Characterization of intracranial atherosclerotic stenosis using high-resolution MRI study--rationale and design

High-resolution magnetic resonance vessel wall imaging in ischemic stroke and carotid artery atherosclerotic stenosis: A review

Ischemic stroke is a significant burden on human health worldwide. Carotid Atherosclerosis stenosis plays an important role in the comprehensive assessment and prevention of ischemic stroke patients. High-resolution vessel wall magnetic resonance imaging has emerged as a successful technique for assessing carotid atherosclerosis stenosis. This advanced imaging modality has shown promise in effectively displaying a wide range of characteristics associated with the condition, leading to a comprehensive evaluation. High-resolution vessel wall magnetic resonance imaging not only enables a comprehensive evaluation of the instability of carotid atherosclerosis stenosis plaques but also provides valuable information for understanding the pathogenesis and predicting the prognosis of ischemic stroke patients. The purpose of this article is to review the application of high-resolution magnetic resonance imaging in ischemic stroke and carotid atherosclerotic stenosis.

Characteristics and evaluation of atherosclerotic plaques: an overview of state-of-the-art techniques

Atherosclerosis is an important cause of cerebrovascular and cardiovascular disease (CVD). Lipid infiltration, inflammation, and altered vascular stress are the critical mechanisms that cause atherosclerotic plaque formation. The hallmarks of the progression of atherosclerosis include plaque ulceration, rupture, neovascularization, and intraplaque hemorrhage, all of which are closely associated with the occurrence of CVD. Assessing the severity of atherosclerosis and plaque vulnerability is crucial for the prevention and treatment of CVD. Integrating imaging techniques for evaluating the characteristics of atherosclerotic plaques with computer simulations yields insights into plaque inflammation levels, spatial morphology, and intravascular stress distribution, resulting in a more realistic and accurate estimation of plaque state. Here, we review the characteristics and advancing techniques used to analyze intracranial and extracranial atherosclerotic plaques to provide a comprehensive understanding of atheroma.

Correlation of the middle cerebral artery atherosclerotic plaque characteristics with ischemic stroke recurrence: a vessel wall magnetic resonance imaging study

This study aims to analyze the imaging features of atherosclerotic plaques in the middle cerebral artery (MCA) of patients with recurrent ischemic stroke using vessel wall magnetic resonance imaging (VWMRI) and investigate the correlation between these imaging features and the recurrence of ischemic stroke. Consecutive patients with ischemic stroke caused by atherosclerotic stenosis of the MCA were collected. The patients were divided into recurrent and non-recurrent ischemic stroke groups. We obtained VWMRI images of MCA plaques using 3.0T MRI by black-blood sequences, and the differences in VWMRI characteristics and clinical information between the two groups were compared. A binary Logistic regression model was used to analyze the VWMRI characteristics and clinical information related to ischemic stroke recurrence. 179 patients were collected from August 2018 to May 2020, and 81 patients were included in the study. The recurrent ischemic stroke group patients had a higher stenosis rate (0.69 vs 0.64). Meanwhile, the rate of centripetal wall thickening was significantly higher in patients with recurrent ischemic stroke (33.3% vs 11.7%). Binary Logistic regression analysis showed that sex (P=0.036, OR:2.983, CI:1.075-8.279), stenosis rate (P=0.038, OR:148.565, CI:1.331-16583.631), and vessel wall thickening pattern (P=0.012, OR:0.171, CI:0.043-0.678) were related to ischemic stroke recurrence. The patients with ischemic stroke caused by atherosclerotic stenosis of MCA, female patients, and those with concentric wall thickening and a high degree of stenosis have a higher risk of recurrence. Our results suggest that VWMRI is a valuable tool for predicting the risk of ischemic stroke recurrence in patients with MCA plaques.

Association between basilar artery stenosis features, vertebral artery stenosis and perforator stroke after stenting

BACKGROUND AND PURPOSE

We investigated the relationship between basilar artery (BA) atherosclerotic stenosis features and vertebral artery (VA) stenosis and explored whether BA stenosis features are associated with perforator stroke after stenting.

METHODS

Patients with BA stenosis who underwent HRMRI and DSA were recruited. Patients were divided into proximal BA stenosis and middle-or-distal BA stenosis groups, and then subgroup analyses were performed based on whether they had VA stenosis. BA plaque features were evaluated by HRMRI. Artery stenosis was measured by DSA. The incidence of perforator stroke after BA stenting was recorded, and the potential association between BA stenosis features and perforator stroke was analyzed.

