Asymptomatic Middle Cerebral Artery Research Articles

Neuroimaging anomalies in asymptomatic middle cerebral artery steno-occlusive disease with normal-appearing white matter.

Asymptomatic chronic cerebrovascular steno-occlusive disease is common, but the cognitive function and alterations in the brain's structural and functional profiles have not been well studied. This study aimed to reveal whether and how patients with asymptomatic middle cerebral artery (MCA) steno-occlusive disease and normal-appearing white matter differ in brain structural and functional profiles from normal controls and their correlations with cognitive function. In all, 26 patients with asymptomatic MCA steno-occlusive disease and 22 healthy controls were compared for neurobehavioral assessments, brain volume, cortical thickness, fiber connectivity density (FiCD) value, and resting-state functional connectivity (FC) using multimodal MRI. We also investigated the associations between abnormal cortical thicknesses, FiCD values, and functional connectivities with the neurobehavioral assessments. Patients performed worse on memory tasks (Auditory Verbal Learning Test-Huashan version) compared with healthy controls. Patients were divided into two groups: the right group (patients with right MCA steno-occlusive disease) and the left group (patients with left MCA steno-occlusive disease). The left group showed significant cortical thinning in the left superior parietal lobule, while the right group showed significant cortical thinning in the right superior parietal lobule and caudal portion of the right middle frontal gyrus. Increased FiCD values in the superior frontal region of the left hemisphere were observed in the left group. In addition, a set of interhemispheric and intrahemispheric FC showed a significant decrease or increase in both the left and right groups. Many functional connectivity profiles were positively correlated with cognitive scores. No correlation was found between cortical thickness, FiCD values, and cognitive scores. Even if the patients with MCA steno-occlusive disease were asymptomatic and had normal-appearing white matter, their cognitive function and structural and functional profiles had changed, especially the FC. Alterations in FC may be an important mechanism underlying the neurodegenerative process in patients with asymptomatic MCA steno-occlusive disease before structural changes occur, so FC assessment may promote the detection of network alterations, which may be used as a biomarker of disease progression and therapeutic efficacy evaluation in these patients.

Nomogram to Predict Cognitive Impairment in Patients with Asymptomatic Middle Cerebral Artery Stenosis.

This study aims to investigate the characteristics and influencing factors of cognitive impairment in patients with asymptomatic middle cerebral artery stenosis (aMCAS) and to construct a nomogram to predict the risk of cognitive impairment in patients with aMCAS. We collected 54 patients with aMCAS and 35 healthy controls to investigate the impaired cognitive domains and pathogenesis in patients with aMCAS. All patients underwent a cranial MRI, CT perfusion, transcranial Doppler ultrasound, blood tests, and a comprehensive neuropsychological evaluation. According to the MoCA score, patients were divided into cognitively normal and cognitively impaired groups. To construct the nomogram, we conducted univariate and multivariate logistic regression analyses to identify factors that affect cognitive function. And the performance of nomogram was evaluated by ROC curves, calibration curves, decision curve analysis (DCA), and clinical impact curve (CIC). In 54 patients with aMCAS, 24 patients presented with cognitive normal, and 30 patients presented with cognitive impairment. The results of multivariate logistic regression suggested that perfusion decompensation, middle cerebral artery mean flow velocity, and LDL-cholesterol levels were independent influencing factors of cognitive impairment. In the following step, a nomogram was constructed. The AUC of the nomogram is 0.862. Calibrating curves show good agreement between nomogram predictions and actual observations, while DCA and CIC show great clinical usefulness. Patients with aMCAS have cognitive impairment in multiple cognitive domains, and impaired executive function was observed during the perfusion compensation period. Furthermore, a nomogram was constructed and validated to predict the risk of cognitive impairment in patients with aMCAS, which can help clinicians to identify at an early stage and improve the management of patients.

Wall Shear Stress Associated with Stroke Occurrence and Mechanisms in Middle Cerebral Artery Atherosclerosis.

