Intracranial arterial wall imaging using high-resolution 3-tesla contrast-enhanced MRI

The Value of High-Resolution Vessel Wall Magnetic Resonance Imaging in the Diagnosis and Management of Primary Angiitis of the Central Nervous System in Children

Purpose: High-resolution vessel wall-magnetic resonance imaging (VW-MRI) has been used to detect regional vessel wall pathology, significantly contributing to the diagnosis of primary angiitis of the central nervous system (PACNS) from other arteriopathies. In this study, we aimed to describe three cases of PACNS initially presenting as acute ischemic stroke, diagnosed and followed up with VW-MRI. Methods: The medical records of three patients diagnosed with PACNS were retrospectively reviewed. We also reviewed the clinical application of VW-MRI in published articles for the pediatric cases since 2016. Results: The initial presenting symptoms were headache, diplopia, confused mentality, hemiplegia, dysarthria, and dizziness. All patients had acute infarction on brain MRI, with suspicion of vasculopathy on magnetic resonance angiography. VW-MRI revealed narrowing of vessels with concentric wall thickening and diffuse enhancement in the anterior cerebral artery (n=1), middle cerebral artery (n=1), posterior cerebral artery (n=2), lenticulostriate artery (n=1), anterior inferior cerebellar artery (n=1), and vertebral artery (n=1), suggestive of vascular wall pathology. After excluding the possible etiologies of vasculitis, the clinical diagnosis of PACNS was established. Three patients received high-dose steroid and cyclophosphamide therapy. Two patients were treated with long-term azathioprine based upon the findings of persistent vessel enhancement on VW-MRI. All patients were regularly followed up with VW-MRI for more than 1 year. We summarized the clinical and radiological features of the published pediatric cases using VW-MRI to date. Conclusion: High-resolution VW-MRI plays an important role in diagnosing childhood PACNS, as results correlate with disease activity.

Current Clinical Applications of Intracranial Vessel Wall MR Imaging

Intracranial vessel wall MR imaging (VWI) is increasingly being used as a valuable adjunct to conventional angiographic imaging techniques. This article will provide an updated review on intracranial VWI protocols and image interpretation. We review VWI technical considerations, describe common VWI imaging features of different intracranial vasculopathies and show illustrative cases. We review the role of VWI for differentiating among steno-occlusive vasculopathies, such as intracranial atherosclerotic plaque, dissections and Moyamoya disease. We also highlight how VWI may be used for the diagnostic work-up and surveillance of patients with vasculitis of the central nervous system and cerebral aneurysms.

Cardiovascular Risk Factors Affect Specific Segments of the Intracranial Vasculature in High-Resolution (HR) Vessel Wall Imaging (VWI)

OBJECTIVES

Luminal-based imaging have identified different risk factors for extracranial and intracranial atherosclerosis (ICAS), but these techniques are known to underestimate the true extent of the disease. High-resolution (HR) vessel wall imaging (VWI) has recently gained recognition as a valuable tool in the assessment of ICAS. The aim of this study is to determine the association between cardiovascular risk factors and specific intracranial vessel segment involvement using HR-VWI.

MATERIALS AND METHODS

From January 2017 to January 2020, consecutive patients ≥ 18 years-old undergoing HR-VWI of the brain were identified. Patients with history of primary or secondary vasculitis, reversible cerebral vasoconstriction syndrome, or moya-moya were excluded. The presence of vessel wall thickening and enhancement were assessed in the perpendicular plane for each vessel segment by two neuroradiologists. Univariate and multivariate analyses were performed to assess associations between imaging findings and cardiovascular risk factors. Interrater reliability was calculated.

RESULTS

Seventy-one patients (39 men; mean age: 55.9 years) were included. Vessel wall enhancement was seen in 39/71 (55%). A total number of 105 vessel segments demonstrated abnormal enhancement and 79/105 (75%) had an eccentric pattern. Eccentric vessel wall enhancement was independently associated with age >65 years-old in the ICA (OR 9.0, CI 2.1 - 38.2, p < 0.01) and proximal MCA (OR 4.0, CI 1.2 - 13.2, p = 0.02), and with hyperlipidemia in the posterior circulation (OR 44.0, CI2.9-661.0, p<0.01).

CONCLUSION

There is a significant association between eccentric vessel wall enhancement of the ICA and proximal MCA in patients with age > 65; and of the proximal posterior circulation (basilar - PCA1) with hyperlipidemia.

Essentials for Interpreting Intracranial Vessel Wall MRI Results: State of the Art

Intracranial vessel wall (VW) MRI has become widely available in clinical practice, providing multiple uses for evaluation of neurovascular diseases. The Vessel Wall Imaging Study Group of the American Society of Neuroradiology has recently reported expert consensus recommendations for the clinical implementation of this technique. However, the complexity of the neurovascular system and caveats to the technique may challenge its application in clinical practice. The purpose of this article is to review concepts essential for accurate interpretation of intracranial VW MRI results. This knowledge is intended to improve diagnostic confidence and performance in the interpretation of VW MRI scans. © RSNA, 2021 Online supplemental material is available for this article.

Intracranial vessel wall imaging

PURPOSE OF REVIEW

To give an overview regarding the potential usefulness of vessel wall imaging (VWI) in distinguishing various intracranial vascular diseases, their common imaging features, and potential pitfalls.

RECENT FINDINGS

VWI provides direct visualization of the vessel wall and allows the discrimination of different diseases such as vasculitis, atherosclerosis, dissection, Moyamoya disease, and reversible cerebral vasoconstriction syndrome. Recent studies showed that concentric and eccentric involvement in the vessel wall, as well as the enhancement pattern were found important for the distinguishing these diseases and evaluating their activity.

SUMMARY

Most of the imaging techniques currently used are based on luminal imaging. However, these imaging methods are not adequate to distinguish different diseases that can demonstrate similar radiological findings. VWI is being increasingly used as a noninvasive imaging method to offset this limitation.

T2-Weighted Whole-Brain Intracranial Vessel Wall Imaging at 3 Tesla With Cerebrospinal Fluid Suppression

Background

T₂-weighted (T₂w) intracranial vessel wall imaging (IVWI) provides good contrast to differentiate intracranial vasculopathies and discriminate various important plaque components. However, the strong cerebrospinal fluid (CSF) signal in T₂w images interferes with depicting the intracranial vessel wall. In this study, we propose a T₂-prepared sequence for whole-brain IVWI at 3T with CSF suppression.

Methods

A preparation module that combines T₂ preparation and inversion recovery (T₂IR) was used to suppress the CSF signal and was incorporated into the commercial three-dimensional (3D) turbo spin echo sequence-Sampling Perfection with Application optimized Contrast using different flip angle Evolution (SPACE). This new technique (hereafter called T₂IR-SPACE) was evaluated on nine healthy volunteers and compared with two other commonly used 3D T₂-weighted sequences: T₂w-SPACE and FLAIR-SPACE (FLAIR: fluid-attenuated inversion recovery). The signal-to-noise ratios (SNRs) of the vessel wall (VW) and CSF and contrast-to-noise ratios (CNRs) between them were measured and compared among these three T₂-weighted sequences. Subjective wall visualization of the three T₂-weighted sequences was scored blindly and independently by two radiologists using a four-point scale followed by inter-rater reproducibility analysis. A pilot study of four stroke patients was performed to preliminarily evaluate the diagnostic value of this new sequence, which was compared with two conventional T₂-weighted sequences.

