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

MR Vessel Wall Imaging for Atherosclerosis and Vasculitis

Conventional imaging modalities, such as computed tomography angiography, MR angiography, transcranial Doppler ultrasonography, and digital subtraction angiography, are utilized in evaluating intraluminal or intravascular pathology of the intracranial vessels. Limitations of luminal imaging techniques can lead to inaccurate diagnosis, evaluation, and risk stratification, as many cerebrovascular pathologies contain an extrinsic vessel wall component. Furthermore, vessel wall imaging can provide information regarding extent, treatment response, and biopsy targets for vasculitis cases. Overall, while vessel wall imaging can provide robust data regarding intracranial pathologies, further prospective, multicenter studies are required to improve diagnostic application and accuracy.

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.

Vessel wall MRI in moyamoya disease: arterial wall enhancement varies depending on age, arteries, and disease progression

OBJECTIVE

To investigate the relationship of followings for patients with moyamoya disease (MMD): arterial wall enhancement on vessel wall MRI (VW-MRI), cross-sectional area (CSA), time-of-flight MR angiography (MRA), age, locations from intracranial internal carotid artery (ICA) to proximal middle cerebral artery (MCA), disease progression, and transient ischemic attack (TIA).

METHODS

Patients who underwent VW-MRI between October 2018 and December 2020 were enrolled in this retrospective study. We measured arterial wall enhancement (enhancement ratio, ER) and CSA at five sections of ICA and MCA. Also, we scored MRA findings. Multiple linear regression (MLR) analysis was performed to explore the associations between ER, age, MRA score, CSA, history of TIA, and surgical revascularization.

RESULTS

We investigated 102 sides of 51 patients with MMD (35 women, 16 men, mean age 31 years ± 18 [standard deviation]). ER for MRA score 2 (signal discontinuity) was higher than ER for other scores in sections D (end of ICA) and E (proximal MCA) on MLR analysis. ER in section E was significantly higher in patients for MRA score 2 with TIA history than without. ER significantly increased as CSA increased in section E, which suggests ER becomes less in decreased CSA due to negative remodeling.

CONCLUSION

Arterial wall enhancement in MMD varies by age, location, and disease progression. Arterial wall enhancement may be stronger in the progressive stage of MMD. Arterial wall enhancement increases with history of TIA at proximal MCA, which may indicate the progression of the disease.

CLINICAL RELEVANCE STATEMENT

Arterial wall enhancement in moyamoya disease varies by age, location of arteries, and disease progression, and arterial wall enhancement may be used as an imaging biomarker of moyamoya disease.

KEY POINTS

It has not been clarified what arterial wall enhancement in moyamoya disease represents. Arterial wall enhancement in moyamoya disease varies by age, location of arteries, and disease progression. Arterial wall enhancement in moyamoya disease increases as the disease progresses.

Endovascular Treatment for Intracranial Artery Dissections in Posterior Circulation

Intracranial artery dissections (IADs), although uncommon, are an important cause of cerebral infarction and subarachnoid hemorrhage (SAH). Some IADs can heal spontaneously after reconstitution of the vessel lumen with excellent prognosis. Meanwhile, others can progress to stroke that requires treatment. The incidence of IAD in the posterior circulation is higher than that in the anterior circulation. Anterior circulation dissections are more likely to develop into ischemia and posterior circulation lesions into hemorrhage. The mortality rate after IAD among patients with SAH is 19%-83%. Further, the mortality rate of IAD without SAH is 0%-3%. Patients with SAH commonly undergo surgery or receive neuroendovascular treatment (EVT) to prevent rebleeding. However, the treatment of IADs is empirical in the absence of data from randomized controlled trials. Recently, EVT has emerged and is considered for IADs because of its less invasiveness and perceived low rates of procedure-related morbidity with good efficacy. EVT strategies can be classified into deconstructive (involving sacrifice of the parent artery) and reconstructive (preserving blood flow via the parent vessel) techniques. In particular, the number of reports on reconstructive techniques is increasing. However, a reconstructive technique for ruptured IADs has not yet been established. This review aimed to provide an overview of IADs in the posterior circulation managed with EVT by performing a literature search.

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.

Association Between Serum Homocysteine Concentration, Aneurysm Wall Inflammation, and Aneurysm Symptoms in Intracranial Fusiform Aneurysm

RATIONALE AND OBJECTIVES

The pathophysiology of fusiform intracranial aneurysm (FIA) involves inflammatory processes, and homocysteine plays a role in the inflammatory processes in the vessel wall. Moreover, aneurysm wall enhancement (AWE) has emerged as a new imaging biomarker of aneurysm wall inflammatory pathologies. To investigate the pathophysiological mechanisms of aneurysm wall inflammation and FIA instability, we aimed to determine the associations between the homocysteine concentration, AWE, and FIAs' related symptoms.

MATERIALS AND METHODS

We retrospectively reviewed the data of 53 patients with FIA who underwent both high-resolution magnetic resonance imaging and serum homocysteine concentration measurement. FIAs' related symptoms were defined as ischemic stroke or transient ischemic attack, cranial nerve compression, brainstem compression, and acute headache. The contrast ratio of the signal intensity of the aneurysm wall to the pituitary stalk (CRstalk) was used to indicate AWE. Multivariate logistic regression and receiver operating characteristic (ROC) curve analyses were performed to determine how well the independent factors could predict FIAs' related symptoms. Predictors of CRstalk were also investigated. Spearman's correlation coefficient was used to identify the potential associations between these predictors.

RESULTS

Fifty-three patients were included, of whom 23 (43.4%) presented with FIAs' related symptoms. After adjusting for baseline differences in the multivariate logistic regression analysis, the CRstalk (odds ratio [OR]=3.207, P = .023) and homocysteine concentration (OR=1.344, P = .015) independently predicted FIAs' related symptoms. The CRstalk was able to differentiate between FIAs with and without symptoms (area under the ROC curve [AUC]=0.805), with an optimal cutoff value of 0.76. The homocysteine concentration could also differentiate between FIAs with and without symptoms (AUC=0.788), with an optimal cutoff value of 13.13. The combination of the CRstalk and homocysteine concentration had a better ability to identify symptomatic FIAs (AUC=0.857). Male sex (OR=0.536, P = .018), FIAs' related symptoms (OR=1.292, P = .038), and homocysteine concentration (OR=1.254, P = .045) independently predicted the CRstalk.

CONCLUSION

A higher serum homocysteine concentration and greater AWE indicate FIA instability. Serum homocysteine concentration may be a useful biomarker of FIA instability; however, this needs to be verified in future studies.

Tetrazine-Based Ratiometric Nitric Oxide Sensor Identifies Endogenous Nitric Oxide in Atherosclerosis Plaques by Riding Macrophages as a Smart Vehicle

Atherosclerosis (AS) is the formation of plaques in blood vessels, which leads to serious cardiovascular diseases. Current research has disclosed that the formation of AS plaques is highly related to the foaming of macrophages. However, there is a lack of detailed molecular biological mechanisms. We proposed a "live sensor" by grafting a tetrazine-based ratiometric NO probe within macrophages through metabolic and bio-orthogonal labeling. This "live sensor" was proved to target the AS plaques with a diameter of only tens of micrometers specifically and visualized endogenous NO at two lesion stages in the AS mouse model. The ratiometric signals from the probe confirmed the participation of NO during AS and indicated that the generation of endogenous NO increased significantly as the lesion progressed. Our proposal of this "live sensor" provided a native and smart strategy to target and deliver small molecular probes to the AS plaques at the in vivo level, which can be used as universal platforms for the detection of reactive molecules or microenvironmental factors in AS.

