High resolution MRI difference between moyamoya disease and intracranial atherosclerosis

Moyamoya Vasculopathy and Moyamoya-Related Systemic Vasculopathy: A Review With Histopathological and Genetic Viewpoints

Systemic vasculopathy has occasionally been reported in cases of moyamoya disease (MMD). Since the pathological relationship between moyamoya vasculopathy (MMV) and moyamoya-related systemic vasculopathy (MMRSV) remains unclear, it was examined herein by a review of histopathologic studies in consideration of clinicopathological and genetic viewpoints. Although luminal stenosis was a common finding in MMV and MMRSV, histopathologic findings of vascular remodeling markedly differed. MMV showed intimal hyperplasia, marked medial atrophy, and redundant tortuosity of the internal elastic lamina, with outer diameter narrowing called negative remodeling. MMRSV showed hyperplasia, mainly in the intima and sometimes in the media, with disrupted stratification of the internal elastic lamina. Systemic vasculopathy has also been observed in patients with non-MMD carrying the RNF213 (ring finger protein 213) mutation, leading to the concept of RNF213 vasculopathy. RNF213 vasculopathy in patients with non-MMD was histopathologically similar to MMRSV. Cases of MMRSV have sometimes been diagnosed with fibromuscular dysplasia. Fibromuscular dysplasia is similar to MMD not only in the histopathologic findings of MMRSV but also from clinicopathological and genetic viewpoints. The significant histopathologic difference between MMV and MMRSV may be attributed to a difference in the original vascular wall structure and its resistance to pathological stress between the intracranial and systemic arteries. To understand the pathogeneses of MMD and MMRSV, a broader perspective that includes RNF213 vasculopathy and fibromuscular dysplasia as well as an examination of the 2- or multiple-hit theory consisting of genetic factors, vascular structural conditions, and vascular environmental factors, such as blood immune cells and hemodynamics, are needed.

Intensity Score of Vessel Wall Contrast Enhancement in MRI Allows Prediction of Disease Progression in Moyamoya Angiopathy

BACKGROUND AND OBJECTIVES

The underlying pathophysiological cause of moyamoya angiopathy (MMA) is still unclear. High-resolution vessel wall imaging has become a useful tool. The aim was to study vessel wall contrast-enhancement (VW-CE) as an imaging marker to predict disease progression in MMA.

METHODS

Patients with MMA, who had undergone serial contrast-enhanced high-resolution MRI with concomitant and follow-up digital subtraction angiography, were analyzed retrospectively. VW-CE was semiquantified by measurement of the signal intensity of the vessel wall in in contrast-enhanced high-resolution MRI. A comparative quotient with the contrast-intensity of the pituitary stalk was calculated and graded accordingly from grade 1 to 5. VW-CE status was correlated with disease status, stroke, cerebrovascular reactivity in CO2-triggered blood-oxygen level-dependent MRI, angiographic disease progression, revascularization surgery, and follow-up imaging.

RESULTS

Forty eight patients met the inclusion criteria. N = 56 MRI and digital subtraction angiography time-intervals were evaluated for 12 vessel sections per hemisphere each (N = 1344). N = 38 (79%) patients showed VW-CE and N = 10 (21%) did not. VW-CE was only observed in the terminal internal carotid artery and the proximal circle of Willis (N = 96/1344). Notably, patients with VW-CE significantly more often presented with acute infarction in the concomitant MRI. The incidence of angiographically proven disease progression was significantly associated with the incidence of VW-CE, and time to disease progression was earlier in higher grades of VW-CE compared with lower grades.

CONCLUSION

VW-CE is a semiquantifiable marker for disease activity in patients with MMA and associated with disease progression and increased risk of stroke. VW-CE analysis can be routinely performed in patients with MMA to estimate the risk for disease progression and stroke.

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.

Diagnostic Yield of High-Resolution Vessel Wall Magnetic Resonance Imaging in the Evaluation of Young Stroke Patients

(1) Background: The mechanism responsible for stroke in patients younger than 50 often remains unknown. This study was designed to assess whether high-resolution intracranial vessel wall MR imaging (icVWI) may be instrumental in determining stroke cause. (2) Methods: Young stroke patients with and without an identified cause of stroke despite an exhaustive investigation were prospectively included. Patients who underwent icVWI were compared to those who did not. We next compared patients with and without intracranial vulnerable plaques on icVWI. (3) Results: Overall, 47 young stroke patients were identified over the span of 2 years and included in this study. Of those, 20 (42%) underwent intracranial icVWI. Cancer prevalence was higher among patients who did not have an icVWI study (19% vs. 0% p = 0.042) but there were no other significant differences between patients who had an icVWI study and those who did not have an icVWI. Among patients who had an icVWI, 11 (55%) had vulnerable plaques and the remaining nine studies were negative. Patients with positive icVWI scans had significantly higher stroke severity at admission (mean ± SD NIHSS score 5.5 ± 3.5 vs. 1.7 ± 2.3, p = 0.012). Patients with positive icVWI scans were more often treated with antiplatelets upon discharge (100% vs. 67%, p = 0.038). (4) Conclusions: icVWI can add significant information relevant to stroke pathogenesis and secondary prevention among young stroke patients with a negative exhaustive diagnostic workup.

Impact of high-resolution intracranial vessel wall magnetic resonance imaging on diagnosis in patients with embolic stroke of unknown source

BACKGROUND

The mechanism responsible for stroke in patients with embolic stroke of unknown source (ESUS) often remains unknown despite extensive investigations. We aimed to test whether high-resolution intracranial vessel wall MR imaging (icVWI) can add to the diagnostic yield in these patients.

PATIENTS AND METHODS

Patients with ESUS were prospectively included into an ongoing registry. Patients that underwent icVWI as part of their diagnostic workup were compared to those that did not have an icVWI. Patients with icVWI positive for intracranial vulnerable plaques were than compared to those without evidence of plaque vulnerability on VWI.

RESULTS

A total of 179 patients with ESUS were included and 48 of them (27%) underwent icVWI. Patients that had an icVWI scan were significantly younger, had lower rates of ischemic heart disease and prior disability as well as significantly lower stroke severity. On regression analysis the only factor that remained associated with not obtaining an icVWI scan was increasing age (Odds ratio [OR] 0.97/year, 95% confidence intervals [CI] 0.95-0.97). Among patients that had an icVWI scan 28 (58%) had evidence of plaque enhancement on VWI in the same distribution of the stroke and the remaining 20 studies were negative. The relative proportion of stroke presumed to be secondary to intracranial non-stenotic atheromatous disease increased from 15% in patients without icVWI scans to 58% among patients with icVWI scans (p = 0.001). On regression analysis the only factor that was associated with vulnerable plaques on icVWI was smoking (OR 11.05 95% CI 1.88-65.17).

CONCLUSIONS

icVWI can add significant information relevant to stroke pathogenesis and treatment in patients with ESUS and a negative initial exhaustive diagnostic workup.

Vessel Wall Imaging of Intracranial Arteries: Fundamentals and Clinical Applications

With the increasing use of 3-tesla MRI scanners and the development of applicable sequences, it has become possible to achieve high-resolution, good contrast imaging, which has enabled the imaging of the walls of small-diameter intracranial arteries. In recent years, the usefulness of vessel wall imaging has been reported for numerous intracranial arterial diseases, such as for the detection of vulnerable plaque in atherosclerosis, diagnosis of cerebral arterial dissection, prediction of the rupture of cerebral aneurysms, and status of moyamoya disease and cerebral vasculitis. In this review, we introduce the histological characteristics of the intracranial artery, discuss intracranial vessel wall imaging methods, and review the findings of vessel wall imaging for various major intracranial arterial diseases.