Various mechanisms are involved in the etiology of stroke caused by atherosclerosis of the middle cerebral artery (MCA). Here, we compared differences in plaque nature and hemodynamic parameters according to stroke mechanism in patients with MCA atherosclerosis. Consecutive patients with asymptomatic and symptomatic MCA atherosclerosis (≥50% stenosis) were enrolled. MCA plaque characteristics (location and plaque enhancement) and wall shear stress (WSS) were measured using high-resolution vessel wall and four-dimensional flow magnetic resonance imaging, respectively, at five points (initial, upstream, minimal lumen, downstream, and terminal). These parameters were compared between patients with asymptomatic and symptomatic MCA atherosclerosis with infarctions of different mechanisms (artery-to-artery embolism vs. local branch occlusion). In total, 110 patients (46 asymptomatic, 32 artery-to-artery embolisms, and 32 local branch occlusions) were investigated. Plaques were evenly distributed in the MCA of patients with asymptomatic MCA atherosclerosis, more commonly observed in the distal MCA of patients with artery-to-artery embolism, and in the middle MCA of patients with local branch occlusion. Maximum WSS and plaque enhancement were more prominent in the minimum lumen area of patients with asymptomatic MCA atherosclerosis or those with local branch occlusion, and were more prominent in the upstream area in those with artery-to-artery embolism. The elevated variability in the maximum WSS was related to stroke caused by artery-to-artery embolism. Stroke caused by artery-to-artery embolism was related to plaque enhancement and the highest maximum WSS at the upstream point of the plaque, and was associated with elevated variability of maximum WSS.

Early Cerebrovascular Ultrasonography as a Predictor of Hemorrhagic Transformation After Thrombectomy

ObjectivesTo determine the predictive value of early transcranial color-coded sonography (TCCS) for intracranial hemorrhage (ICH) in patients with large artery occlusion (LAO) stroke of carotid circulation, who were submitted to endovascular therapy (EVT) with successful reperfusion. Materials and MethodsRetrospective study evaluating a cohort of consecutive stroke patients with LAO of the carotid circulation that were recanalyzed with EVT. We measured angle-corrected peak systolic velocities, end-diastolic velocities and mean flow velocities (PSV, EDV and MFV) of the symptomatic and asymptomatic middle cerebral artery (MCA). The ratio between MFV of the symptomatic MCA and MFV of the asymptomatic MCA (MCA-Ra) was calculated. Parenchymal hematoma in the 24 hours control CT was considered as ICH. Univariate associations and multivariate analyses were used to identify early independent predictors for ICH among TCCS findings. ResultsWe included 234 patients, mean age 72.5 (SD 12.6) years, 52.1% male. The mean time between recanalization and TCCS was 12.3 hours (range 3-22). Patients who developed postinterventional ICH showed a higher MCA-Ra (1.02 ± 0.26 vs 1.16 ± 0,21, p = 0.036). In multivariate analysis, only higher MCA-Ra remained independently associated with postinterventional ICH (OR: 6.778, 95%CI: 1.152–39.892, p = 0.034). A value of MCA-Ra ≥ 1,05 was associated with ICH, showing a sensitivity of 81.3% and a specificity of 65.9%; the AUC based of the ROC analysis was 0.688 (95% CI 0.570-0.806). ConclusionTCCS performed within the first 24 hours after stroke onset can help to predict hemorrhagic transformation in patients with LAO.

Temporary application of lower body positive pressure improves intracranial velocities in symptomatic acute carotid occlusion or tight stenosis: A pilot study

Patients with isolated cervical carotid artery occlusion not eligible to recanalization therapies but with compromised intracranial hemodynamics may be at risk of further clinical events. Apart from lying flat until spontaneous recanalization or adjustment of the collateral circulation hopefully occurs, no specific treatment is currently implemented. Improving collateral flow is an attractive option in this setting. Lower body positive pressure (LBPP) is known to result in rapid venous blood shift from the lower to the upper body part, in turn improving cardiac preload and output, and is routinely used in acute hemorrhagic shock. We report here cerebral blood flow velocities measured during LBPP in this patient population. This is a retrospective analysis of the clinical, physiological, and transcranial Doppler monitoring data collected during and 15 min after LBPP in 21 consecutive patients (10 females, median age: 54 years) with recently symptomatic isolated carotid occlusion/tight stenosis (unilateral in 18) mostly due to atherosclerosis or dissection. LBPP was applied for 90 min at a median 5 days after symptom onset. At baseline, middle-cerebral artery velocities were markedly lower on the symptomatic, as compared to asymptomatic, side. LBPP significantly improved blood flow velocities in both the symptomatic and asymptomatic middle-cerebral artery as well as the basilar artery, which persisted 15 min after discontinuing the procedure. LBPP also resulted in mild but significant increases in mean arterial blood pressure. LBPP improved intracranial hemodynamics downstream recently symptomatic carotid occlusion/tight stenosis as well as in the contralateral and posterior circulations, which persisted after LBPP deflation. Randomized trials should determine if this easy-to-use, noninvasive, nonpharmacologic approach has long-lasting benefits on the intracranial circulation and improves functional outcome.