Plaque enhancement predicts recurrence in acute ischemic stroke patients with large artery intracranial atherosclerosis

BACKGROUND

The association between the degree of plaque enhancement and ischemic brain stroke recurrence remains unclear. We aimed to establish models to predict plaque enhancement and stroke recurrence.

METHODS

Seventy-eight participants with acute ischemic brain stroke due to intracranial arterial stenosis were recruited and divided into high enhancement (HE) and non-HE groups. The relationship between imaging characteristics (degree of stenosis, minimal lumen area, intraplaque hemorrhage, and plaque burden) and the degree of plaque contrast enhancement was analyzed. Inflammatory cytokine expression was examined by flow cytometry. Independent predictors of stroke recurrence were investigated via multivariate Cox proportional hazards regression analysis. Nomogram was used to construct a prediction model. Harrell's concordance indices (c-indices) and calibration curves were used to assess the discrimination of the nomogram. A risk prediction nomogram for prognosis was constructed.

RESULTS

Thirty-three participants were assigned to the HE group and 45 to the non-HE group. The degree of stenosis and plaque burden in the HE group was higher than that in the non-HE group (P<0.05). Multiple linear regression analysis showed the degree of stenosis was associated with HE (β=0.513; P=0.000). After adjusting for confounding factors, age (HR=1.115; 95%CI=1.034-1.203, P=0.005) and HE plaques (HR=10.457; 95%CI=1.176-93.018; P=0.035) were independent risk factors of stroke recurrence, whereas cytokine levels were not statistically significant between two group.

CONCLUSIONS

HE of intracranial atherosclerosis plaques is an independent factor for ischemic brain stroke recurrence.

The prevalence and prognosis of asymptomatic intracranial atherosclerosis in a community-based population: Results based on high-resolution magnetic resonance imaging

BACKGROUND AND PURPOSE

Intracranial atherosclerotic disease (ICAD) is a major cause of ischemic stroke in China, but the prevalence and prognosis of asymptomatic ICAD detected using high-resolution magnetic resonance imaging (HR-MRI) is largely unknown. The aim of this study was to investigate the prevalence and prognosis in order to guide neurologists in interpreting ICAD detected on HR-MRI.

METHODS

We included stroke-free participants from a community-based prospective cohort (Shunyi study participants) who underwent HR-MRI between July 2014 and April 2016. The participants were divided into two groups: those with or without ICAD (ICAD+ and ICAD- , respectively). ICAD included intracranial artery stenosis and non-stenotic plaque. The primary outcome was ischemic stroke. Cox proportional hazard models were used to evaluate the association between ICAD and event outcomes.

RESULTS

A total of 1060 stroke-free participants evaluated by HR-MRI were included from the Shunyi study. The median age at HR-MRI was 56 years and 64.7% were female. The ICAD prevalence was 36.3% (n = 385). The ICAD+ group was older and had more cerebrovascular risk factors. The rates of ischemic stroke in the ICAD- and ICAD+ groups were 1.3% (n = 9) and 5.2% (n = 20), respectively, with a median follow-up time of 54 months. ICAD was associated with an increased risk of ischemic stroke in the unadjusted and adjusted Cox models, with hazard ratios of 4.12 (95% confidence interval [CI] 1.87-9.05) and 2.50 (95% CI 1.05-5.94), respectively. The greatest risk of an event outcome was observed in participants with ≥70% stenosis or occlusion. The features of high-risk plaques were also identified.

CONCLUSIONS

We found that ICAD detected using HR-MRI increases the long-term risk of a first-ever ischemic stroke in a stroke-free population, suggesting that the current primary prevention protocol of stroke awaits further optimization.

The association of intracranial atherosclerosis with cerebral small vessel disease imaging markers: a high-resolution magnetic resonance imaging study

To evaluate the association of intracranial non-stenotic atherosclerotic plaque with cerebral small vessel disease (CSVD) imaging markers in a CSVD population using 3.0 T high-resolution magnetic resonance imaging (HRMRI), which was validated in embolic stroke of undetermined source (ESUS) cohort. We retrospectively recruited consecutive patients who were diagnosed with CSVD or ESUS from January 2015 to December 2019. All patients underwent intracranial HRMRI to assess intracranial non-stenotic atherosclerotic plaques. Baseline and imaging data were collected and were measured among all patients. Among 153 patients with CSVD, there were 59 with intracranial atherosclerotic plaque (IAP) and 94 with non-IAP, including 36 with intracranial atherosclerotic complicated plaque (IACP). Among 227 ESUS patients, there were 155 with IAP and 72 with non-IAP, including 127 with IACP. In the CSVD population, we found that: (1) CSVD burden was associated with IAP (p = 0.036) and IACP (p = 0.008); (2) IAP was associated with white matter hyperintensity (51% vs. 34%; P = 0.039), and IACP was associated with lacunes (69% vs. 35%; P = 0.009) and enlarge perivascular space (69% vs. 39%; P = 0.022). A similar association of CSVD imaging markers with IAP or IACP was found in the ESUS population. Furthermore, the association of unilateral IAP or IACP with CSVD imaging markers of ipsilateral hemisphere was identified in the two cohorts. This is the first report that intracranial non-stenotic atherosclerotic plaque, especially complicated plaque, is closely associated with CSVD imaging markers, which provide further evidence for the association of large artery atherosclerosis with CSVD.

Characteristics of intracranial plaque in patients with non-cardioembolic stroke and intracranial large vessel occlusion

OBJECTIVE

To determine the characteristics of intracranial plaque proximal to large vessel occlusion (LVO) in stroke patients without major-risk cardioembolic source using 3.0 T high-resolution MRI (HR-MRI).

METHODS

We retrospectively enrolled eligible patients from January 2015 to July 2021. The multidimensional parameters of plaque such as remodelling index (RI), plaque burden (PB), percentage lipid-rich necrotic core (%LRNC), presence of discontinuity of plaque surface (DPS), fibrous cap rupture, intraplaque haemorrhage and complicated plaque were evaluated by HR-MRI.

RESULTS

Among 279 stroke patients, intracranial plaque proximal to LVO was more prevalent in the ipsilateral versus contralateral side to stroke (75.6% vs 58.8%, p<0.001). The larger PB (p<0.001), RI (p<0.001) and %LRNC (p=0.001), the higher prevalence of DPS (61.1% vs 50.6%, p=0.041) and complicated plaque (63.0% vs 50.6%, p=0.016) were observed in the plaque ipsilateral versus contralateral to stroke. Logistic analysis showed that RI and PB were positively associated with an ischaemic stroke (RI: crude OR: 1.303, 95% CI 1.072 to 1.584, p=0.008; PB: crude OR: 1.677, 95% CI 1.381 to 2.037, p<0.001). In subgroup with <50% stenotic plaque, the greater PB, RI, %LRNC and the presence of complicated plaque were more closely related to stroke, which was not evident in subgroup with ≥50% stenotic plaque.

CONCLUSION

This is the first study to report the characteristics of intracranial plaque proximal to LVO in non-cardioembolic stroke. It provides potential evidence to support different aetiological roles of <50% stenotic vs ≥50% stenotic intracranial plaque in this population.

Imaging features of vertebrobasilar dolichoectasia combined with posterior circulation ischemic stroke: A vessel wall magnetic resonance imaging study

PURPOSE

To elucidate the vessel wall changes of vertebrobasilar dolichoectasia (VBD) with ischemic stroke, using vessel wall magnetic resonance imaging (VW-MRI).