The diagnostic performance of high-resolution magnetic resonance-vessel wall imaging in differentiating atherosclerosis-associated moyamoya vasculopathy from moyamoya disease

OBJECTIVES

To evaluate the diagnostic performance of high-resolution magnetic resonance-vessel wall imaging (HRMR-VWI) in differentiating moyamoya disease (MMD) from atherosclerosis-associated moyamoya vasculopathy (AS-MMV) and investigate an accurate approach for the differential diagnosis.

METHODS

Adult patients who were diagnosed as MMD or AS-MMV and underwent HRMR-VWI were retrospectively included. The three vessel wall features (outer diameter (OD), remodeling index (RI), and pattern of vessel wall thickening) of middle cerebral artery (MCA) in identifying MMD from AS-MMV were assessed and compared. Furthermore, subgroup analysis stratified by degree of luminal stenosis was performed and the cutoff values of different vessel wall features in differentiating MMD from AS-MMV were also calculated.

RESULTS

A total of 265 patients (160 cases of MMD and 105 AS-MMV) were included. Patients with AS-MMV had greater OD and RI and were more likely to exhibit eccentric thickening of vessel wall compared to those with MMD (all p < 0.001). The ROC analysis showed that the AUC value of OD was greater than that of RI (0.912 vs. 0.889, p = 0.007) in differentiating MMD from AS-MMV, and their corresponding cutoff values were 1.77 mm and 0.27, respectively. And the AUC value of pattern of vessel wall thickening was 0.786 in non-occluded patients. With the increase of lumen stenosis, the discrimination power of the three indicators enhanced correspondingly.

CONCLUSIONS

HRMR-VWI is valuable in distinguishing MMD from AS-MMV. The OD of MCA has better diagnostic performance in differentiating AS-MMV from MMD compared to RI and pattern of vessel wall thickening.

CLINICAL RELEVANCE STATEMENT

The outer diameter of the involved artery proved to be both accurate and convenient in distinguishing atherosclerosis-associated moyamoya vasculopathy from moyamoya disease and may provide a quantitative reference for clinical diagnosis.

KEY POINTS

High-resolution magnetic resonance-vessel wall imaging is valuable in distinguishing atherosclerosis-associated moyamoya vasculopathy from moyamoya disease. Compared to remodeling index and pattern of vessel wall thickening, outer diameter is more accurate in differentiating atherosclerosis-associated moyamoya vasculopathy from moyamoya disease. With the increase of lumen stenosis, the discrimination power of outer diameter, remodeling index, and pattern of vessel wall thickening enhanced correspondingly.

Evaluation of vessel-wall contrast-enhancement on high-resolution MRI in European patients with Moyamoya disease

OBJECTIVES

Data regarding MR vessel-wall imaging (VWI) in patients with Moyamoya disease (MMD) is sparse, particularly in non-asian cohorts. We contribute data regarding the frequency of vessel wall contrast-enhancement (VW-CE) and its potential clinical significance in a European patient group.

MATERIALS AND METHODS

Patients with a diagnosis of MMD who were examined by VWI were included in the study. VW-CE of stenoocclusive lesions of the terminal internal carotid artery and/or its proximal branches was rated qualitatively. Changes of VW-CE on available follow-up were recorded. VW-CE was correlated with diffusion-restricted lesions and magnetic resonance angiography (MRA) findings.

RESULTS

Eleven patients (eight female, three male) were included. Twenty-eight stenoocclusive lesions were analyzed, of which 16 showed VW-CE (57.1%). VW-CE was mostly concentric (n=15), rather than eccentric (n=1). In all three patients in whom follow-up VWI was available, changes of VW-CE were documented. Diffusion-restricted lesions were more frequently related to stenoocclusive lesions with VW-CE (n=9) than without VW-CE (n=2), bordering statistical significance. The affected arteries were assessed as stenotic and as occluded in 14 cases each and VW-CE was seen significantly more often in stenotic (n=12) than in occluded arteries (n=4). No correlation was found between the presence of VW-CE and moyamoya stages determined by MRA.

CONCLUSIONS

Our data suggest that concentric VW-CE is a relatively frequent finding in European MMD patients. VW-CE may change over time and occur in certain stages, possibly representing "active stenosing". Larger studies are needed to validate these findings and determine the clinical relevance of VW-CE in MMD.

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.

Vessel wall enhancement as a predictor of arterial stenosis progression and poor outcomes in moyamoya disease

OBJECTIVES

This study aimed to determine the association between vessel wall enhancement and progression of arterial stenosis and clinical outcomes in patients with moyamoya (MMD) using high-resolution magnetic resonance (HRMR) vessel wall imaging.

METHODS

Consecutive participants diagnosed with MMD were prospectively recruited and underwent HRMR at baseline and during follow-up, which had an interval period of ≥ 6 months and were clinically followed up for ≤ 24 months to record the occurrence of ischemic stroke. The relationship between vessel wall enhancement and arterial stenosis progression and stroke occurrence was evaluated.

RESULTS

HRMR vessel wall imaging was used to identify 309 stenotic lesions at the internal carotid artery (ICA) in 170 participants (mean age: 37.7 ± 11.3 years old, male: 44.1%). The baseline presence (adjusted odds ratio [aOR] = 3.57, 95% CI = 1.97-6.44, p < 0.001) and progression (aOR = 2.96, 95% CI = 1.29-6.80, p = 0.010) of vessel wall enhancement and middle cerebral artery (MCA) involvement (aOR = 4.98, 95% CI = 1.50-16.52, p = 0.009) were significantly associated with rapid progression of arterial stenosis. Furthermore, vessel wall enhancement (adjusted HR = 3.59, 95% CI = 1.33-9.70, p = 0.011) and rapid progression of arterial stenosis (adjusted HR = 4.52, 95% CI = 1.48-13.81, p = 0.008) were correlated with future stroke occurrence.

CONCLUSION

The baseline presence of vessel wall enhancement was associated with rapid progression of arterial stenosis and increased risk for stroke in MMD patients. Our findings suggest that vessel wall enhancement may serve as a predictor of disease progression and poor outcomes in MMD.

KEY POINTS

• The baseline presence of vessel wall enhancement was significantly associated with the rapid progression of arterial stenosis. • The baseline presence of vessel wall enhancement and rapid progression of arterial stenosis were both correlated with increased risk for future occurrence of stroke. • Our findings suggest that vessel wall enhancement may serve as a predictor of rapid progression of arterial stenosis and poor outcomes in MMD patients.

Long-term outcomes of moyamoya disease versus atherosclerosis-associated moyamoya vasculopathy using high-resolution MR vessel wall imaging

OBJECTIVES

We aimed to compare the long-term outcomes and surgical benefits between moyamoya disease (MMD) and atherosclerosis-associated moyamoya vasculopathy (AS-MMV) using high-resolution MRI (HRMRI).

METHODS

MMV patients were retrospectively included and divided into the MMD and AS-MMV groups according to vessel wall features on HRMRI. Kaplan-Meier survival and Cox regression were performed to compare the incidence of cerebrovascular events and prognosis of encephaloduroarteriosynangiosis (EDAS) treatment between MMD and AS-MMV.

