Isolated MCA Disease in Patients Without Significant Atherosclerotic Risk Factors

Endovascular treatment for proximal middle cerebral artery occlusion due to underlying intracranial atherosclerotic disease: A retrospective single-center case series

OBJECTIVE

To compare treatment outcomes between patients who received a front-line stent-retriever thrombectomy (SRT) or first stenting without retrieval (FRESH) for treating proximal M1 occlusion due to underlying intracranial atherosclerotic disease (ICAD).

METHODS

We retrospectively reviewed consecutive acute ischemic stroke (AIS) patients with intracranial large vessel occlusion (LVO) in the anterior circulation who underwent endovascular treatment (EVT) between January 2017 and August 2021 at Yeungnam University Medical Center. LVO in the anterior circulation was classified according to etiology as follows: Embolic group and ICAD group. Occlusion of the proximal M1 due to ICAD were enrolled in this study. The ICAD group was divided into SRT and FRESH groups according to the treatment method.

RESULTS

Among the 72 patients in the ICAD group, 55 patients had occlusion of the M1, and 27 had occlusion of the proximal M1 (27/55, 49.1 %). Among the 27 patients, 11 (40.7 %) underwent SRT and 16 (59.3 %) underwent FRESH. The puncture-to-recanalization time was significantly shorter in the FRESH group (28 min vs. 52 min, p = 0.023). Symptomatic ICH tended to occur more frequently in the SRT group than in the FRESH group (27.3 % vs. 0.0 %, p=0.056). There was a nonsignificant trend towards a good functional outcome in the FRESH group compared to the SRT group (81.3 % vs. 45.5 %, p=0.097).

CONCLUSION

In the FRESH group, the puncture-to-recanalization time was significantly shorter, symptomatic ICH tended to occur less frequently, and good functional outcomes were more common.

High Level of Serum Complement C3 Expression is Associated with Postoperative Vasculopathy Progression in Moyamoya Disease

Background

The immune system plays an important role in the onset and development of moyamoya disease (MMD), but the specific mechanisms remain unclear. This study aimed to explore the relationship between the expression of complements and immunoglobulin in serum and progression of MMD.

Methods

A total of 84 patients with MMD and 70 healthy individuals were enrolled. Serum immunoglobulin and complement C3 and C4 expression were compared between healthy individuals and MMD patients. Follow-up was performed at least 6 months post-operation. Univariate and multivariate analysis after adjusting different covariates were performed to explore predictive factors associated with vasculopathy progression. A nomogram basing on the results of multivariate analysis was established to predict vasculopathy progression.

Results

Compared to healthy individuals, MMD patients had significantly lower expression of serum complements C3 (P = 0.003*). Among MMD patients, C3 was significantly lower in those with late-stage disease (P = 0.001*). Of 84 patients, 27/84 (32.1%) patients presented with vasculopathy progression within a median follow-up time of 13.0 months. Age (P=0.006*), diastolic blood pressure (P=0.004*) and serum complement C3 expression (P=0.015*) were associated with vasculopathy progression after adjusting different covariables.

Conclusion

Complement C3 is downregulated in moyamoya disease and decreases even further in late-Suzuki stage disease. Age, diastolic blood pressure and serum complement C3 expression are associated with vasculopathy progression, suggesting that the complement might be involved in the development of moyamoya disease.

Multimodal imaging approach for the diagnosis of intracranial atherosclerotic disease (ICAD): Basic principles, current and future perspectives

PURPOSE

To review the different imaging modalities utilized in the diagnosis of Intracranial Atherosclerotic Disease (ICAD) including their latest development and relevance in management of ICAD.

METHODS

A review of the literature was conducted through a search in google scholar, PubMed/Medline, EMBASE, Scopus, clinical trials.gov and the Cochrane Library. Search terms included, "imaging modalities in ICAD," "ICAD diagnostic," "Neuroimaging of ICAD," "Evaluation of ICAD". A summary and comparison of each modality's basic principles, advantages and disadvantages were included.

RESULTS

A total of 144 articles were identified and reviewed. The most common imaging used in ICAD diagnoses were DSA, CTA, MRA and TCD. They all had proven accuracy, their own benefits, and limitations. Newer modalities such as VWI, IVUS, OCT, PWI and CFD provide more detailed information regarding the vessel walls, plaque characteristics, and flow dynamics, which play a tremendous role in treatment guidance. In certain clinical scenarios, using more than one modality has been shown to be helpful in ICAD identification. The rapidly evolving software related to imaging studies, such as virtual histology, are very promising for the diagnostic and management of ICAD.

CONCLUSIONS

ICAD is a common cause of recurrent ischemic stroke. Its management can be both medical and/or procedural. Many different imaging modalities are used in its diagnosis. In certain clinical scenario, a combination of two more modalities can be critical in the management of ICAD. We expect that continuous development of imaging technique will lead to individualized and less invasive management with adequate outcome.

A Vessel Wall MRI Investigation in Patients With Moyamoya or Quasi-Moyamoya Disease: Diagnosis, Features, and Outcomes

BACKGROUND AND PURPOSE

None of the previous studies have investigated the pathologic authenticity of affected arteries in moyamoya disease (MMD) and Quasi-MMD diagnosed by angiography. This study aimed to confirm the angiographic diagnosis of moyamoya as well as investigate the pathologic mechanisms in angiographically proven MMD and Quasi-MMD using high-resolution magnetic resonance imaging (MRI) in a large sample.

METHODS

We prospectively studied 116 patients who had angiographically proven MMD and Quasi-MMD. Each affected internal carotid artery, and middle cerebral artery was independently evaluated. In addition, clinical features and postoperative outcomes were compared between hemispheres with MMD and moyamoya syndrome (MMS).

RESULTS

Among 116 patients analyzed, 88 and 22 patients had angiographically proven MMD and Quasi-MMD, respectively. high-resolution magnetic resonance imaging confirmed bilateral MMD in 73 (83.0%) patients, 1 hemisphere with MMD and the other with intracranial atherosclerotic disease (ICAD) in 10 (11.4%) patients, and bilateral hemispheres with different vasculopathies in 5 (5.7%) patients. Detailed analysis of 204 affected hemispheres showed that several combinations of different vasculopathies were observed in the internal carotid artery and middle cerebral artery of the same hemisphere, such as ICAD-ICAD, ICAD-MMD, dissection-ICAD, and dissection-MMD. Hemispheres were assigned to MMD and MMS groups according to their vasculopathies. Transient ischemic attack occurred more frequently in hemispheres with MMD (48.1% versus 21.1%, P =0.024), whereas symptomatic ischemia was more common in hemispheres with MMS (57.9% versus 24.9%, P =0.002). However, postoperative cerebral infarction, symptom improvement and neo-formative collaterals showed no significant difference between hemispheres with MMD and MMS ( P >0.05).

CONCLUSIONS

Patients with angiographically proven MMD or Quasi-MMD needed more accurate evaluation combined with high-resolution magnetic resonance imaging. Highly selected patients with MMS might also obtain benefits from surgical revascularization.

Dural arteriovenous fistula with spinal dural arteriovenous fistula: a case report and review of the literature

BACKGROUND

This paper analyzed the cases of dural arteriovenous fistula (DAVF) with spinal dural arteriovenous fistula (SDAVF) in the diagnosis and treatment process.

CASE PRESENTATION

One case involving dural arteriovenous fistula (DAVF) with spinal dural arteriovenous fistula (SDAVF) from the 306th Hospital of PLA was retrospectively analyzed. The patient consulted the doctor due to lower limb sensory and motor disorders while exhibiting symptoms of urinary dysfunction. A computed tomographic angiography (CTA) and cerebral angiography confirmed the diagnosis of dural arteriovenous fistula (DAVF), necessitating surgical treatment. The patient was referred to our hospital for an magnetic resonance imaging (MRI) and a spinal angiography to obtain a confirmed diagnosis for spinal arteriovenous fistula, after which they underwent surgical fistula resection. The invasive intracranial dural arteriovenous fistula (DAVF) resection proceeded smoothly but did not ease the patient's symptoms. However, postoperative symptoms were partially relieved by the lumbar open spinal dural arteriovenous fistula adminstration.