Results

T₂IR-SPACE had the highest CNR (11.01 ± 6.75) compared with FLAIR-SPACE (4.49 ± 3.15; p < 0.001) and T₂w-SPACE (-56.16 ± 18.58; p < 0.001). The subjective wall visualization score of T₂IR-SPACE was higher than those of FLAIR-SPACE and T₂w-SPACE (T₂IR-SPACE: 2.35 ± 0.59; FLAIR-SPACE: 0.52 ± 0.54; T₂w-SPACE: 1.67 ± 0.58); the two radiologists' scores showed excellent agreement (ICC = 0.883).

Conclusion

The T₂IR preparation module markedly suppressed the CSF signal without much SNR loss of the other tissues (i.e., vessel wall, white matter, and gray matter) compared with the IR pulse. Our results suggest that T₂IR-SPACE is a potential alternative T₂-weighted sequence for assessing intracranial vascular diseases.

Cerebral amyloid angiopathy and related inflammatory disorders

Inflammatory cerebral amyloid angiopathy is a largely reversible inflammatory vasculopathy that develops in an acute or subacute fashion in reaction to amyloid protein deposition in the central nervous system blood vessels. There are two recognized pathologically characterized variants: cerebral amyloid angiopathy-related inflammation (CAAri) and A beta-related angiitis (ABRA). Both variants produce a clinical picture that resembles primary angiitis of the CNS but is distinguished by a characteristic radiologic appearance. Although originally defined as a clinicopathologic diagnosis, it can now often be diagnosed based on clinicoradiologic criteria, though confirmation with brain and meningeal biopsy is still required in some cases. This disorder typically responds to steroids but addition of other immune suppressants may be needed in some cases to control the disease.

Association of Plaque Features with Infarct Patterns in Patients with Acutely Symptomatic Middle Cerebral Artery Atherosclerotic Disease

BACKGROUND AND PURPOSE

Understanding the stroke mechanism of middle cerebral artery (MCA) atherosclerosis is important for stroke triage and future trial design. The aim of this study was to characterize intrinsic MCA plaque and acute cerebral infarct in vivo by using high-resolution black-blood (BB) and diffusion-weighted magnetic resonance (MR) imaging and to investigate the relationship between plaque features and infarct patterns.

METHODS

A single-center retrospective study was conducted at a tertiary referral center between March 2017 and August 2019. Patients consecutively admitted for acute ischemic stroke with MCA stenosis underwent diffusion-weighted and BB MR imaging. Plaque features and infarct patterns were assessed. The association between plaque features and infarct patterns (binary variable: single/multiple) was evaluated using a multivariate logistic regression model.

RESULTS

Of 49 patients with MCA atherosclerotic stenosis, diffusion-weighted MR imaging showed that 28 patients (57%) had multiple acute cerebral infarcts and 21 patients had single acute cerebral infarcts. In contrast to single infarct, multiple infarcts were associated with greater plaque burden (81.9±7.24 versus 71.3±13.7; P=0.012). A multivariate logistic regression model adjusted for 7 potential confounders confirmed a statistically significant positive association between plaque burden and multiple acute infarcts (adjusted R² =0.432, P< 0.001). The rate of plaque surface irregularity was significantly greater in patients with multiple infarcts than those with single infarct (71% versus 43%, P=0.044). For single acute penetrating artery infarct, patients with infarct size > 2cm had greater plaque burden compared with patients with infarct size < 2cm (75.3±13.4 versus 63.4±10.9; P = 0.016).

CONCLUSIONS

Increased plaque burden, plaque surface irregularity in patients with MCA stenosis is associated with its likelihood to have caused an artery-to-artery embolism that produces multiple cerebral infarcts, especially along the border zone region, and increased plaque burden may promote subcortical single infarct size by occluding penetrating arteries. Our results provide important insight into stroke mechanism of MCA atherosclerosis.

Intracranial Atherosclerotic Plaque as a Potential Cause of Embolic Stroke of Undetermined Source

BACKGROUND

Previous studies investigated the potential mechanism of embolic stroke of undetermined source (ESUS) from extracranial artery plaque, but there has been no study other than a case report on high-risk intracranial plaque in ESUS.

OBJECTIVES

The aim of this study was to investigate the issue by evaluating the morphology and composition of intracranial plaque in patients with ESUS and small-vessel disease (SVD) using 3.0-T high-resolution magnetic resonance imaging.

METHODS

Two hundred forty-three consecutive patients with ESUS and 160 patients with SVD-associated stroke between January 2015 and December 2019 were retrospectively enrolled. Multidimensional parameters involving the presence of plaque on both sides, including remodeling index (RI), plaque burden, presence of discontinuity of plaque surface, thick fibrous cap, intraplaque hemorrhage, and complicated American Heart Association type VI plaque at the maximal luminal narrowing site, were evaluated using intracranial high-resolution magnetic resonance imaging.

RESULTS

Among 243 patients with ESUS, the prevalence of intracranial plaque was much higher in the ipsilateral than the contralateral side (63.8% vs. 42.8%; odds ratio [OR]: 5.25; 95% confidence interval [CI]: 2.83 to 9.73), a finding that was not evident in patients with SVD (35.6% vs. 30.6%; OR: 2.14; 95% CI: 0.87 to 5.26; p = 0.134). Logistic analysis showed that RI was independently associated with ESUS in model 1 (OR: 2.329; 95% CI: 1.686 to 3.217; p < 0.001) and model 2 (OR: 2.295; 95% CI: 1.661 to 3.172; p < 0.001). RI alone with an optimal cutoff of 1.162, corresponding to an area under the curve of 0.740, had good diagnostic efficiency for ESUS.

CONCLUSIONS

The present study supports an etiologic role of high-risk nonstenotic intracranial plaque in ESUS.

Relation of Magnetic Resonance Imaging Based Arterial Signal Enhancement to Markers of Peripheral Artery Disease

Peripheral artery disease (PAD) is associated with impaired lower extremity function. We hypothesized that contrast-enhanced magnetic resonance imaging (CE-MRI) based arterial signal enhancement (SE) measures are associated with markers of PAD. A total of 66 participants were enrolled, 10 were excluded due to incomplete data, resulting in 56 participants for the final analyses (36 PAD, 20 matched controls). MR imaging was performed postreactive hyperemia using bilateral thigh blood-pressure cuffs. First pass-perfusion images were acquired at the mid-calf region with a high-resolution saturation recovery gradient echo pulse sequence, and arterial SE was measured for the lower extremity arteries. As expected, peak walking time (PWT) was reduced in PAD patients compared with controls (282 [248 to 317] sec, vs 353 [346 to 360] sec; p = 0.002), and postexercise ankle brachial index (ABI) decreased in PAD patients but not in controls (PAD: 0.75 ± 0.2, 0.60 [0.5 to 0.7]; p <0.001; vs Controls: 1.17 ± 0.1, 1.19 [1.1 to 1.2]; p = 0.50). Intraclass correlation coefficients were excellent for inter- and intraobserver variability of arterial tracings (n = 10: 0.95 (95%-confidence interval [CI]: 0.94 to 0.96), n = 9: 1.0 (CI: 1.0 to 1.0). Minimum arterial SE was reduced in PAD patients compared with matched controls (128 [110 to 147] A.U. vs 192 [149 to 234] A.U., p = 0.003). Among PAD patients but not in controls the maximum arterial SE was associated with the estimated glomerular filtration rate (eGFR), a marker of renal function (n = 36, ß = 1.37, R² = 0.12, p = 0.025). In conclusion, CE-MRI first-pass arterial perfusion is impaired in PAD patients compared with matched controls and associated with markers of lower extremity ischemia.