RESULTS

One hundred and seventy-four patients were consecutively enrolled. Patients with proximal BA stenosis had a higher proportion of severe stenosis than those with middle-or-distal BA stenosis (P = 0.027). In the subgroup analysis, this difference mainly existed in patients complicated with VA stenosis (P = 0.023). Patients with proximal BA stenosis had a higher proportion of strong plaque enhancement than those with middle-or-distal BA stenosis (P < 0.001), especially in those with vertebrobasilar junction (VBJ) stenosis (P < 0.001). Perforator stroke after BA stenting occurred in five patients, of whom four had lateral wall BA plaques, four had plaque enhancement and four had proximal BA stenosis.

CONCLUSION

Patients with proximal BA stenosis had a higher proportion of severe stenosis and strong plaque enhancement, particularly in patients complicated with VA stenosis and VBJ stenosis. Perforator stroke after BA stenting may be related to distribution, burden and characteristics of BA lesions.

Endovascular therapy versus medical treatment for symptomatic intracranial artery stenosis

BACKGROUND

Intracranial artery stenosis (ICAS) is an arterial narrowing in the brain that can cause stroke. Endovascular therapy (ET) and conventional medical treatment (CMT) may prevent recurrent ischaemic stroke caused by ICAS. However, there is no consensus on the best treatment for people with ICAS.

OBJECTIVES

To evaluate the safety and efficacy of endovascular therapy plus conventional medical treatment compared with conventional medical treatment alone for the management of symptomatic intracranial artery stenosis.

SEARCH METHODS

We searched the Cochrane Stroke Group Trials Register, CENTRAL, MEDLINE, Embase, four other databases, and three trials registries on 16 August 2022. We contacted study authors and researchers when we required additional information.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing ET plus CMT with CMT alone for the treatment of symptomatic ICAS. ET modalities included angioplasty alone, balloon-mounted stent, and angioplasty followed by placement of a self-expanding stent. CMT included antiplatelet therapy in addition to control of risk factors such as hypertension, hyperlipidaemia, and diabetes.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the records to select eligible RCTs, then extracted data from them. We resolved any disagreements through discussion, reaching consensus decisions among the full team. We assessed risk of bias and applied the GRADE approach to assess the certainty of the evidence. The primary outcome was death by any cause or non-fatal stroke of any type within three months of randomisation. Secondary outcomes included all-cause death or non-fatal stroke of any type occurring more than three months after randomisation, ipsilateral stroke, transient ischaemic attack, ischaemic stroke, haemorrhagic stroke, death, restenosis, dependency, and health-related quality of life.

MAIN RESULTS

We included four RCTs with 989 participants who had symptomatic ICAS, with an age range of 18 to 85 years. We identified two ongoing RTCs. All trials had high risk of performance bias, as it was impossible to blind participants and personnel to the intervention. Three trials were terminated early. One trial was at high risk of attrition bias because of substantial loss to follow-up after one year and a high proportion of participants transferring from ET to CMT. The certainty of evidence ranged from low to moderate; we downgraded for imprecision. Compared to CMT alone, ET plus CMT probably increases the risk of short-term death or stroke (risk ratio (RR) 2.93, 95% confidence interval (CI) 1.81 to 4.75; 4 RCTs, 989 participants; moderate certainty), short-term ipsilateral stroke (RR 3.26, 95% CI 1.94 to 5.48; 4 RCTs, 989 participants; moderate certainty), short-term ischaemic stroke (RR 2.24, 95% CI 1.30 to 3.87; 4 RCTs, 989 participants; moderate certainty), and long-term death or stroke (RR 1.49, 95% CI 1.12 to 1.99; 4 RCTs, 970 participants; moderate certainty). Compared to CMT alone, ET plus CMT may increase the risk of short-term haemorrhagic stroke (RR 13.49, 95% CI 2.59 to 70.15; 4 RCTs, 989 participants; low certainty), short-term death (RR 5.43, 95% CI 1.21 to 24.40; 4 RCTs, 989 participants; low certainty), and long-term haemorrhagic stroke (RR 7.81, 95% CI 1.43 to 42.59; 3 RCTs, 879 participants; low certainty). It is unclear if ET plus CMT compared with CMT alone has an effect on the risk of short-term transient ischaemic attack (RR 0.79, 95% CI 0.30 to 2.07; 3 RCTs, 344 participants; moderate certainty), long-term transient ischaemic attack (RR 1.05, 95% CI 0.50 to 2.19; 3 RCTs, 335 participants; moderate certainty), long-term ipsilateral stroke (RR 1.78, 95% CI 1.00 to 3.17; 4 RCTs, 970 participants; moderate certainty), long-term ischaemic stroke (RR 1.56, 95% CI 0.77 to 3.16; 4 RCTs, 970 participants; moderate certainty), long-term death (RR 1.61, 95% CI 0.77 to 3.38; 4 RCTs, 951 participants; moderate certainty), and long-term dependency (RR 1.51, 95% CI 0.93 to 2.45; 4 RCTs, 947 participants; moderate certainty). No subgroup analyses significantly modified the effect of ET plus CMT versus CMT alone. The trials included no data on restenosis or health-related quality of life.