CONCLUSIONS

Since not enough is understood about these two diseases, the rate of misdiagnosis is significantly increased. Early diagnosis and treatment of spinal dural arteriovenous fistula (SDAVF) can play a positive role during the recovery from neural function damage.

Five-Year Stroke Risk and Its Predictors in Asymptomatic Moyamoya Disease: Asymptomatic Moyamoya Registry (AMORE)

BACKGROUND

Long-term outcomes are unknown in patients with asymptomatic moyamoya disease. In this report, we aimed to clarify their 5-year risk of stroke and its predictors.

METHODS

We are conducting a multicenter, prospective cohort study (Asymptomatic Moyamoya Registry) in Japan. Participants were eligible if they were 20 to 70 years, had bilateral or unilateral moyamoya disease, experienced no episodes suggestive of TIA and stroke; and were functionally independent (modified Rankin Scale score 0-1). Demographic and radiological information was collected at enrollment. In this study, they are still followed up for 10 years. In this interim analysis, we defined the primary end point as a stroke occurring during a 5-year follow-up period. Independent predictors for stroke were also determined, using a stratification analysis method.

RESULTS

Between 2012 and 2015, we enrolled 109 patients, of whom 103 patients with 182 involved hemispheres completed the 5-year follow-up. According to the findings on DSA and MRA, 143 hemispheres were judged as moyamoya disease and 39 hemispheres as questionable manifestations (isolated middle cerebral artery stenosis). The patients with questionable hemispheres were significantly older, more often male, and more frequently had hypertension than those with moyamoya hemisphere. Moyamoya hemispheres developed 7 strokes, including 6 hemorrhagic and 1 ischemic stroke, during the first 5 years. The annual risk of stroke was 1.4% per person, 0.8% per hemisphere, and 1.0% per moyamoya hemisphere. Independent predictor for stroke was Grade-2 choroidal anastomosis (hazard ratio, 5.05 [95% CI, 1.24-20.6]; P=0.023). Furthermore, microbleeds (hazard ratio, 4.89 [95% CI, 1.13-21.3]; P=0.0342) and Grade-2 choroidal anastomosis (hazard ratio, 7.05 [95% CI, 1.62-30.7]; P=0.0093) significantly predicted hemorrhagic stroke. No questionable hemispheres developed any stroke.

CONCLUSIONS

The hemispheres with asymptomatic moyamoya disease may carry a 1.0% annual risk of stroke during the first 5 years, the majority of which are hemorrhagic stroke. Grade-2 choroidal anastomosis may predict stroke, and the microbleeds and Grade-2 choroidal anastomosis may carry the risk for hemorrhagic stroke.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: UMIN000006640.

The Role of High-Resolution Magnetic Resonance Imaging in Cerebrovascular Disease: A Narrative Review

High-resolution magnetic resonance imaging (HRMRI) is the most important and popular vessel wall imaging technique for the direct assessment of vessel wall and cerebral arterial disease. It can identify the cause of stroke in high-risk plaques and differentiate the diagnosis of head and carotid artery dissection, including inflammation, Moya Moya disease, cerebral aneurysm, vasospasm after subarachnoid hemorrhage, reversible cerebral vasoconstriction syndrome, blunt cerebrovascular injury, cerebral arteriovenous malformations, and other stenosis or occlusion conditions. Through noninvasive visualization of the vessel wall in vitro, quantified assessment of luminal stenosis and pathological features of the vessel wall can provide clinicians with further disease information. In this report, technical considerations of HRMRI are discussed, and current clinical applications of HRMRI are reviewed.

Impact on etiology diagnosis by high-resolution vessel wall imaging in young adults with ischemic stroke or transient ischemic attack

PURPOSE

The etiological features of stroke in young adults are different from those in older adults. We aimed to investigate the impact of high-resolution vessel wall imaging (HRVWI) on etiologic diagnosis in young adults with ischemic stroke or transient ischemic attack (TIA).

METHODS

A total of 253 young adults (aged 18-45 years) who consecutively underwent HRVWI for clarifying stroke etiology were retrospectively recruited. Two experienced neurologists classified stroke etiology for each patient using Trial of Org 10,172 in Acute Stroke Treatment categories with and without the inclusion of HRVWI diagnosis. Multivariate logistic regression was performed to determine which etiologic category would be significantly impacted after including HRVWI.

RESULTS

The etiologic classification was altered in 39.1% (99/253) of patients after including HRVWI in the conventional investigations. The proportion of patients classified as having stroke of undetermined etiology (SUE) and the proportion of patients classified as having small-artery occlusion (SAO) both significantly decreased (36.4 to 13.8% and 9.1 to 2.0%), whereas the proportion of patients classified as having large artery atherosclerosis (LAA) significantly increased (28.5 to 58.1%) (all P < 0.001). The inclusion of HRVWI had a significant diagnostic impact on young adults who were primarily classified as SAO (odds ratio [OR] 14.4, 95% confidence interval [CI] [2.9, 71.8], P < 0.001) or SUE (OR 8.3, 95% CI [2.2, 31.5], P < 0.01).

CONCLUSIONS

HRVWI had a substantial impact on etiologic classification in young adults with ischemic stroke or TIA, particularly for those primarily classified as having SAO or SUE. This impact of HRVWI will be beneficial for therapeutic decision-making.

Plaque Characteristics in Young Adults With Symptomatic Intracranial Atherosclerotic Stenosis: A Preliminary Study

Purpose

To determine how intracranial vascular wall and atherosclerosis plaque characteristics differ between young and old adults with sICAS.

Methods

Eighty-four consecutive patients with sICAS who underwent high-resolution magnetic resonance imaging (HRMRI) from December 2017 to July 2020 were retrospectively collected. These participants were divided into young adult group (18–50 years, n = 28) and old adult group (>50 years, n = 56). Reviewers were blinded to any clinical information and HRMRI scans were analyzed for qualitative and quantitative indicators of vascular walls and plaque at the maximal lumen narrowing site using the independent-sample t-test, Mann–Whitney U-test, chi-square test or Fisher exact test, and logistic regression analysis.

Results

Young patients with sICAS had significantly smaller maximum wall thickness (1.45 ± 0.38 vs.1.75 ± 0.51 mm², P = 0.003), higher prevalence of positive remodeling (53.57 vs. 21.43%, P = 0.003), and lower prevalence of diabetes mellitus (14.29 vs. 35.71%, P = 0.04) than old patients. Plaque burden and other plaque features were comparable between young and old patients.

Conclusion

Young patients with sICAS have smaller maximum wall thickness and greater ability to reconstruct, and are more likely to show positive remodeling, which may lead to some atherosclerotic lesions being missed. Young patients with evidence of vessel narrowing should be carefully examined for presence of high-risk atherosclerotic plaque.

High-resolution MR vessel wall imaging in determining the stroke aetiology and risk stratification in isolated middle cerebral artery disease

PURPOSE

High-resolution MR vessel wall imaging (HRVWI) can characterise vessel wall pathology affecting intracranial circulation and helps in differentiating intracranial vasculopathies. The aim was to differentiate intracranial pathologies involving middle cerebral artery (MCA) in patients with ischemic stroke and characterise the high-risk plaques in intracranial atherosclerotic disease (ICAD) using HRVWI.

METHODS

Patients with ischemic stroke with isolated MCA disease with ≥ 50% luminal narrowing by vascular imaging were enrolled within 2 weeks of onset and underwent high-resolution (3 T) intracranial vessel wall imaging (VWI). The pattern of vessel wall thickening, high signal on T1-weighted images, juxtaluminal hyperintensity, pattern and grade of enhancement were studied. The TOAST classification before and after HRVWI and the correlation of the recurrence of ischemic events at 3 months with imaging characteristics were analysed.

RESULTS

Of the 36 patients, the mean age was 49.53 ± 15.61 years. After luminal imaging, by TOAST classification, 12 of 36 patients had stroke of undetermined aetiology. After vessel wall imaging, lesions in MCA were analysed. Of them, 23 patients had ICAD, 8 had vasculitis, and 2 had partially occlusive thrombus in MCA. The ability of HRVWI to bring a change in diagnosis was significant (p = 0.031). Of the 23 patients with ICAD, 12 patients had recurrent strokes within 3 months. The presence of grade 2 contrast enhancement (p = 0.02) and type 2 wall thickening (p = 0.03) showed a statistically significant association with recurrent ischemic events.