Central nervous system vasculitis: advances in diagnosis

PURPOSE OF REVIEW

The main purpose of this review is to present advances in diagnostics of central nervous system vasculitis (CNS-V).

RECENT FINDINGS

Progress in molecular technologies and neuroimaging have added formidably to our knowledge of CNS-V. Next-generation sequencing has the promise to enhance our ability to diagnose, interrogate, and track infectious diseases, making this test attractive and capable of avoiding brain biopsy in cases where CNS infections are suspected. Further the continuum of neuroimaging progress has advanced our ability to diagnose CNS-V. Our capability to visualize the vessel wall have added a great value in differentiating inflammatory from noninflammatory vasculopathies. New genetic variations are being exposed with exome and genome sequences which will aid future diagnosis.

SUMMARY

We have witnessed tremendous advances in CNS-V mainly by our ability to rule out mimics. Progress in molecular technologies, neuroimaging and genetic studies will continue to enhance the field further.

Comparison of plaque characteristics of small and large subcortical infarctions in the middle cerebral artery territory using high-resolution magnetic resonance vessel wall imaging

Background

The characteristics of plaque that ultimately lead to different subcortical infarctions remain unclear. We explored the differences in plaque characteristics between patients with small subcortical infarction (SSI) and large subcortical infarction (LSI) of the middle cerebral artery (MCA) using high-resolution magnetic resonance vessel wall imaging (HR-MRVWI).

Methods

The study group comprised 71 patients (mean age, 47.49±11.5 years; 55 male) with MCA territory ischemic stroke. Whole-brain HR-MRVWI was performed using a three-dimensional T1-weighted variable-flip-angle turbo spin echo (SPACE) sequence. Patients were divided into SSI and LSI groups based on routine MRI images. Plaque distribution was classified as the superior, inferior, ventral, or dorsal wall of the MCA. The number of quadrants with plaque formation, location of plaque, plaque burden (PB), arterial remodeling pattern (positive or negative), and degree of stenosis were analyzed and compared between groups.

Results

Of the 71 patients, 43 (60.6%) and 28 (39.4%) were identified as the SSI and LSI groups, respectively. The proportion of plaques involving only one quadrant was significantly higher in the SSI group, and these plaques were located in the superior or dorsal MCA vessel wall. There was no significant difference between groups in the proportion of plaques involving two or more quadrants, plaque distribution, or PB. Most plaques in both groups showed positive remodeling, and the percentage of remodeling pattern was similar. A significantly higher incidence of low-grade stenosis (<50%) was observed in the SSI group.

Conclusions

Both SSI and LSI may be associated with major intracranial artery atherosclerosis, but patients with SSI showed relatively fewer quadrants with plaque formation and a lesser degree of stenosis.

Black blood imaging of intracranial vessel walls

Traditional vascular imaging focuses on non-invasive cross-sectional imaging to assess luminal morphology; however, the vessel wall itself may be specifically involved in many diseases. Newer pulse sequences, and particularly black blood MRI of intracranial vessels, have brought a paradigm shift in understanding the pathophysiology of many vasculopathies. Black blood MRI of intracranial vessel walls can help in a range of pathologies with differing pathophysiology, including intracranial atherosclerosis, aneurysms, vasculitis and vasculopathy, moyamoya disease, dissection and vertebrobasilar hypoplasia. This review highlights how vessel wall imaging can contribute to the clinical diagnosis and management of patients with intracranial vascular pathology.

Diagnostic value of HR-MRI and DCE-MRI in unilateral middle cerebral artery inflammatory stenosis

PURPOSE

High-resolution magnetic resonance imaging (HR-MRI) has high spatial resolution and can simultaneously perform wall and lumen imaging. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) can evaluate the integrity of the blood-brain barrier. In this paper, the result of 3.0T HR-MRI and 3.0T DCE-MRI has been evaluated to explore the application value of unilateral middle cerebral artery inflammatory stenosis and changes in vascular permeability parameters of stroke events.

METHODS

Thirty-six cases of neurological suspicion of central nervous system vasculitis of our hospital were selected from 20 January 2018 to 1 January 2019, who were diagnosed as unilateral middle cerebral artery M1 stenosis/occlusion by 3D TOF MRA. 3.0T HR-MRI and 3.0T DCE-MRI has been applied.

RESULTS

Among the 36 patients who met the inclusion criteria, 23 patients with central nervous system vasculitis were diagnosed. The 23 patients with HR-MRI showed diffuse thickening and enhanced stenosis. The K^trans value of 10/23 patients with acute-subacute cerebral infarction and 3/23 patients in chronic phase were significantly higher than that of the mirror side, and the K^trans value of these patients remeasured in the same region of interest is lower than before after 6 months treatment. The K^trans value in the target area of 10 patients without cerebrovascular events was not statistically significant compared with the mirror side. The K^trans value of patients with acute-subacute cerebral infarction was significantly higher than that without cerebrovascular events (0.098 ± 0.038 vs. 0.007 ± 0.001, p = .000), and there was no significant difference between K^trans in the chronic infarction group and the other two groups (0.098 ± 0.038 vs. 0.044 ± 0.012, p = .058; 0.044 ± 0.012 vs. 0.007 ± 0.001, p = .057).

CONCLUSION

HR-MRI is an accurate direct imaging method and has a high value for the etiological diagnosis of central nervous system vasculitis. DCE-MRI could be an effective way to evaluate and monitor blood-brain barrier to prevent clinical ischemic stroke.

Vessel wall MR imaging for the detection of intracranial inflammatory vasculopathies

Intracranial vasculopathies are routinely investigated by lumen-based modalities such as magnetic resonance angiography (MRA), computed tomography angiography (CTA), and digital subtraction angiography (DSA). These techniques are useful to analyze the vessel lumen, allowing to detect vessel stenosis or occlusion. However, the primum movins of the disease, i.e., an abnormal thickening of the vessel wall, remains within the arterial wall. The vasculopathy can moreover be present without always narrowing the lumen or modifying its regularity. Hence, there is a need to detect directly and analyze vessel wall abnormalities. Development of 3D high-resolution black blood sequences for intracranial vessel wall MR imaging (VW-MRI) enabled routine clinical applications not only vasculitis, but also of intracranial atherosclerotic disease (ICAD), intracranial dissections, reversible intracranial dissections, reversible cerebral vasoconstriction syndrome (RCVS), Moyamoya disease, and intracranial aneurysms. This high-resolution intracranial VW- MRI approach is increasingly used on a clinical basis at many centers to solve diagnostic problems, especially in patients with ischemic stroke or intracranial hemorrhage. An expert consensus Guideline from the American Society of Neuroradiology provides recommendations for clinical implementation of intracranial vessel wall MRI. There are several technical aspects needed to be considered when implementing VW-MRI in intracranial vessels, including flow suppression, both in blood and cerebrospinal fluid (CSF), spatial resolution and signal-to-noise ratio (SNR). In this article, we review the technical aspects of VW-MRI, and recommend applications for vascular diseases including non-occlusive intracranial vasculopathies, Moyamoya disease, and identifying culprit plaques. We also give a focus on the utility of VW-MRI for determining stroke etiology in adults and in children and young adults.