RESULTS

Of the 1173 patients (mean age: 42.4±11.0 years; male: 51.0%) included in the study, 881 were classified into the MMD group and 292 into the AS-MMV group. During the average follow-up of 46.0±24.7 months, the incidence of cerebrovascular events in the MMD group was higher compared with that in the AS-MMV group before (13.7% vs 7.2%; HR 1.86; 95% CI 1.17 to 2.96; p=0.008) and after propensity score matching (6.1% vs 7.3%; HR 2.24; 95% CI 1.34 to 3.76; p=0.002). Additionally, patients treated with EDAS had a lower incidence of events than those not treated with EDAS, regardless of whether they were in the MMD (HR 0.65; 95% CI 0.42 to 0.97; p=0.043) or AS-MMV group (HR 0.49; 95% CI 0.51 to 0.98; p=0.048).

CONCLUSIONS

Patients with MMD had a higher risk of ischaemic stroke than those with AS-MMV, and patients with both MMD and AS-MMV could benefit from EDAS. Our findings suggest that HRMRI could be used to identify those who are at a higher risk of future cerebrovascular events.

Predictors of improvement for patients with CNS vasculitis stenoses: A high-resolution vessel wall MRI follow-up study

PURPOSE

To investigate the predictors of the improvement for patients with isolated intracranial vasculitis stenoses using high-resolution vessel wall magnetic resonance imaging (HR VW-MRI).

METHODS

We retrospectively reviewed data from consecutive patients with confirmed intracranial vasculitis under the same conventional conservative treatment based on a prospectively established HR VW-MRI database between December 2016 and December 2020. According to the changes between the degree of stenosis at baseline compared to follow-up MR angiography, the patients were divided into an improvement group and a non-improvement group. A multivariate analysis was performed to identify the predictive factors associated with the improvement of stenoses secondary to intracranial vasculitis.

RESULTS

Overall, 41 patients (mean age 32.0 ± 10.1 years, 16 females) with isolated intracranial vasculitis stenoses were included (41.5 % [17/41] in the improvement group, and 58.5 % [24/41] were in the non-improvement group). The degree of wall enhancement on follow-up imaging was significantly reduced compared with that on the baseline imaging in the improvement group (P = 0.004). The multivariate analysis showed that the degree of enhancement (OR, 0.219, 95 % CI, 0.054 to 0.881; P = 0.033) at baseline was an independent predictive factor associated with the improvement in the intracranial vasculitis stenoses.

CONCLUSIONS

In patients with isolated intracranial vasculitis stenoses, the less enhancement the vessel wall was, the more likely the degree of stenosis would be reduced by conventional conservative therapy.

Vessel wall imaging features of Moyamoya disease in a North American population: patterns of negative remodelling, contrast enhancement, wall thickening, and stenosis

Background

This study characterized vessel wall imaging (VWI) features of Moyamoya disease (MMD) in a predominantly adult population at a North American center.

Methods

Consecutive patients with VWI were included. Twelve arterial segments were analyzed for wall thickening, degree and pattern of contrast enhancement, and remodeling.

Results

Overall, 286 segments were evaluated in 24 patients (mean age = 36.0 years [range = 1–58]). Of 172 affected segments, 163 (95%) demonstrated negative remodeling. Complete vessel wall obliteration was most frequent in the proximal M1 (17/48, 35%). Affected segments enhanced in 72/172 (42%) (n = 15 for grade II; n = 54 for concentric and n = 18 for eccentric); 20 of 24 (83%) patients had at least one enhancing segment. Both enhancing and non-enhancing segments were present in 19/20 (95%) patients. Vessel wall enhancement was most common in the proximal segments and correlated to the degree of stenosis (p < 0.001), and outer wall diameter (p < 0.001), but not disease duration (p = 0.922) or Suzuki score (p = 0.477). Wall thickening was present in 82/172 (48%) affected segments and was associated with contrast enhancement (p < 0.001), degree of stenosis (p < 0.001), and smaller outer wall diameter (p = 0.004).

Conclusion

This study presents VWI findings in North American patients with MMD. Negative remodeling was the most common finding. Most patients had both enhancing and non-enhancing abnormal segments. Vessel wall enhancement was most common in proximal segments, variable in pattern or degree and was correlated to the degree of stenosis and smaller outer wall diameter.

Intracranial Artery Morphology in Pediatric Moya Moya Disease and Moya Moya Syndrome

BACKGROUND

Moya Moya disease (MMD) and Moya Moya syndrome (MMS) are cerebrovascular disorders, which affect the internal carotid arteries (ICAs). Diagnosis and surveillance of MMD/MMS in children mostly rely on qualitative evaluation of vascular imaging, especially MR angiography (MRA).

OBJECTIVE

To quantitatively characterize arterial differences in pediatric patients with MMD/MMS compared with normal controls.

METHODS

MRA data sets from 17 presurgery MMD/MMS (10M/7F, mean age = 10.0 years) patients were retrospectively collected and compared with MRA data sets of 98 children with normal vessel morphology (49 male patients; mean age = 10.6 years). Using a level set segmentation method with anisotropic energy weights, the cerebral arteries were automatically extracted and used to compute the radius of the ICA, middle cerebral artery (MCA), anterior cerebral artery (ACA), posterior cerebral artery (PCA), and basilar artery (BA). Moreover, the density and the average radius of all arteries in the MCA, ACA, and PCA flow territories were quantified.

RESULTS

Statistical analysis revealed significant differences comparing children with MMD/MMS and those with normal vasculature (P < .001), whereas post hoc analyses identified significantly smaller radii of the ICA, MCA-M1, MCA-M2, and ACA (P < .001) in the MMD/MMS group. No significant differences were found for the radii of the PCA and BA or any artery density and average artery radius measurement in the flow territories (P > .05).

CONCLUSION

His study describes the results of an automatic approach for quantitative characterization of the cerebrovascular system in patients with MMD/MMS with promising preliminary results for quantitative surveillance in pediatric MMD/MMS management.

7T MRI for Intracranial Vessel Wall Lesions and Its Associated Neurological Disorders: A Systematic Review

Intracranial vessel wall lesions are involved in a variety of neurological diseases. The advanced technique 7T MRI provides greater efficacy in the diagnosis of the pathology changes in the vessel wall and helps to identify potential subtle lesions. The purpose of this literature review was to systematically describe and evaluate the existing literature focusing on the use of 7T MRI in the detection and characterization of intracranial vessel wall lesions and their associated neurological disorders, to highlight the current knowledge gaps, and to formulate a framework to guide future applications and investigations. We systematically reviewed the existing articles up to July 2021, seeking the studies that assessed intracranial vessel wall lesions and their associated neurological disorders using 7T MRI. The literature search provided 12 studies that met the inclusion criteria. The most common intracranial vessel wall lesions were changes related to intracranial atherosclerosis (n = 8) and aneurysms (n = 4), such as intracranial atherosclerosis burden and aneurysm wall enhancement. The associated neurological disorders included aneurysms, ischemic stroke or TIA, small vessel disease, cognitive decline, and extracranial atherosclerosis. No paper studied the use of 7T MRI for investigating vessel wall conditions such as moyamoya disease, small vessel disease, or neurological disorders related to central nervous vasculitis. In conclusion, the novel 7T MRI enables the identification of a wider spectrum of subtle changes and associations. Future research on cerebral vascular diseases other than intracranial atherosclerosis and aneurysms may also benefit from 7T MRI.

Moyamoya Vasculopathy: Cause, Clinical Manifestations, Neuroradiologic Features, and Surgical Management

In moyamoya disease, the progressive occlusion of the distal portion of the internal carotid artery and its major branches is typically responsible for the formation of an extensive network of collateral vessels at the base of the brain. When moyamoya collateral network develops in association with various systemic or acquired diseases, the term moyamoya syndrome is used to denote this phenomenon. Sudden changes in the supraclinoid internal carotid artery and middle cerebral artery can be recognized with noninvasive neurovascular imaging techniques, which also allow a differential diagnosis with similar diseases such as degenerative steno-occlusive disease, cerebral vasculitis, and twig-like middle cerebral artery. Once the diagnosis is established, the definitive treatment for moyamoya disease is surgical revascularization, with the goal of increasing cerebral blood flow and preventing recurrent stroke. We provide a comprehensive review of the clinical and radiologic features in moyamoya vasculopathy along with its surgical management.