AUTHORS' CONCLUSIONS

This review provides moderate-certainty evidence that ET plus CMT compared with CMT alone increases the risk of short-term stroke and death in people with recent symptomatic severe ICAS. This effect was still apparent at long-term follow-up but appeared to be due to the early risks of ET; therefore, there may be no clear difference between the interventions in terms of their effects on long-term stroke and death. The impact of delayed ET intervention (more than three weeks after a qualifying event) warrants further study.

High-risk features of basilar artery atherosclerotic plaque

INTRODUCTION

High-resolution magnetic resonance imaging (HR-MRI) is used to characterize atherosclerotic plaque. The present study aimed to determine the high-risk features of the basilar artery (BA) atherosclerotic plaque.

METHODS

Patients with advanced BA stenosis were screened. The features including the ruptured fibrous cap (RFC), lipid core, intraplaque hemorrhage (IPH), plaque enhancement, and calcification were assessed by using high-resolution MRI. The relationship between the features and acute infarction was analyzed.

RESULTS

From 1 June 2014 to 31 December 2018, a total of 143 patients with 76 new strokes were included. RFC was identified in 25% of symptomatic and 10.4% of asymptomatic patients. IPH was identified in 48.7% of symptomatic and 25.4% of asymptomatic patients. RFC (3.157, 95% CI 1.062 to 9.382, p = 0.039) and IPH (2.78, 95% CI 1.127 to 6.505, p = 0.026) were independent risk factors for acute infarction.

CONCLUSION

Our study showed that RFC and IPH of BA plaque were independent risk factors for acute infarction.

Association of distal hyperintense vessel sign and recurrent stroke in patients with symptomatic intracranial stenosis

OBJECTIVE

The distal hyperintense vessel sign (DHV) on fluid-attenuated inversion recovery magnetic resonance image (MRI) is an imaging biomarker of slow leptomeningeal collateral flow in the presence of large artery stenosis or occlusion reflecting impaired cerebral hemodynamics. In this study, we aim to investigate the significance of the DHV sign in patients with symptomatic ≥ 70% intracranial atherosclerotic stenosis.

METHODS

We retrospectively reviewed patients with ischemic stroke or transient ischemic attack admitted to a single center from January 2010 to December 2017. Patients were included if they had symptomatic ≥ 70% atherosclerotic stenosis of the intracranial internal carotid artery or middle cerebral artery. The presence of the DHV sign was evaluated by blinded neuroradiologist and vascular neurologists. Recurrent ischemic stroke in the vascular territory of symptomatic intracranial artery was defined as new neurological deficits with associated neuroimaging findings during the follow up period.

RESULTS

A total of 109 patients were included in the study, of which 55 had DHV sign. Average duration of follow up was 297 ± 326 days. Four patients were lost during follow up. Patients with the DHV sign had a higher rate of recurrent ischemic stroke (38%), compared to patients without the DHV sign (17%; p=0.018). In multivariate regression analysis, the presence of DHV sign was an independent predictor of recurrent ischemic stroke. A DHV score of ≥ 2 had a 63% sensitivity and 69% specificity for recurrent ischemic stroke.

