Unilateral Middle Cerebral Artery Stenosis Research Articles

Diffusion spectrum imaging of patients with middle cerebral artery stenosis

ObjectiveWe aimed to detect microstructural changes in the brains of patients with unilateral middle cerebral artery (MCA) stenosis and to assess the integrity of the fiber structure and the small-world networks using diffusion spectrum imaging (DSI). MethodsA total of 21 healthy controls and 48 patients with unilateral MCA stenosis underwent 3.0 T MRI examination using DSI technique. Differential tractography, diffusion connectometry, and structural networks were performed by using DSI software. The correlation between the stenosis and quantitative anisotropy (QA) were analyzed using multiple regression models in the correlation tractography. ResultsDifferential tractography analysis showed that the left or right MCA stenosis group had decreased fiber connectivity in the brain network compared with the control group. The correlation tractography analysis of the patients with MCA stenosis showed that QA was negatively correlated with stenosis in the bilateral arcuate fasciculus, bilateral corticostriatal and corticothalamic pathway, bilateral corticopontine and corticospinal tract, right superior longitudinal fasciculus, right cingulum, corpus callosum, and left frontal aslant tract. Statistically significant differences were shown between the MCA stenosis groups and control group in graph density, global efficiency, network path length, and rich club coefficient. ConclusionDSI revealed that stroke-free patients with unilateral MCA stenosis have a disrupted structural network and damaged white matter fibers. Furthermore, the fiber connection disruption is more severe in the ipsilateral hemisphere and less prominent in the contralateral hemisphere in patients with unilateral MCA stenosis. Therefore, microstructural impairment has happened to patients with unilateral MCA stenosis even at a subclinical stage.

Evaluating iron deposition in gray matter nuclei of patients with unilateral middle cerebral artery stenosis using quantitative susceptibility mapping

Iron mediated oxidative stress is involved in the process of brain injury after long-term ischemia. While increased iron deposition in the affected brain regions was observed in animal models of ischemic stroke, potential changes in the brain iron content in clinical patients with cerebral ischemia remain unclear. Quantitative susceptibility mapping (QSM), a non-invasive magnetic resonance imaging technique, can be used to evaluate iron content in the gray matter (GM) nuclei reliably. In this study, we aimed to quantitatively evaluate iron content changes in GM nuclei of patients with long-term unilateral middle cerebral artery (MCA) stenosis/occlusion-related cerebral ischemia using QSM.Forty-six unilateral MCA stenosis/occlusion patients and 38 age-, sex- and education-matched healthy controls underwent QSM. Clinical variables of history of hypertension, diabetes, hyperlipidemia, hyperhomocysteinemia, smoking, and drinking in all patients were evaluated. The iron-related susceptibility of GM nucleus subregions, including the bilateral caudate nucleus (CN), putamen (PU), globus pallidus (GP), thalamus, substantia nigra (SN), red nucleus, and dentate nucleus, was assessed. Susceptibility was compared between the bilateral GM nuclei in patients and controls. Receiver operating characteristic curve analysis was used to evaluate the efficacy of QSM susceptibility in distinguishing patients with unilateral MCA stenosis/occlusion from healthy controls. Multiple linear regression analysis was used to evaluate the relationship between ipsilateral susceptibility levels and clinical variables.Except for the CN, the susceptibility in most bilateral GM nucleus subregions was comparable in healthy controls, whereas for patients with unilateral MCA stenosis/occlusion, the ipsilateral PU, GP, and SN exhibited significantly higher susceptibility than the contralateral side (all P < 0.05). Compared with controls, susceptibility of the ipsilateral PU, GP, and SN and of contralateral PU in patients were significantly increased (all P < 0.05). The area under the curve (AUC) was greater for the ipsilateral PU than for the GP and SN (AUC = 0.773, 0.662 and 0.681; all P < 0.05). Multiple linear regression analysis showed that the increased susceptibility of the ipsilateral PU was significantly associated with hypertension, of the ipsilateral GP associated with smoking, and of the ipsilateral SN associated with diabetes (all P < 0.05).Our findings provide support for abnormal iron accumulation in the GM nuclei after chronic MCA stenosis/occlusion and its correlation with some cerebrovascular disease risk factors. Therefore, iron deposition in the GM nuclei, as measured by QSM, may be a potential biomarker for long-term cerebral ischemia.