Vessel Wall Magnetic Resonance Imaging in Cerebrovascular Diseases

Cerebrovascular diseases are a leading cause of disability and death worldwide. The definition of stroke etiology is mandatory to predict outcome and guide therapeutic decisions. The diagnosis of pathological processes involving intracranial arteries is especially challenging, and the visualization of intracranial arteries’ vessel walls is not possible with routine imaging techniques. Vessel wall magnetic resonance imaging (VW-MRI) uses high-resolution, multiparametric MRI sequences to directly visualize intracranial arteries walls and their pathological alterations, allowing a better characterization of their pathology. VW-MRI demonstrated a wide range of clinical applications in acute cerebrovascular disease. Above all, it can be of great utility in the differential diagnosis of atherosclerotic and non-atherosclerotic intracranial vasculopathies. Additionally, it can be useful in the risk stratification of intracranial atherosclerotic lesions and to assess the risk of rupture of intracranial aneurysms. Recent advances in MRI technology made it more available, but larger studies are still needed to maximize its use in daily clinical practice.

A case report of critical ischemic stroke in moyamoya-like vasculopathy accompanied by systemic lupus erythematosus

Moyamoya-like vasculopathy (MMV) is a rare, chronic, progressive cerebrovascular disorder characterized by stenosis or occlusion of the terminal portion of the bilateral internal carotid arteries and development of abnormal collateral vessels at the base of the brain. This disorder develops in association with various systemic diseases and conditions, including neurofibromatosis type 1, Down syndrome, thyroid disease, radiation therapy, and autoimmune disease. We report a case of a 51-year-old female patient with low-activity systemic lupus erythematosus (SLE) who had a sudden onset of global aphasia and right hemiplegia. Three months previous, she had been on antiplatelet medication due to a single transient ischemic attack. Brain magnetic resonance imaging demonstrated a massive infarct of the left middle cerebral artery territory. Conventional angiography showed complete occlusion of the left middle cerebral artery with poor development of basal collateral vessels. This case demonstrates that a patient with underlying autoimmune disease such as SLE accompanied by MMV should be considered vulnerable to ischemic stroke.

Structural Abnormalities in Pediatric Moyamoya Disease Revealed by Clinical Magnetic Resonance Imaging, Regionally Distributed Relative Signal Intensities and Volumes

Moyamoya disease (MMD) is a rare, progressive cerebrovascular disorder, with an unknown etiology and pathogenesis. It is characterized by steno-occlusive changes at the terminal portion of the internal carotid artery (ICA), which is accompanied by variable development of the basal collaterals called moyamoya vessels. In this study, we investigate the potential for structural T1 magnetic resonance imaging (MRI) to help characterize MMD clinically, with the help of regionally distributed relative signal intensities (RRSIs) and volumes (RRVs). These RRSIs and RRVs provide the ability to characterize aspects of regional brain development and represent an extension to existing automated biomarker extraction technologies. This study included 269 MRI examinations from MMD patients and 993 MRI examinations from neurotypical controls, with regional biomarkers compared between groups with the area under the receiver operating characteristic curve (AUC). Results demonstrate abnormal presentation of RRSIs and RRVs in the insula (15-20 year old cohort, left AUC: 0.74, right AUC: 0.71), and the lateral orbitofrontal region (5-10 year old cohort, left AUC: 0.67; 15-20 year cohort, left AUC: 0.62, right AUC: 0.65). Results indicate that RRSIs and RRVs may help in characterizing brain development, assist in the assessment of the presentation of the brains of children with MMD, and may help overcome standardization challenges in multi-protocol clinical MRI. Further investigation of the potential for RRSIs and RRVs in clinical imaging is warranted and supported through the release of open source software.

Pathophysiology of Vascular Stenosis and Remodeling in Moyamoya Disease

Moyamoya disease (MMD) and moyamoya syndrome (MMS) are progressive vascular pathologies unique to the cerebrovasculature that are important causes of stroke in both children and adults. The natural history of MMD is characterized by primary progressive stenosis of the supraclinoid internal carotid artery, followed by the formation of fragile collateral vascular networks. In MMS, stenosis and collateralization occur in patients with an associated disease or condition. The pathological features of the stenosis associated with MMD include neointimal hyperplasia, disruption of the internal elastic lamina, and medial attenuation, which ultimately lead to progressive decreases in both luminal and external arterial diameter. Several molecular pathways have been implicated in the pathophysiology of stenosis in MMD with functions in cellular proliferation and migration, extracellular matrix remodeling, apoptosis, and vascular inflammation. Importantly, several of these molecular pathways overlap with those known to contribute to diseases of systemic arterial stenosis, such as atherosclerosis and fibromuscular dysplasia (FMD). Despite these possible shared mechanisms of stenosis, the contrast of MMD with other stenotic pathologies highlights the central questions underlying its pathogenesis. These questions include why the stenosis that is associated with MMD occurs in such a specific and limited anatomic location and what process initiates this stenosis. Further investigation of these questions is critical to developing an understanding of MMD that may lead to disease-modifying medical therapies. This review may be of interest to scientists, neurosurgeons, and neurologists involved in both moyamoya research and treatment and provides a review of pathophysiologic processes relevant to diseases of arterial stenosis on a broader scale.

Cortical thickness in clinical moyamoya disease: A magnetic resonance imaging study

Moyamoya disease (MMD) is a progressive cerebrovascular disorder, with an unknown pathogenesis and aetiology. MMD is characterized by steno-occlusive changes at the terminal portion of the internal carotid artery (ICA), which is accompanied by variable development of the basal collaterals, also known as moyamoya vessels. Patients with MMD show variable patterns of brain damage and may experience recurrent multiple transient ischaemic attacks, intracranial bleeding and cerebral infarction. In this study, we investigate the potential for structural T1 magnetic resonance imaging (MRI) to help characterize abnormal cortical development in MMD clinically, with an analysis of both average and variability of regional cortical thicknesses. This study also included a machine learning analysis to assess the predictive capacity of the cortical thickness abnormalities observed in this research. This study included 993 MRI examinations from neurotypical controls and 269 MRI examinations from MMD patients. Results demonstrate abnormal cortical presentation of the insula, caudate, postcentral, precuneus and cingulate regions, in agreement with previous literature cortical thickness findings as well as alternative methods such as functional MRI (fMRI) and digital angiography. To the best of our knowledge, this is the first manuscript to report cortical thickness abnormalities in the middle temporal visual area in MMD and the first study to report on cortical thickness variability abnormalities in MMD.

Diagnosis and follow-up evaluation of central nervous system vasculitis: an evaluation of vessel-wall MRI findings

Objective

To approach the clinical value of MRI with vessel wall imaging (VWI) in patients with central nervous system vasculitis (CNSV), we analyzed patterns of VWI findings both at the time of initial presentation and during follow-up.

Methods

Stenoocclusive lesions, vessel-wall contrast enhancement (VW-CE) and diffusion-restricted lesions were analyzed in patients with a diagnosis of CNSV. On available VWI follow-up, progression, regression or stability of VW-CE were evaluated and correlated with the clinical status.