METHOD

Thirty-four patients with VBD (22 with stroke and 12 without stroke) who underwent VW-MRI were recruited. Forty-one patients without VBD who underwent VW-MRI were also recruited if they had a recent stroke due to atherosclerosis in the basilar artery or the intracranial vertebral artery. The vessel wall features of VBD were compared between stroke and non-stroke groups. The plaque characteristics were compared between VBD and non-VBD stroke patients.

RESULTS

The frequency of plaques was higher (54.5% vs. 8.3%, P = 0.011) in VBD patients with stroke than that in non-stroke patients, while the frequencies of aneurysm, dissection, intraluminal thrombus, and diffuse/concentric wall enhancement did not differ. When the plaque features were compared between plaque-positive stroke patients with and without VBD, the degree of stenosis (31.0% ± 26.8% vs. 71.5% ± 19.0%, P < 0.001), normalized wall index (NWI) (0.7 ± 0.1 vs. 0.9 ± 0.1, P < 0.001), and remodeling index (RI) (1.0 ± 0.4 vs. 1.3 ± 0.4, P = 0.023) were lower in the VBD group, while intraplaque hemorrhage, and enhancement ratio showed no difference.

CONCLUSIONS

This preliminary study suggests that atherosclerosis may be an important cause of stroke in VBD patients. Symptomatic plaques in VBD patients have a lower degree of stenosis, NWI, and RI than that in non-VBD patients. VW-MRI may help to assess stroke mechanisms and identify VBD patients at high risk.

Progressive arteriopathy with vasospasm in focal cerebral arteriopathy in childhood: a case report

BACKGROUND

Focal cerebral arteriopathy (FCA) is a clinically important disease that often causes progressive arteriopathy. We report a case of FCA with progressive arteriopathy due to arterial shrinkage of the outer diameter found on T2-weighted three-dimensional sampling perfection with application optimized contrasts using different flip angle evolutions (3D-SPACE) imaging.

CASE PRESENTATION

The patient was a 9-year-old girl who developed right hemiparesis. Acute infarction was detected in the basal ganglia. Vascular images revealed stenosis from the distal internal carotid artery (ICA) to the middle cerebral artery (MCA). Intravenous heparin was administered for 8 days, and the symptoms improved. However, 29 days after onset, right hemiparesis transiently developed again and magnetic resonance angiography (MRA) showed progressive stenosis from the ICA to MCA, while 3D-SPACE showed similar shrinkage of the outer diameter. Aspirin was started, and there was no subsequent recurrence. After 12 months, MRA and 3D-SPACE showed improvement of stenosis and arterial shrinkage.

CONCLUSIONS

Given the time course, the change in the outer diameter was thought to be vasospasm. Thus, vasospasm may be one of the causes of progressive arteriopathy in FCA.

Advanced Neuromonitoring Modalities on the Horizon: Detection and Management of Acute Brain Injury in Children

Timely detection and monitoring of acute brain injury in children is essential to mitigate causes of injury and prevent secondary insults. Increasing survival in critically ill children has emphasized the importance of neuroprotective management strategies for long-term quality of life. In emergent and critical care settings, traditional neuroimaging modalities, such as computed tomography and magnetic resonance imaging (MRI), remain frontline diagnostic techniques to detect acute brain injury. Although detection of structural and anatomical abnormalities remains crucial, advanced MRI sequences assessing functional alterations in cerebral physiology provide unique diagnostic utility. Head ultrasound has emerged as a portable neuroimaging modality for point-of-care diagnosis via assessments of anatomical and perfusion abnormalities. Application of electroencephalography and near-infrared spectroscopy provides the opportunity for real-time detection and goal-directed management of neurological abnormalities at the bedside. In this review, we describe recent technological advancements in these neurodiagnostic modalities and elaborate on their current and potential utility in the detection and management of acute brain injury.

Endovascular treatment of intracranial vertebral artery dissecting aneurysm, a case series study with two years follow up on complications

Background

This study is aimed to analyze the clinical outcomes of endovascular treatments for patients with intracranial vertebral artery dissecting aneurysms.

Methods

Clinical data of 32 patients with vertebral artery dissecting aneurysms who underwent endovascular procedures in the Department of Neurosurgery of our University from January 2016 to December 2019 were retrospectively analyzed. Nine cases were treated with endovascular occlusion; 23 cases received reconstructive treatment, including 20 cases of stent combined with coil embolization, and 3 cases of stent implantation. The angiography taken at 3-22 months after surgery was reviewed.

Results

The endovascular treatments for all 32 cases were successful. Thirty-one cases had no postoperative complications during index hospital. Mid-term follow-up showed that: 27 cases (84%) had embolism; 5 cases (16%) had recurrence, of which 4 cases were treated again with endovascular procedures followed with no further complications and no recurrence, and 1 case received closely monitor but no reoperation. During an average follow-up of 10.5 months, except for one case that was self-discharged due to end-stage brainstem compression and respiratory failure, the rest of the patients were in stable conditions without bleeding or infarction.

Conclusion

Endovascular treatment of intracranial vertebral artery dissecting aneurysms is safe and effective. Recurrent vertebral artery dissecting aneurysms can be treated with endovascular reoperations with satisfactory outcomes.

The incomplete circle of Willis is associated with vulnerable intracranial plaque features and acute ischemic stroke

BACKGROUND

The circle of Willis (CoW) plays a significant role in intracranial atherosclerosis (ICAS). This study investigated the relationship between different types of CoW, atherosclerosis plaque features, and acute ischemic stroke (AIS).

METHODS

We investigated 97 participants with AIS or transient ischemic attacks (TIA) underwent pre- and post-contrast 3T vessel wall cardiovascular magnetic resonance within 7 days of the onset of symptoms. The culprit plaque characteristics (including enhancement grade, enhancement ratio, high signal in T1, irregularity of plaque surface, and normalized wall index), and vessel remodeling (including arterial remodeling ratio and positive remodeling) for lesions were evaluated. The anatomic structures of the anterior and the posterior sections of the CoW (A-CoW and P-CoW) were also evaluated. The plaque features were compared among them. The plaque features were also compared between AIS and TIA patients. Finally, univariate and multivariate regression analysis was performed to evaluate the independent risk factors for AIS.

RESULT

Patients with incomplete A-CoW showed a higher plaque enhancement ratio (P = 0.002), enhancement grade (P = 0.01), and normalized wall index (NWI) (P = 0.018) compared with the patients with complete A-CoW. A higher proportion of patients with incomplete symptomatic P-CoW demonstrated more culprit plaques with high T1 signals (HT1S) compared with those with complete P-CoW (P = 0.013). Incomplete A-CoW was associated with a higher enhancement grade of the culprit plaques [odds ratio (OR):3.84; 95% CI: 1.36-10.88, P = 0.011], after adjusting for clinical risk factors such as age, sex, smoking, hypertension, hyperlipemia, and diabetes mellitus. Incomplete symptomatic P-CoW was associated with a higher probability of HT1S (OR:3.88; 95% CI: 1.12-13.47, P = 0.033), after adjusting for clinical risk factors such as age, sex, smoking, hypertension, hyperlipemia, and diabetes mellitus. Furthermore, an irregularity of the plaque surface (OR: 6.24; 95% CI: 2.25-17.37, P < 0.001), and incomplete symptomatic P-CoW (OR: 8.03, 95% CI: 2.43-26.55, P = 0.001) were independently associated with AIS.