Analysis of cerebral perfusion of leptomeningeal branch and perforating branch of unilateral middle cerebral artery with severe stenosis or occlusion based on multi-delay arterial spin labeling

Objective: To compare the cerebral perfusion differences between the symptomatic patients and the asymptomatic patients with unilateral middle cerebral artery (MCA) severe stenosis or occlusion by using three post labeling delays (PLD) of the three-dimensional pseudo-continuous arterial spin labeling (pCASL) technique. Methods: The clinical characteristics and ASL data of the 27 patients with severe stenosis or occlusion of unilateral MCA (18 symptomatic, 9 asymptomatic) were prospectively enrolled from April 2018 to November 2019 in the Department of Radiology of China-Japan Friendship Hospital. There were 16 males and 11 females, age range from 29 to 85 (55±13) years. According to the symptoms, they were divided into symptomatic group (18 cases) and asymptomatic group (9 cases). The parameters of cerebral blood flow (CBF), mean cerebral blood flow (mCBF), arterial transit time (ATT) and arterial cerebral blood volume (aCBV) were obtained using the Cereflow software. One-way multivariate analysis of variance (one-way MANOVA) was used to compare the differences of cerebral perfusion parameters between symptomatic group and asymptomatic group, and between the affected side and the control side in the two groups. Two-way ANOVA was used to evaluate the effects of symptoms, hemisphere (affected and control side), PLD times (1.5, 2.0 and 2.5 s) and the interaction between the two factors. Results: The CBF of the affected leptomeningeal branch and perforating branch of MCA in symptomatic group was lower than that in asymptomatic group [(36.8±10.2) ml·100 g-1·min-1 versus (46.6±13.9) ml·100 g-1·min-1, F(1, 75)=13.279, P=0.000 49; (32.3±8.3) ml·100 g-1·min-1 versus (36.2±7.5) ml·100 g-1·min-1, F (1, 75)=4.065, P=0.047], and there was no interaction between the symptom and PLD [F(2, 75) =0.061, P=0.940]. In the symptomatic group, the CBF of the leptomeningeal branch and perforating branch of MCA in affected side was lower than that in control side [(36.8±10.2) ml·100 g-1·min-1 versus (43.7±10.0) ml·100 g-1·min-1, F(1, 102)=12.559, P=0.000 59; (32.3±8.3) ml·100 g-1·min-1 versus (36.4±8.0) ml·100 g-1·min-1, F(1, 102)=6.493, P=0.012]. In the symptomatic group, the CBF of leptomeningeal branch of MCA when PLD was 2.5 s was 7.34 ml·100 g-1·min-1, which were higher than that when PLD of 1.5 s (95%CI: 0.72-13.9, P=0.03). There was no interaction between PLD and hemisphere [F(2, 102) =0.307, P=0.736]. Conclusions: The collateral circulation in the blood supply area of MCA in asymptomatic patients with severe unilateral MCA stenosis or occlusion is more abundant than that in symptomatic patients. ASL can be an effective technique for evaluating the cerebral perfusion of collateral circulation in patients with severe stenosis or occlusion of MCA.

Can 3D Pseudo‐Continuous Territorial Arterial Spin Labeling Effectively Diagnose Patients With Recanalization of Unilateral Middle Cerebral Artery Stenosis?

A typical patient with R-MCA undergoing stenting before (top row) and after (bottom row) surgery. A 65-year-old male with severe R-MCA stenosis. (a) DSA showed that after stenting, the R-MCA stenosis was significantly alleviated, the blood flow was recanalized, and the distal branches were well visualized. (b) DWI showed no obvious high signal before and after the operation. (c) Preoperative 3D pcASL showed that low perfusion area was visible in M6, and postoperative low perfusion had returned to normal. (d) and (e) Preoperative tASL showed that the perfusion in M3, M5, and M6 areas was lower than that of the contralateral side, and the postoperative hypoperfusion area had returned to normal by Wang et al (175–183).

Can 3D Pseudo-Continuous Territorial Arterial Spin Labeling Effectively Diagnose Patients With Recanalization of Unilateral Middle Cerebral Artery Stenosis?