Vessel wall MR imaging of intracranial atherosclerosis

Intracranial atherosclerotic disease (ICAD) is one of the most common causes of ischemic stroke worldwide. Along with high recurrent stroke risk from ICAD, its association with cognitive decline and dementia leads to a substantial decrease in quality of life and a high economic burden. Atherosclerotic lesions can range from slight wall thickening with plaques that are angiographically occult to severely stenotic lesions. Recent advances in intracranial high resolution vessel wall MR (VW-MR) imaging have enabled imaging beyond the lumen to characterize the vessel wall and its pathology. This technique has opened new avenues of research for identifying vulnerable plaque in the setting of acute ischemic stroke as well as assessing ICAD burden and its associations with its sequela, such as dementia. We now understand more about the intracranial arterial wall, its ability to remodel with disease and how we can use VW-MR to identify angiographically occult lesions and assess medical treatment responses, for example, to statin therapy. Our growing understanding of ICAD with intracranial VW-MR imaging can profoundly impact diagnosis, therapy, and prognosis for ischemic stroke with the possibility of lesion-based risk models to tailor and personalize treatment. In this review, we discuss the advantages of intracranial VW-MR imaging for ICAD, the potential of bioimaging markers to identify vulnerable intracranial plaque, and future directions of artificial intelligence and its utility for lesion scoring and assessment.

Factors for Enhancement of Intracranial Atherosclerosis in High Resolution Vessel Wall MRI in Ischemic Stroke Patients

Introduction: High resolution vessel wall MRI (VW-MRI) has enabled to characterize intracranial atherosclerosis (ICAS). We studied to identify the factors for enhancement of ICAS in VW-MRI in patients with acute ischemic stroke. Methods: Consecutive patients with acute ischemic stroke or TIA who underwent VW-MRI between January 2017 and December 2017 were included. Enhancement on VW-MRI was defined as an increase in intensity on contrast-enhanced T1-weighted sequence. We compared the clinical and the radiologic findings between patients with wall enhancement and those without wall enhancement. Results: Of the 48 patients with ICAS, 28 patients revealed enhancement on VW-MRI. Patients with enhancement were more likely to have severe stenotic lesions and higher levels of total cholesterol, triglycerides, low-density cholesterol, Apo (b), and Apo (b)/Apo (a) lipoprotein ratio (p < 0.05). Multivariable analysis demonstrated that total cholesterol (OR: 5.378, 95% CI, 1.779-16.263), triglycerides (OR: 3.362, 95% CI, 1.008-11.209), low density lipoprotein cholesterol (OR: 4.226, 95% CI, 1.264-14.126), Apo (b) lipoprotein (OR: 3639.641, 95% CI, 17.854-741954.943) levels, and Apo (b)/Apo (a) lipoprotein ratio (OR, 65.514; 95% CI, 1.131-3680.239) were independently associated with enhancement of ICAS. High-density lipoprotein cholesterol and Apo (a) lipoprotein levels were not significantly different between the patients with wall enhancement and those without wall enhancement. Conclusions: The presence and severity of enhancement of ICAS was significantly associated with dyslipidemic conditions. These results suggest that strict lipid modification should be achieved for the management of ICAS.

Fusion of subarachnoid hemorrhage data and computed tomography angiography data is helpful to identify the rupture source in patients with multiple intracranial aneurysms

Determining the rupture source is imperative in patient with aneurysmal subarachnoid hemorrhage (SAH). About one third of SAH cases with multiple intracranial aneurysms cannot be certain of the rupture source according to the hemorrhage pattern. This study aims to identify of the rupture source in patients with multiple intracranial aneurysms by fusing SAH data and computed tomography angiography (CTA) data. This retrospective study included 52 aneurysmal SAH patients with multiple intracranial aneurysms. In the 52 patients, 36 had definitive hemorrhage patterns on computed tomography imaging. And the other 16 patients had non-definitive hemorrhage patterns, which were bewildered for us to determine the ruptured aneurysms. Fusion of SAH data and CTA data was performed to demonstrate the spatial relationship between the SAH with each aneurysm by using the 3D Slicer software. For the patients with definitive bleed patterns, all of the suspected ruptured aneurysms were confirmed to be accurate according to the surgical records. Interestingly, the suspected rupture sources were correct in 14 of 16 patients with non-definitive hemorrhage patterns. For all 52 patients with multiple intracranial aneurysms, the ruptured aneurysms were identified in 50 cases (96.2%). In conclusion, fusion of SAH data and CTA data can precisely demonstrate the spatial relationship between the SAH with each aneurysm, which is helpful to determine the ruptured aneurysm in patients with multiple intracranial aneurysms.

Heritable and non-heritable uncommon causes of stroke

Despite intensive investigations, about 30% of stroke cases remains of undetermined origin. After exclusion of common causes of stroke, there is a number of rare heritable and non-heritable conditions, which often remain misdiagnosed, that should be additionally considered in the diagnosis of cryptogenic stroke. The identification of these diseases requires a complex work up including detailed clinical evaluation for the detection of systemic symptoms and signs, an adequate neuroimaging assessment and a careful family history collection. The task becomes more complicated by phenotype heterogeneity since stroke could be the primary or unique manifestation of a syndrome or represent just a manifestation (sometimes minor) of a multisystem disorder. The aim of this review paper is to provide clinicians with an update on clinical and neuroradiological features and a set of practical suggestions for the diagnostic work up and management of these uncommon causes of stroke. The identification of these stroke causes is important to avoid inappropriate and expensive diagnostic tests, to establish appropriate management measures, including presymptomatic testing, genetic counseling, and, if available, therapy. Therefore, physicians should become familiar with these diseases to provide future risk assessment and family counseling.

MRI Vessel Wall Imaging after Intra-Arterial Treatment for Acute Ischemic Stroke

BACKGROUND AND PURPOSE

Vessel wall imaging is increasingly performed in the diagnostic work-up of patients with ischemic stroke. The aim of this study was to compare vessel wall enhancement after intra-arterial thrombosuction with that in patients not treated with thrombosuction.

MATERIALS AND METHODS

From 2009 to 2017, forty-nine patients with an ischemic stroke underwent 7T MR imaging within 3 months after symptom onset as part of a prospective intracranial vessel wall imaging study. Fourteen of these patients underwent intra-arterial treatment using thrombosuction (intra-arterial treatment group). In the intra-arterial treatment group, vessel walls were evaluated for major vessel wall changes. All patients underwent pre- and postcontrast vessel wall imaging to assess enhancing foci of the vessel wall using coregistered subtraction images. A Wilcoxon signed rank test was performed to test for differences.