CONCLUSION

High-resolution MRVWI can help in identifying the aetiology of stroke. The HRVWI characteristics in ICAD can help in risk stratification.

Long-term mortality in patients with moyamoya angiopathy according to stroke presentation type in South Korea

BACKGROUND

Incidence, prevalence, and long-term survival outcomes in patients with moyamoya angiopathy (MMA) according to stroke presentation type and age group have not been clearly elucidated.

METHODS

We investigated mortality in patients with MMA (moyamoya disease, probable moyamoya disease, moyamoya syndrome) of whose International Classification Disease 10 code was I67.5 from 2006 to 2015 using the Korean National Health Insurance database. MMA at diagnosis was classified into 3 types (ischemic, hemorrhagic, and asymptomatic or else) according to stroke presentation. Survival analysis was performed according to stroke presentation type and age group (< 15 years and ≥ 15 years) using the Kaplan-Meier method.

RESULTS

There were 12,146 newly diagnosed moyamoya cases, with a female-to-male ratio of 1.81; the ischemic type was identified in 3671 (30.2%) patients, the hemorrhagic type in 2449 (20.2%) patients, and the asymptomatic or else type in 6026 (49.6%) patients. The mean age at diagnosis according to stroke presentation was 33.1 (± 14.8) years in asymptomatic or else type, 41.2 (± 17.3) years in ischemic type, and 45.4 (± 14.3) years in hemorrhagic type (P < 0.001). The 10-year survival rates in ischemic-, hemorrhagic-, and asymptomatic or else-type patients were 88.9%, 76.3%, and 94.3%, respectively (log-rank test; P < 0.001). Pediatric MMA (< 15 years) and adult MMA (≥ 15 years) showed different survival curves according to stroke presentation type (log-rank test; P = 0.017, P < 0.001, respectively).

CONCLUSIONS

Our study showed that moyamoya patients had different diagnosis ages and distinct survival courses according to stroke presentation type. Adult moyamoya patients with hemorrhagic presentation had the worst survival outcomes.

Imaging Features of Symptomatic MCA Stenosis in Patients of Different Ages: A Vessel Wall MR Imaging Study

BACKGROUND AND PURPOSE

The prevalence of intracranial artery stenosis is high in Asian people. This study aimed to investigate whether there are differences in the imaging features of symptomatic MCA stenosis in patients of different ages using vessel wall MR imaging.

MATERIALS AND METHODS

We retrospectively reviewed the data of consecutive patients with unilateral MCA stenosis based on a prospectively established vessel wall MR imaging data base between January 2017 and December 2018. According to age, the patients were divided into the young group (18-45 years of age) and the middle-aged and elderly group (older than 45 years of age).

RESULTS

Overall, 131 patients with unilateral MCA stenosis were included (45.8% in the young group and 54.2% in the middle-aged and elderly group). Middle-aged and elderly patients had a higher prevalence of hypertension (P = .01) and diabetes (P = .05). The lesion length (P < .0001), proportion of circular involvement (P = .006), and proportion of circular enhancement (P = .03) were higher in the young group than in the middle-aged and elderly group. The analysis of the atherosclerotic subgroup showed that compared with middle-aged and elderly patients, young patients had longer lesions (P = .002). The atherosclerotic-versus-nonatherosclerotic subgroup analysis showed that the maximal wall thickness in the patients with atherosclerosis was larger than that of patients without it (P = .002).

CONCLUSIONS

Compared with the middle-aged and elderly group, young patients with MCA stenosis tended to have longer lesions and more circular wall involvement and circular enhancement, which may indicate the differences in underlying vascular pathophysiologic and developmental mechanisms in symptomatic MCA stenosis.

Role of Blood Lipid Levels and Lipid-Lowering Therapy in Stroke Patients with Different Levels of Cerebral Artery Diseases: Reconsidering Recent Stroke Guidelines

Hyperlipidemia is an important risk factor for ischemic stroke; the Stroke Prevention by Aggressive Reduction in Cholesterol Level and Treat Stroke to Target studies have shown that statins are beneficial for patients with stroke and that a low target for low-density lipoprotein cholesterol (LDL-C) concentration may maximize this benefit. Based on these results, recent guidelines have emphasized the application of "high-intensity statins" and "low LDL-C target" strategies in patients with stroke. However, it should be kept in mind that the role of blood lipids as a risk factor and benefit of lipid-lowering therapy are different among patients with different levels of cerebral arterial diseases. Studies have suggested that hypolipidemia, but not hyperlipidemia, is a risk factor for small vessel diseases (SVDs) such as intracerebral hemorrhages, microbleeds, white matter hyperintensities, and perhaps, lacunar infarction. Although lipid-lowering agents might benefit certain patients with SVD, high-intensity statin and low LDL-C target strategies cannot be applied. In contrast, these strategies are important in patients with extracranial atherosclerosis, such as internal carotid disease, considering ample evidence of the benefits of lipid-lowering agents. Imaging studies have shown that statins stabilize vulnerable plaques in these patients. Although lipid-lowering agents are likely to benefit patients with intracranial atherosclerosis, the degree of their benefit and appropriate target LDL-C level for these patients remain unclear. More studies are needed to elucidate the appropriate lipid-modifying strategies in patients with stroke with different levels of cerebral artery disease.

Prevalence and outcome of young stroke patients with middle cerebral artery stenosis

Background

Etiologies of acute ischemic stroke in young adults are heterogeneous. Middle cerebral artery (MCA) stenosis is a common finding in Asians which may be an important cause of stroke in young adults. However, studies of stroke in young Asian populations are rare. Our study was to investigate the prevalence and outcome of young stroke patients with MCA stenosis in Chinese populations.

Methods

Young patients with MCA territory infarction between January 2013 and September 2018 were retrospectively recruited. Subjects were defined as stenosis group (MCA stenosis ≥50%) and no-stenosis group (MCA stenosis<50% or no stenosis) by their MCA stenosis. For patients in stenosis group, they were categorized as uni-MCA stenosis subgroup and multiple stenosis subgroup. Demographic data, risk factors, imaging feature and complications were compared between groups. Prevalence of MCA stenosis and risk factor score (score ≥ 2 or 3) in different age groups were investigated. Modified Rankin Scale (mRS) was used for evaluating functional outcome at discharge (unfavorable outcome: 3–6). Binary logistic regression was performed to determine independent risk factors of unfavorable outcome.

Results

Two hundred forty-nine young stroke patients were included in our study and 110 (44.2%) patients were defined as stenosis group. 55 (50%) patients were categorized as uni-MCA stenosis subgroup and 55 (50%) were multiple stenosis subgroup. The most common traditional vascular risk factors included hypertension, hyperlipemia, smoking, hyperhomocysteinemia and alcohol consumption. Prevalence of risk factor score ≥ 2 or 3 increased with age, but not incidence of MCA stenosis. By TOAST classification, the most common etiologies were large-artery atherosclerosis (41.0%) and small vessel disease (33.7%). Compared with no-stenosis group, patients in stenosis group were more likely to have large territorial infarct, develop complications and have unfavorable outcome. No significant difference was found between patients in uni-MCA stenosis and multiple stenosis subgroups except history of stroke/TIA, risk factor score ≥ 3 and silent infarct. By logistic regression, hypertension (OR = 3.561; 95%CI, 1.494 to 8.492; p = 0.004), NIHSS scores at admission (OR = 1.438; 95%CI, 1.276 to 1.620; p = 0,000) and infarct size (p = 0.015) independently predicted unfavorable outcome.

Conclusions

Forty-four point two percent young Chinese adults with MCA territory infarction had MCA stenosis. Prevalence of MCA stenosis did not increase with age. Patients with MCA stenosis had worse clinical outcome, however, only hypertension, NIHSS scores at admission and infarct size were independent predictors.