Evaluating the Velocity and Extent of Cortical Venous Filling in Patients With Severe Middle Cerebral Artery Stenosis or Occlusion.

Objective: To investigate the velocity and extent of cortical venous filling (CVF) and its association with clinical manifestations in patients with severe stenosis or occlusion of the middle cerebral artery (MCA) using dynamic computed tomography angiography (CTA).Methods: Fifty-eight patients (36 symptomatic and 22 asymptomatic) with severe unilateral stenosis (≥70%) or occlusion of the MCA M1 segment who underwent dynamic CTA were included. Collateral status, antegrade flow, and CVF of each patient were observed using dynamic CTA. Three types of cortical veins were selected to observe the extent of CVF, and the absence of CVF (CVF-) was recorded. Based on the appearance of CVF in the superior sagittal sinus, instances of CVF, including early (CVF1), peak (CVF2), and late (CVF3) venous phases, were recorded. The differences in CVF times between the affected and contralateral hemispheres were represented as rCVFs, and CVF velocity was defined compared to the median time of each rCVF.Results: All CVF times in the affected hemisphere were longer than those in the contralateral hemisphere (p < 0.05). Patients with symptomatic MCA stenosis had more ipsilateral CVF- (p = 0.02) and more delayed CVF at rCVF2 and rCVF21 (rCVF2-rCVF1) (p = 0.03 and 0.001, respectively) compared to those with asymptomatic MCA stenosis. For symptomatic patients, fast CVF at rCVF21 was associated with poor collateral status (odds ratio [OR] 6.42, 95% confidence interval [CI] 1.37–30.05, p = 0.02), and ipsilateral CVF- in two cortical veins was associated with poor 3-month outcomes (adjusted OR 0.025, 95% CI 0.002–0.33, p = 0.005).Conclusions: Complete and fast CVF is essential for patients with symptomatic MCA stenosis or occlusion. The clinical value of additional CVF assessment should be explored in future studies to identify patients with severe MCA stenosis or occlusion at a higher risk of stroke occurrence and poor recovery.

New Vessels or MCA Stem: A Case of Asymptomatic Chronic Middle Cerebral Artery Occlusion on TCCS

New Vessels or MCA Stem: A Case of Asymptomatic Chronic Middle Cerebral Artery Occlusion on TCCS

Plaque Distribution Correlates With Morphology of Lenticulostriate Arteries in Single Subcortical Infarctions.

We aimed to use novel whole-brain vessel-wall magnetic resonance imaging (WB-VWI) to investigate the association between plaque distribution of middle cerebral artery (MCA) and morphological changes of the lenticulostriate arteries (LSAs) in single subcortical infarctions. Forty single subcortical infarction patients with no relevant MCA disease on magnetic resonance angiography were prospectively enrolled. Plaque location in the MCA was dichotomized as proximal (located adjacent to the LSA origin) or distal (located distal to the LSA origin) on whole-brain vessel-wall magnetic resonance imaging. The MCAs with proximal plaques were divided into the symptomatic and asymptomatic side, and asymptomatic side MCAs without proximal plaques were the control group. The morphological characteristics of the LSAs and features of proximal plaques were analyzed. A total of 71 MCAs in 40 patients were analyzed (31 on the symptomatic side, 22 on the asymptomatic side, and 18 in the control group). Superior-wall plaques of MCAs were observed more frequently on the symptomatic side than the asymptomatic side (45.2% versus 9.1%, P=0.005). The wall area index, plaque burden, and remodeling index did not differ significantly between the symptomatic and asymptomatic side. The number of LSA branches was smaller (P=0.011) in the symptomatic side (5.48±1.88) compared with the control group (6.83±1.92). The symptomatic side exhibited shorter average length of the LSAs (23.23±3.44 versus 25.75±3.76 mm, P=0.025) and shorter average distance of the LSAs (16.47±3.11 versus 21.53±4.76 mm, P<0.001) compared with the asymptomatic side. Superiorly distributed MCA plaques at the LSA origin are closely associated with morphological changes of the LSA in symptomatic MCAs, suggesting that the distribution, rather than the inherent features of plaques, determines the occurrence of single subcortical infarctions. Our findings provide insight into the etiologic mechanism of branch atheromatous disease in single subcortical infarctions.