RESULTS

In the intra-arterial treatment group, 11 of 14 patients (79%) showed vessel wall enhancement compared with 17 of 35 patients without intra-arterial treatment (49%). In the intra-arterial treatment group, more enhancing foci were detected on the ipsilateral side (n = 18.5) compared with the contralateral side (n = 3, P = .005). Enhancement was more often concentric on the ipsilateral side (n = 8) compared with contralateral side (n = 0, P = .01). No differences were found in the group without intra-arterial treatment between the number and configuration of ipsilateral and contralateral enhancing foci.

CONCLUSIONS

Patients with intra-arterial treatment by means of thrombosuction showed more (concentric) enhancing foci of the vessel wall ipsilateral compared with contralateral to the treated artery than the patients without intra-arterial treatment, suggesting reactive changes of the vessel wall. This finding should be taken into account when assessing vessel wall MR images in patients with stroke.

Intracranial vessel wall imaging: applications, interpretation, and pitfalls

Vessel wall imaging (VWI) is being increasingly used as a non-invasive diagnostic method to evaluate the intra- and extracranial vascular bed. Whereas conventional vascular imaging primarily assesses the vessel lumen, VWI changes the focus of analysis toward the vessel wall. As the technical challenges of high spatial resolution, signal-to-noise ratio, and contrast-to-noise ratio and long scans times are addressed, interest in the clinical applications of this technique has steadily increased over the years. In this review, the authors will discuss the various applications of VWI as well as principles of interpretation and common imaging findings, focusing on intracranial atherosclerosis, vascular dissection, vasculitides (such as primary angiitis of the central nervous system (PACNS) and neurosarcoidosis), vasculopathies (such as reversible cerebral vasoconstriction syndrome (RCVS), cocaine-induced vasculopathy, moyamoya disease, and radiation-induced arteriopathy), aneurysms, and post-thrombectomy changes. The authors will also discuss the potential pitfalls of VWI and helpful cues to avoid being tricked.

Intensive Statin Treatment in Acute Ischaemic Stroke Patients with Intracranial Atherosclerosis: a High-Resolution Magnetic Resonance Imaging study (STAMINA-MRI Study)

OBJECTIVE

Intracranial atherosclerosis is a major cause of ischaemic stroke worldwide. A number of studies have shown the effects of statin treatment on coronary and carotid artery plaques, but there is little evidence on the effects of statin treatment on intracranial atherosclerotic plaques.

METHODS

The Intensive Statin Treatment in Acute Ischaemic Stroke Patients with Intracranial Atherosclerosis - High-Resolution Magnetic Resonance Imaging (STAMINA-MRI) Trial is a single-arm, prospective, observational study monitoring imaging and clinical outcomes of high-dose statin treatment among statin-naive patients with acute ischaemic stroke caused by symptomatic intracranial atherosclerosis. The primary outcome was the change in vascular remodelling and plaque characteristics before and after 6 months (median: 179 days, IQR 163-189 days) of statin treatment measured by high-resolution MRI (HR-MRI).

RESULTS

A total of 77 patients (mean age: 62.6±13.7 years, 61.0% women) were included in this study. Low-density lipoprotein cholesterol (LDL-C) levels (mg/dL) at initial and follow-up assessments were 125.81±35.69 and 60.95±19.28, respectively. Overall, statin treatment significantly decreased enhancement of plaque volume (mm³, 32.07±39.15 vs 17.06±34.53, p=0.013), the wall area index (7.50±4.28 vs 5.86±4.05, p=0.016) and stenosis degree (%, 76.47±20.23 vs 64.05±21.29, p<0.001), but not the remodelling index (p=0.195). However, 35% patients showed no change or increased enhancement volume and stenosis degree after statin treatment. Higher reduction of LDL-C and longer duration of statin treatment were associated with decreased enhancement volume after statin treatment.

CONCLUSIONS

High-dose statin treatment effectively stabilised symptomatic intracranial atherosclerotic plaques as documented by HR-MRI. Further study is needed to determine laboratory and genetic factors associated with poor response to statins and alternative therapeutic options, such as proprotein convertase subtilisin-kexin type 9 inhibitors, for these patients.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov NCT02458755.

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.

Magnetic resonance vessel wall imaging in cerebrovascular diseases

Cerebrovascular diseases manifest as abnormalities of and disruption to the intracranial vasculature and its capacity to carry blood to the brain. However, the pathogenesis of many cerebrovascular diseases begins in the vessel wall. Traditional luminal and perfusion imaging techniques do not provide adequate information regarding the differentiation, onset, or progression of disease. Intracranial high-resolution MR vessel wall imaging (VWI) has emerged as an invaluable technique for understanding and evaluating cerebrovascular diseases. The location and pattern of contrast enhancement in intracranial VWI provides new insight into the inflammatory etiology of cerebrovascular diseases and has potential to permit earlier diagnosis and treatment. In this report, technical considerations of VWI are discussed and current applications of VWI in vascular malformations, blunt cerebrovascular injury/dissection, and steno-occlusive cerebrovascular vasculopathies are reviewed.

Focal irregularities in 7-Tesla MRI of unruptured intracranial aneurysms as an indicator for areas of altered blood-flow parameters

OBJECTIVE

In the last several decades, various factors have been studied for a better evaluation of the risk of rupture in incidentally discovered intracranial aneurysms (IAs). With advanced MRI, attempts were made to delineate the wall of IAs to identify weak areas prone to rupture. However, the field strength of the MRI investigations was insufficient for reasonable image resolution in many of these studies. Therefore, the aim of this study was to analyze findings of IAs in ultra-high field MRI at 7 Tesla (7 T).

METHODS

Patients with incidentally found IAs of at least 5 mm in diameter were included in this study and underwent MRI investigations at 7 T. At this field strength a hyperintense intravascular signal can be observed on nonenhanced images with a brighter "rim effect" along the vessel wall. Properties of this rim effect were evaluated and compared with computational fluid dynamics (CFD) analyses.

RESULTS

Overall, 23 aneurysms showed sufficient image quality for further evaluation. In 22 aneurysms focal irregularities were identified within this rim effect. Areas of such irregularities showed significantly higher values in wall shear stress and vorticity compared to areas with a clearly visible rim effect (p = 0.043 in both).

CONCLUSIONS

A hyperintense rim effect along the vessel wall was observed in most cases. Focal irregularities within this rim effect showed higher values of the mean wall shear stress and vorticity when compared by CFD analyses. Therefore, these findings indicate alterations in blood flow in IAs within these areas.

Primary Angiitis of the Central Nervous System Mimicking Glioblastoma: A Case Report and Literature Review

Primary angiitis of the central nervous system (PACNS) is a rare disorder resulting in idiopathic inflammation affecting the parenchymal and leptomeningeal vessels confined to the central nervous system (CNS), of which a tumor-like mass lesion is an even rare subtype. We described a case of PACNS initially misdiagnosed as glioblastoma. The patient was a 35 year-old female with right-sided weakness and expressive dysphasia. Brain MRI showed a tumor-like lesion highly suggestive of glioblastoma, therefor surgical removal was done. After a resection and an exhaustive workup, PACNS was ultimately diagnosed. The case illustrates a type of imaging presentation of PACNS that is often misdiagnosed as high-grade glioma. Differentiation between tumor-like PACNS lesions and actual CNS tumors is challenging due to similar MR images. To avoid unnecessary surgical interventions, we summarized previously reported mass-forming PACNS cases in adults from January 1, 2000, to December 31, 2018 and the imaging characteristics of PACNS. Some less commonly used diagnostic methods such as MR spectroscopy may also help clinicians distinguish PACNS from its mimics.