Contemporary and emerging magnetic resonance imaging methods for evaluation of moyamoya disease

Numerous recent technological advances offer the potential to substantially enhance the MRI evaluation of moyamoya disease (MMD). These include high-resolution volumetric imaging, high-resolution vessel wall characterization, improved cerebral angiographic and perfusion techniques, high-field imaging, fast scanning methods, and artificial intelligence. This review discusses the current state-of-the-art MRI applications in these realms, emphasizing key imaging findings, clinical utility, and areas that will benefit from further investigation. Although these techniques may apply to imaging of a wide array of neurovascular or other neurological conditions, consideration of their application to MMD is useful given the comprehensive multidimensional MRI assessment used to evaluate MMD. These MRI techniques span from basic cross-sectional to advanced functional sequences, both qualitative and quantitative.The aim of this review was to provide a comprehensive summary and analysis of current key relevant literature of advanced MRI techniques for the evaluation of MMD with image-rich case examples. These imaging methods can aid clinical characterization, help direct treatment, assist in the evaluation of treatment response, and potentially improve the understanding of the pathophysiology of MMD.

MR Intracranial Vessel Wall Imaging: A Systematic Review

The purpose of this systematic review is to identify trends and extent of variability in intracranial vessel wall MR imaging (VWI) techniques and protocols. Although variability in selection of protocol design and pulse sequence type is known, data on what and how protocols vary are unknown. Three databases were searched to identify publications using intracranial VWI. Publications were screened by predetermined inclusion/exclusion criteria. Technical development publications were scored for completeness of reporting using a modified Nature Reporting Summary Guideline to assess reproducibility. From 2,431 articles, 122 met the inclusion criteria. Trends over the last 23 years (1995-2018) show increased use of 3-Tesla MR (P < .001) and 3D volumetric T1-weighted acquisitions (P < .001). Most (65%) clinical VWI publications report achieving a noninterpolated in-plane spatial resolution of ≤.55 mm. In the last decade, an increasing number of technical development (n = 20) and 7 Tesla (n = 12) publications have been published, focused on pulse sequence development, improving cerebrospinal fluid suppression, scan efficiency, and imaging ex vivo specimen for histologic validation. Mean Reporting Summary Score for the technical development publications was high (.87, range: .63-1.0) indicating strong scientific technical reproducibility. Innovative work continues to emerge to address implementation challenges. Gradual adoption into the research and scientific community was suggested by a shift in the name in the literature from "high-resolution MR" to "vessel wall imaging," specifying diagnostic intent. Insight into current practices and identifying the extent of technical variability in the literature will help to direct future clinical and technical efforts to address needs for implementation.

Color-coded duplex sonography vs. 3.0 Tesla magnetic resonance angiography for detection of intracranial stenosis of the internal carotid artery: A prospective cohort study

Hemodynamic changes may provide important information for clinical decision-making in internal carotid artery (ICA) stenosis. The degree of stenosis is responsible for the hemodynamic changes. For detection of intracranial stenosis, each diagnostic method has its own advantages and disadvantages. The goal of the present study was to compare the sensitivity and accuracy of color-coded duplex sonography with that of magnetic resonance angiography (MRA) for the detection of intracranial stenosis. Patients with 3 vessels and/or left stem coronary artery disease were subjected to transcranial and extracranial color-coded duplex sonography (n=998), MRA (n=998) and invasive catheter angiography (n=939). The degree of stenosis was defined according to the Warfarin-Aspirin Symptomatic Intracranial Disease methodology. A ≥50% reduction in artery diameter was considered as a positive obstructive lesion. The benefits of each imaging method were assessed by clinical decision-making analysis. Color-coded duplex sonography and MRA, had sensitivities of 0.935 and 0.957 and accuracies of 0.92 and 0.974, respectively, when using invasive catheter angiography as a gold standard. The number of false-positive obstructive lesions detected by MRA was significantly higher than that for color-coded duplex sonography (53 vs. 13, P<0.0001). Color-coded duplex sonography was able to detect an obstructive lesion in one single image for ICAs with ≥57% stenosis, while MRA was only capable of detecting an obstructive lesion in one single image for ICAs with ≥80% stenosis. In conclusion, color-coded duplex sonography is a reliable method for the detection of intracranial stenosis in patients with coronary artery disease.

Qualitative Assessment and Reporting Quality of Intracranial Vessel Wall MR Imaging Studies: A Systematic Review

BACKGROUND

Over the last quarter-century, the number of publications using vessel wall MR imaging has increased. Although many narrative reviews offer insight into technique and diagnostic applications, a systematic review of publication trends and reporting quality has not been conducted to identify unmet needs and future directions.

PURPOSE

We aimed to identify which intracranial vasculopathies need more data and to highlight areas of strengths and weaknesses in reporting.

DATA SOURCES

PubMed, EMBASE, and MEDLINE databases were searched up to September 2018 in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

DATA ANALYSIS

Two independent reviewers screened and extracted data from 128 articles. The Strengthening the Reporting of Observational Studies in Epidemiology guidelines were used to assess the reporting quality of analytic observational studies.

DATA SYNTHESIS

There has been an exponentially increasing trend in the number of vessel wall MR imaging publications during the past 24 years (P < .0001). Intracranial atherosclerosis is the most commonly studied intracranial vasculopathy (49%), followed by dissections (13%), aneurysms (8%), and vasculitis (5%). Analytic observational study designs composed 48% of the studies. Transcontinental collaborations showed nonsignificantly higher reporting quality compared with work originating from single continents (P = .20).

LIMITATIONS

A limitation is the heterogeneity in study designs.

CONCLUSIONS

Investigations on the diagnostic utility of vessel wall MR imaging in less commonly studied intracranial vasculopathies such as dissections, aneurysms, and vasculitis are warranted. More consistent adherence to the Strengthening the Reporting of Observational Studies in Epidemiology guidelines should improve transparency and maximize effective synthesis for clinical translation. Diverse collaborative teams are encouraged to advance the understanding of intracranial vasculopathies using vessel wall MR imaging.

High-resolution MRI of intracranial large artery diseases: how to use it in clinical practice?

High-resolution MRI (HRMRI) has emerged as a useful tool for clinical research in recent years. Compared with traditional cranial and vessel imaging, HRMRI provides more additional valuable pathophysiology information that is helpful for the differential diagnosis of intracranial atherosclerosis, dissection and vasculitis. However, there are some points that a neurologist should keep in mind. First, although enhanced vessel wall imaging is widely applied for research purposes, it is not appropriate for routine clinical use. Any injury or inflammation within vessel wall can result in enhancement, which is unspecific for a diagnosis. Second, although plaque components identified on HRMRI arouse researchers' interest, they may have limited positive predictive value for future stroke. Ruptured plaques may have higher prevalence in asymptomatic patients than expected. More prospective observational studies are required. Third, the vessel wall morphology features remain the useful and reliable clue for a diagnosis. It is true that eccentric vessel wall lesions most likely represent atherosclerosis if vessel dissection is easily excluded. For concentric wall lesions, however, the underlying pathophysiology is complicated, either atherosclerotic or non-atherosclerotic. Fourth, HRMRI can show luminal thrombus directly and provide valuable details. All in all, when HRMRI is used by a neurologist, it should not be viewed as the only key for a diagnosis. The diagnosis should be made based on patient history, lab works, other imaging technique and even genetic examinations.

Endovascular Therapy for Acute Ischemic Stroke of Intracranial Atherosclerotic Origin-Neuroimaging Perspectives

Large vessel occlusion (LVO) due to intracranial atherosclerosis (ICAS) is a common cause of acute ischemic stroke (AIS) in Asians. Endovascular therapy (EVT) has been established as the mainstay of treatment in patients with AIS and LVO. However, only a few patients of Asian descent with ICAS-related LVO (ICAS-LVO) were included in recent randomized controlled trials of EVT for AIS. Therefore, the findings of these trials cannot be directly applied to Asian patients with ICAS-LVO. In embolic LVO due to thrombus from the heart or a more proximal vessel, rapid, and complete recanalization can be achieved in more than 70-80% of patients, and it is important to exclude patients with large cores. In contrast, patients with ICAS-LVO usually have favorable hemodynamic profiles (good collateral status, small core, and less severe perfusion deficit), but poor response to EVT (more rescue treatments and longer procedure times are required for successful recanalization due to higher rates of reocclusion). Patients with ICAS-LVO may have different anatomic (plaque, angioarchitecture), hemodynamic (collateral status), and pathophysiologic (thrombus composition) features on neuroimaging compared to patients with embolic LVO. In this review, we discuss these neuroimaging features, their clinical implications with respect to determination of EVT responses, and the need for development of specific EVT devices and procedures for patients with ICAS-LVO.