CONCLUSIONS

This study demonstrated that incomplete A-CoW was associated with enhancement grade of the culprit plaque, and incomplete symptomatic side P-CoW was associated with the presence of HT1S of culprit plaque. Furthermore, an irregularity of plaque surface and incomplete symptomatic side P-CoW were associated with AIS.

Diagnosis and management of adult primary angiitis of the central nervous system: an international survey on current practices

BACKGROUND

Primary angiitis of the central nervous system (PACNS) is a rare disease, for which no validated guidelines exist. We report the findings of a survey on the clinical practice of physicians who manage adults with PACNS.

METHODS

An online survey was distributed through neurology, internal medicine, and rheumatology societies in Canada and Europe. Participants who were directly involved as treating physicians for at least two adult patients with PACNS were eligible for the survey.

RESULTS

Ninety-six physicians completed the survey. Most participants were neurologists (n = 38, 40%), internists (n = 34, 35%) or rheumatologists (n = 22, 23%). Participants obtained a CNS biopsy in a median of 25% (IQR: 5-50%) of suspected PACNS cases. When determining the degree to which eight scenarios justified a CNS biopsy, participants achieved fair inter-rater agreement (Gwet's AC₂ 0.30, 95% CI 0.23-0.41). For induction therapy, 81 (84%) participants reported using glucocorticoids and cyclophosphamide in > 50% of patients. After obtaining remission, 85 (89%) participants systematically introduced or maintained immunosuppressive therapy. Glucocorticoids were prescribed for a median of 12 months. Maintenance therapy with another immunosuppressant was continued for a median of 24 months. In patients who achieved remission, we explored how eight scenarios with different imaging and CSF results supported an increase in treatment. Inter-rater agreement was substantial if the patient was symptomatic (0.66, 95% CI 0.58-0.80) and moderate (0.50, 95% CI 0.45-0.60) if asymptomatic.

CONCLUSION

This survey illustrates current real-world management of PACNS and emphasizes several areas for which physicians still lack study-based evidence and/or clinical practice guidelines.

Childhood Cerebral Vasculitis : A Multidisciplinary Approach

Cerebral vasculitis is increasingly recognized as a common cause of pediatric arterial stroke. It can present with focal neurological deficits, psychiatric manifestations, seizures, and encephalopathy. The etiopathogenesis of childhood cerebral vasculitis (CCV) is multifactorial, making an inclusive classification challenging. In this review, we describe the common and uncommon CCV with a comprehensive discussion of etiopathogenesis, the role of various imaging modalities, and advanced techniques in diagnosing CCV. We also highlight the implications of relevant clinical, laboratory, and genetic findings to reach the final diagnosis. Based on the clinicoradiological findings, a stepwise diagnostic approach is proposed to facilitate CCV diagnosis and rule out potential mimics. Identification of key clinical manifestations, pertinent blood and cerebrospinal fluid results, and evaluation of central nervous system vessels for common and disease-specific findings will be emphasized. We discuss the role of magnetic resonance imaging, MR angiography, and vessel wall imaging as the imaging investigation of choice, and reservation of catheter angiography as a problem-solving tool. We emphasize the utility of brain and leptomeningeal biopsy for diagnosis and exclusion of imitators and masqueraders.

Vulnerable plaque of the petrous internal carotid artery in embolic stroke of undetermined source

BACKGROUND AND PURPOSE

The association between nonstenotic plaque at the petrous internal carotid artery (ICA) and embolic stroke of undetermined source (ESUS) remains unknown. We aimed to test the hypothesis that the presence of a larger build-up of petrous plaque is more prevalent in the ipsilateral versus the contralateral side among ESUS patients without plaque in the intracranial and proximal ICA.

METHODS

From a total of 243 patients with ESUS and 160 patients with small-vessel disease (SVD) without proximal ICA plaque, we enrolled 88 ESUS and 103 SVD patients without ipsilateral nonstenotic intracranial and proximal ICA plaque in the present study. Targeting the petrous segment of the ICA on two sides, plaque burden including plaque thickness, lumen area, vessel area, wall area, and percentage of luminal stenosis, and composition features (presence/absence of the ruptured fibrous cap, ulcer plaque, thrombus, discontinuity of plaque surface [DPS], intraplaque hemorrhage and complicated plaque) were assessed by high-resolution magnetic resonance imaging.

RESULTS

We found a higher prevalence of petrous plaque thickness ≥3.5 mm ipsilateral versus contralateral to the stroke (25/88 [28.4%] vs. 12/88 [13.6%], odds ratio [OR] 3.60, 95% confidence interval [CI] 1.34-9.70), but this imbalance was not seen in SVD. In patients with plaque thickness ≥3.5 mm, the presence of DPS (OR 4.05, 95% CI 1.11-14.78) and complicated plaque (OR 5.00, 95% CI 1.10-22.82) was more closely related to an index ESUS, a finding that was not evident in the subgroup with petrous plaque <3.5 mm (p for interaction = 0.027).

CONCLUSIONS

The present study provided the first evidence supporting a potential etiological role of vulnerable petrous plaque in ESUS.

Impact of lesion size on reproducibility of quantitative measurement and radiomic features in vessel wall MRI

OBJECTIVES

To investigate reproducibility of quantitative measurement and radiomic features in vessel wall MRI (VW-MRI), evaluate the impact of lesion size, and identify reproducible radiomic features.

METHODS

This retrospective, single-center study included 251 patients (mean age, 53 ± 12 years; 128 women) with atherosclerosis, dissection, aneurysm, moyamoya disease, and vasculitis of the intracranial arteries who underwent three-dimensional turbo spin echo T1-weighted image. Lesion thickness, volume, and signal intensity were measured, and 157 radiomic features were extracted. Intra-observer reproducibility of quantitative measurement and radiomic features was evaluated by calculating the concordance correlation coefficient (CCC) and proportion of radiomic features above the predefined CCC. The reproducibility of quantitative measurement and radiomic features according to lesion size (binary comparison and stratification into 5 and 18 groups) was evaluated.

RESULTS

There was an overall serial increase in CCC for thickness measurement when stratified by lesion thickness and volume. There was an overall serial increase in the median CCC for radiomic features and proportion of radiomic features with CCC > 0.85 when stratified by lesion thickness and volume. Reproducibility of radiomic features was higher in the lesions with thickness ≥ 2.5 mm (median CCC, 0.97 vs. 0.89, p < .001; proportion with CCC > 0.85, 88.5% vs. 59.6%, p < .001) and volume ≥ 50 mm³ (median CCC, 0.97 vs. 0.88, p < .001; proportion with CCC > 0.85, 90.4% vs. 59.0%, p < .001). Intensity-based statistical features remained most reproducible in the thinnest and smallest lesions.

CONCLUSIONS

Intra-observer reproducibility of thickness measurement and radiomic features was affected by lesion size in VW-MRI although intensity-based statistical features remained most reproducible.

KEY POINTS

• There was an overall serial increase in CCC for thickness measurement when stratified by lesion size. • There was an overall serial increase in the median CCC for radiomic features and proportion of radiomic features with CCC > 0.85 when stratified by lesion size. • Intensity-based statistical features remained most reproducible in the thinnest and smallest lesions.