Unilateral middle cerebral artery (MCA) stenosis, as an independent risk factor for stroke, requires an intervention operation for vessel recanalization. Accurate perfusion measurement is thus essential after the operation. To explore the feasibility of three-dimensional (3D) pseudo-continuous territorial arterial-spin-labeling (tASL) in evaluating MCA recanalization. Prospective and longitudinal. Forty-seven patients with unilateral MCA stenosis or occlusion. A 3.0 T, 3D time-of-flight fast-field-echo magnetic resonance (MR) angiography sequence, spin-echo echo-planar diffusion-weighted imaging sequence, 3D fast-spin-echo pseudo-continuous ASL (pcASL) and tASL sequences. All patients underwent MR examination before and after MCA recanalization and scored using the National Institutes of Health Stroke Scale (NIHSS) and modified Rankin Scale (mRS) at admission and discharge. An mRS score <2 was defined as a good prognosis. 3D-pcASL and tASL cerebral blood flow (CBF) maps were obtained, and the corresponding Alberta Stroke Program Early CT Score (ASPECTS)-based scores were evaluated. The Kolmogorov-Smirnov test, intra-class correlation coefficient, paired t-test, receiver operating characteristic (ROC) curve, and multivariable logistic regression analysis. After recanalization, tASL derived absolute CBFs between the affected and contralateral sides were significantly higher than before the operation (mean: 34.3 ± 8.5 mL/100 g/min vs. 40.6 ± 9.2 mL/100 g/min, 42.6 ± 9.8 mL/100 g/min vs. 43.5 ± 9.9 mL/100 g/min, both P < 0.05). In ROC analysis, tASL provided good prognosis (area under ROC curve [AUC]=0.829; 95% CI: 0.651-1.000, P < 0.05), while pcASL had lower prognostic value (AUC=0.760; 95% CI: 0.574-0.946, P < 0.05). The NIHSS score before recanalization, pcASL, and tASL-based ASPECTS scores were significantly associated with good clinical outcome (P < 0.05). Multivariable analysis revealed that ASPECTS-based scores of pcASL and tASL before and after surgery were independent predictors of good clinical outcome (all P < 0.05). DATA CONCLUSION: tASL can determine hypoperfusion in the responsible vascular perfusion area and predict clinical outcome. 4 TECHNICAL EFFICACY: Stage 2.

Hemodynamics is associated with vessel wall remodeling in patients with middle cerebral artery stenosis.

To evaluate the relationship between hemodynamics and vessel wall remodeling patterns in middle cerebral artery (MCA) stenosis based on high-resolution magnetic resonance imaging and computational fluid dynamics (CFD). Forty consecutive patients with recent ischemic stroke or transient ischemic attack attributed to unilateral atherosclerotic MCA stenosis (50-99%) were prospectively recruited. All patients underwent a cross-sectional scan of the stenotic MCA vessel wall. The parameters of the vessel wall, the number of patients with acute infarction, translesional wall shear stress ratio (WSSR), wall shear stress in stenosis (WSSs), and translesional pressure ratio were obtained. The patients were divided into positive remodeling (PR) and negative remodeling (NR) groups. The differences in vessel wall parameters and hemodynamics were compared. Correlations between the parameters of the vessel wall and hemodynamics were calculated. Of the 40 patients, 16 had PR, 19 had NR, and the other 5 displayed non-remodeling. The PR group had a smaller lumen area (p = 0.004), larger plaque area (p < 0.001), normal wall index (p = 0.004), and higher WSSR (p = 0.004) and WSSs (p = 0.023) at the most narrowed site. The PR group had more enhanced plaques (12 vs 6, p = 0.03). The number of patients with acute stroke in the PR group was more than that in the NR group (11 vs 4, p = 0.01). The remodeling index (r = 0.376, p = 0.026) and plaque area (r = 0.407, p = 0.015) showed a positive correlation with WSSR, respectively. Hemodynamics plays a role in atherosclerotic plaques and vessel wall remodeling. Individuals with greater hemodynamic values might be more prone to stroke. • Stenotic plaques in middle cerebral artery with positive remodeling have smaller lumen area and larger resp. higher plaque area, normal wall index, translesional wall shear stress ratio, and wall shear stress than negative remodeling. • The remodeling index and plaque area are positively correlated with translesional wall shear stress ratio. • Hemodynamic may help to understand the role of positive remodeling in the development of acute stroke.