The Clinical and Vascular Characteristics of RNF213 c.14576G>A Variant-Related Intracranial Major Artery Disease in China

Background and Purpose

Recently, several studies indicated the c.14576G>A variant on the ring finger protein 213 (RNF213), a founder variant of moyamoya diseases (MMD), was associated with non-MMD intracranial major artery stenosis/occlusion (non-MMD ICASO). We proposed that RNF213 variant-related ICASO including MMD might be a special entity with its own characteristics based on a genetic background. The aim of the study was to learn the clinical and vascular features of RNF213 variant-related ICASO. Moreover, we tried to explore the clinical significance of a testing variant in ICASO patients in China.

Methods

Clinical material and routine image data were collected in 160 Chinese patients with ICASO, including 41 verified MMD and 119 non-MMD. DNA samples were extracted, and the c.14576G>A variant on RNF213 was genotyped. Then, the clinical and vascular features were compared between the patients with and without a relevant variant. Furthermore, the patients with RNF213 mutation were performed with high resolution magnetic resonance imaging (HR-MRI) examination to conclude features of the artery wall.

Results

There were 16 (10%) patients (including 9 MMD and 7 non-MMD ICASO) presenting a heterozygous c.14576G>A variant while none of homozygote was found. Compared to the patients without the c.14576G>A variant, the variant group had more female, less symptomatic patients, and more possibility of having collateral vessels in vascular imaging. In the symptomatic subgroup, there is no significant difference in clinical presentation (p > 0.05) between two groups. However, RNF213 variant-related ICASO had lower scores in NIHSS (1.0 ± 3.0 vs. 3.9 ± 5.0, p < 0.05) but not in mRS. In the symptomatic subgroup, in addition, most of the HR-MRI images of variant ICASO (77.8%, 7 of 9) were characterized by a shrunken outer diameter, concentric thickening vessel wall, and collateral vessel structures on the stenotic portion, which was prone to be diagnosed as HR-MMD (a MMD diagnosis diagnosed by HR-MRI). The rest of the two variants showed a relatively eccentric luminal narrow, normal outer diameter without collateral vessel findings, identified as HR-ICAD (intracranial atherosclerotic disease diagnosed by HR-MRI).

Conclusions

Our study demonstrated that the c.14576G>A variant on RNF213 may be a biomarker to good outcome of ICASO in Chinese. The variant-related ICASO was characterized by both features of MMD and ICAD diagnosed by HR-MRI.

Cigarette Smoking Preferentially Affects Intracranial Vessels in Young Males: A Propensity-Score Matching Analysis

Purpose

Cigarette smoking (CS) is one of the major risk factors of cerebral atherosclerotic disease, however, its level of contribution to extracranial and intracranial atherosclerotic stenosis (ECAS and ICAS) was not fully revealed yet. The purpose of our study was to assess the association of CS to cerebral atherosclerosis along with other risk factors.

Materials and Methods

All consecutive patients who were angiographically confirmed with severe symptomatic cerebral atherosclerotic disease between January 2002 and December 2012 were included in this study. Multivariate logistic regression analyses were performed to identify risk factors for ECAS and ICAS. Thereafter, CS group were compared to non-CS group in the entire study population and in a propensity-score matched population with two different age-subgroups.

Results

Of 1709 enrolled patients, 794 (46.5%) had extracranial (EC) lesions and the other 915 (53.5%) had intracranial (IC) lesions. CS group had more EC lesions (55.8% vs. 35.3%, P<0.001) whereas young age group (<50 years) had more IC lesion (84.5% vs. 47.6%, P<0.001). In multivariate analysis, seven variables including CS, male, old age, coronary heart disease, higher erythrocyte sedimentation rate, multiple lesions, and anterior lesion were independently associated with ECAS. In the propensity-score matched CS group had significant more EC lesion compared to non-CS group (65.7% vs. 47.9%) only in the old age subgroup.

Conclusion

In contrast to a significant association between CS and severe symptomatic ECAS shown in old population, young patients did not show this association and showed relatively higher preference of ICAS.

The ability of magnetic resonance black blood vessel wall imaging to evaluate blunt cerebrovascular injury following acute trauma

BACKGROUND AND PURPOSE

Blunt cerebrovascular injury (BCVI) is associated with a significant risk of ischemic stroke when left untreated. Cross-sectional imaging is vital to early BCVI diagnosis and treatment; however, conventional luminal vessel imaging is limited in its ability to evaluate for vessel wall pathology. The purpose of this study is to evaluate the ability of vessel wall magnetic resonance imaging (VWI) to detect and evaluate BCVI in acutely injured trauma patients relative to neck computed tomographic angiography (CTA).

MATERIALS AND METHODS

Trauma patients with suspected BCVI on initial neck CTA were prospectively recruited for VWI evaluation. Two neuroradiologists blinded to patient clinical history and CTA findings evaluated each artery independently on VWI and noted the presence and grade of BCVI. These results were subsequently compared to neck CTA findings relative to expert clinical consensus review. Interrater reliability of VWI for detecting BCVI was evaluated using a weighted Cohen κ-statistic.

RESULTS

Ten trauma patients (40 cervical arteries) were prospectively evaluated using both CTA and VWI. Out of 18 vascular lesions identified as suspicious for BCVI on CTA, six lesions were determined to represent true BCVI by expert consensus review. There was almost perfect agreement between VWI and expert consensus regarding the presence and grade of BCVI (κ=0.82). This agreement increased when considering only low grade BCVI. There was only fair agreement between CTA and expert clinical consensus (κ=0.36). This agreement decreased when considering only low grade BCVI.

CONCLUSIONS

VWI can potentially accurately identify and evaluate BCVI in acutely injured trauma patients with excellent inter-rater reliability.

Intracranial artery stenosis magnetic resonance imaging aetiology and progression study: Rationale and design

BACKGROUND

It has been shown that intracranial artery stenosis (ICAS) plays a key role in Chinese ischemic stroke or transient ischemic attack (TIA) patients. Many vascular diseases can lead to ICAS, such as atherosclerosis, dissection, vasculitis, moyamoya disease, and reversible cerebral vasoconstriction syndrome (RCVS). In addition, progression of intracranial atherosclerotic disease (ICAD) will increase the risk of ischemic cerebrovascular events. The ICASMAP study primarily aims to determine the etiology and disease distribution of ICAS using noninvasive magnetic resonance (MR) imaging and evaluate the rate for progression of ICAD in symptomatic population.

METHODS

The ICASMAP study is a prospective, observational, and multicenter study by recruiting 300 subjects (18-80 years old) with recent stroke or TIA (within 2 weeks after onset of symptoms) in China. All the subjects will undergo MR imaging examination including brain and intracranial artery MR imaging at baseline. In addition, the clinical risk factors will be collected and blood biomarkers will be tested. A subgroup of more than 200 subjects who were diagnosed with ICAD according to baseline MR imaging will be followed up for 2 years. During the follow-up study, MR imaging examination will be performed at 12 and 24 months. The primary end point is presence of progression of intracranial artery atherosclerotic plaques.

CONCLUSIONS

The ICASMAP study investigates the etiology of ICAS and progression of ICAD in Chinese stroke patients and may help to improve the precise diagnosis and intervention of ICAS and stroke prevention.

Outcomes after ischemic stroke caused by intracranial atherosclerosis vs dissection

OBJECTIVE

To compare the outcomes between patients with nontraumatic intracranial arterial dissection (ICAD) and intracranial atherosclerotic stenosis (ICAS) using high-resolution MRI (HR-MRI).

METHODS

We conducted a prospective study using HR-MRI in patients with acute symptomatic cerebrovascular disease due to intracranial occlusive disease and no dissection on luminal images. Patients were followed-up for 27.9 ± 19.3 months. We compared the functional outcome, recurrence, and changes in vascular status between patients with ICAD (dissection and no plaque on HR-MRI) and ICAS (atherosclerosis plaque on HR-MRI).