Magnetic Resonance Imaging-Derived Microvascular Perfusion Modeling to Assess Peripheral Artery Disease

Background Computational fluid dynamics has shown good agreement with contrast-enhanced magnetic resonance imaging measurements in cardiovascular disease applications. We have developed a biomechanical model of microvascular perfusion using contrast-enhanced magnetic resonance imaging signal intensities derived from skeletal calf muscles to study peripheral artery disease (PAD). Methods and Results The computational microvascular model was used to study skeletal calf muscle perfusion in 56 individuals (36 patients with PAD, 20 matched controls). The recruited participants underwent contrast-enhanced magnetic resonance imaging and ankle-brachial index testing at rest and after 6-minute treadmill walking. We have determined associations of microvascular model parameters including the transfer rate constant, a measure of vascular leakiness; the interstitial permeability to fluid flow which reflects the permeability of the microvasculature; porosity, a measure of the fraction of the extracellular space; the outflow filtration coefficient; and the microvascular pressure with known markers of patients with PAD. Transfer rate constant, interstitial permeability to fluid flow, and microvascular pressure were higher, whereas porosity and outflow filtration coefficient were lower in patients with PAD than those in matched controls (all P values ≤0.014). In pooled analyses of all participants, the model parameters (transfer rate constant, interstitial permeability to fluid flow, porosity, outflow filtration coefficient, microvascular pressure) were significantly associated with the resting and exercise ankle-brachial indexes, claudication onset time, and peak walking time (all P values ≤0.013). Among patients with PAD, interstitial permeability to fluid flow, and microvascular pressure were higher, while porosity and outflow filtration coefficient were lower in treadmill noncompleters compared with treadmill completers (all P values ≤0.001). Conclusions Computational microvascular model parameters differed significantly between patients with PAD and matched controls. Thus, computational microvascular modeling could be of interest in studying lower extremity ischemia.

Uncommon causes of ischaemic stroke: how to approach the diagnosis

Stroke is a common neurological emergency and although most cases are associated with traditional vascular risk factors leading to cerebral ischaemia by well-recognised pathophysiological mechanisms, around 4% of ischaemic strokes are due to rare conditions. These are important to recognise due to their different management, which is often specific and effective, and due to their different prognosis from otherwise cryptogenic ischaemic strokes. We outline a practical approach to identifying uncommon causes of ischaemic stroke by highlighting diagnostic 'red flags' and propose a structured approach to investigating them.

Correlation between characteristics of intracranial atherosclerotic plaques and ischemic stroke in high-resolution vascular wall MRI

BACKGROUND

Intracranial atherosclerotic stenosis is a major cause of ischemic stroke, accounting for 30% of ischemic strokes in Asian populations.

PURPOSE

To investigate the relationship between the degree of arterial stenosis and enhancement grade of intracranial atherosclerotic disease (ICAD), the plaque characteristics in different remodeling patterns, and its potential impact.

MATERIAL AND METHODS

A total of 210 patients diagnosed with ICAD were enrolled in this retrospective study. Patients were divided into the middle cerebral artery (MCA) group (101 cases), posterior cerebral artery (PCA) group (14 cases), basilar artery (BA) group (71 cases), and intracranial segment of vertebral artery (VA) group (90 cases) according to the difference of diseased vessels. Data on presence or absence of ischemic infarction, intracranial vascular position of lesions, plaque characteristics, ICAD enhancement grade, remodeling index, and degree of arterial stenosis were collected for analysis.

RESULTS

The incidence of ischemic infarction in enhancement grade 2 was significantly higher than that in enhancement grade 1 in MCA group (P = 0.019). Enhancement grade 2 of ICAD was an independent risk factor for the development of ischemic infarction (odds ratio = 4.60; 95% confidence interval: 1.91-11.03; P = 0.001). There was no significant statistical difference in infarct rate between different remodeling modalities (P>0.05).

CONCLUSION

Enhancement grade of ICAD is significantly associated with the degree of stenosis and the occurrence of ischemic stroke, which varies in different intracranial vessels. The pattern of vascular remodeling varies among different intracranial vessels, and the pattern of vascular remodeling has a significant impact on plaque characteristics.

Sequential detection rates of intramural hematoma for diagnosing spontaneous intracranial artery dissection

BACKGROUND AND PURPOSE

Spontaneous intracranial artery dissection (IAD) can be definitively diagnosed by detecting intramural hematoma (IMH) on arterial wall imaging. However, evidence of a time-dependent natural history for the development of radiological findings is lacking. Therefore, this study aimed to determine when imaging detects IAD.

METHODS

We obtained data from our cohort databases between March 2011 and August 2018 on consecutive patients who had definite, probable, or possible IAD based on the multidisciplinary expert consensus criteria. We assessed IMH on initial and follow-up high-resolution three-dimensional T1-weighted imaging (HR-3D-T1WI). We retrospectively investigated the association between IMH detection and days from symptom onset to initial HR-3D-T1WI and compared the IMH detection rate with other definitive diagnostic arterial dissection findings.

RESULTS

We analyzed 106 patients (mean age = 51 ± 13 years, 31 women) with at least initial HR-3D-T1WI data. The final diagnoses were definite, probable, and possible IAD in 83, 18, and 5 patients, respectively. IMHs were observed in 63 patients (59%, 95% confidence interval [CI] = 49%-69%). Overall IMH detection rate was 55% (95% CI = 45%-64%), 20% (95% CI = 3%-60%), 40% (95% CI = 21%-64%), and 50% (95% CI = 37%-63%) on the initial HR-3D-T1WI and Days 3, 7, and 13, respectively. Among 68 patients evaluated with digital subtraction angiography and HR-3D-T1WI, IMH was confirmed more frequently than other definitive diagnostic arterial dissection findings.

CONCLUSIONS

The overall IMH detection rate on HR-3D-T1WI was >50% and peaked in 1-2 weeks. IMH was a frequently detectable finding for the diagnosis of IAD compared to other radiological findings.

Acute internal carotid artery occlusion due to dissection of the paraclinoid segment: Diagnostic usefulness of angiographic findings during stent retriever deployment

Intracranial artery dissection is an uncommon but possible cause of ischemic stroke, and is usually diagnosed based on imaging findings such as mural hematoma and dissection flap. However, it is challenging to recognize the underlying dissection in cases of acute large vessel occlusion. In this report, we present a case of acute internal carotid artery occlusion, in which the underlying dissection of the paraclinoid segment was found during the thrombectomy procedure. Two thrombectomy procedures failed to recanalize the acute internal carotid artery occlusion without removing any clot. Angiography performed during a Trevo stent retriever deployment in the first pass showed obscure contrast defects in the stent strut with temporary flow restoration. In the next pass, the appearance of the contrast defects changed and a parallel linear contrast appeared on the outside of the vessel wall. These angiographic findings were identified as mural hematoma and dissection flap, indicating dissection of the paraclinoid as the cause of the occlusion. During antiplatelet loading and preparation of a dedicated intracranial stent, the Trevo stent retriever was left deployed again at the occlusion site to maintain the blood flow. After permanent stenting with an Enterprise stent, angiography revealed complete recanalization. The patient recovered fully after the procedure. In the present case, stent retriever deployment revealed the hallmarks of dissection on angiography, such as mural hematoma, dissection flap, and temporal morphological changes, by restoring the blood flow temporarily. Such angiographic findings can provide useful information on the occlusion characteristics and real-time feedback for optimal treatment strategy.

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.

Utility of high-resolution magnetic resonance vessel wall imaging in differentiating between atherosclerotic plaques, vasculitis, and arterial dissection

PURPOSE

Differentiating between atherosclerosis, vasculitis, and dissection is a diagnostic challenge because of inconclusive findings on conventional imaging and some overlap in the vessel wall patterns. The aim of this study was to determine whether vessel wall MRI patterns can differentiate between these vasculopathies.