The Relationship between Patterns of Remodeling and Degree of Enhancement in Patients with Atherosclerotic Middle Cerebral Artery Stenosis: A High-Resolution MRI Study.

The aim of this research was to investigate the relationship between remodeling patterns and degree of enhancement in patients with atherosclerotic middle cerebral artery (MCA) stenosis using high-resolution magnetic resonance imaging (HR-MRI). From August 2015 to May 2016, 38 consecutive patients with unilateral MCA stenosis on time-of-flight (TOF) MR angiography were prospectively enrolled. The routine MR scan and cross-sectional images of the stenotic MCA vessel wall on HR-MRI were performed in all patients. Among them, 17 patients displayed positive remodeling (PR) and the other 21 patients displayed negative remodeling or non-remodeling (non-PR). The patients displaying hyperintense on diffusion-weighted imaging (DWI) in the territory of ipsilateral stenotic MCA were considered to have had acute stroke. Subsequently, the differences in the degree of enhancement and the number of acute stroke patients between the PR group and the non-PR group were compared. The Spearman rank correlation analysis of the enhancement degree (ED) and the remodeling index (RI) was calculated. Then, receiver operating curve (ROC) was used to evaluate diagnostic efficiency of RI and ED for acute infarction. The PR group had more obvious enhancement plaques than the non-PR group (10 versus 3, P = 0.006). The PR group also had a larger number of acute stroke patients than the non-PR group (15 versus 4, P = 0.000). The spear-man rank correlation analysis showed that the degree of enhancement had a weak positive correlation with the remodeling index (r = 0.379, P = 0.019). The area under the curve (AUC) of RI and ED was higher than that of RI (0.924: 0.842). The PR, obvious enhancement predicted vulnerable plaques that were more prone to causing acute stroke. RI and ED had valuable diagnostic efficiency for acute infarction.

Association Between Plasma Lipoprotein-Associated Phospholipase A2 and Plaque Vulnerability in TIA Patients With Unilateral Middle Cerebral Artery Stenosis.

Background: Plasma lipoprotein-associated phospholipase A2 (Lp-PLA2) has emerged as a novel biomarker for coronary atherosclerosis. However, the association between Lp-PLA2 and plaque vulnerability in atherosclerosis of cervicocerebral arteries remains poorly defined, especially for intracranial atherosclerotic stenosis (ICAS). We aimed to investigate the association between Lp-PLA2 and plaque vulnerability in transient ischemic attack (TIA) patients with unilateral middle cerebral artery stenoses (MCAs).Methods: In this study, a total of 207 patients were enrolled from April 2017 to April 2020. Clinical data were collected, and MCA plaques were examined with high-resolution magnetic resonance imaging (HRMRI). Baseline characteristics of patients were collected during hospitalization. Statistical comparisons were performed using Pearson's chi-squared test, Mann–Whitney U test, and the Breslow–Day/Tarone's test for the determination of heterogeneity in different age strata. Multivariate binary logistic analysis was used to investigate the potential independent predictors that were highly correlated to plaque vulnerability.Results: The results showed that a high Lp-PLA2 level (>221 ng/ml) was associated with plaque vulnerability in TIA patients with unilateral MCAs. High Lp-PLA2 was independently associated with plaque vulnerability in patients ≤ 60 years old [multivariate adjusted odds ratio (OR) = 9.854; 95% CI, 2.458–39.501] but not in patients >60 years old (multivariate adjusted OR = 1.901; 95% CI, 0.640–5.650). Predictors of plaque vulnerability in different age strata were also different.Conclusion: Lp-PLA2 levels may be correlated to plaque vulnerability in TIA patients with unilateral MCAs and might be a diagnostic biomarker for plaque vulnerability in this kind of patients, especially for ones aged ≤ 60 years old.

Perfusion and plaque evaluation to predict recurrent stroke in symptomatic middle cerebral artery stenosis

Background and purposeWe investigated the baseline demographics of patients with severe unilateral atherosclerotic stenosis of the middle cerebral artery (MCA) using multimodal MRI and evaluated the haemodynamic impairments and plaque...