Results

Of the 45 patients included, 28 exhibited stenoses visible on MR angiography (MRA-positive) while 17 had no stenosis (MRA-negative). VW-CE was found in 2/17 MRA-negative and all MRA-positive patients (p < 0.05). 79.1% (53/67) of stenoses showed VW-CE. VW-CE was concentric in 88.3% and eccentric in 11.7% of cases. Diffusion-restricted lesions were found more frequently in relation to stenoses with VW-CE than without VW-CE (p < 0.05). 48 VW-CE lesions in 23 patients were followed over a median time of 239.5 days. 13 VW-CE lesions (27.1%) resolved completely, 14 (29.2%) showed partial regression, 17 (35.4%) remained stable and 4 (8.3%) progressed. 22/23 patients received immunosuppressive therapy for the duration of follow-up. Patients with stable or progressive VW-CE were more likely (p < 0.05) to have a relapse (14/30 cases) than patients with partial or complete regression of VW-CE (5/25 cases).

Conclusion

Concentric VW-CE is a common finding in medium/large-sized vessel CNSV. VW-CE might represent active inflammation in certain situations. However, follow-up VWI findings proved ambiguous as persisting VW-CE despite immunosuppressive therapy and clinical remission was a frequent finding.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00415-021-10683-7.

High-resolution MRI of the vessel wall helps to distinguish moyamoya disease from atherosclerotic moyamoya syndrome

AIM

To evaluate the value of high-resolution magnetic resonance imaging of the vessel wall (VWI) for differentiating moyamoya disease (MMD) from atherosclerotic moyamoya syndrome (AS-MMS).

MATERIALS AND METHODS

Twenty-one patients with MMD or AS-MMS were assessed retrospectively by two independent raters regarding and magnetic resonance angiography (MRA) stage grading score; collateral development in the lateral fissure and basal ganglia on MRA; and pattern of the thickening of the arterial wall; presence, degree, and pattern of enhancement; presence and distribution of deep tiny flow voids (DTFVs) and collateral development in the lateral fissure and basal ganglia on VWI. After univariate analysis between the two groups, logistic regression models based on imaging findings of MRA or VWI were implemented respectively, and receiver operating characteristic (ROC) curves were generated to compare the discriminatory power of the two imaging methods for diagnosis of MMD. Interrater agreement was analysed using an unweighted Cohen's κ or interclass correlation coefficient (ICC).

RESULTS

MMD manifested as more concentric thickening, more homogeneous enhancement, higher presence of DTFV, smaller outer-wall boundary area of stenosis or occlusion, and smaller remodelling index on VWI. After Bonferroni-Holm correction for multiple comparisons, for AS-MMS, collaterals in both the lateral fissure and basal ganglia were not usually present on either MRA or VWI. The diagnostic performance of the multivariate logistic regression model based on VWI with an accuracy of 87.1% for classification was higher than MRA. Interrater agreement was moderate or substantial for all the imaging findings.

CONCLUSIONS

VWI might be a useful and feasible method for differentiating MMD from AS-MMS and a prospective tool for guiding first-line treatment.

A High Resolution MRI Study of the Relationship Between Plaque Enhancement and Perforator Stroke after Stenting for Symptomatic Vertebrobasilar Artery Stenosis

BACKGROUND AND PURPOSE

Perforator stroke is one of the most common complications of vertebrobasilar arterial stenting. We investigated whether perforator stroke after vertebrobasilar arterial stenting is associated with plaque enhancement in patients with severe vertebrobasilar artery stenosis.

METHODS

We studied patients with symptomatic vertebrobasilar arterial stenosis who underwent stenting from January 2017 to July 2020. Patients who underwent high resolution magnetic resonance imaging were recruited among them. Demographic data, risk factors of atherosclerosis, procedure details, and characteristics of imaging were extracted from electronic health records and imaging data. Plaque features were investigated by high resolution magnetic resonance imaging.

RESULTS

136 patients were enrolled in this study, 39 of whom fulfilled the inclusion criteria. 18 patients (46.2%) had obvious plaque enhancement among the 39 patients, and 21 (53.8%) had plaque non-enhancement. 21 patients (53.8%) had diffuse distribution, and 22 patients (56.4%) had irregular plaques surface. Patients were divided into plaque enhanced and plaque non-enhanced groups according to the degree of plaque enhancement. Clinical characteristics and other plaque features were similar between two groups. Procedure-related perforator stroke was identified in 4 patients (10.3%). Patients with plaque enhancement were more likely to have perforator stroke after stenting compared with those with plaque non-enhancement (22.2% versus 0%, P = 0.037).

CONCLUSIONS

Plaque enhancement in high resolution magnetic resonance imaging may be associated with perforator stroke after vertebrobasilar artery stenting.

Imaging endpoints of intracranial atherosclerosis using vessel wall MR imaging: a systematic review

PURPOSE

The vessel wall MR imaging (VWI) literature was systematically reviewed to assess the criteria and measurement methods of VWI-related imaging endpoints for symptomatic intracranial plaque in patients with ischemic events.

METHODS

PubMed, Scopus, Web of Science, EMBASE, and Cochrane databases were searched up to October 2019. Two independent reviewers extracted data from 47 studies. A modified Guideline for Reporting Reliability and Agreement Studies was used to assess completeness of reporting.

RESULTS

The specific VWI-pulse sequence used to identify plaque was reported in 51% of studies. A VWI-based criterion to define plaque was reported in 38% of studies. A definition for culprit plaque was reported in 40% of studies. Frequently scored qualitative imaging endpoints were plaque quadrant (21%) and enhancement (21%). Frequently measured quantitative imaging endpoints were stenosis (19%), lumen area (15%), and remodeling index (14%). Reproducibility for all endpoints ranged from good to excellent (range: ICC_{T1 hyperintensity} = 0.451 to ICC_stenosis = 0.983). However, rater specialty and years of experience varied among studies.

CONCLUSIONS

Investigators are using different criteria to identify and measure VWI-imaging endpoints for culprit intracranial plaque. Early awareness of these differences to address methods of acquisition and measurement will help focus research resources and efforts in technique optimization and measurement reproducibility. Consensual definitions to detect plaque will be important to develop automatic lesion detection tools particularly in the era of radiomics.

Vessel Wall and Lumen Features in North American Moyamoya Patients

PURPOSE

To apply intracranial vessel wall imaging (VWI) to determine changes in vessel wall characteristics between North American moyamoya patients and controls, as well as with standard clinical measures of moyamoya disease severity.

METHODS

North American moyamoya patients and controls underwent intracranial 3.0 T VWI. Moyamoya patients also underwent digital subtraction angiography (DSA), from which modified Suzuki scores (mSS) were calculated. Lumen and outer vessel wall diameters of the supraclinoid internal carotid arteries (ICAs) and basilar artery on VWI were measured by two readers from which wall thickness was calculated. Controls and moyamoya patients were compared in logistic regression using disease category (moyamoya or none) as the dependent variable and wall thickness, age, gender, and side as the explanatory variables (significance: two-sided p < 0.05). In moyamoya patients, regression was performed with mSS as the dependent variable and wall thickness, age, gender, and side as the explanatory variables. Analyses were repeated for each lumen diameter and outer vessel wall diameter in place of wall thickness.

RESULTS

Patients with moyamoya (n = 23, gender = 3/20 male/female; age = 43 ± 12 years) and controls (n = 23, gender = 3/20 male/female, age = 43 ± 13 years) were included. Moyamoya patients showed a significantly smaller ICA lumen and outer vessel wall diameter compared to controls (p < 0.05) but no significant change in vessel wall thickness. Similarly, ICA lumen and outer vessel wall diameters decreased with increasing mSS (p < 0.05).