METHODS

We retrospectively reviewed 3T high-resolution vessel wall imaging studies of patients diagnosed with atherosclerotic plaques, vasculitis, and dissection. The patterns of involvement, wall enhancement, and T1 and T2 signals, as well as the specific patterns, were assessed and compared between the three diseases.

RESULTS

Fifty-nine patients with atherosclerosis (n = 33), vasculitis (n = 13), and dissection (n = 13) were enrolled. There were significant differences in the pattern of involvement between the three groups (P < 0.001), with concentric wall thickening in vasculitis patients (84.6%) and eccentric wall thickening in atherosclerosis (97%) and dissection (92.3%) patients. There was also a significant difference in the specific pattern (P < 0.001), with intimal flap (76.9%) and intramural hematoma (23.1%) in dissection patients and intraplaque hemorrhage (18.2%) in atherosclerosis patients. Furthermore, subgroup analysis showed a significant difference in the wall enhancement pattern between atherosclerosis and vasculitis patients (P < 0.05). Finally, there was a significant difference in the location of involvement between the three groups (P < 0.001).

CONCLUSION

By using the pattern of involvement, wall enhancement, and specific patterns, vessel wall MRI can help differentiate between atherosclerosis, vasculitis, and dissection.

Vessel wall imaging and quantitative flow assessment in arteriovenous malformations: A feasibility study

INTRODUCTION

Cerebral arteriovenous malformations (AVMs) carry a rupture rate of 2-3% per year. Several architectural factors may influence rupture rate, and a recently theorized model of AVMs describes the influence of vessel wall inflammation. A novel imaging modality, vessel wall imaging (VWI), has been developed to view inflammatory processes in vessel wall foci but has not yet been examined in AVMs, which is the aim of this study.

METHODS

This retrospective review studies prospectively collected data on patients with ruptured and unruptured AVMs between 2019 and 2021. Inclusion criteria included adult patients (≥18 years) with radiographically diagnosed AVM who underwent VWI. Charts were reviewed for medical history, clinical presentation, hospital course, discharge condition, and follow-up. Angioarchitectural features, blood flow, and VWI were compared in patients with and without hemorrhagic patients.

RESULTS

Nine patients underwent VWI, mean age 37.7 ± 9.9 years. Four presented with hemorrhage (44.4%). Seven (77.7%) received glue embolization and 6 (66.7%) underwent surgical resection. All patients (4/4) with a history of hypertension presented with hemorrhage (p = 0.0027). Size and Spetzler-Martin grade were not associated with hemorrhage (p = 0.47, p = 0.59). Net AVM flow was higher in patients presenting with hemorrhage, although nonsignificant (p = 0.19). With VWI, 3 (75%) hemorrhagic AVMs showed visible nidus and draining veins, and all three demonstrated positive post-contrast wall enhancement in at least one of their draining veins; conversely, of fivenonhemorrhagic AVMs, only 2 (40%) demonstrated post-contrast wall enhancement in any draining vein (p = 0.090).

CONCLUSION

This pilot study successfully demonstrated capture of venous walls in AVMs using VWI. In this study, draining vein enhancement occurred more often in hemorrhagic AVM and in those with higher venous volumetric flow.

Plaque characteristics after endovascular treatment in patients with intracranial atherosclerotic disease

BACKGROUND

Endovascular treatment (EVT) is an alternative option for symptomatic intracranial atherosclerotic disease (ICAD). However, the effect of EVT treatment on ICAD plaques is still unclear. This study describes the ICAD plaque characteristics after EVT treatment and analyzes the effect of different EVT treatments on plaque characteristics.

METHOD

From 2017 January to 2022 January, ICAD patients who underwent endovascular treatment and had follow-up high-resolution magnetic resonance image (HRMRI) were enrolled in the study. Multiple plaque characteristics, including plaque enhancement, plaque burden, were measured based on preoperative, and follow-up HRMRI. Plaque characteristics and postoperative plaque changes were analyzed between different treatment groups.

RESULT

Finally, 50 intracranial atherosclerotic plaques in 45 patients were included. Including 28 male patients and 17 female, media age 63.0 years old. Among 50 plaques, 41 received percutaneous angioplasty (including 22 plain balloons and 19 drug-coated balloons (DCB)) and the other 9 underwent stenting. Stenosis rate, plaque burden and eccentricity index at the lesion site were significantly decreased after EVT compared with preoperative periods (p <0.001). And only the DCB group showed a significant reduction in plaque enhancement at follow-up (p < 0.001). No significant preoperative and postoperative changes in other plaque characteristics were found.

CONCLUSION

EVT treatment could compromise the characteristics of intracranial periarterial atherosclerotic plaques, and DCB treatment may result in a reduction in plaque enhancement after treatment.

Diagnostic and therapeutic approach to adult central nervous system vasculitis

The clinical manifestations of central nervous system (CNS) vasculitis are highly variable. In the absence of a positive CNS biopsy, CNS vasculitis is particularly suspected when markers of both vascular disease and inflammation are present. To facilitate the clinical and therapeutic approach to this rare condition, CNS vasculitis can be classified according to the size of the involved vessels. Vascular imaging is used to identify medium vessel disease. Small vessel disease can only be diagnosed with a CNS biopsy. Medium vessel vasculitis usually presents with focal neurological signs, while small vessel vasculitis more often leads to cognitive deficits, altered level of consciousness and seizures. Markers of CNS inflammation include cerebrospinal fluid pleocytosis or elevated protein levels, and vessel wall, parenchymal or leptomeningeal enhancement. The broad range of differential diagnoses of CNS vasculitis can be narrowed based on the disease subtype. Common mimickers of medium vessel vasculitis include intracranial atherosclerosis and reversible cerebral vasoconstriction syndrome. The diagnostic workup aims to answer two questions: is the neurological presentation secondary to a vasculitic process, and if so, is the vasculitis primary (i.e., primary angiitis of the CNS) or secondary (e.g., to a systemic vasculitis, connective tissue disorder, infection, malignancy or drug use)? In primary angiitis of the CNS, glucocorticoids and cyclophosphamide are most often used for induction therapy, but rituximab may be an alternative. Based on the available evidence, all patients should receive maintenance immunosuppression. A multidisciplinary approach is necessary to ensure an accurate and timely diagnosis and to improve outcomes for patients with this potentially devastating condition.

Atherosclerosis as a Potential Cause of Deep Embolic Stroke of Undetermined Source: A 3T High‐Resolution Magnetic Resonance Imaging Study

Background

The potential causes or sources of embolic stroke of undetermined source (ESUS) vary. This study aimed to investigate the main cause of deep ESUS by evaluating nonstenotic intracranial atherosclerotic plaque.

Methods and Results

We retrospectively screened consecutive patients with unilateral anterior circulation ESUS. After excluding the patients with possible embolism from an extracranial artery such as aortic arch plaque, carotid plaque, and so on, the enrolled patients with ESUS were categorized into 2 groups: deep ESUS and cortical with/without deep ESUS. All patients underwent intracranial high‐resolution magnetic resonance imaging to assess the characteristics of nonstenotic intracranial atherosclerotic plaque. Biomarkers of atrial cardiopathy (ie, P‐wave terminal force in lead V1 on ECG, NT‐proBNP [N‐terminal pro–brain natriuretic peptide] and left atrial diameter) were collected. A total of 155 patients with ipsilateral nonstenotic intracranial atherosclerotic plaque were found, with 76 (49.0%) in deep ESUS and 79 (51.0%) in cortical with/without deep ESUS. We found more prevalent plaque in the M1 segment of the middle cerebral artery and the ostia of the perforator, with a smaller remodeling index plaque burden, and less frequent occurrence of complicated plaque in deep ESUS versus cortical with/without deep ESUS. Higher BNP (brain natriuretic peptide) levels and a higher prevalence of atrial cardiopathy in cortical with/without deep ESUS versus deep ESUS. Moreover, the discrimination of vulnerable plaque for predicting ESUS was significantly enhanced after adjusting for or further excluding patients with deep ESUS.