RESULTS

We included 312 patients (mean age, 59.0 ± 14.2 years; men, 58.3%), of whom 113 had ICAD and 199 had ICAS. The functional outcome (as measured by modified Rankin Scale score) on the 90th day after symptom onset was not different between the groups, after adjusted for other factors (p = 0.095). However, recurrent ischemic cerebrovascular disease on the relevant vascular territory was lower in the ICAD group (7 patients, 6.2%) than in the ICAS group (37 patients, 18.6%). ICAD was a significant independent determinant of disease recurrence (hazard ratio, 0.43; 95% confidence interval, 0.19-0.98). Improvement in vascular stenosis on follow-up vascular studies was more frequently observed in ICAD (50.7%) than in ICAS (11.6%). ICAD was an independent determinant of vascular improvement (odds ratio, 7.94; 95% confidence interval, 3.32-19.01).

CONCLUSION

Considering the high prevalence of ICAD in the patients with presumed ICAS and the differential outcomes between ICAD and ICAS, HR-MRI may be a useful diagnostic tool in this population.

New vessels formation in young strokes with isolated steno-occlusive MCA

OBJECTIVE

New vessels formation (NVF) along the steno-occlusive middle cerebral artery (MCA) is often observed in digital subtraction angiography (DSA) imaging. In the study, we aim to explore the clinical relevance of NVF in young ischemic stroke patients with isolated middle cerebral artery (MCA) stenosis.

METHODS

We retrospectively reviewed the digital subtraction angiography (DSA) images of 93 young ischemic stroke patients (age ≤ 45 years old) in our center from January 2006 to June 2016. All the patients were diagnosed with isolated steno-occlusive middle cerebral artery (MCA) disease.NVF was defined as new vessels formation along the stenotic MCA on anteroposterior DSA projection. The association between NVF and functional outcome was analyzed.

RESULTS

The prevalence of NVF was 0 in moderate stenosis, 15.8% in severe stenosis, and 53.7% in MCA occlusions. The presence of NVF had a strong correlation with the severity of MCA stenosis (r = 0.467, p < 0.001). Compared to patients without NVF, patients with NVF were more likely to suffer an unfavorable functional outcome (6.2% vs. 21.4%, p = 0.061) at 3 months. Univariate logistic regression analysis showed that NVF was associated with unfavorable outcome [Odds Ratio (OR) = 4.159, 95% confidence intervals (CI) = (1.072, 16.137), p = 0.039].

CONCLUSIONS

This study demonstrated that NVF were associated with poor clinical outcome in young ischemic stroke patients who were diagnosed with isolated steno-occlusive MCA.

Intracranial Large Artery Disease of Non-Atherosclerotic Origin: Recent Progress and Clinical Implications

Intracranial large artery disease (ILAD) is the major cause of stroke worldwide. With the application of recently introduced diagnostic techniques, the prevalence of non-atherosclerotic ILAD is expected to increase. Herein, we reviewed recent reports and summarized progress in the diagnosis and clinical impact of differentiation between ILAD of atherosclerotic and non-atherosclerotic origin. Our review of the literature suggests that more careful consideration of non-atherosclerotic causes and the application of appropriate diagnostic techniques in patients with ILAD may not only provide better results in the treatment of patients, but it may also lead to more successful clinical trials for the treatment of intracranial atherosclerosis.

The association between the ring finger protein 213 gene R4810K variant and intracranial major artery stenosis/occlusion in the Han Chinese population and high-resolution magnetic resonance imaging findings

BACKGROUND AND PURPOSE:

The ring finger protein 213 (RNF213) gene R4810K variant, a susceptibility locus for moyamoya disease (MMD), has recently been identified to be associated with intracranial major artery stenosis/occlusion (ICASO) without satisfying the diagnostic criteria of MMD in the Japanese population. However, further studies are needed to determine whether this variant is associated with ICASO in other populations and whether R4810K variant-related ICASO could be categorized as MMD. The aim of this study is to elucidate whether the R4810K variant was associated with ICASO among the Han Chinese population and potential histopathology of R4810K variant-related ICASO.

MATERIALS AND METHODS:

We conducted a case–control study to evaluate association and performed high-resolution (HR) magnetic resonance imaging (MRI) to investigate arterial wall feature of ICASO. The R4810K variant was genotyped in 114 ICASO patients and 268 controls. Then, patients with R4810K variant-related ICASO were subjected to HR MRI examination and presumptively diagnosed based on the characteristics thus observed.

STATISTICAL ANALYSIS:

The relationship between R4810K variant and ICASO was evaluated by Fisher's exact test with odds ratios (OR) and 95% confidence interval (CI).

RESULTS:

The R4810K variant was associated with ICASO and increased the risk for ICASO (P < 0.01; OR: 20.2; 95% CI: 2.5–163.11). Presumptive MMD was diagnosed in all female patients with R4810K variant. However, presumptive intracranial atherosclerotic stenosis was diagnosed in one of three males harboring this variant.

CONCLUSIONS:

The R4810K variant is a genetic risk factor for ICASO among the Han Chinese population and that R4810K variant-related ICASO should be identified as MMD in female but not uncertain in male patients.

Medical Treatment of Intracranial Atherosclerosis: An Update

For patients with symptomatic intracranial atherosclerosis (ICAS), antithrombotic agents are the mainstay of therapy. Anticoagulation (warfarin) is not widely used since it is not more effective than aspirin and carries a high risk of bleeding. New oral anticoagulants are showing promise, but their use has not been investigated in appropriate clinical trials. Since the recurrent stroke risk is high with aspirin monotherapy, dual antiplatelets are considered in the early stage of symptomatic ICAS. Based on the Clopidogrel in High-Risk Patients with Acute Nondisabling Cerebrovascular Events (CHANCE) and Stenting and Aggressive Medical Management for Preventing Recurrent Stroke in Intracranial Stenosis (SAMMPRIS) results, aspirin plus clopidogrel has been recommended. However, this combination was not superior to aspirin monotherapy in patients with ICAS in the CHANCE substudy. Progression of ICAS is common, and it is associated with recurrent strokes. In the Trial of Cilostazol in Symptomatic Intracranial Arterial Stenosis (TOSS) study, aspirin plus cilostazol was more effective than aspirin monotherapy in preventing progression. The TOSS II trial showed that the overall change in stenosis was better with aspirin plus cilostazol than with aspirin plus clopidogrel. Aside from antithrombotic therapy, risk factor management is critical for secondary prevention, and high blood pressure is clearly linked to recurrent stroke. However, blood pressure may have to be cautiously managed in the early stage of stroke. Considering that ICAS is the major cause of stroke worldwide, further investigations are needed to establish optimal management strategies for patients with ICAS.

Etiology of intracranial stenosis in young patients: a high-resolution magnetic resonance imaging study

BACKGROUND

Using high-resolution magnetic resonance imaging (HRMRI), we sought to investigate the underlying etiology of intracranial stenosis in young patients.

METHODS

We retrospectively studied 122 Chinese young adult patients (from 18 to 45 years old, mean age 36.2±7.5 years) with unilateral middle cerebral artery (MCA) stenosis based on a prospectively established HRMRI database. The eccentricity, degree of stenosis, and remodeling types of MCA lesions were analyzed. The MCA lesions were classified as eccentric (presumed atherosclerosis) or concentric stenosis (presumed non-atherosclerosis). The clinical data and vessel wall properties were compared between the patients >35 years old and the patients ≤35 years old.

RESULTS

Eccentric stenosis was observed in 98 (80.3%) patients and concentric stenosis in 24 (19.7%) patients. The patients with eccentric stenosis were older (37.5±6.8 vs. 31.4±8.4 years old, P<0.001) and more likely had atherosclerosis risk factors (56.1% vs. 25.0%, P=0.006). The patients >35 years old had higher prevalence (90.1% vs. 66.7%, P=0.001) of eccentric stenosis and atherosclerosis factors (60.6% vs. 35.3%, P=0.006) than the patients ≤35 years old. Most of the patients with concentric stenosis were ≤35 years old (17/24, 70.8%) and were female (16/24, 66.7%). Binary Logistic analysis suggested smoking (OR =3.171; 95% CI, 1.210-8.314) and remodeling ratio (OR =1.625; 95% CI, 1.001-2.636) were independent predictive factors for symptomatic stenosis.

CONCLUSIONS

Atherosclerosis is the most common cause of intracranial stenosis in Chinese young patients. Non-atherosclerosis disease is an important etiology in young female, especially in the patients aged 35 years old or younger.