INTERPRETATION

In patients with severe symptomatic intracranial atherosclerotic stenosis, those with a DHV sign on MRI are at higher risk of recurrent ischemic stroke.

Standard-Dose Atorvastatin Treatment in Patients With Symptomatic Middle Cerebral Artery Atherosclerotic Stenosis: A Vessel Wall Magnetic Resonance Imaging Study

Background and Purpose: Ischemic stroke can be caused by atherosclerotic lesions of the middle cerebral artery (MCA). Some studies have described the effects of statin treatment on carotid artery plaques, but little is known about the effects of statin treatment on MCA plaques. The purpose of this study was to validate the efficacy of standard-dose atorvastatin (20 mg/day) in patients with symptomatic MCA atherosclerotic stenosis (SMAS) in northern China.

Materials and Methods: This study is a prospective, single-arm, single-center, 12-month follow-up observational study monitoring imaging, and clinical outcomes of standard-dose atorvastatin treatment among patients with SMAS. The primary outcomes were changes in vessel wall magnetic resonance imaging (VWMRI) and serum lipid profiles before and after (1, 3, 6, and 12 months) statin treatment.

Results: A total of 46 patients were recruited for this study, and 24 patients completed the follow-up. During the follow-up period, serum non-high-density lipoprotein cholesterol concentrations gradually decreased in the patients. Fourteen patients (54.33%) had a reversal of MCA plaques and 10 patients (41.67%) had no significant progression of MCA plaques and remained stable at the follow-up endpoint. At the 12 months follow-up time-point, the treatment did not reverse vascular remodeling or change the shape and distribution of plaques. Altered serum low-density lipoprotein cholesterol (LDL-C) concentrations in patients were strongly associated with plaque reversal.

Conclusion: Vessel wall magnetic resonance imaging could accurately characterize changes in MCA plaques after lipid-lowering therapy. Standard-dose atorvastatin treatment could stabilize and reverse plaques in northern Chinese patients with SMAS.

Characteristics of symptomatic plaque on high-resolution magnetic resonance imaging and its relationship with the occurrence and recurrence of ischemic stroke

BACKGROUND

Atherosclerosis is the most common cause of ischemia stroke. Computed tomographic angiography (CTA) and digital subtraction angiography (DSA) are used to evaluate the degree of lumen stenosis. However, these examinations are invasive and can only reveal mild to moderate stenosis. High-resolution magnetic resonance imaging (HRMRI) seems a more intuitive way to show the pathological changes of vascular wall. Hence, we conducted a systematic retrospective study to determine the characteristics of symptomatic plaques in patients with intracranial atherosclerosis on HRMRI and their association with the occurrence and recurrence of ischemic stroke events.

METHODS

The PubMed database was searched for relevant studies reported from January 31, 2010, to October 31, 2020.

RESULTS

We selected 14 clinical outcome studies. We found that plaque enhancement and positive remodeling on HRMRI indicate symptomatic plaques. Besides, intraplaque hemorrhage and positive remodeling index are closely related to the occurrence of stroke. However, it is still controversial whether the initial enhancement of plaque and the occurrence and recurrence of stroke are related. There is also no significant correlation between vascular stenosis and symptomatic plaque or the occurrence and recurrence of ischemic stroke.

CONCLUSION

High-resolution magnetic resonance imaging can be used as an assessment tool to predict the risk of stroke onset and recurrence in patients with atherosclerosis, but further research is also needed.

Detection of Carotid Webs by CT Angiography, High-Resolution MRI, and Ultrasound

BACKGROUND AND PURPOSE

We sought to examine carotid webs (intimal variant fibromuscular dysplasia) by studying their clinical features and imaging profiles.

METHODS

All patients (n = 893) of the Department of Neurology at Beijing Tiantan Hospital between January and December 2019 were retrospectively reviewed for computed tomography angiography (CTA), high-resolution magnetic resonance imaging (HRMRI), and Doppler ultrasound data. Carotid webs were identified by two experienced neuroimaging experts according to the characteristics of a thin intraluminal filling defect along the posterior wall of the carotid bulb on sagittal CTA and a septum structure in arteries on axial CTA.