Conclusions

The current study provides the first high‐resolution magnetic resonance imaging evidence that cortical with/without deep ESUS and deep ESUS should be 2 distinct entities and that atherosclerosis, not embolism, might be the main cause of deep ESUS.

Cerebral Arteriopathies of Childhood - Current Approaches

Up to more than half of previously healthy children presenting with their first arterial ischemic stroke have a cerebral arteriopathy. Cerebral arteriopathies during childhood can be congenital, reflecting abnormal vessel development, or acquired when caused by disruption of vascular homeostasis. Distinguishing different types of cerebral arteriopathies in children can be challenging but of great clinical value as they may dictate different disease and treatment courses, and clinical and radiologic outcomes. Furthermore, children with stroke due to a specific arteriopathy exhibit distinctive features when compared to those with stroke due to other causes or a different type of arteriopathy. These features become crucial in the management of pediatric stroke by choosing appropriate diagnostic and treatment strategies. The objective of this article is to provide the reader with a comprehensive up-to-date review of the classification, symptoms, diagnosis, treatment, and outcome of cerebral arteriopathies in children.

Identification of high-risk intracranial plaques with 3D high-resolution magnetic resonance imaging-based radiomics and machine learning

BACKGROUND

Identifying high-risk intracranial plaques is significant for the treatment and prevention of stroke.

OBJECTIVE

To develop a high-risk plaque model using three-dimensional (3D) high-resolution magnetic resonance imaging (HRMRI) based radiomics features and machine learning.

METHODS

136 patients with documented symptomatic intracranial artery stenosis and available HRMRI data were included. Among these patients, 136 and 92 plaques were identified as symptomatic and asymptomatic plaques, respectively. A conventional model was developed by recording and quantifying the radiological plaque characteristics. Radiomics features from T1-weighted images (T1WI) and contrast-enhanced T1WI (CE-T1WI) were used to construct a high-risk plaque model with linear support vector classification (linear SVC). The radiological and radiomics features were combined to build a combined model. Receiver operating characteristic (ROC) curves were used to evaluate these models.

RESULTS

Plaque length, burden, and enhancement were independently associated with clinical symptoms and were included in the conventional model, which had an AUC of 0.853 vs. 0.837 in the training and test sets. While the radiomics and the combined model showed an improved AUC: 0.923 vs. 0.925 for the training sets and 0.906 vs. 0.903 in the test sets. Both the radiomics model (p = 0.024, p = 0.018) and combined model (p = 0.042, p = 0.049) outperformed the conventional model in the two sets, whereas the performance of the combined model was not significantly different from that of the radiomics model in the two sets (p = 0.583 and p = 0.606).

CONCLUSION

The radiomics model based on 3D HRMRI can accurately differentiate symptomatic from asymptomatic intracranial arterial plaques and significantly outperforms the conventional model.

Vessel wall MR imaging in neuroradiology

Vessel wall MR imaging (VW-MRI) has been introduced into clinical practice and applied to a variety of diseases, and its usefulness has been reported. High-resolution VW-MRI is essential in the diagnostic workup and provides more information than other routine MR imaging protocols. VW-MRI is useful in assessing lesion location, morphology, and severity. Additional information, such as vessel wall enhancement, which is useful in the differential diagnosis of atherosclerotic disease and vasculitis could be assessed by this special imaging technique. This review describes the VW-MRI technique and its clinical applications in arterial disease, venous disease, vasculitis, and leptomeningeal disease.

Vessel wall MR imaging of aortic arch, cervical carotid and intracranial arteries in patients with embolic stroke of undetermined source: A narrative review

Despite advancements in multi-modal imaging techniques, a substantial portion of ischemic stroke patients today remain without a diagnosed etiology after conventional workup. Based on existing diagnostic criteria, these ischemic stroke patients are subcategorized into having cryptogenic stroke (CS) or embolic stroke of undetermined source (ESUS). There is growing evidence that in these patients, non-cardiogenic embolic sources, in particular non-stenosing atherosclerotic plaque, may have significant contributory roles in their ischemic strokes. Recent advancements in vessel wall MRI (VW-MRI) have enabled imaging of vessel walls beyond the degree of luminal stenosis, and allows further characterization of atherosclerotic plaque components. Using this imaging technique, we are able to identify potential imaging biomarkers of vulnerable atherosclerotic plaques such as intraplaque hemorrhage, lipid rich necrotic core, and thin or ruptured fibrous caps. This review focuses on the existing evidence on the advantages of utilizing VW-MRI in ischemic stroke patients to identify culprit plaques in key anatomical areas, namely the cervical carotid arteries, intracranial arteries, and the aortic arch. For each anatomical area, the literature on potential imaging biomarkers of vulnerable plaques on VW-MRI as well as the VW-MRI literature in ESUS and CS patients are reviewed. Future directions on further elucidating ESUS and CS by the use of VW-MRI as well as exciting emerging techniques are reviewed.

Vessel wall magnetic resonance and arterial spin labelling imaging in the management of presumed inflammatory intracranial arterial vasculopathy

Optimal criteria for diagnosing and monitoring response to treatment for infectious and inflammatory medium–large vessel intracranial vasculitis presenting with stroke are lacking. We integrated intracranial vessel wall MRI with arterial spin labelling into our routine clinical stroke pathway to detect presumed inflammatory intracranial arterial vasculopathy, and monitor disease activity, in patients with clinical stroke syndromes. We used predefined standardized radiological criteria to define vessel wall enhancement, and all imaging findings were rated blinded to clinical details. Between 2017 and 2018, stroke or transient ischaemic attack patients were first screened in our vascular radiology meeting and followed up in a dedicated specialist stroke clinic if a diagnosis of medium–large inflammatory intracranial arterial vasculopathy was radiologically confirmed. Treatment was determined and monitored by a multi-disciplinary team. In this case series, 11 patients were managed in this period from the cohort of young stroke presenters (<55 years). The median age was 36 years (interquartile range: 33,50), of which 8 of 11 (73%) were female. Two of 11 (18%) had herpes virus infection confirmed by viral nucleic acid in the cerebrospinal fluid. We showed improvement in cerebral perfusion at 1 year using an arterial spin labelling sequence in patients taking immunosuppressive therapy for >4 weeks compared with those not receiving therapy [6 (100%) versus 2 (40%) P = 0.026]. Our findings demonstrate the potential utility of vessel wall magnetic resonance with arterial spin labelling imaging in detecting and monitoring medium–large inflammatory intracranial arterial vasculopathy activity for patients presenting with stroke symptoms, limiting the need to progress to brain biopsy. Further systematic studies in unselected populations of stroke patients are needed to confirm our findings and establish the prevalence of medium–large artery wall inflammation.

