　临床资料1 1　一般资料　本组 5 8例 ,男 41例 ,女 17例 ,年龄 42～78岁 ,平均 6 2岁。发病至首检ＣＴ时间为 1～ 16ｈ ,平均8 5ｈ ,复查ＣＴ时间为发病后第 2～ 5ｄ。本组病人发病后18例血压正常 ,40例有血压升高 ,血压波动在 2 2～ 2 8/14～ 16ｋＰａ ,临床症状头晕 38例 ,呕吐 10例 ,运动性失语 35例 ,5 8例均有偏侧面舌瘫…