Smaller outer diameter of atherosclerotic middle cerebral artery associated with RNF213 c.14576G>A Variant (rs112735431)

Background:

Intracranial atherosclerosis (ICAS) involves diverse histologies and several remodeling patterns. Ring finger protein 213 (RNF213) c.14576G>A variant (rs112735431), recently reported to be associated with ICAS, may be linked with negative remodeling (outer diameter – reducing morphological alteration) of intracranial arteries. This study investigated the outer diameter of atherosclerotic middle cerebral artery (MCA).

Methods:

Patients with unilateral atherosclerotic MCA stenosis/occlusion were enrolled in this single-hospital-based case-control study at The University of Tokyo Hospital. The patients were divided into two groups by the presence of RNF213 c.14576G>A (variant group and wild-type group) and the outer diameter of the MCA was measured with high-resolution magnetic resonance imaging.

Results:

Twenty-eight patients with the wild type and 19 patients with the variant type were included. The outer diameter of the stenotic side MCA was smaller in the variant group than in the wild-type group (P = 8.3 × 10^-6). The outer diameter of the normal side MCA was also smaller in the variant group than in the wild-type group (P = 5.2 × 10^-3). The ratio of stenotic side to normal side was also smaller in the variant group than in the wild-type group (P = 1.5 × 10^-5).

Conclusions:

This study indicates that RNF213 c.14576G>A is associated with negative remodeling of ICAS.

Etiologic classification of ischemic stroke: Where do we stand?

Despite major technological advances in ischemic stroke diagnostic techniques, our current understanding of stroke mechanisms and etiology continues to remain unclear in a significant percent of patients. As a result, several etiological ischemic stroke classifications have emerged during the last two decades but their reliability and validity is far from perfect and further world-wide research is needed in order to achieve the so much needed "standard reference language". An ideal ischemic stroke classification should both comprise all underlying pathologies that could potentially concur to an index event and emphasize the most likely etiological and pathophysiological mechanism. Currently available approaches to ischemic stroke classification are either phenotypic or causative in nature, a multitude of criteria being published by different authors. Phenotypic classifications are targeted towards describing the concurring underlying pathologies, without highlighting the most probable ischemic stroke etiology, while causative classifications focus on establishing the most likely cause, neglecting other associated diseases. A judicious use of this two different concepts might improve clinical research as well as daily clinical practice.

RNF213 p.R4810K Variant and Intracranial Arterial Stenosis or Occlusion in Relatives of Patients with Moyamoya Disease

BACKGROUND

This study aimed to determine the effectiveness of genetic testing for the p.R4810K variant (rs112735431) of the Mysterin/RNF213 gene, which is associated with moyamoya disease and other intracranial vascular diseases, in the family members of patients with moyamoya disease.

METHODS

We performed genotyping of the RNF213 p.R4810K polymorphism and magnetic resonance angiography on 59 relatives of 18 index patients with moyamoya disease. Nineteen individuals had follow-up magnetic resonance angiography with a mean follow-up period of 7.2 years.

RESULTS

Six of the 34 individuals with the GA genotype (heterozygotes for p.R4810K) showed intracranial steno-occlusive lesions in the magnetic resonance angiography, whereas none of the 25 individuals with the GG genotype (wild type) showed any abnormalities. Follow-up magnetic resonance angiography revealed de novo lesions in 2 and disease progression in 1 of the 11 individuals with the GA genotype, despite none of the 8 individuals with the GG genotype showing any changes. Accordingly, 8 individuals had steno-occlusive lesions at the last follow-up, and all had the p.R4810K risk variant. The prevalence of steno-occlusive intracranial arterial diseases in family members with the p.R4810K variant was 23.5% (95% confidence interval: 9.27%-37.78%), which was significantly higher than in those without the variant (0%, P = .0160).

CONCLUSIONS

Genotyping of the p.R4810K missense variant is useful for identifying individuals with an elevated risk for steno-occlusive intracranial arterial diseases in the family members of patients with moyamoya disease.

High-resolution Magnetic Resonance Vessel Wall Imaging for Intracranial Arterial Stenosis

OBJECTIVE

To discuss the feasibility and clinical value of high-resolution magnetic resonance vessel wall imaging (HRMR VWI) for intracranial arterial stenosis.

DATE SOURCES

We retrieved information from PubMed database up to December 2015, using various search terms including vessel wall imaging (VWI), high-resolution magnetic resonance imaging, intracranial arterial stenosis, black blood, and intracranial atherosclerosis.

STUDY SELECTION

We reviewed peer-reviewed articles printed in English on imaging technique of VWI and characteristic findings of various intracranial vasculopathies on VWI. We organized this data to explain the value of VWI in clinical application.

RESULTS

VWI with black blood technique could provide high-quality images with submillimeter voxel size, and display both the vessel wall and lumen of intracranial artery simultaneously. Various intracranial vasculopathies (atherosclerotic or nonatherosclerotic) had differentiating features including pattern of wall thickening, enhancement, and vessel remodeling on VWI. This technique could be used for determining causes of stenosis, identification of stroke mechanism, risk-stratifying patients, and directing therapeutic management in clinical practice. In addition, a new morphological classification based on VWI could be established for predicting the efficacy of endovascular therapy.

CONCLUSIONS

This review highlights the value of HRMR VWI for discrimination of different intracranial vasculopathies and directing therapeutic management.

High-resolution Magnetic Resonance Imaging of Moyamoya Disease

Objective:

To introduce the imaging characteristics of moyamoya disease (MMD) using high-resolution magnetic resonance imaging (HR-MRI) and to discuss the role of HR-MRI in differentiating MMD from other intracranial artery diseases, especially intracranial atherosclerotic disease (ICAD).

Data Sources:

This review was based on the data in articles published between 2005 and 2015, which were obtained from PubMed. The keywords included HR-MRI, MMD, ICAD, and intracranial artery diseases.

Study Selection:

Articles related to HR-MRI for MMD or other intracranial artery diseases were selected for review.

Results:

There are differences between the characteristic patterns of HR-MRI in MMD and ICAD. MMD is associated with inward remodeling, smaller outer diameters, concentric occlusive lesions and homogeneous signal intensity, while ICAD is more likely to be associated with outward remodeling, normal outer diameters, eccentric occlusive lesions, and heterogeneous signal intensity. Other intracranial artery diseases, such as dissection and vasculitis, also have distinctive characteristics in HR-MRI. HR-MRI may become a useful tool for the differential diagnosis of MMD in the future.

Conclusions:

HR-MRI of MMD provides a more in-depth understanding of MMD, and it is helpful in evaluating pathological changes in the vessel wall and in differentiating MMD from other intracranial artery steno-occlusive diseases, particularly ICAD.

Vessel wall differences between middle cerebral artery and basilar artery plaques on magnetic resonance imaging

A recent study showed that posterior circulation plaques have a greater capacity for positive remodeling in a non-Asian population. We aimed to investigate if the features of plaques in the middle cerebral artery (MCA) were different from those in the basilar artery (BA) in a northern Chinese population. We retrospectively analysed the records of 71 consecutive patients with acute ischemic stroke. All patients had at least one MCA or BA plaque with early or mild (<50% stenosis) atherosclerosis identified using vessel wall magnetic resonance imaging. The remodeling ratio, eccentricity index, and plaque range were compared between MCA and BA plaques using multilevel analysis. A total of 101 plaques were included. There were 70 plaques located in the MCA and 31 plaques located in the BA. The features of non-advanced atherosclerotic plaques did not differ between the MCA and BA when accounting for the degree of stenosis or plaque burden in a northern Chinese population. Symptomatic plaques were associated with a higher eccentricity index and smaller plaque range than asymptomatic plaques under the same plaque burden. Further studies are warranted to investigate the progression of atherosclerosis in different intracranial arteries.