Mismatch of cognition and neural networks in asymptomatic middle cerebral artery steno-occlusive disease.

The role of intracranial steno-occlusive disease in cognitive impairment and dementia is unclear and has not been well studied. A total of 32 consecutive patients (13 males, aged 54±12years) with asymptomatic steno-occlusive middle cerebral artery (MCA) disease, defined as >70% stenosis on maximum intensity projection images or a complete signal loss of MCA trunk on magnetic resonance angiography, and 20 age- and education-matched normal controls (12 males, 60±8years old) were compared for neuropsychological performance, gray matter volume and neural network analysis. The patient group did not show a significant decrease in gray matter volume or cognitive tests except for their performance on the grooved pegboard test. However, graph analysis of resting-state functional magnetic resonance imaging showed significant decreases in network strength, global efficiency and the clustering coefficient, as well as a longer characteristic path length (P<0.05). The diffusive decrease pattern was particularly located in interhemispheric connectivity and there was no compensatory hyperconnectivity in any brain regions. In asymptomatic steno-occlusive MCA disease, cognition and neural network changes are mismatched and have underlying pathophysiological mechanisms that are different from those of neurodegenerative disease.

Statin treatment and accrual of covert cerebral ischaemia on neuroimaging: a systematic review and meta-analysis of randomized trials.

Prevention of ischaemic stroke and cardiovascular events is an established benefit of statin therapy, but the effects of statin treatment on the accrual of magnetic resonance imaging (MRI) markers of ischaemic cerebral injury remain unknown. A systematic review was performed to identify all studies that randomized patients with cardiovascular risk factors to statin treatment and assessed the effect of statin treatment on covert infarcts (asymptomatic, evident only on neuroimaging) and white matter hyperintensity (WMH) accrual on MRI. A systematic review in MEDLINE and Scopus from inception to 23 October 2019 was performed. A random-effects model was used to calculate the pooled estimates of the crude risk ratios and standardized mean differences. Data from three randomized controlled trials (1430 participants) were included evaluating the effect of rosuvastatin (10mg/day) in 668 hypertensive patients older than 60years of age over 5years, pravastatin (40mg/day) in 554 elderly people more than 70years of age over 3years and simvastatin (20mg/day) in 208 patients with asymptomatic middle cerebral artery stenosis over 2years. Patients randomized to statin treatment had decreased accrual of new covert infarcts (risk ratio 0.63, 95% confidence interval 0.46-0.88) during a mean follow-up of 2-6years. Only one study reported WMH decreased volume change in patients randomized to statin treatment compared to patients randomized to non-statin treatment (standardized mean difference -1.17; 95% confidence interval -1.33, -1.00). Our findings suggest that, in addition to stroke prevention, statin treatment can reduce the accrual of covert MRI markers of ischaemic cerebral injury.

Abstract TP437: Statin Treatment and Accrual of Covert Cerebral Ischemia on Neuroimaging: A Systematic Review and Meta-Analysis of Randomized Trials

Introduction: Stroke prevention is an established benefit of statin therapy, but the effects of statin treatment on the accrual of MRI markers of ischemic cerebral injury remain unknown. Methods: We performed a systematic review of MEDLINE and SCOPUS databases from inception to July 29 th , 2019 to identify all studies that randomized patients to statin treatment and assessed the effect of statin treatment on incident infarcts (asymptomatic and symptomatic), covert infarcts (asymptomatic evident only in neuroimaging) and white matter hyperintensity (WMH) accrual on magnetic resonance imaging. We included only studies reporting WMH change following normal distribution. We used random effects model to calculate the pooled estimates of the crude risk ratios (RRs) and standardized mean differences (SMDs). Results: We included data from 3 randomized controlled trials with a total of 1399 participants evaluating the effect of rosuvastatin (10mg/d) in 637 hypertensive patients older than 60 years of age over 5 years, pravastatin (40mg/d) in 554 elderly people more than 70 years of age over 3 years and simvastatin (20mg/d) in 208 patients with asymptomatic middle cerebral artery stenosis over 2 years. Patients randomized to statin treatment had decreased accrual of new infarcts (RR=0.59; 95%CI: 0.36, 0.95), new covert infarcts (RR=0.64, 95%CI: 0.46-0.89). Only one study reported WMH decreased volume change in patients randomized to statin treatment compared to patients randomized to non-statin treatment (SMD= -1.16; -1.33, -1.00). Conclusion: Our findings suggest that statin treatment can reduce the accrual of covert MRI markers of ischemic cerebral injury. Dose-response effect and population disparities need to be investigated in future studies.