CONCLUSION

Findings suggest decreased ICA lumen and outer vessel wall diameters, but no significant difference in wall thickness, between patients and controls. Lumen and outer vessel wall diameters also decreased with disease severity.

Luminal and Wall Changes in Intracranial Arterial Lesions for Predicting Stroke Occurrence

BACKGROUND AND PURPOSE

Luminal imaging (degree of stenosis) currently serves as the gold standard to predict stroke recurrence and guide therapeutic strategies in patients with intracranial large artery diseases (ILADs). We comparatively evaluated the importance of vessel wall and luminal changes in predicting stroke occurrence.

METHODS

Consecutive patients with ILAD in the proximal middle cerebral artery or distal internal carotid artery without proximal sources of embolism from the carotid and heart underwent time-of-flight magnetic resonance angiography, high-resolution magnetic resonance imaging, and the ring finger protein 213 (RNF213) gene variant test. Patients were followed up for >3 months.

RESULTS

Of the 675 patients, 241 (35.7%) had atherosclerotic ILAD and 434 (64.3%) showed nonatherosclerotic ILAD (315 [46.7%] moyamoya disease cases and 119 [17.6%] dissection cases). The RNF213 variant was detected in 74.9%, 33.6%, and 3.4% patients with moyamoya disease, atherosclerosis, and dissection, respectively. Three hundred (44.4%) patients had asymptomatic ILAD, whereas 375 (55.6%) patients had symptomatic ILAD. Multivariate analysis showed that vessel enhancement and etiological subtypes, not degree of stenosis, determined by high-resolution magnetic resonance imaging and RNF213 gene variant analysis were independently associated with symptomatic ILAD. The presence of the RNF213 variant was also independently associated with recurrent cerebrovascular events.

CONCLUSIONS

This study demonstrates the prevalence of nonatherosclerotic ILAD in East Asian patients with ILAD. Unlike luminal changes, wall changes determined by high-resolution magnetic resonance imaging and presence of the RNF213 variant could predict stroke occurrence in patients with ILADs.

Vessel Wall Thickening and Enhancement in High-Resolution Intracranial Vessel Wall Imaging: A Predictor of Future Ischemic Events in Moyamoya Disease

BACKGROUND AND PURPOSE

Very few data are available with regard to high-resolution intracranial vessel wall imaging characteristics of Moyamoya disease and their relation to ischemic stroke risk. We investigated the high resolution imaging characteristics of MMD and its correlation with recent ischemic events.

MATERIALS AND METHODS

Patients with Moyamoya disease confirmed by DSA, including patients after revascularization, were enrolled. All the patients underwent high-resolution intracranial vessel wall imaging. Vessel wall thickening, enhancement, and the remodeling index of the bilateral distal ICA and proximal MCA were noted. The patients were followed up at 3 months and 6 months after high-resolution intracranial vessel wall imaging and the association of ischemic events with imaging characteristics was assessed.

RESULTS

Twenty-nine patients with Moyamoya disease were enrolled. The median age at symptom onset was 12 years (range, 1-51 years). A total of 166 steno-occlusive lesions were detected by high-resolution intracranial vessel wall imaging. Eleven lesions with concentric wall thickening (6.6%) were noted in 9 patients. Ten concentric contrast-enhancing lesions were observed in 8 patients, of which 3 patients (4 lesions) showed grade II enhancement. The presence of contrast enhancement (P = .01) and wall thickening (P ≤ .001) showed a statistically significant association with ischemic events within 3 months before and after the vessel wall imaging. Grade II enhancement showed a statistically significant (P = .02) association with ischemic events within 4 weeks of high-resolution intracranial vessel wall imaging. The mean ± standard deviation outer diameter of the distal ICA (right, -3.3 ± 0.68 mm; left, 3.4 ± 0.60 mm) and the remodeling index (right, 0.71 ± 0.13; left, 0.69 ± 0.13) were lower in Moyamoya disease.

CONCLUSIONS

High-resolution intracranial vessel wall imaging characteristics of concentric wall thickening and enhancement are relatively rare in our cohort of patients with Moyamoya disease. The presence of wall thickening and enhancement may predict future ischemic events in patients with Moyamoya disease.

Cav-1 (Caveolin-1) and Arterial Remodeling in Adult Moyamoya Disease

Background and Purpose- Moyamoya disease (MMD) is a unique cerebrovascular occlusive disease characterized by progressive stenosis and negative remodeling of the distal internal carotid artery (ICA). We hypothesized that cav-1 (caveolin-1)-a protein that controls the regulation of endothelial vesicular trafficking and signal transduction-is associated with negative remodeling in MMD. Methods- We prospectively recruited 77 consecutive patients with MMD diagnosed via conventional angiography. Seventeen patients with intracranial atherosclerotic stroke and no RNF213 mutation served as controls. The outer distal ICA diameters were examined using high-resolution magnetic resonance imaging. We evaluated whether the degree of negative remodeling in the patients with MMD was associated with RNF213 polymorphism, cav-1 levels, or various clinical and vascular risk factors. We also investigated whether the derived factor was associated with negative remodeling at the cellular level using the tube formation and apoptosis assays. Results- The serum cav-1 level was lower in the patients with MMD than in the controls (0.47±0.29 versus 0.86±0.68 ng/mL; P=0.034). The mean ICA diameter was 2.48±0.98 mm for the 126 affected distal ICAs in patients with MMD and 3.84±0.42 mm for the asymptomatic ICAs in the controls ( P<0.001). After adjusting for confounders, cav-1 levels (coefficient, 1.018; P<0.001) were independently associated with the distal ICA diameter in patients with MMD. In vitro analysis showed that cav-1 downregulation suppressed angiogenesis in the endothelial cells and induced apoptosis in the smooth muscle cells. Conclusions- Our findings suggest that cav-1 may play a major role in negative arterial remodeling in MMD.

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.

Arterial wall contrast enhancement in progressive moyamoya disease

OBJECTIVE

The purpose of this study was to evaluate chronological patterns of arterial wall contrast enhancement in contrast-enhanced high-resolution MRI (CE-HR-MRI) in patients with moyamoya disease (MMD).

METHODS

The authors performed a blinded analysis of clinical and imaging data from MMD patients. Data were analyzed chronologically for each patient and the intensity of arterial wall enhancement was correlated with the clinical and imaging-based progression status of the disease.

RESULTS

A total of 31 MMD patients and 61 imaging time points were included. CE-HR-MRI results were available for 56 time points, representing 112 hemispheric analyses. No arterial wall contrast enhancement (grade 1) was seen in 54 (48%) of the analyses, mild enhancement (grade 2) in 24 (21%), moderate enhancement (grade 3) in 15 (13%), and strong (grade 4) mainly concentric arterial wall contrast enhancement in 19 (17%). Grade 4 contrast enhancement was significantly (p < 0.001) associated with clinical disease progression within 6 months (before or after the MRI) compared to grades 1-3, with positive and negative predictive values of 0.8 and 0.88, respectively. Grades 1 and 2 (no contrast enhancement and only mild contrast enhancement) were highly predictive for stable disease (negative predictive value: 0.95).

CONCLUSIONS

A specific chronological increasing and decreasing pattern of arterial wall contrast enhancement associated with "beginning" as well as progression of angiopathy occurs in MMD patients. In clinical practice, CE-HR-MRI of the arterial wall may help to identify patients at risk of new strokes caused by disease progression and hence impel early treatment for future stroke prevention. Understanding of this temporary enhancement of the arterial wall might also bring new insights into the etiology of MMD.