Decreased Signal Intensity Ratio on MRA Reflects Misery Perfusion on SPECT in Patients with Intracranial Stenosis

Acetazolamide reactivity on 123 I-IMP SPECT is used to detect misery perfusion due to intracranial atherosclerosis. Noninvasive fractional flow assessed by signal intensity ratio (SIR) on time of flight-magnetic resonance angiography (TOF-MRA) might offer a feasible alternative to identify high-risk intracranial stenosis. Data from consecutive patients with unilateral middle cerebral artery (MCA) stenosis who underwent both TOF-MRA and acetazolamide reactivity on 123 I-IMP SPECT were retrospectively analyzed. Signal intensity was measured in the background and on the MCA proximal and distal to the stenotic lesion on TOF-MRA. Mean cerebral blood flow (CBF) at rest and cerebrovascular reactivity were measured in the target MCA territory. CBF patterns of the MCA were divided into three groups (Powers' stage 0-II). A total of 56 sets of diagnostic imaging in 33 patients were assessed. Four CBF patterns were stage II in four MCA territories, stage I in 31, and stage 0 in 21. Median SIR of the MCA was .53 (interquartile range .46-.69) for stage II, .78 (.63-.90) for stage I, and .91 (.85-.95) for stage 0. The optimal cutoff for SIR obtained from receiver operating characteristic curve analysis to predict stage II was < .56. In patients with unilateral MCA stenosis, decreased SIR was correlated with misery perfusion, providing a simpler, widely available predictor of high-risk intracranial stenosis.

Influence of cerebrovascular reactivity on outcome of the patients with ≥50% symptomatic unilateral middle cerebral artery stenosis

ABSTRACTPurpose/aim of the study: Cerebrovascular reactivity (CVR) reflects the vasodilatory reserve of cerebral resistance vessels, which is an important marker for assessing cerebrovascular disease. The present study is to investigate whether CVR impairment increases adverse long-term outcome risk of patients with ≥ 50% symptomatic unilateral middle cerebral artery (MCA) stenosis (ischemic stroke (IS) or transient ischemic attack (TIA)).Material and methods: Digital subtraction angiography (DSA) was used to assess the degree of stenosis, and perfusion CT and 5% CO2 inhalation were adopted to evaluate CVR. Patients with ≥ 50% symptomatic unilateral MCA stenosis were assigned to non-CVR impairment group and CVR impairment group according to CVR status. The long-term follow-up endpoint was composite of any IS ( in the territory of the studied MCA) or death within 12 months.Results: Seventy-three patients with ≥ 50% symptomatic unilateral MCA stenosis, involving 31 non-CVR impairment cases and 42 CVR impairment cases, were included in the present study. Finally, IS occurred in six CVR impairment patients, and no endpoint happened in the non-CVR impairment group. Therefore, the annual rate of IS was 14.29% in the CVR impairment group and 0% in the non-CVR impairment group (P = 0.035). Besides, further Kaplan-Meier analysis found CVR impairment was closely associated with the IS risk (Kaplan-Meier Log-rank 4.719, P = 0.030).Conclusions: Our results showed that for patients with ≥ 50% symptomatic unilateral MCA stenosis, there was significant difference between non-CVR impairment cases and CVR impairment cases in the annual rate of IS. It suggests that CVR impairment increases the risk of adverse long-term outcomes.

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.

A High-Resolution MRI Study of Relationship between Remodeling Patterns and Ischemic Stroke in Patients with Atherosclerotic Middle Cerebral Artery Stenosis

Purpose: Recently, high-resolution magnetic resonance imaging (HR-MRI) has been used to depict the wall characteristics of the intracranial arteries. The aim of this study was to explain the relationship between the remodeling patterns and acute ischemic stroke in patients with atherosclerotic middle cerebral artery (MCA) stenosis using HR-MRI.Materials and Methods: From August 2015 to May 2016, we prospectively screened 33 consecutive patients with unilateral MCA stenosis using time-to-flight MR angiography, including 15 patients with symptomatic MCA stenosis and 18 patients with asymptomatic MCA stenosis. Among them, 14 patients were diagnosed as positive remodeling (PR) and 19 as negative remodeling or non-remodeling. The cross-sectional images of the stenotic MCA wall on HR-MRI including T1WI, T2WI, and PDWI were compared between the symptomatic group and the asymptomatic group as well as the PR group and the non-PR group, based on the vessel area, lumen area, wall area, plaque area, degree of stenosis, remodeling index, and NIHSS score.Results: The symptomatic group had larger wall area (P = 0.040), plaque area (P<0.001), degree of stenosis (P = 0.038), remodeling index (P < 0.001), and NIHSS score (P = 0.003) as well as smaller lumen area (P = 0.001) than the asymptomatic group. In addition, more PR patients were observed in symptomatic group. The PR group had larger plaque area (P = 0.014) and NIHSS score (P = 0.037) than the non-PR group. Demographic and clinical characteristics between the symptomatic group and the asymptomatic group, the PR group and the non-PR group showed no statistical difference.Conclusion: The current study suggests that the HR-MRI has emerged as a promising tool to detect the characteristics of intracranial arteries wall and reveal the relationship between remodeling patterns and ischemic stroke. The PR is an unsafe remodeling way and is prone to cause acute ischemic stroke.