RESULTS

We found eight carotid web patients by CTA and Doppler ultrasound. Four of eight (50%) carotid webs were observed in the bilateral carotid arteries and other four of eight (50%) were ipsilateral. The mean age of the 8 patients was 50.75 (range 38-65) years; two were in women. Six of 8 patients (75%) with carotid webs had acute ischemic stroke. Two-thirds of patients with ischemic stroke were treated with carotid revascularization. Doppler ultrasound indicated that the septum projected into the carotid arteries in all patients. Half of the carotid web patients underwent HRMRI, showing features consistent with CTA findings. The Cohen's kappa coefficient for interobserver agreement in diagnosing carotid webs was .76.

CONCLUSIONS

Doppler ultrasound combined with CTA and HRMRI is effective and reliable method to identifying carotid webs, which may be associated with stroke.

Endovascular therapy versus medical treatment for symptomatic intracranial artery stenosis

BACKGROUND

Intracranial atherosclerotic stenosis (ICAS) is an arterial narrowing in the brain that can cause stroke. Endovascular therapy and medical management may be used to prevent recurrent ischaemic stroke caused by ICAS. However, there is no consensus on the best treatment for people with ICAS.

OBJECTIVES

To compare the safety and efficacy of endovascular therapy (ET) plus conventional medical treatment (CMT) with CMT alone for the management of symptomatic ICAS.

SEARCH METHODS

We searched the Cochrane Stroke Group Trials Register (30 August 2019), Cochrane Central Register of Controlled Trials (CENTRAL: to 30 August 2019), MEDLINE Ovid (1946 to 30 August 2019), Embase Ovid (1974 to 30 August 2019), Scopus (1960 to 30 August 2019), Science Citation Index Web of Science (1900 to 30 July 2019), Academic Source Complete EBSCO (ASC: 1982 to 30 July 2019), and China Biological Medicine Database (CBM: 1978 to 30 July 2019). We also searched the following trial registers: ClinicalTrials.gov, WHO International Clinical Trials Registry Platform, and Stroke Trials Registry. We also contacted trialists and researchers where additional information was required.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing ET plus CMT with CMT alone for the treatment of symptomatic ICAS. ET modalities included angioplasty alone, balloon-mounted stent, and angioplasty followed by placement of a self-expanding stent. CMT included antiplatelet therapy in addition to control of risk factors such as hypertension, hyperlipidaemia, and diabetes.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened trials to select potentially eligible RCTs and extracted data. Any disagreements were resolved by discussing and reaching consensus decisions with the full team. We assessed risk of bias and applied the GRADE approach to assess the quality of the evidence. The primary outcome was death of any cause or non-fatal stroke of any type within three months of randomisation. Secondary outcomes included any-cause death or non-fatal stroke of any type more than three months of randomisation, ipsilateral stroke, type of recurrent event, death, restenosis, dependency, and health-related quality of life.

MAIN RESULTS

We included three RCTs with 632 participants who had symptomatic ICAS with an age range of 18 to 85 years. The included trials had high risks of performance bias and other potential sources of bias due to the impossibility of blinding of the endovascular intervention and early termination of the trials. Moreover, one trial had a high risk of attrition bias because of the high rate of loss of one-year follow-up and the high proportion of participants transferred from endovascular therapy to medical management. The quality of evidence ranged from low to moderate, downgraded for imprecision. Compared to CMT, ET probably results in a higher rate of 30-day death or stroke (risk ratio (RR) 3.07, 95% confidence interval (CI) 1.80 to 5.24; 3 RCTs, 632 participants, moderate-quality evidence), 30-day ipsilateral stroke (RR 3.54, 95% CI 1.98 to 6.33; 3 RCTs, 632 participants, moderate-quality evidence), 30-day ischaemic stroke (RR 2.52, 95% CI 1.37 to 4.62; 3 RCTs, 632 participants, moderate-quality evidence), and 30-day haemorrhagic stroke (RR 15.53, 95% CI 2.10 to 115.16; 3 RCTs, 632 participants, low-quality evidence). ET was also likely associated with a worse outcome in one-year death or stroke (RR 1.69, 95% CI 1.21 to 2.36; 3 RCTs, 632 participants, moderate-quality evidence), one-year ipsilateral stroke (RR 2.28, 95% CI 1.52 to 3.42; 3 RCTs, 632 participants, moderate-quality evidence), one-year ischaemic stroke (RR 2.07, 95% CI 1.37 to 3.13; 3 RCTs, 632 participants, moderate-quality evidence), and one-year haemorrhagic stroke (RR 10.13, 95% CI 1.31 to 78.51; 2 RCTs, 521 participants, low-quality evidence). There were no significant differences between ET and CMT in 30-day transient ischaemic attacks (TIA) (RR 0.52, 95% CI 0.11 to 2.35, P = 0.39; 2 RCTs, 181 participants, moderate-quality evidence), 30-day death (RR 5.53, 95% CI 0.98 to 31.17, P = 0.05; 3 RCTs, 632 participants, low-quality evidence), one-year TIA (RR 0.82, 95% CI 0.32 to 2.12; 2 RCTs, 181 participants, moderate-quality evidence), one-year death (RR 1.20, 95% CI 0.50 to 2.86, P = 0.68; 3 RCTs, 632 participants, moderate-quality evidence), and one-year dependency (RR 1.90, 95% CI 0.91 to 3.97, P = 0.09; 3 RCTs, 613 participants, moderate-quality evidence). No data on restenosis and health-related quality of life for meta-analysis were available from the included trials. Two RCTs are ongoing.