Clinical interpretation of high-resolution vessel wall MRI of intracranial arterial diseases

Intracranial arterial pathology has traditionally been evaluated with luminal imaging. Recently, high-resolution vessel wall imaging (HR-VWI) with MRI has facilitated submillimetre evaluation of the arterial walls. This technique can help differentiate various causes of intracranial steno-occlusive disease, identify culprit atherosclerotic plaques with a recent cerebral infarct, locate vessel wall pathology in areas with minimal or no narrowing on luminal imaging, predict aneurysm stability and identify a ruptured aneurysm when multiple aneurysms are present. Interpretation of HR-VWI examinations requires a solid understanding of the pathophysiology, clinical features, serum and cerebrospinal fluid laboratory findings, treatment administered and fundamental patterns of VWI abnormalities that may be encountered with the intracranial vasculopathies. This pictorial essay aimed to illustrate the essential findings of common conditions encountered with HR-VWI including intracranial atherosclerosis, moyamoya disease, intracranial vasculitis, varicella zoster vasculopathy, reversible cerebral vasoconstriction syndrome and aneurysms.

Nonatheroscleotic Isolated Middle Cerebral Artery Disease May Be Early Manifestation of Moyamoya Disease

Background and Purpose—

Middle cerebral artery steno-occlusive disease (MCAD) is not an uncommon cause of ischemic stroke in young Asians. Aside from atherosclerosis, the pathogenesis of MCAD include various nonatherosclerotic vasculopathies, most of which are yet to be defined. This study investigated the pathogenesis of symptomatic isolated MCAD in young Asian patients using high-resolution magnetic resonance imaging (HR-MRI) and mutation analysis of RNF213 .

Methods—

Patients aged <60 years with stroke or transient ischemic attack caused by MCAD were prospectively enrolled. Patients with a confirmed diagnosis of moyamoya disease, dissection, and vasculitis; with significant steno-occlusion in cerebral arteries other than the MCA; or with high-risk cardioembolic source were excluded. Using high-resolution MRI, patients were classified into an atherosclerosis group and a nonatherosclerosis group.

Results—

Eighty-one patients were enrolled, 45 (56.6%) in the atherosclerosis and 36 (44.4%) in the nonatherosclerosis group. The nonatherosclerosis group was significantly younger ( P =0.013), had a smaller number of vascular risk factors ( P =0.001), showed a lower homocysteine level ( P <0.001), thinner intima-media thickness ( P =0.006), and had more frequent heterozygotes at RNF213 ( P =0.045) than the atherosclerosis group. Diffusion-weighted image lesion pattern showed no significant differences in assumed stroke mechanisms between the 2 groups.

Conclusions—

Nonatherosclerotic pathogenesis are common in young Asians with symptomatic isolated MCAD. Clinical findings, high-resolution MRI features, and results of RNF213 mutation analysis suggest that moyamoya disease is responsible etiologically for a significant portion of nonatherosclerotic lesions. Symptomatic isolated MCAD may be an early manifestation of moyamoya disease in young Asian adults.

More Precise Imaging Analysis and Diagnosis of Moyamoya Disease and Moyamoya Syndrome Using High-Resolution Magnetic Resonance Imaging

BACKGROUND

The diagnosis of moyamoya disease (MMD) is often uncertain. Moyamoya syndrome (MMS) is often misdiagnosed as MMD. High-resolution magnetic resonance imaging (HR-MRI) enables vessel wall assessment to obtain more precise diagnoses. The aim of this study was to determine the true etiologies of arterial steno-occlusion in patients with an angiographic diagnosis of MMD or MMS using HR-MRI.

METHODS

HR-MRI was performed in 21 adult patients with angiographically proven MMD or MMS. A definite diagnosis was based on the HR-MRI findings. The diagnoses made via the 2 different imaging technologies were compared, and significant findings were analyzed.

RESULTS

A total of 21 patients were enrolled, including 7 patients with angiographically proven MMD and 14 patients with angiographically proven MMS. Among the 7 patients with MMD, HR-MRI confirmed the diagnosis of MMD in 6; the remaining patient was considered to have atherosclerosis in the bilateral distal internal carotid arteries (ICAs) and the left middle cerebral artery. Among the 14 patients with MMS, HR-MRI confirmed MMD in 6 patients (including 2 patients with unilateral MMD), atherosclerosis in 5 patients (including 3 patients with bilateral atherosclerosis and 2 with unilateral atherosclerosis), arterial dissection of the left ICA in 1 patient, and MMD in the left cerebral hemisphere with atherosclerosis in the right hemisphere in 2 patients.

CONCLUSIONS

Differentiating MMD from MMS is difficult in certain situations, and HR-MRI may help provide a more in-depth understanding of MMD and MMS, thereby achieving a more reliable diagnosis.

Visualization of the Intimal Flap in Intracranial Arterial Dissection Using High-Resolution 3T MRI

BACKGROUND AND PURPOSE

Presence of an intimal flap is a critical imaging finding in diagnosing intracranial artery dissection (ICAD). Recent reports showed that high-resolution magnetic resonance imaging (MRI) was better at identifying intimal flaps as compared with routine MRI techniques used in clinical settings. However, no current standardized sequence for high-resolution MRI without gadolinium enhancement produces images of satisfactory quality with clinically tolerable scanning times. This study evaluated a nonenhanced high-resolution fast spin echo (HR-FSE) MRI sequence for visualizing intimal flaps in patients with ICAD.

SUBJECTS AND METHODS

Three patients with ICAD underwent plain MRI examination using a 2-dimensional T2-weighted FSE imaging sequence optimized for our 3T system (in-plane pixel size, .23 mm × .23 mm; slice thickness 3 mm with no interslice gap), as well as scanning with conventional modalities, including CT angiography, magnetic resonance angiography, and digital subtraction angiography. We assessed whether these imaging methods could visualize an intimal flap and/or double lumen sign in the participants and compared the results between HR-FSE and the other modalities.

RESULTS

HR-FSE images clearly showed intimal flaps and double lumen signs in all 3 patients, whereas the conventional modalities identified a double lumen sign in only 2 of the 3 patients.

CONCLUSIONS

The present method of optimized HR-FSE imaging with a 3T system improved visualization of intimal flaps and should thus be considered for assessing patients with suspected ICAD that cannot be definitively diagnosed by conventional imaging modalities.

Middle cerebral artery stenosis in patients with nasopharyngeal carcinoma after radiotherapy: the incidence of stenosis and the risk factors

OBJECTIVE

The purpose of the present study was to investigate the incidence of middle cerebral artery (MCA) stenosis by contrast-enhanced MR angiography (CE-MRA), and to evaluate the risk factors for significant (>50%) MCA stenosis in patients with nasopharyngeal carcinoma (NPC) after radiotherapy.

METHODS

116 patients with NPC after radiotherapy were recruited into the irradiation group to investigate the incidence and degree of MCA stenosis by CE-MRA. The results were compared with those of the control group, which comprised 57 newly diagnosed patients with NPC who did not receive radiotherapy. Furthermore, the risk factors for significant MCA stenosis were evaluated.

RESULTS

There was a higher incidence of MCA stenosis in the irradiation group than in the control group in terms of patient number (p = 0.000) and vessel involvement (p = 0.000), respectively. The incidence of significant MCA stenosis in the irradiation group was 8.6% (10/116 patients) and 5.2% (12/232 patients) in terms of patient number and vessel involvement, respectively. However, no significant MCA stenosis was found in the control group. Univariate analysis showed that hypercholesterolaemia, T(3-4) stage and longer time interval from radiotherapy were the risk factors related to significant MCA stenosis. Multivariate analysis demonstrated that only T stage was the independent risk factor for significant MCA stenosis development.

CONCLUSION

The results showed that radiation can cause MCA stenosis in patients with NPC after radiotherapy, especially in those with T(3-4) stage, and further study is needed.

ADVANCES IN KNOWLEDGE

Radiation-induced MCA stenosis exists in patients with NPC after radiotherapy, and its prevalence is more common in patients with clinical T(3-4) stage.

Considerations When Subtyping Ischemic Stroke in Asian Patients

Both the incidence and prevalence of stroke in Asia are steadily increasing, and the burden of stroke is particularly high in Asian countries. Although strokes in Asians and Caucasians share many common features, there are some differences that are probably due to differences in lifestyle and genetic background. While there have been advances in the stroke classification system, the assignment of Asian stroke patients to etiological categories has received little attention. The current classification system may not be well suited to Asian patients with ischemic stroke because the proportions and relative importance of stroke subtypes may differ with race and ethnicity. This review addresses concerns about the use of the current stroke classification system in Asian patients with ischemic stroke, and proposes a classification system that is more specific to the Asian population, in conjunction with discussing advances in diagnostic techniques.