Performance of computed tomography angiography to determine anterograde and collateral blood flow status in patients with symptomatic middle cerebral artery stenosis.

Background The purpose of this study was to determine the performance of computed tomography angiography (CTA) by using a scoring system to predict anterograde and collateral blood flow status in patients with symptomatic middle cerebral artery (MCA) stenosis with use of conventional angiography as standard reference. Methods We retrospectively identified all consecutive patients with unilateral symptomatic MCA stenosis in our center who underwent conventional angiography and CTA within 1 month. The anterograde and collateral blood flow (AnCo) scoring system consisted of anterograde score (AnS) and collateral score (CoS). Evaluation of the CTA images was done independently by two readers, based on the AnCo scoring system. The conventional angiography was assessed by using the Thrombolysis in Cerebral Infarction (TICI) and American Society of Interventional and Therapeutic Neuroradiology (ASITN/SIR) scoring system to determine the status of anterograde and collateral blood flow. Diagnostic performance of AnCo was evaluated by using the area under the receiver operating characteristic (ROC) curve. Results A total of 61 patients were included in the analysis with mean age of 53.4 ± 11.0 years. AnS demonstrated a strong correlation with TICI with statistical significance ( r = 0.786; p < 0.001). CoS had a modest yet statistically significant correlation with ASITN/SIR ( r = 0.574; p < 0.001). The ROC curve analysis for AnS demonstrated an area under the curve (AUC) of 0.894 ( p < 0.001) and the ROC curve analysis for CoS showed an AUC of 0.824 ( p < 0.001). Conclusions CTA was a potential method to evaluate anterograde and collateral blood flow status in patients with symptomatic unilateral MCA stenosis.

Assessment of cerebrovascular reserve in unilateral middle cerebral artery stenosis using perfusion CT and CO2 inhalation tests

Purpose/Aim of the study: Cerebrovascular reactivity (CVR) is an important marker for assessing cerebrovascular disease. This study assessed the CVR by perfusion computed tomography (CT) and CO2 inhalation tests in patients with unilateral middle cerebral artery (MCA) stenosis disease. Materials and Methods: Thirty-one patients with unilateral MCA stenosis disease diagnosed by digital subtraction angiography were studied. Patients were divided into two groups according to the degree of stenosis: severe and moderate. The regional cerebral blood flow (CBF) before and after CO2 inhalation was determined by perfusion CT. Regional CVR values were obtained by the following formula: increase (%) = (post-CBF) − (pre-CBF)/(pre-CBF) × 100%. Results: No significant differences in the mean CBF in the MCA stenosis region were found between the affected and contralateral sides before the CO2 inhalation test; after the test, CBF was more significantly decreased on the affected side than on the contralateral side. The changes in CBF on the affected side were categorized into three types: increased CBF (17 cases), decreased CBF (12 cases) and no change in CBF (2 cases). The rate of CVR impairment among severe stenosis patients (13/19) was higher than that among moderate stenosis patients (3/12). CVR was significantly correlated with the degree of stenosis (r = 0.423, P = 0.018). Conclusion: CVR impairment was found in approximately half of patients with unilateral MCA stenosis. Along with an increase in the degree of stenosis, patients with unilateral MCA stenosis were more likely to exhibit CVR impairment. It is important to assess the CVR in patients with unilateral MCA stenosis, especially those with severe stenosis.

Arterial Spin Labeling Magnetic Resonance Imaging Estimation of Antegrade and Collateral Flow in Unilateral Middle Cerebral Artery Stenosis.