AUTHORS' CONCLUSIONS

This systematic review provides moderate-quality evidence showing that ET, compared with CMT, in people with recent symptomatic severe intracranial atherosclerotic stenosis probably does not prevent recurrent stroke and appears to carry an increased hazard. The impact of delayed ET intervention (more than three weeks after a qualifying event) is unclear and may warrant further study.

Different risk factors in identical features of intracranial atherosclerosis plaques in the posterior and anterior circulation in high-resolution MRI

Background:

We constructed a high-volume registry to identify whether risk factors of intracranial atherosclerotic plaque (ICAP) features differ in the posterior and anterior circulation in patients with symptomatic intracranial atherosclerotic stenosis (ICAS) investigated by high-resolution magnetic resonance imaging (HRMRI).

Methods:

The registry was constructed for patients with symptomatic ICAS who underwent HRMRI for culprit plaques. ICAP-vulnerable features included positive remodelling, diffuse distribution, intraplaque haemorrhage and strong enhancement.

Results:

We analysed risk factors for the same ICAP features between the posterior and anterior circulation in data of 97 patients in the posterior circulation and 105 patients in the anterior circulation ICAPs. In patients with diffuse distribution, the probability of being female were lower [odds ratio (OR):0.08; 95% confidence interval (CI):0.02–0.34; p = 0.001] and having diabetes mellitus was higher (OR: 7.75; 95% CI:1.75–34.39; p = 0.007) in posterior circulation patients. In patients with strong enhancement, the probability of having diabetes was higher in posterior circulation patients (OR:6.71; 95% CI:1.37–32.81; p = 0.019).

Conclusions:

Our results demonstrate more risk factors in the posterior than in the anterior circulation in patients with the same ICAP-vulnerable features, highlighting the need for stratification of risk factors in symptomatic ICAPs.

Trial Registration:

URL: http://www.clinicaltrials.gov. Unique identifier: NCT02705599.

Influence of Vertebrobasilar Stenotic Lesion Rigidity on the Outcome of Angioplasty and Stenting

Stenotic lesion rigidity (SLR) has an unclear influence on the outcome of percutaneous transluminal angioplasty and stenting (PTAS) for intracranial arterial stenosis. This study evaluated the outcome of PTAS and the relationship of vertebrobasilar SLR to features on vessel wall MRI (VW-MRI) for identifying pathologies of vertebrobasilar stenosis (VBS) and evaluating PTAS outcome. We retrospectively evaluated the results of PTAS in 31 patients with severe VBS. Stenotic lesions were classified as soft (based on predilatation pressure [PP] ≦ 4 atm) in 15 patients or hard (PP >4 atm) in 16 patients. We examined the relationship of SLR to clinical and MR findings. Patients with hard vs soft lesions had atherosclerosis (8/16 [50.0%] vs 2/15 [13.3%]), dissection (0/16 [0.0%] vs 12/15 [80.0%]), and dissection in atherosclerosis (8/16 [50.0%] vs 1/15 [6.7%], P < 0.0001); high intensity signal on the T1WI of VW-MRI (5/16 [31.3%] vs 14/15 [93.3%]) and iso- to low intensity signal (11/16 [68.7%] vs 1/15 [6.7], P = 0.001), and significant in-stent restenosis (>50%) in 5/15 (33.3%) vs 0/15 (0.0%) (P = 0.0421) in the 30 patients who successfully completed PTAS. Vertebrobasilar SLR correlated well with lesion etiology, findings on VW-MRI, and PTAS outcome. Patients with hard stenotic lesions need close follow-up after PTAS.