[Primary central nervous system vasculitis]

Primary vasculitis (angiitis) of the central nervous system (PACNS) is a rare disease targeting the vessels of the brain, spinal cord and leptomeninges without systemic involvement. The etiology is not clear enough. The authors review clinical, laboratory and radiological features of PACNS. Clinical manifestations are variable and depend on the caliber of affected vessels. The main clinical manifestations of small sized vessel vasculitis include encephalopathy (cognitive disorders, epileptic seizures), headache and transient cerebral ischemia. The main clinical presentation of vasculitis of medium/large cerebral arteries is ischemic strokes, which usually develop in different vascular territories. CSF findings in the majority of patients show modest lymphocytic pleocytosis, elevated protein level and occasionally the presence of oligoclonal bands. MRI data are not specific and include infarcts, hyperintensity (FLAIR) and sometimes tumor-like lesions. The gold standard for the verification of PACNS affected small-sized arteries is brain and leptomeningeal biopsy. Cerebral angiography allows the verification of vasculitis of medium and large cerebral arteries revealing segmental narrowings (beading). High resolution black blood MRI before and after contrast injection may visualize intracranial vessel wall contrast enhancement - the sign of inflammation in intracranial arteries. Treatment of PACNS includes corticosteroids and cyclophosphamide. In the case of patient intolerance, rituximab and blockers of tumor necrosis factor may be used.

Diagnostic Impact of Intracranial Vessel Wall MRI in 205 Patients with Ischemic Stroke or TIA

BACKGROUND AND PURPOSE

Secondary prevention of ischemic stroke depends on determining the cause of the initial ischemic event, but standard investigations often fail to identify a cause or identify multiple potential causes. The purpose of this study was to characterize the impact of intracranial vessel wall MR imaging on the etiologic classification of ischemic stroke.

MATERIALS AND METHODS

This was a single-center, retrospective study of 205 consecutive patients who were referred for vessel wall MR imaging to clarify the etiology of an ischemic stroke or TIA. An expert panel classified stroke etiology before and after incorporating vessel wall MR imaging results using a modified Trial of Org 10172 in Acute Stroke Treatment system. We measured the proportion of patients with an altered etiologic classification after vessel wall MR imaging.

RESULTS

The median age was 56 years (interquartile range = 44-67 years), and 51% (106/205) of patients were men. Vessel wall MR imaging altered the etiologic classification in 55% (112/205) of patients. The proportion of patients classified as having intracranial arteriopathy not otherwise specified decreased from 31% to 4% (64/205 versus 9/205; P < .001) and the proportion classified as having intracranial atherosclerotic disease increased from 23% to 57% (48/205 versus 116/205; P < .001). Conventional work-up classification as intracranial arteriopathy not otherwise specified was an independent predictor of vessel wall MR imaging impact (OR = 8.9; 95% CI, 3.0-27.2). The time between symptom onset and vessel wall MR imaging was not a predictor of impact.

CONCLUSIONS

When vessel wall MR imaging is performed to clarify the etiology of a stroke or TIA, it frequently alters the etiologic classification. This is important because the etiologic classification is the basis for therapeutic decision-making.

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.

Primary Angiitis of the Central Nervous System: New Potential Imaging Techniques and Biomarkers in Blood and Cerebrospinal Fluid

Primary angiitis of the central nervous system (PACNS) is an inflammatory brain disease affecting the medium and small vessels of the CNS. Although recent data of patients with PACNS have advanced the understanding of the disease, the diagnosis remains challenging. Clinical presentation of PACNS is broad and unspecific and the majority of the diagnostic approaches are hallmarked by a low specificity. Thus, PACNS is commonly misdiagnosed. In addition, due to its potential aggressive course which may be altered by an adequate immunosuppressive treatment, delineation from other vasculopathies and PACNS mimics is crucial. New diagnostic tools and biomarkers which increase specificity and facilitate the diagnosis for patients with suspected PACNS are highly desirable. This short review summarizes the current procedures within the diagnostic process and aims to illustrate its difficulties and challenges. Furthermore, it highlights emerging biomarkers in the cerebrospinal fluid and peripheral venous blood as well as novel potential imaging tools that may corroborate the diagnosis. With new imaging techniques and a panel of biomarkers the certainty of the diagnosis may be increased and diagnostic processes more accelerated in the future.

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.

Intracranial arterial wall imaging: Techniques, clinical applicability, and future perspectives

Purpose

To review the current state of the art and future development of intracranial vessel wall imaging.

Methods

Recent literature review and expert opinion about intracranial arterial wall imaging.

Results

Intracranial large artery diseases represent an important cause of stroke and vascular cognitive impairment worldwide. Our traditional understanding of intracranial large artery diseases is based on the observation of luminal narrowing or occlusion with angiographic or ultrasound techniques. Recently, novel imaging techniques have made the intracranial artery wall accessible for noninvasive visualization. The main advantage of vessel-wall imaging as compared to conventional imaging techniques for visualization of intracranial arteries is the ability to detect vessel wall changes even before they get to cause any significant luminal stenosis. This diagnostic capacity is provoking a revolutionary change in the way we see the intracranial circulation. In this article, we will review the current state of magnetic resonance imaging and computed tomography-based intracranial arterial wall imaging, focusing on technical considerations and their clinical applicability. Moreover, we will provide the readers with our vision on the future development of vessel-wall imaging techniques.

Conclusion

Intracranial arterial wall imaging methods are gaining increasing potential to impact the diagnosis and treatment of patients with cerebrovascular diseases.

Asymptomatic Basilar Artery Plaque Distribution and Vascular Geometry

AIM

Development of atherosclerotic plaques is affected by vascular geometry and hemodynamics. Hemodynamics in the basilar artery (BA) is unique as the flow converges from vertebral arteries (VAs). Here, we investigated the characteristics of BA plaque based on VA and BA geometry.

METHODS

Consecutive patients evaluated using high-resolution magnetic resonance imaging (MRI) at a general health center were screened. Geometric characteristics of VA (VA dominancy and VA-BA angles) and BA (BA convexity and BA angles) were assessed. The burden of BA plaques was investigated in each wall (anterior, posterior, left, and right lateral). The characteristics of BA plaques were compared according to VA dominancy (right vs. left), BA angle of lateral view (lateral mid-BA angle; dichotomized), and total plaque burden (divided by tertiles).

RESULTS

Of the 1029 subjects, BA plaques were observed in 98 (9.5%) patients, and were more frequently located at the anterior wall (32.4%) and posterior wall (35.0%) than the right wall (15.3%) and left lateral wall (17.6%). Right and left lateral plaques were more frequent in the left and right convex BA, respectively (p=0.009 and p=0.024, respectively). Anterior plaques were more frequently observed in low lateral mid-BA angle (p= 0.043). BA plaques were predominant in anterior and posterior walls in patients with lower plaque burden, whereas they were predominant in right and left lateral walls in patients with higher plaque burden (p=0.001 and p=0.025, respectively).