Three-dimensional pseudocontinuous arterial spin labeling with multiple postlabeling delays has been used to assess cerebral blood flow (CBF). We used this modality to estimate antegrade and collateral flow in patients with unilateral middle cerebral artery stenosis. Consecutive patients with unilateral middle cerebral artery 50% to 99% stenosis at 2 centers underwent pseudocontinuous arterial spin labeling with a postlabeling delays of 1.5 and 2.5 s. Mean CBF of bilateral middle cerebral artery territory at the postlabeling delays 1.5 and 2.5 s was measured. Early-arriving flow proportion was defined as (CBF 1.5 s at lesion side/CBF 2.5 s at normal side)×100%. Late-arriving retrograde flow proportion was defined as ([CBF 2.5 s-CBF 1.5 s] at lesion side-[CBF 2.5 s-CBF 1.5 s] at normal side)/CBF 2.5 s at normal side×100%. Antegrade and collateral scales were evaluated in patients with conventional angiography. Spearman correlation coefficients were calculated between early-arriving flow and late-arriving retrograde flow proportions on arterial spin labeling and antegrade and collateral scales on conventional angiography, respectively. Forty-one patients (46.0±12.0 years) were enrolled. The mean early-arriving flow proportion was 78.3±14.9%. The mean late-arriving retrograde flow proportion was 16.1±10.2%. In 21 patients with conventional angiography, Spearman correlation coefficient was 0.53 (95% confidence interval, 0.11-0.79) between antegrade grade and early-arriving flow proportion (P=0.01) and 0.81 (95% confidence interval, 0.56-0.92) between collateral grade and late-arriving retrograde flow proportion (P<0.0001). Three-dimensional pseudocontinuous arterial spin labeling with 2 postlabeling delays may provide an empirical approach for estimating antegrade and collateral flow in patients with unilateral middle cerebral artery stenosis. URL: http://www.clinicaltrials.gov. Unique identifier: NCT02479243.

Dynamic Cerebral Autoregulation in Asymptomatic Patients With Unilateral Middle Cerebral Artery Stenosis.

The aim of the study was to assess the capacity of dynamic cerebral autoregulation (dCA) in asymptomatic patients with unilateral middle cerebral artery (MCA) stenosis.Fifty-seven patients with asymptomatic mild, moderate, and severe unilateral MCA stenosis and 8 patients with symptomatic severe unilateral MCA stenosis diagnosed by transcranial Doppler were enrolled. Twenty-four healthy volunteers served as controls. The noninvasive continuous cerebral blood flow velocity and arterial blood pressure were recorded simultaneously from each subject in the supine position. Transfer function analysis was applied to determine the autoregulatory parameters (phase difference [PD] and gain).The PD values in the severe stenosis groups were significantly lower than those of the control group (60.71 ± 18.63°), the asymptomatic severe stenosis group was impaired ipsilaterally (28.94 ± 27.43°, P < 0.001), and the symptomatic severe stenosis group was impaired bilaterally (13.74 ± 19.21°, P < 0.001; 19.68 ± 14.50°, P = 0.006, respectively). The PD values in the mild and moderate stenosis groups were not significantly different than the controls (44.49 ± 27.93°; 48.65 ± 25.49°, respectively). The gain values in the mild and moderate groups were higher than in the controls (1.00 ± 0.58 cm/s/mm Hg vs 0.86 ± 0.34 cm/s/mm Hg, and 1.20 ± 0.59 cm/s/mm Hg vs 0.86 ± 0.34 cm/s/mm Hg, respectively). The gain values in the severe stenosis groups were significantly lower than that in the control group: the asymptomatic severe stenosis group was lower bilaterally (0.56 ± 0.32 cm/s/mm Hg, P = 0.003; 0.60 ± 0.32 cm/s/mm Hg, P < 0.05, respectively), whereas the symptomatic severe group was lower unilaterally (on the contralateral side) (0.53 ± 0.43 cm/s/mm Hg, P < 0.05).In asymptomatic patients with unilateral MCA stenosis, only the dCA of the severe stenosis was ipsilaterally impaired. Acute stroke may aggravate the impaired dCA and even spread contralaterally.

Safety and Feasibility of Remote Limb Ischemic Preconditioning in Patients With Unilateral Middle Cerebral Artery Stenosis and Healthy Volunteers.