Frequency, risk factors, and outcomes in patients with significant carotid artery disease admitted to King Abdulaziz Medical City, Riyadh with Ischemic Stroke

OBJECTIVE

To determine the frequency, risk factors, and outcomes of significant carotid artery disease (CAD) in patients with ischemic stroke.

METHODS

The frequency of significant CAD in patients admitted to the Stroke Unit between January 2014 and December 2015 was determined from radiological data. Outcomes were determined clinically and radiologically.

RESULTS

Among 435 patients, 273 were men (62.8%), with a mean age of 57.4+/-12.2 years. Significant CAD was found in 48 vessels in 40 (9.2%) patients, of which 30 patients were symptomatic. Nine of these patients were treated with carotid artery stenting, one underwent carotid endarterectomy, and 3 underwent an urgent thrombectomy, without stenting. Seventeen symptomatic patients were not treated for the following reasons: patient/family refusal (n=2), contraindications (n=5), and complete occlusion (n=10). One (7.7%) of the 13 treated patients had an ipsilateral stroke on follow up, one (7.7%) had contralateral transient ischemic attack (TIA), 9 (69.2%) had no recurrence, and no clinical data were available for 2 patients. Among the 17 untreated patients, one (5.9%) had an ipsilateral stroke, 7 (41.2%) had no recurrence, and 9 (52.9%) were lost to follow up.

CONCLUSION

Significant carotid artery disease is uncommon in our cohort found in less than 10% of patients. Vascular risk factors are more or less similar between patients with or without CAD except obesity which appears to have inverse relation with CAD. A small number of patients received carotid intervention with no recurrence of stroke at limited follow up.

Application of High-Resolution CUBE Sequence in Exploring Stroke Mechanisms of Atherosclerotic Stenosis of Middle Cerebral Artery

BACKGROUND

This study aimed to analyze the vascular wall and atherosclerotic plaques of the middle cerebral artery (MCA) and compare their differences between patients with cerebral infarction and transient ischemic attack (TIA) using 3-dimensional fast-spin-echo T1-weighted sequence (namely CUBE).

METHODS

Forty-seven patients with atherosclerotic stenosis of the MCA were included in this study. They received magnetic resonance examinations with routine T1WI, T2WI, 3-dimensional time-of-flight magnetic resonance angiography and diffusion-weighted imaging, as well as high-resolution CUBE T1WI sequence. Two physicians independently observed the location and degree of enhancement of the atheromatous plaques. The vessel area and lumen area at the maximal-lumen-narrowing and reference site were measured to calculate the plaque area, rate of stenosis, and remodeling index of the MCA. The chi-squared test was used to compare the differences of degree of enhancement between the cerebral infarction and TIA groups. The differences of rate of stenosis and remodeling index were compared by independent sample t test.

RESULTS

Twenty-five lesion vessels in the infarction group and 22 in the TIA group were analyzed. The difference of stenosis rate between the groups was not statistically significant. The lesion vessels of infarction group had a significantly larger remodeling index and plaque area, and the plaques had a significantly higher degree of enhancement, compared to the TIA group.

CONCLUSIONS

CUBE T1WI can be used to characterize the MCA vessel wall and atherosclerotic plaque. Positive remodeling and enhanced plaques are closely correlated with the occurrence of brain stroke.