Cognitive Decline in Asymptomatic Middle Cerebral Artery Stenosis Patients with Moderate and Poor Collaterals: A 2-Year Follow-Up Study.

BackgroundThe aim of this study was to determine whether poor collaterals contribute to the occurrence of certain types of cognitive disorders in asymptomatic middle cerebral artery stenosis (MCAS).Material/MethodsPatients aged ≥45 years with asymptomatic MCAS confirmed by computed tomography angiography were included in a single-center retrospective study. They did not have prior stroke or dementia. Within 7 days of admission, MRI and comprehensive neuropsychological assessment were performed. Cognitive assessment was conducted after 2 years. Two independent neuroradiologists evaluated intracranial collaterals by using the Miteff scale. Demographic date and Fazekas scores were collected.ResultsA total of 173 patients with asymptomatic MCAS (66% men, mean age 59.4 years) and 42 controls (45% men, mean age 61.4 years) were enrolled. Executive function, attention, and information-processing speed in poor collateral circulation patients were more frequently and more often impaired than those in good collateral circulation patients. Throughout the study period, patients with poor collateral circulation had worse executive function, attention, and information-processing speed than those with moderate collateral circulation. Over time, MCAS patients with good collateral circulation did not show an association with cognitive function.ConclusionsMCAS patients with moderate and poor collateral circulation have impairment of ≥1 cognitive domain over time. The affected domains are consistent with the profile of vascular cognitive impairment. Good collateral circulation is more important in patients with MCAS, and is associated with less risk of cognitive disorders.

A comparison of transcranial Doppler and magnetic resonance imaging for long term changes in middle cerebral artery stenosis

ObjectivesIntracranial arterial stenosis may progress or regress, of which the diagnosis is important to predict the risk of stroke or to evaluate the response of treatment. Transcranial Doppler (TCD) seems to be useful for this purpose, however, optimal diagnostic criteria have not been validated yet. Our study was designed to compare TCD changes with magnetic resonance angiography (MRA) to validate optimal TCD criteria for progression or regression of middle cerebral artery (MCA). Patients and methodsWe prospectively enrolled patients who visited our neurology department due to MCA stenosis on TCD examination. Brain MRA was used to identify patients with stenosis of the same site of MCA. Progression or regression was defined by change of MRA grading (normal, mild, moderate, severe or occlusion). Various criteria of mean flow velocity (MFV) difference and percent change were assessed. To register more patients for reliable analysis, additional patients with the same inclusion criteria were recruited retrospectively. All patients enrolled in the study were symptomatic or asymptomatic atherosclerotic MCA stenosis. ResultsEighteen patients were enrolled and 21 MCAs with completed follow-up TCD and MRA were analyzed (mean age 68.4 years, mean follow-up 17.8 months). In addition, 40 MCAs from 30 retrospective patients were also analyzed (mean age 65.7 years, mean follow-up 22.3 months). Among assessed criteria, the most optimal cutoff value for the progression of stenosis was 20 cm/s, at which the sensitivity and specificity were 100% and 91% in prospective group, and were 80% and 93% in retrospective group. In the % difference analysis, prospective group showed sensitivity 100% and specificity 82% in the 20% cutoff. The retrospective group showed sensitivity 80% and specificity 93% in the 15% cutoff. However, results of the regression group were not consistent. ConclusionsDiagnosis of progression of MCA stenosis with serial TCD examination is feasible and MFV change of 20 cm/s and % change of 15–20% are suggested as optimal cut-off value but not in the regression. These criteria would be useful for the clinical research and real-world practice.