CONCLUSIONS

Asymptomatic BA plaque location was associated with BA convexity and lateral mid-BA angle. The anteriorly and posteriorly located BA plaques may extend to the lateral walls as the plaque burden increases.

Clinical and Radiological Characteristics of Intracranial Artery Dissection Using Recently Proposed Diagnostic Criteria

BACKGROUND

Data on the clinical and radiological characteristics of intracranial artery dissection (IAD) have remained limited. Our purpose was to reveal the clinical and radiological characteristics of IAD according to diagnostic criteria for IAD as recently reported by a group of international experts.

METHODS

Patients were retrospectively enrolled using a prospective single-center stroke registry between 2011 and 2016. Baseline characteristics and radiological findings including conventional magnetic resonance imaging (MRI) sequences, magnetic resonance angiography (MRA), high-resolution 3-dimensional T1-weighted imaging (HR-3D-T1WI), and digital subtraction angiography were reviewed. We performed statistical comparisons to determine which findings from which modalities are useful.

RESULTS

We identified 118 patients with suspected artery dissection, with 64 patients (median age, 51 [interquartile range, 45-56) years; 16 women) finally meeting the criteria for definite (n = 47), probable (n = 15), or possible (n = 2) idiopathic IAD. Ischemic stroke alone was found in 31 patients (48%) on admission. There were 36 patients (56%) suffering from hypertension and 39 (61%) with smoking history. The vertebral artery alone was the most affected in 42 patients (66%). Intramural hematoma (IMH) was more frequently detected on HR-3D-T1WI than on conventional MRI/MRA (odds ratio, 4.72; 95% confidence interval, 1.71-13.00). In 54 patients (84%), the modified Rankin Scale score after 3 months was 0-1.

CONCLUSIONS

Male dominance and age at IAD onset were similar to previous studies, and more than half had hypertension and smoking history. We confirmed that HR-3D-T1WI is useful for detecting IMH in the diagnostic criteria.

High-resolution contrast-enhanced vessel wall imaging in patients with suspected cerebral vasculitis: Prospective comparison of whole-brain 3D T1 SPACE versus 2D T1 black blood MRI at 3 Tesla

Purpose

Vessel wall imaging (VWI) using T1 dark blood MRI can depict inflammation of intracranial arteries in patients with cerebral vasculitis. Recently, 3D VWI sequences were introduced at 3 Tesla. We aimed to compare 2D and 3D VWI for detection of intracranial vessel wall enhancement (VWE) in patients suspected of cerebral vasculitis.

Methods

44 MRI scans of 39 patients were assessed that included bi-planar 2D T1 and whole-brain 3D T1 SPACE dark blood VWI pre and post contrast. Visibility and VWE were analyzed in 31 pre-specified intracranial artery segments. Additionally, leptomeningeal and parenchymal contrast enhancement was assessed.

Results

Overall, more arterial segments were visualized with 3D VWI (p<0.0001). Detection of VWE showed fair agreement between 2D and 3D VWI (κ = 0.583). On segmental level, more VWE was detected in intradural ICA by 2D VWI (p<0.001) and in VA V4 segment by 3D VWI (p<0.05). 3D VWI showed more leptomeningeal (p<0.05) and parenchymal (p<0.01) contrast enhancement. In patients with positive diagnosis of cerebral vasculitis, sensitivity was of 67% (2D and 3D VWI) and specificity was 44% (2D VWI) and 48% (3D VWI); more VWE was seen in arteries distal to VA and ICA compared to non-vasculitic patients.

Conclusion

2D and 3D VWI differed in the ability to detect VWE. Whole brain coverage with better evaluability of VAs and distal intracranial artery segments, and depiction of more parenchymal and leptomeningeal enhancement make 3D VWI more favorable. As VWE in arteries distal to VA and ICA may be used for discrimination of vasculitic and non-vasculitic patients, future increase in spatial resolution of 3D VWI sequences may be beneficial.

Progressive stenosis and radiological findings of vasculitis over the entire internal carotid artery in moyamoya vasculopathy associated with graves' disease: a case report and review of the literature

Background

Moyamoya vasculopathy (MMV) associated with Graves’ disease (GD) is a rare condition resulting in ischemic stroke accompanied by thyrotoxicity. Radiological findings of vasculitis have been reported in the walls of distal internal carotid arteries (ICAs) in these patients; however, no reports have described in detail the processes of progression of the lesions in the proximal ICA. Moreover, treatments to prevent recurrence of ischemic stroke and progression of MMV have not yet been sufficiently elucidated.

Case presentation

We report a progressive case of MMV associated with GD and review the literature to clarify relationships among recurrence, progression, thyrotoxicity and treatment. Our patient developed cerebral infarction during thyrotoxicity with no obvious stenosis of ICAs. Five months later, transient ischemic attacks recurred with thyrotoxicity. Antiplatelet therapy and intravenous methylprednisolone stopped the attacks. Stenosis of the left ICA from the proximal to distal portion and champagne bottle neck sign (CBN) were found. She declined any surgery. Afterward, gradual progression with mild thyrotoxicity was observed. Eventually, we found smooth, circumferential, concentric wall thickening with diffuse gadolinium enhancement of the left ICA from the proximal to the distal portion on T1-weighted imaging, suggesting vasculitis radiologically. The clinical and radiological similarities to Takayasu arteritis encouraged us to provide treatment as for vasculitis of medium-to-large vessels. In a euthyroid state and after administration of prednisolone and methotrexate, improved flow in the cerebrovascular arteries on magnetic resonance angiography was observed. Based on our review of the literature, all cases with recurrence or progression were treated with anti-thyroid medication (ATM) alone and accompanied by thyrotoxicity. CBN was observed in all previous cases for which images of the proximal ICA were available.

Conclusions

We report the details of progressive stenosis from a very early stage and radiological findings of vasculitis over the entire ICA in MMV associated with GD. Cerebral infarction can occur with no obvious stenosis of the ICA. We treated the patient as per vasculitis of a medium-to-large vessel. Management of GD by ATM alone seems risky in terms of recurrence. Adequate management of GD and possible vasculitis may be important for preventing recurrence and progression.

Electronic supplementary material

The online version of this article (10.1186/s12883-019-1262-1) contains supplementary material, which is available to authorized users.

Intracranial Vessel Wall Segmentation Using Convolutional Neural Networks

OBJECTIVE

To develop an automated vessel wall segmentation method using convolutional neural networks to facilitate the quantification on magnetic resonance (MR) vessel wall images of patients with intracranial atherosclerotic disease (ICAD).

METHODS

Vessel wall images of 56 subjects were acquired with our recently developed whole-brain three-dimensional (3-D) MR vessel wall imaging (VWI) technique. An intracranial vessel analysis (IVA) framework was presented to extract, straighten, and resample the interested vessel segment into 2-D slices. A U-net-like fully convolutional networks (FCN) method was proposed for automated vessel wall segmentation by hierarchical extraction of low- and high-order convolutional features.

RESULTS

The network was trained and validated on 1160 slices and tested on 545 slices. The proposed segmentation method demonstrated satisfactory agreement with manual segmentations with Dice coefficient of 0.89 for the lumen and 0.77 for the vessel wall. The method was further applied to a clinical study of additional 12 symptomatic and 12 asymptomatic patients with >50% ICAD stenosis at the middle cerebral artery (MCA). Normalized wall index at the focal MCA ICAD lesions was found significantly larger in symptomatic patients compared to asymptomatic patients.