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.

Stenosis Severity-Dependent Shrinkage of Posterior Cerebral Artery in Moyamoya Disease

OBJECTIVE

The involved carotid forks in moyamoya disease (MMD) will show decreases in both luminal caliber and outer diameter. The present study aimed to clarify the changes in the outer diameter associated with luminal stenosis/occlusion of the posterior cerebral artery (PCA) in patients with MMD.

METHODS

The present study included 24 pediatric and 48 adult patients with MMD and 17 healthy adult controls. Using magnetic resonance angiography, the degree of PCA involvement was classified into 3 grades: grade 0, normal; grade 1, stenotic; and grade 2, occluded. Using 3-dimensional constructive interference in steady state, the outer diameters were quantified in the P2 segment. All the patients were followed up to identify the disease progression in the PCA.

RESULTS

The outer diameter of the P2 segment significantly decreased in a stepwise fashion in parallel with the severity of the luminal stenosis. In pediatric patients, the outer diameters of the P2 segments were 2.0 ± 0.26 mm, 1.5 ± 0.42 mm, and 0.87 ± 0.15 mm in those with grade 0, 1, and 2, respectively (P < 0.001). In adult patients, the outer diameters of the P2 segments were 2.0 ± 0.34 mm, 1.5 ± 0.34 mm, and 1.1 ± 0.17 mm in those with grade 0, 1, and 2, respectively (P < 0.001). We found no significant difference between grade 0 PCA of the adult patients and the PCA of the healthy controls (P = 0.92). Disease progression led to further arterial shrinkage of the P2 segment (n = 4).

CONCLUSIONS

The results of our study have shown that the involved PCA demonstrates, not only luminal stenosis, but also arterial shrinkage in MMD. This finding strongly suggests that the underlying mechanism in the development of MMD is common in both the carotid fork and PCA.

A High-Resolution MRI Study of the Relationship Between Plaque Enhancement and Ischemic Stroke Events in Patients With Intracranial Atherosclerotic Stenosis

Purpose: To investigate the relationships among the degree of intracranial atherosclerotic stenosis (ICAS), plaque enhancement (PE), and ischemic stroke events (ISEs) using 3. 0 T high-resolution magnetic resonance imaging (HR-MRI). Materials and Methods: Fifty-two ICAS patients who underwent HR-MRI were retrospectively analyzed. The patients were divided into two groups according to the results of whole-brain digital subtraction angiography (DSA): the mild-moderate stenosis group (group MID) and the severe stenosis group (group SEV). According to the onset time of the ISEs, the plaques were divided into the acute/sub-acute phase culprit plaque group (group ACU, within 1 month), the chronic-phase culprit plaque group (group CHR, more than 1 month), and the non-culprit plaque group (group NON). Two neuroradiologists independently measured the signal intensity of PE and pituitary enhancement in the HR-MRI and calculated the ratio of the two indices. According to the ratio, the patients were divided into three groups: the marked enhancement group (group MA), the mild enhancement group (group ME), and the no enhancement plaque group (group NO). The relationships among the degree of ICAS, the degree of PE and ISEs were analyzed. Results: Seventy-two ICAS plaques were identified in 52 patients. The multiple independent samples Kruskal-Wallis H test showed that the differences among group ACU, CHR, and NON were significant in the degree of PE (P = 0.002). Group CHR and group NON were combined as the non-acute phase group (group non-ACU). Group NO and group ME were combined as the non-marked enhancement group (group non-MA). The comparison between group ACU and group non-ACU showed significant differences in the degree of both ICAS (P = 0.014) and PE (P = 0.006) according to the univariate logistic regression. The multivariate logistic regression model was used to analyze the impact of the degree of ICAS and PE on ISEs, and the results showed that severe stenosis (P = 0.036) and marked PE (P = 0.013) were independent risk factors for acute ISEs, respectively. Conclusion: Severe intracranial arterial stenosis and marked plaque enhancement are independent risk factors for acute ischemic stroke events, respectively. The study provides new ideas for further exploring the pathogenesis of stroke caused by intracranial atherosclerotic stenosis.

Proximal internal carotid artery stenosis associates with diffuse wall thickening in petrous arterial segment of moyamoya disease patients: a three-dimensional magnetic resonance vessel wall imaging study

PURPOSE

To investigate the association between proximal internal carotid artery (ICA) luminal narrowing and diffuse wall thickening (DWT) in ipsilateral petrous ICA in moyamoya disease (MMD) patients.

METHODS

Forty-one MMD (mean age 42.8 ± 11.0 years, 19 males) and 36 atherosclerotic patients (mean age 61.5 ± 7.1 years, 31 males) and 41 healthy controls were recruited and underwent carotid MR vessel wall imaging. The luminal narrowing of proximal ICA was evaluated by the diameter ratio of ICA to common carotid artery (DR_ICA/CCA). The wall thickness of petrous ICA was measured on T1-VISTA images. The enhancement degree of petrous ICA was recorded and graded into four grades (none to marked) on the CE-T1-VISTA images. The correlation between wall thickness in petrous ICA and DR_ICA/CCA was analyzed_. RESULTS: In total, 81 arteries of MMD patients and 64 arteries of atherosclerotic patients were included for analysis. The DR_ICA/CCA was significantly correlated with the wall thickness in petrous ICA in MMD (r = - 0.434, P < 0.001) and atherosclerotic groups (r = - 0.604, P < 0.001). Logistic regression analysis revealed that odds ratio (OR) of DR_ICA/CCA was 4.433 (95% CI 1.980-9.925, P < 0.001) and 2.212 (95% CI 1.253-3.905, P = 0.006) in MMD and atherosclerotic groups in discriminating petrous ICA DWT after adjusting for confounding factors. An increasing trend was found in prevalence of DWT and wall thickness with enhancement grades in petrous ICA in MMD (P = 0.02 and P = 0.01) and atherosclerotic groups (P < 0.001 and P < 0.001), respectively.

CONCLUSIONS

The proximal ICA luminal narrowing is significantly associated with wall thickness and diffuse wall thickening in ipsilateral petrous ICA in patients with carotid steno-occlusive diseases regardless of MMD or atherosclerosis.

CD59 deficiency presenting as polyneuropathy and Moyamoya syndrome with endothelial abnormalities of small brain vessels

CD59 is involved in lymphocyte signal transduction and regulates complement-mediated cell lysis by inhibiting the membrane attack complex. In the cases reported so far, congenital isolated CD59 deficiency was associated with recurrent episodes of hemolytic anemia, peripheral neuropathy, and strokes. Here, we report on a patient from a consanguineous Turkish family, who had a first episode of hemolytic anemia at one month of age and presented at 14 months with acute Guillain-Barré syndrome (GBS). The child suffered repeated infection-triggered relapses leading to the diagnosis of chronic inflammatory demyelinating polyneuropathy (CIDP). Although partly steroid-responsive, the polyneuropathy failed to be stabilized by a number of immunosuppressive agents. At the age of 6 years, he developed acute hemiparesis and showed progressive stenosis of proximal cerebral arteries, evolving into Moyamoya syndrome (MMS) with recurrent infarctions leading to death at 8 years of age. Post-mortem genetic analysis revealed a pathogenic p.(Asp49Valfs*31) mutation in CD59. Re-analysis of brain biopsy specimens showed absent CD59 expression and severe endothelial damage. Whereas strokes are a known feature of CD59 deficiency, MMS has not previously been described in this condition. Therefore, we conclude that in MMS combined with hemolysis or neuropathy CD59 deficiency should be considered. Establishing the diagnosis and targeted therapy with eculizumab might have prevented the lethal course in our patient.