Surgical management of middle cerebral artery aneurysms

Background. The middle cerebral artery (MCA) harbors approximately 14% to 30% of all ruptured cerebral aneurysms. They can occur at multiple sites throughout the course of the middle cerebral artery, but most often are found at the bifurcation of the first segment (M1).&#x0D; Methods. A retrospective review of 116 consecutive patients with an MCA aneurysm treated by surgical clipping, by two senior neurosurgeons, was performed. The data of all our consecutive patients were searched to obtain patient characteristics, details of the aneurysm size and orientation, treatment details, complications and follow up. At admission, the clinical condition of all patients was classified according to the Hunt and Hess scale. Clinical outcome was graded according to the modified Rankin scale. The follow-up period varied widely from 2 to 72 months (mean 30 months).&#x0D; Results. Surgical clipping was performed for 113 ruptured MCA aneurysms; only in 3 cases the aneurysm was unruptured. Fourteen patients presented with significant hematoma which required the evacuation of the clot. Post-operative control angiography was performed in 32 patients (27.5%), from which we reported a full occlusion of the aneurysm in 32 patients (93.75%). Perioperative mortality was 5.2% (6 patients), due to neurological (4 patients) or systemic causes (2 patients). The outcome was graded mRankin 0–2 in 72.5% of the cases (84 patients) at the end of the first postoperative months, and 78.5% (91 patients) at six months follow-up. The most important improvement was recorded for patients graded mRankin 1-2 at the first month follow-up. All 3 patients with a surgically treated asymptomatic MCA aneurysm had an excellent outcome (mRS 0) at both follow-up, 1 months and respectively 6 months.&#x0D; Conclusions. For the experienced neurovascular team, MCA aneurysms currently make microsurgical treatment the preferred treatment modality for most MCA aneurysms.

Quantitative score of the vessel morphology in middle cerebral artery atherosclerosis

BackgroundWe aimed to quantitatively assess the vessel morphology of middle cerebral artery (MCA) atherosclerosis and explore its value in discriminating plaque types. MethodsPatients were selected from a high-resolution magnetic resonance imaging (HRMRI) study from January 2007 to December 2015. One hundred and three patients with acute cerebral infarcts due to MCA stenosis (>50%) and eighty-nine patients with asymptomatic MCA stenosis (>50%) were included. Quantitative measurements of MCA morphology, including lumen area, outer-wall and wall area at stenotic site and reference site, stenotic degree, plaque length, remodeling index and plaque eccentricity, were performed on HRMRI with observers blinded to clinical presentations. Firth's penalized logistic regression analysis was used to construct a symptomatic plaque score (SPS) model. Then, the HRMRI data of 39 patients prospectively enrolled from January 2016 to January 2017 were used to validate the SPS model. ResultsThe HRMRI data of 103 patients with symptomatic MCA stenosis and 89 patients with asymptomatic MCA stenosis in the construction cohort were analyzed. Four main factors were found to be associated with symptomatic plaques: stenotic lumen area ≥ 2.28 mm2, stenotic wall area ≥ 8.88 mm2, plaque length and presence of an eccentric plaque. Summation of each logistic regression coefficient multiplying the corresponding score produced the SPS with an area under curve (AUC) of 0.890 on receiver operating characteristics analysis. Validation of the score of 39 plaques (19 symptomatic and 20 asymptomatic) revealed an AUC of 0.862, confirming the continued diagnostic ability. When the data were pooled in all 235 plaques, the optimal cutoff score of discriminating symptomatic and asymptomatic plaques was 2.79 (SPS ≥ 2.79 indicating a symptomatic plaque) with AUC = 0.886, sensitivity 81.1% and specificity 80.5%. ConclusionsThe quantitative analysis of MCA morphology can independently and accurately discriminate plaque types, suggesting its close association with the underlying pathophysiology. Further prospective studies are required to verify whether the SPS model is clinically valuable in monitoring plaque progression and assessing the vulnerability.

Middle cerebral artery geometric features are associated with plaque distribution and stroke.

We aimed to investigate the geometric features of the middle cerebral artery (MCA) and their relevance to plaque distribution and ischemic stroke. We reviewed our institutional vessel wall imaging database. Patients with symptomatic MCA atherosclerosis, asymptomatic MCA atherosclerosis, or without MCA atherosclerosis were included. The MCA geometric features, including M1 segment shape and M1 curve orientation, were defined on magnetic resonance angiography. Plaque distribution and other plaque parameters were identified on vessel wall imaging. The association among MCA geometric features, plaque distribution, and ischemic stroke were analyzed. A total of 977 MCAs were analyzed (87 atherosclerotic symptomatic MCAs, 459 atherosclerotic asymptomatic MCAs, and 431 plaque-free MCAs). Overall, curved M1 segments were the predominant shape across all groups. In 91.1% of curved atherosclerotic MCAs, the plaque involved the inner wall of the curve. Plaque not involving the inner wall was shorter (p < 0.0001) and thinner (p = 0.005) compared to plaque involving the inner wall. Inferior plaque was observed in 39.9% of inferior-oriented M1 curves compared to 21.7% in non-inferior-oriented M1 curves (p < 0.0001). The absence of an inferior-oriented M1 curve (odds ratio 0.45, 95% confidence interval 0.27-0.77) and presence of superior plaque (odds ratio 2.67, 95% confidence interval 1.52-4.67) were independently associated with stroke after adjusting for plaque length and thickness, degree of stenosis, and remodeling ratio. MCA geometric features are associated with plaque distribution and stroke. Our findings provide insight into the vascular pathophysiology of MCA atherosclerosis.