CONCLUSION

We have presented an automated vessel wall segmentation method based on FCN as well as the IVA framework for 3-D intracranial MR VWI.

SIGNIFICANCE

This approach would make large-scale quantitative plaque analysis more realistic and promote the adoption of MR VWI in ICAD management.

Assessment of quantitative methods for enhancement measurement on vessel wall magnetic resonance imaging evaluation of intracranial atherosclerosis

PURPOSE

Quantitative measures of vessel wall magnetic resonance imaging (vwMRI) for the evaluation of intracranial atherosclerotic disease (ICAD) offers standardization not available with previously used qualitative approaches that may be difficult to replicate.

METHODS

vwMRI studies performed to evaluate ICAD that had caused a stroke were analyzed. Two blinded reviewers qualitatively rated culprit lesions for the presence of enhancement on T1 delay alternating with nutation for tailored excitation (DANTE) SPACE images. At least 3 months later, quantitative analysis was performed of the same images, comparing lesion enhancement to reference structures. Cohen's kappa and intraclass correlation coefficients were calculated to assess agreement. Ratios of enhancement of lesions to references were compared to qualitative ratings.

RESULTS

Studies from 54 patients met inclusion criteria. A mean of 49 (90.7%) lesions were qualitatively rated as enhancing, with good inter-rater agreement (κ = 0.783). Among reference structure candidates, low infundibulum demonstrated the highest inter-rater agreement on pre- and post-contrast imaging. The ratio of percentage increase in plaque signal following contrast to the same measure in low infundibulum demonstrated the highest agreement with qualitative assessment, with highest agreement seen with a ratio of 0.8 set as a threshold (κ = 0.675).

CONCLUSION

Quantitative metrics can yield objective data to better standardize techniques and acceptance of vwMRI evaluation of ICAD. The low infundibulum had the highest inter-rater agreement on both pre- and post-contrast images and is best suited as a normally enhancing reference structure. Such quantitative techniques should be implemented in future research of vwMRI for the evaluation of ICAD.

Imaging of Carotid Dissection

PURPOSE OF REVIEW

Here, we describe the four primary imaging modalities for identification of carotid artery dissection, advantages, limitations, and clinical considerations. In addition, imaging characteristics of carotid dissection associated with each modality will be described.

RECENT FINDINGS

Recent advances in etiopathogenesis describe the genetic factors implicated in cervical artery dissection. MRI/MRA (magnetic resonance angiography) with fat suppression is regarded as the best initial screening test to detect dissection. Advances in magnetic resonance imaging for the diagnosis of dissection include the use of susceptibility-weighted imaging (SWI) for the detection of intramural hematoma and multisection motion-sensitized driven equilibrium (MSDE), which causes phase dispersion of blood spin using a magnetic field to suppress blood flow signal and obtain 3D T1- or T2*-weighted images. Digital subtraction angiography (DSA) remains the gold standard for identifying and characterizing carotid artery dissections. Carotid artery dissection is the result of a tear in the intimal layer of the carotid artery. This leads to a "double lumen" sign comprised of the true vessel lumen and the false lumen created by the tear. The most common presentation of carotid artery dissection is cranial and/or cervical pain ipsilateral to the dissection. However, severe neurological sequelae such as embolic ischemic stroke, intracranial hemorrhage, and subarachnoid hemorrhage can also result from carotid artery dissection. Carotid artery dissection can be identified by a variety of different imaging modalities including computed tomographic angiography (CTA), MRI, carotid duplex imaging (CDI), and digital subtraction angiography (DSA).

Utility of intracranial high-resolution vessel wall magnetic resonance imaging in differentiating intracranial vasculopathic diseases causing ischemic stroke

PURPOSE

High-resolution vessel wall imaging (HRVWI) by MRI is a novel noninvasive imaging tool which provides direct information regarding vessel wall pathologies. The utility of HRVWI in differentiating various intracranial vasculopathies among ischemic stroke is still evolving.

METHODS

Consecutive ischemic stroke/TIA patients within 2 weeks of symptom onset between January 2016 to December 2017, with symptomatic vessel stenosis of 50% or more/occlusion on baseline luminal imaging studies were recruited into the study. Stroke subtypes were classified as per TOAST classification initially on the basis of luminal imaging findings alone and subsequently after incorporation of HRVWI findings as well.

RESULTS

Forty-nine subjects were recruited into the study. The median age of the population was 42 years (range 11 to 75) with 69% being males. Incorporation of HRVWI findings classified 38.8% subjects into intracranial atherosclerotic disease (ICAD), 32.6% as stroke of other determined aetiology (ODE) (inflammatory vasculopathy [IVas] being the major subgroup [81.2%]) and 28.6% into stroke of undetermined aetiology (UE). HRVWI enabled a diagnostic reclassification in an additional 47.3% among the baseline UE category as against luminal imaging findings alone. ICAD was likelier to have eccentric vessel wall thickening, eccentric vessel wall enhancement and T2 juxtaluminal hyperintensity with surrounding hypointensity (P < 0.001), while IVas were more likely to exhibit concentric vessel wall thickening with homogenous enhancement (P < 0.001).

CONCLUSION

HRVWI is a useful noninvasive adjunctive tool in the diagnostic evaluation of intracranial vasculopathies, with maximum benefit in ICAD and IVas subtypes.

Interstudy reproducibility of dark blood high-resolution MRI in evaluating basilar atherosclerotic plaque at 3 Tesla

PURPOSE

We aimed to evaluate the interscan, intraobserver, and interobserver reproducibility of basilar atherosclerotic plaque employing dark blood high-resolution magnetic resonance imaging (HR-MRI) at 3 Tesla.

METHODS

Sixteen patients (14 males and 2 females) with > 30% basilar stenosis as identified by conventional magnetic resonance angiography were prospectively recruited for scan and rescan examinations on a 3 Tesla MRI system using T2-weighted turbo spin-echo protocol. Two observers independently measured the areas of vessels and lumens. Wall area was derived by subtracting the lumen area from the vessel area. Areas of vessels, lumens and walls were compared for the evaluation of interscan variability of basilar plaque. To assess the intraobserver variability, one observer reevaluated all the images of the first scan after a 4-week interval.

RESULTS

Fourteen patients were included in the final analysis. No clinically significant difference was observed for interscan, intraobserver, and interobserver measurements. The intraclass correlations for vessel, lumen, and wall areas were excellent and ranged from 0.973 to 0.981 for the interscan measurements, 0.997 to 0.998 for the intraobserver measurements and 0.979 to 0.985 for the interobserver measurements. The coefficients of variation for quantitative basilar morphology measurements were 4.31%-10.35% for the interscan measurements, 1.41%-4.62% for the intraobserver measurements and 3.79%-8.46% for the interobserver measurements. Compared with the interscan and interobserver measurements, narrow intervals of the scatterplots were observed for the intraobserver measurements by Bland-Altman plots.

CONCLUSION

Basilar atherosclerotic plaque imaging demonstrates excellent reproducibility at 3 Tesla. The study proves that dark blood HR-MRI may serve as a reliable tool for clinical studies focused on the progression and treatment response of basilar atherosclerosis.