3D Black-Blood Luminal Angiography Derived from High-Resolution MR Vessel Wall Imaging in Detecting MCA Stenosis: A Preliminary Study

BACKGROUND AND PURPOSE

3D high-resolution vessel wall imaging is increasingly used for intracranial arterial diseases. This study compared the diagnostic performance of black-blood luminal angiography derived from 3D vessel wall imaging with source images of vessel wall imaging and TOF-MRA in detecting middle cerebral artery stenosis.

MATERIALS AND METHODS

Sixty-two patients with suspected MCA atherosclerosis underwent TOF-MRA, vessel wall imaging, and CTA. Intracranial black-blood luminal angiography was created from source images of vessel wall imaging using minimum intensity projection. The degree and length of MCA stenosis were measured on source images of vessel wall imaging, TOF-MRA, and black-blood luminal angiography and compared using CTA as a reference standard.

RESULTS

The image quality of black-blood luminal angiography was diagnostic in most patients. The intra- and interobserver agreement for both stenosis degree and length measurements was excellent for black-blood luminal angiography. It was comparable with that of source images of vessel wall imaging in grading stenosis. Compared with TOF-MRA, black-blood luminal angiography showed significantly higher sensitivity for the detection of severe stenosis (89.3% versus 64.3%, P = .039) and higher specificity for the detection of occlusion (95.4% versus 84.6%, P = .039). Lesion length estimated on source images of vessel wall imaging was significantly greater than that measured by CTA and black-blood luminal angiography (P < .001 and P = .010).

CONCLUSIONS

Black-blood luminal angiography is better than TOF-MRA in detecting severe stenosis and occlusion of the MCA. Compared with source images of vessel wall imaging, it is more accurate in evaluating stenosis length. Black-blood luminal angiography can be produced as a derivative from vessel wall imaging and implemented as an adjunct to vessel wall imaging and TOF-MRA without extra acquisition time.

Significance of hyperintense arteries on Gd-enhanced 3D T1W black-blood imaging in acute stroke

OBJECTIVES

To elucidate the pathogenesis of hyperintense arteries on Gd-enhanced 3D T1W BB FSE and their clinical significance in acute middle cerebral artery (MCA) stroke.

METHODS

We retrospectively reviewed 20 patients with MCA infarction. We measured the contrast-to-noise ratio between hyperintense artery and adjacent grey matter on T2-FLAIR and Gd-enhanced 3D T1W BB FSE and compared them by using Student's t test. The agreement of positive hyperintense artery between T2 FLAIR and Gd-enhanced 3D T1WI BB FSE was estimated with intraclass correlation coefficient. Our cohort was dichotomised into two groups depending on hyperintense artery scores, and clinical data were compared between two groups by using Student's t test and chi-square test.

RESULTS

The contrast between hyperintense artery and grey matter on Gd-enhanced 3D T1W BB FSE was significantly higher than that on T2-FLAIR (2.27 ± 1.65 versus 0.94 ± 0.86, p = 0.01). Overall, agreement of hyperintense arteries on T2-FLAIR and Gd-enhanced 3D T1W BB FSE was excellent (ρ = 0.76, p < 0.01). Patients with higher hyperintense artery scores had higher perfusion deficits that those with lower hyperintense artery scores (196.7 ± 41.4 vs 100.1 ± 130.1, p = 0.03).

CONCLUSION

Hyperintense arteries on Gd-enhanced 3D T1W BB FSE in acute MCA stroke may be associated with slow collateral flows. Their territories corresponded to those of FLAIR, but had a better contrast. The patients with hyperintense arteries in a wider territory showed larger perfusion deficit than those with hyperintense arteries in a narrower territory.

KEY POINTS

• Hyperintense arteries on Gd-enhanced 3D T1W BB FSE are slow collateral flows. • Hyperintense arteries on Gd-enhanced 3D T1W BB FSE are well matched with FLAIR hyperintense vessels. • Hyperintense arteries are associated with perfusion deficit in stroke patients.

Progress in moyamoya disease

Moyamoya disease is characterized by progressive stenosis or occlusion of the intracranial portion of the internal carotid artery and their proximal branches, resulting in ischemic or hemorrhagic stroke with high rate of disability and even death. So far, available treatment strategies are quite limited, and novel intervention method is being explored. This review encapsulates current advances of moyamoya disease on the aspects of epidemiology, etiology, clinical features, imaging diagnosis and treatment. In addition, we also bring forward our conjecture, which needs to be testified by future research.

Prediction of Intracranial Arterial Stenosis Progression in Patients with Moyamoya Vasculopathy: Contrast-Enhanced High-Resolution Magnetic Resonance Vessel Wall Imaging

OBJECTIVE

Moyamoya vasculopathy (MMV) is characterized by progressive stenosis of the intracranial arteries. MMV currently has no curative treatments, and cerebral ischemia and hemorrhage are the major outcomes. Evaluation of the stroke risk of each patient resulting from the progression of intracranial arterial stenosis is clinically important.

METHODS

We prospectively reviewed patients with intracranial arterial stenosis and already diagnosed MMV. High-resolution magnetic resonance imaging using contrast agent is the novel vessel wall imaging (VWI) technique for directly evaluating vascular walls and intracranial artery disease. All patients underwent high-resolution vessel wall imaging and magnetic resonance angiography at the time of registration, and they underwent follow-up magnetic resonance angiography. The Fisher exact test was used to assess associations between the degrees of wall enhancement and between stable and progressive intracranial arterial stenosis.

RESULTS

A total of 24 patients (17 female; mean age, 36.1 ± 16.8 years; range 3-67 years) with MMV were consecutively recruited to this study. Progression of stenosis was shown in 6 lesions (66.6%) on strong enhancement, 2 lesions (12.5%) on mild enhancement, and 1 lesion (4.3%) on lack of enhancement. Arterial vessel wall enhancement in MMV patients correlated closely with progression of intracranial arterial stenosis (P = 0.002).

CONCLUSIONS

Arterial vessel wall enhancement in MMV patients was closely related to progression of intracranial arterial stenosis. Strong enhancement of the intracranial vessel wall was associated with intracranial arterial stenosis progression, and lack of enhancement correlated with the stability of intracranial arterial stenosis.

Contrast-Enhanced Color-Coded Doppler Sonography in Moyamoya Disease: A Retrospective Study

The purpose of this study was to validate the feasibility of contrast-enhanced transcranial Doppler sonography (CE-TCCD) in the diagnosis of Moyamoya disease (MMD). CE-TCCD data on patients with MMD were analyzed. The CE-TCCD data were classified qualitatively into four patterns by two independent investigators: normal vascular color Doppler signal (pattern 1), augmented color Doppler signal with identifiable vascular structure (pattern 2), confluent color Doppler signal filling more than two-thirds of the display frame without identifiable vascular structure (pattern 3) and confluent color Doppler signal filling full display (pattern 4). To investigate the validity, we compared the CE-TCCD data with traditional transcranial Doppler data and Suzuki grades on cerebral angiography. A total of 32 CE-TCCD studies from 16 MMD patients (male 37.5%, median age 48) were included in this study. The CE-TCCD findings were distributed across patterns 1 (n = 3), 2 (n = 12), 3 (n = 10) and 4 (n = 7) and were correlated with the Suzuki grades (p <0.005) and hemodynamic parameters. Inter-rater reliability was promising (Cronbach α = 0.883). The CE-TCCD test provides distinctive patterns in MMD, according to their stage of progression. CE-TCCD patterns seem to be a reliable and valid means for the evaluation of MMD.