Abstract TP121: High-Resolution Magnetic Resonance Imaging Characteristics of Intracranial Atherosclerotic Plaque and Perforating Artery

Objective: Intracranial atherosclerotic disease (ICAD) is a cause of ischemic stroke, with the middle cerebral artery (MCA) being commonly affected. The vulnerable plaque is considered as the cause of stroke. High resolution magnetic resonance imaging (HR-MRI) can help us assess the morphology characteristics and vulnerability of intracranial atherosclerosis plaque. HR-MRI could also provide us such information as microvascular structure of perforating arteries from MCA. The aim of our study was to distinguish the differences in the plaque morphology between symptomatic and asymptomatic MCA stenoses, and the relationship between MCA stenosis and perforating artery. Method: 41 MCAs with symptomatic stenoses and 33 MCAs with asymptomatic stenoses (both between 50% and 99%) were included. The characteristics of plaques and the perforating arteries were evaluated by HR-MRI. Results: Between symptomatic and asymptomatic MCA stenosis groups,vessel morphological characteristics such as the degree of stenosis, remodeling index, wall area index didn’t differ. However, patients with symptomatic MCA stenoses had heavier plaque burden (79.74 ± 1.380 vs 66.72 ± 2.776, P &lt; 0.001). , Symptomatic MCA stenoses showed stronger plaque gadolinium enhancement, including bigger ROI area (4.27 ± 0.266 vs 2.75 ± 0.197 P &lt; 0.001), higher enhancement index (0.46 ± 0.061 vs 0.20 ± 0.067 P = 0.005) and larger enhancement volume (116.34 ± 21.960 vs 35.21 ± 6.535 P &lt; 0.001). With multivariate regression analysis, the plaque burden, the region of interested area, and the enhancement index were independently associated with symptomatic MCA stenosis. The number of perforating arteries of MCAs with moderate to severe stenoses was less than that of normal controls (symptomatic MCA: 3.82 ± 0.165, asymptomatic MCA: 3.85 ± 0.177, normal MCA :4.47±0.162, P=0.006). Conclusions: The plaque burden may be a new index in assessing the vulnerability of intracranial atherosclerosis plaques. The plaque burden, the region of interested area, and the enhancement index are independently associated with symptomatic MCA stenosis. The perforating arteries from symptomatic and asymptomatic MCA stenosis are both less than those from normal MCA controls.

Abstract WMP43: Bright Signals of MCA Plaque on T2 Weighted Vessel Wall Imaging are Associated With Ischemic Stroke

Objective: Hyperintensity of intracranial atherosclerotic plaque on T2 weighted vessel wall imaging (VWI) may indicate certain components such as fibrous caps, juxtaluminal thrombus, or intraplaque hemorrhage. We aim to explore if the plaque signal of middle cerebral artery (MCA) stenosis on T2 weighted VWI is associated with ischemic stroke. Methods: Patients with recent stroke (&lt;2 weeks) were reviewed in our institutional and prospectively-collected VWI database. Patients with cardioembolism, carotid artery stenosis, or non-atherosclerotic MCA stenosis were excluded. Culprit MCAs and contralateral asymptomatic MCAs that exceeded 50% stenosis were analyzed. Stenosis degree and remodeling ratio were measured on the maximal narrowing site. Plaque area was manually delineated on T2 weighted VWI. The plaque signal was normalized (divided by masseter or buccinator muscle signal, Fig1). The thresholds of normalized plaque signal (≥1.0 to 1.8 with an increment of 0.1) were tested. Logistic regression and Receiver operating characteristic (ROC) analysis were performed to determine the optimal signal threshold of predicting culprit MCA. Results: Eighty-two MCAs were analyzed (from 66 patients, 51 male, mean age 58±16 years, mean stenosis degree 68±14%, mean remodeling ratio 1.10±0.21), including 60 culprit MCAs and 22 contralateral asymptomatic MCAs. Logistic regression analysis indicated the model of pixel number with normalized plaque signal ≥1.4 (OR 1.08 per 1-pixel increase, 95% CI 1.01-1.15) and remodeling ratio (OR 1.90 per 0.1 increase, 95% CI 1.25-2.89) was of the highest diagnostic value (AUC 0.861, 95% CI 0.779-0.943). Stenosis degree was not independently associated with culprit MCA. Other tested thresholds from 1.0 to 1.8 also had good diagnostic value with AUC 0.814-0.858. Conclusions: The bright signals of MCA plaque on T2 weighted VWI are associated with ischemic stroke. Further study is required to clarify the underlying pathophysiology.