Previous studies have indicated a neuroprotective effect of remote limb ischemic preconditioning. The aim of the present study was to assess whether upper arm ischemic preconditioning is feasible and safe in patients with unilateral middle cerebral artery (MCA) stenosis compared to healthy volunteers. Ten patients with unilateral MCA stenosis and 24 healthy volunteers underwent limb ischemic preconditioning, consisting of five cycles of 5-min inflations of a blood pressure cuff to 200 mmHg around an upper limb followed by 5 min of reperfusion. Limb ischemic preconditioning has no significant effect on the heart rate, oxygenation index, or mean flow velocity in patients with unilateral MCA stenosis or healthy volunteers. However, healthy volunteers showed a reduction in blood pressure 30 min following reperfusion of the last cycle. Limb ischemic preconditioning was found to be safe and well tolerated in both patients and healthy volunteers. We highlight the potential of limb ischemic preconditioning as an adjunct to neuroprotective treatment.

Hemodynamic alterations in unilateral chronic middle cerebral artery stenosis patients and the effect of percutaneous transluminal angioplasty and stenting: a perfusion-computed tomography study.

The Stenting and Aggressive Medical Management for Preventing Recurrent Stroke in Intracranial Stenosis (SAMMPRIS) trial indicated that most patients with symptomatic intracranial atherosclerosis are not good candidates for percutaneous transluminal angioplasty and stenting (PTAS) because of a higher complication risk than with conservative treatment. However, enrollment of SAMMPRIS patients was based on lesion severity only, without functional imaging. To determine whether perfusion computed tomography (PCT) can effectively evaluate hemodynamic compromise in unilateral chronic middle cerebral artery stenosis and the alterations of hemodynamics after PTAS. In this prospective study, 89 patients with unilateral middle cerebral artery (MCA) stenosis/occlusion were enrolled and classified into four groups according to the degree of stenosis. Cerebral hemodynamics was evaluated by measuring cerebral blood flow (CBF), cerebral blood volume (CBV), and time to peak (TTP) in the ipsilateral and contralateral hemispheres by PCT before and after intervention with PTAS. Differences in hemodynamic parameters before and after intervention were analyzed. Three different hemodynamic patterns were observed in these patients. Patients with severe MCA stenosis (70-99%) or MCA occlusion demonstrated a significant increase of ipsilateral CBV and TTP, indicating hemodynamic compromise. Ten severe stenosis patients with recurrent ischemic symptoms despite of maximal conservative therapy were selected for PTAS. PTAS induced a rapid recovery of cerebral hemodynamics (especially TTP) at 1 week post intervention. PCT appears to be a valuable noninvasive technique to evaluate hemodynamic compromise in unilateral chronic MCA stenosis and the improvements after PTAS.

Evaluation of flow velocity in unilateral middle cerebral artery stenosis by Transcranial Doppler.

To determine the optimal velocity values in diagnosing unilateral middle cerebral artery (MCA) stenosis by Transcranial Doppler (TCD), and improve the diagnostic accuracy using magnetic resonance angiography (MRA), a total of 302 unilateral MCA stenosis patients undergoing TCD also consented to a MRA of the intracranial arteries. The peak systolic velocity (PSV) and each MCA spectrum for each patient were recorded. Using the MRA to confirm, the degree of middle cerebral artery stenosis was categorized into four groups: normal (normal caliber and signal), mild (<50 %), moderate (50-69 %), severe (70-99 %, or no flow detected). The velocity difference among these four groups was significant (P < 0.001). The optimal PSV values for normal and stenosis were 160 cm/s. For mild and moderate were 200 cm/s, for moderate and severe were 280 cm/s. Using PSV as the diagnostic criteria, the Kappa number was >0.668. The optimal PSV differential value for mild and moderate was 70 cm/s, for moderate and severe at 120 cm/s. Optimal combined criteria for moderate stenosis were PSV >200 cm/s and PSV differential value >70 cm/s (specificity 87.2 %), for severe stenosis were PSV >280 cm/s and PSV differential value >120 cm/s (sensibility 81.6 %). Transcranial Doppler distinguishes normal and MCA stenosis with a reduced lumen diameter of less than 50 %. Using the PSV criteria, TCD has a high coincidence rate with MRA in the diagnosis of MCA stenosis. Combined PSV differential value and the abnormal spectrum may improve the accuracy of TCD in diagnosing moderate or severe stenosis.