Stroke Caused by Atherosclerosis of the Major Intracranial Arteries

Our goal in this review is to discuss the pathophysiology, diagnosis, and treatment of stroke caused by atherosclerosis of the major intracranial arteries. References for the review were identified by searching PubMed for related studies published from 1955 to June 2016 using search terms intracranial stenosis and intracranial atherosclerosis. Reference sections of published randomized clinical trials and previously published reviews were searched for additional references. Intracranial atherosclerotic disease is a highly prevalent cause of stroke that is associated with a high risk of recurrent stroke. It is more prevalent among blacks, Hispanics, and Asians compared with whites. Diabetes mellitus, hypertension, metabolic syndrome, smoking, hyperlipidemia, and a sedentary lifestyle are the major modifiable risk factors associated with intracranial atherosclerotic disease. Randomized clinical trials comparing aggressive management (dual antiplatelet treatment for 90 days followed by aspirin monotherapy and intensive management of vascular risk factors) with intracranial stenting plus aggressive medical management have shown medical management alone to be safer and more effective for preventing stroke. As such, aggressive medical management has become the standard of care for symptomatic patients with intracranial atherosclerotic disease. Nevertheless, there are subgroups of patients who are still at high risk of stroke despite being treated with aggressive medical management. Future research should aim to establish clinical, serological, and imaging biomarkers to identify high-risk patients, and clinical trials evaluating novel therapies should be focused on these patients.

Development of a high resolution MRI intracranial atherosclerosis imaging phantom

BACKGROUND AND PURPOSE

Currently, there is neither a standard protocol for vessel wall MR imaging of intracranial atherosclerotic disease (ICAD) nor a gold standard phantom to compare MR sequences. In this study, a plaque phantom is developed and characterized that provides a platform for establishing a uniform imaging approach for ICAD.

MATERIALS AND METHODS

A patient specific injection mold was 3D printed to construct a geometrically accurate ICAD phantom. Polyvinyl alcohol hydrogel was infused into the core shell mold to form the stenotic artery. The ICAD phantom incorporated materials mimicking a stenotic vessel and plaque components, including fibrous cap and lipid core. Two phantoms were scanned using high resolution cone beam CT and compared with four different 3 T MRI systems across eight different sites over a period of 18 months. Inter-phantom variability was assessed by lumen dimensions and contrast to noise ratio (CNR).

RESULTS

Quantitative evaluation of the minimum lumen radius in the stenosis showed that the radius was on average 0.80 mm (95% CI 0.77 to 0.82 mm) in model 1 and 0.77 mm (95% CI 0.74 to 0.81 mm) in model 2. The highest CNRs were observed for comparisons between lipid and vessel wall. To evaluate manufacturing reproducibility, the CNR variability between the two models had an average absolute difference of 4.31 (95% CI 3.82 to 5.78). Variation in CNR between the images from the same scanner separated by 7 months was 2.5-6.2, showing reproducible phantom durability.

CONCLUSIONS

A plaque phantom composed of a stenotic vessel wall and plaque components was successfully constructed for multicenter high resolution MRI standardization.

Characterization of intracranial atherosclerotic stenosis using high-resolution MRI study--rationale and design

BACKGROUND

Intracranial atherosclerosis is a leading cause of stroke, but little is known about the composition of the intracranial atherosclerotic lesion and how intracranial plaque morphology is related to the risk of stroke. High-resolution magnetic resonance imaging (HR MRI) has been used in patients with extracranial carotid atherosclerosis as an in vivo tool to identify, with high-interrater agreement, histologically defined plaque components (i.e., intraplaque hemorrhage, fibrous cap, and lipid core), which have been shown to be predictors of recurrent stroke. With careful imaging the components of atherosclerotic plaque can be visualized in the intracranial arteries using HR MRI, but there are no reports of reproducibility or interrater reliability.

METHODS/STUDY DESIGN

The Characterization of intracranial atherosclerotic stenosis using high-resolution MRI (CHIASM) study is a single-center NIH-funded prospective observational study, to (1) demonstrate high -interrater agreement for identifying intracranial plaque components on HR MRI, (2) determine the frequency of these components in symptomatic versus asymptomatic plaques, and (3) estimate the 1-year rate of stroke in the territory of high-risk plaque components. CHIASM will recruit 90 patients with 50-99% intracranial atherosclerosis to undergo HRMRI of the intracranial artery plaque at enrollment and 1-year follow-up. Both symptomatic and asymptomatic subjects will be recruited.

CONCLUSION

Determination of good interrater reliability is an important first step in the development of HR MRI as a tool to predict risk in patients with intracranial atherosclerosis. This study will inform the design of future multicenter studies to determine the prevalence and prognosis of intracranial atherosclerotic plaque components. Such studies could lead to new understanding of the pathophysiological mechanisms of cerebral ischemia in patients with atherosclerotic intracranial stenosis, improvements in risk stratification, and potentially to new treatments of this common and serious disease.