Abstract 90: Geometric Characteristics of Middle Cerebral Artery Atherosclerosis and Clinical Stroke

Objectives: We aimed to investigate the geometric characteristics of middle cerebral artery (MCA) atherosclerosis and their clinical relevance. Methods: Vessel wall magnetic resonance imaging was obtained in patients with recent stroke in MCA territory or suspected asymptomatic MCA atherosclerosis without cardioembolism or carotid artery stenosis. MCAs were classified as atherosclerotic or plaque-free based on whether plaque was present. Atherosclerotic MCAs were divided into MCAs with or without stroke. Geometric characteristics including M1 segment shape (Fig.1), plaque location, plaque length, plaque thickness, stenosis degree, and remodeling ratio were assessed. These geometric characteristics were compared between the groups. Results: A total of 1006 MCAs were analyzed, including 577 atherosclerotic MCAs (124 MCAs with stroke and 457 MCAs without stroke) and 429 plaque-free MCAs. Curvy MCAs were more prevalent than straight MCAs (79.2% vs 20.2%). The inferior-oriented M1 curve was the most prevalent (61.5%). In 90.4% of curvy atherosclerotic MCAs, the inner side of the M1 curve was involved by plaque. Only 9.6% of curvy atherosclerotic MCAs had no plaque involving the inner sides. Inferior and anterior plaque were found in 67.3% of atherosclerotic MCAs while superior and posterior plaque were found in 32.7%. The absence of an inferior-oriented M1 curve (OR 0.54, 95%CI 0.35-0.83), presence of superior plaque (OR 2.42, 95%CI 1.52-3.86), greater plaque length (OR 1.14, 95%CI 1.07-1.22), greater plaque thickness (OR 2.55, 95%CI 1.49-4.36), higher remodeling ratio (OR 1.15, 95%CI 1.04-1.27), and fewer quadrants involved by plaque (OR 0.68, 95%CI 0.51-0.91) were independently associated with MCAs with clinical stroke. Conclusions: MCA plaque tended to develop in the same orientation as the M1 inner curve. In addition, the inferior-oriented M1 curve was associated with MCAs without stroke, while superior plaque was associated with MCAs with stroke.

Collateral perfusion using arterial spin labeling in symptomatic versus asymptomatic middle cerebral artery stenosis

The purpose was to assess the difference of collaterals in symptomatic versus asymptomatic patients with unilateral middle cerebral artery (MCA) stenosis by comparing cerebral blood flow (CBF) at two post labeling delays (PLD) using three-dimensional pseudo-continuous arterial spin labeling (3D pCASL). Eighty-one patients (49 symptomatic and 32 asymptomatic) with unilateral MCA stenosis ≥50% who underwent pCASL with two PLDs were included. Mean CBF and CBF subtraction images between two PLDs of MCA territories were compared in symptomatic and asymptomatic groups, respectively. Compared with the asymptomatic group, patients with symptomatic MCA stenosis had significantly lower CBF in the MCA territory of stenotic side at each PLD. The CBF of stenotic territory showed greater increase than that of normal side from PLD 1.5 to 2.5 s. The CBF of asymptomatic MCA territory increased similarly with that of symptomatic MCA territory from PLD of 1.5 to 2.5 s in stenotic side, while symptomatic patients experienced significantly slower antegrade flow. On CBF subtraction images, asymptomatic patients showed larger volume of differences between PLD of 1.5 and 2.5 s compared with those of symptomatic patients (p = 0.037). The results suggest that more robust collateral perfusion on two-delay 3D pCASL is present in asymptomatic patients compared with symptomatic patients.