The characteristics of intracranial plaques of unilateral, anterior circulation embolic stroke of undetermined source: an analysis of different subtypes based on high-resolution imaging

BACKGROUND AND PURPOSE

To investigate the characteristics of non-stenotic intracranial plaque (NSIP) among embolic stroke of undetermined source (ESUS) subtypes by high-resolution magnetic resonance imaging (HR-MRI).

METHODS

we retrospectively enrolled consecutive patients with ESUS who were mandatory for HR-MRI. Based the location and arterial supply of the infarct, ESUS were categorized into three types: cortical ESUS, subcortical ESUS and mixed ESUS. The NSIP parameters including plaque location, morphology (plaque distribution, remodeling index and plaque burden) and composition (thick fibrous cap, discontinuity of plaque surface, intraplaque hemorrhage and complicated plaque) were evaluated among subtypes.

RESULTS

Among 243 patients, there were 87 (35.8%) cortical ESUS, 127 (52.3%) subcortical ESUS and 29 (11.9%) mixed ESUS. We found significant differences in plaque location (P < 0.001), plaque quadrant (P < 0.001), remodeling index (P < 0.001), plaque burden (P < 0.001), discontinuity of plaque surface (P < 0.001), intraplaque hemorrhage (P = 0.001) and complicated plaque (P < 0.001) of ipsilateral NISP among different ESUS subtypes, except for fibrous cap (P = 0.135). But we found no differences among contralateral NISP. In addition, the clinical characteristics of the differences among ESUS subtypes were striking, including age (P = 0.004), initial National Institute of Health Stroke Scale (P < 0.001), coronary artery disease (P = 0.039), serum urea (P = 0.011) and creatinine (P = 0.002).

CONCLUSION

This is the first report of significantly heterogeneous characteristics of ipsilateral NSIP and clinical findings among ESUS subtypes, which may suggest their different underlying mechanisms.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Macrohistory of Moyamoya Disease Analyzed Using Artificial Intelligence

INTRODUCTION

Moyamoya disease is characterized by progressive stenotic changes in the terminal segment of the internal carotid artery and the development of abnormal vascular networks called moyamoya vessels. The objective of this review was to provide a holistic view of the epidemiology, etiology, clinical findings, treatment, and pathogenesis of moyamoya disease. A literature search was performed in PubMed using the term "moyamoya disease," for articles published until 2021.

RESULTS

Artificial intelligence (AI) clustering was used to classify the articles into 5 clusters: (1) pathophysiology (23.5%); (2) clinical background (37.3%); (3) imaging (13.2%); (4) treatment (17.3%); and (5) genetics (8.7%). Many articles in the "clinical background" cluster were published from the 1970s. However, in the "treatment" and "genetics" clusters, the articles were published from the 2010s through 2021. In 2011, it was confirmed that a gene called Ringin protein 213 (RNF213) is a susceptibility gene for moyamoya disease. Since then, tremendous progress in genomic, transcriptomic, and epigenetic profiling (e.g., methylation profiling) has resulted in new concepts for classifying moyamoya disease. Our literature survey revealed that the pathogenesis involves aberrations of multiple signaling pathways through genetic mutations and altered gene expression.

CONCLUSION

We analyzed the content vectors in abstracts using AI, and reviewed the pathophysiology, clinical background, radiological features, treatments, and genetic peculiarity of moyamoya disease.

Cerebrovascular Complications After Adult-Onset Varicella-Zoster Virus Encephalitis in the Central Nervous System: A Literature Review

BACKGROUND

Cerebrovascular complications after adult-onset varicella-zoster virus (VZV) encephalitis have been increasingly recognized. The aim of this study was to analyze clinical and neuroimaging findings, treatment and outcome of these patients.

METHODS

Literature review from January 2000 to December 2019. We searched for studies published in PubMed, Embase and Chinese Biomedical Literature Database. Clinical symptoms, neuroimaging findings, treatment and outcome were evaluated.

RESULTS

We analyzed 31 articles with a total of adult-onset 34 cases, including 25 cases of ischemic stroke, 6 of intracerebral hemorrhage and 3 with venous sinus thrombosis. Ischemic stroke was the major complication after VZV encephalitis accounting of 73.35%. There were more males than females in ischemia or venous sinus thrombosis groups. The middle-aged was prone to cerebral infarction, the elderly was for cerebral hemorrhage, and the young was for venous sinus thrombosis. Cognitive impairment was the most common symptom either in the ischemic group or hemorrhagic group. The lesions of VZV-associated cerebral infarction or hemorrhage were multifocal and mostly involved in the parietal lobe, followed by frontal or temporal lobes. Venous sinus thrombosis was common in the transverse sinus. Multiple stenosis of the anterior and posterior circulation vessels was found. A 60.87% of the patients with antiviral treatment in the ischemic group had favorable prognosis. All patients with anticoagulant therapy in venous sinus thrombosis group improved well; however, 60% of the patients with intracerebral hemorrhage had a poor prognosis or died.

CONCLUSION

Ischemic stroke was the majority of cerebrovascular complications after VZV encephalitis, which mainly occurred in middle-aged men. The lesions of VZV-associated cerebral infarction or hemorrhage were multifocal and did not accord with the characteristics of cerebrovascular diseases induced by atherosclerosis. The patients with venous sinus thrombosis had a relatively good prognosis. When the patient represents with some neurological symptoms about one month after VZV encephalitis, and multiple lesions probably induced by vasculitis are showed in neuroimaging, cerebrovascular complications related to VZV infection should be considered.

High-resolution magnetic resonance imaging for the follow-up of intracranial arterial dissections

High-resolution magnetic resonance imaging (HRMRI) with a 3-T system can be utilized to identify intracranial arterial dissections (ICADs) as it reveals more than three key features with better clarity than other conventional imaging modalities. This study aimed to assess the changes in the key features of ICADs on HRMRI over time. We screened patients who had undergone HRMRI within 7 days of symptom onset for the evaluation of characteristics associated with intracranial steno-occlusive lesions. Among them, patients who (1) were diagnosed with ICAD based on HRMRI findings and (2) underwent follow-up HRMRI 3-12 months after the initial HRMRI were included in the final study. Baseline HRMRI revealed an intramural hematoma, a flap, and a double lumen in 17 (100%), 15 (88%), and 10 (59%) individuals, respectively. At the 3-months follow-up, an intramural hematoma was still observed in two patients; however, there were various changes in the double lumen and intimal flap. At the 6-months follow-up, an intramural hematoma was not observed in most patients, whereas the double lumen and intimal flap persisted in most patients. The 9-months follow-up displayed distinct differences from the initial status, whereas the 12-months follow-up exhibited no intramural hematomas, intimal flaps, or double lumens in most patients. In those with ICAD, radiological changes were observed between the initial HRMRI and subsequent HRMRI. Moreover, typical ICAD features were hardly retained at the 1-year follow-up. These changes might reflect dynamic processes, including the healing state of the patients.

High-Resolution Vessel Wall Imaging in Primary Angiitis of Central Nervous System

Background:

High-resolution vessel wall imaging (HRVWI) can aid in differentiating the various intracranial vasculopathies, but has been sparingly used in the diagnosis of primary angiitis of central nervous system (PACNS). This study is aimed to describe the vessel wall imaging characteristics of PACNS.

Materials and Methods:

Patients with confirmed diagnosis of PACNS according to the Calabrese and Mallek criteria who had abnormal HRVWI were included in this retrospective descriptive study. Magnetic resonance image of brain, conventional four-vessel cerebral digital subtraction angiogram, and HRVWI were read by a neuroradiologist. The vessel wall parameters assessed were T1W and T2W appearances, pattern of wall thickening and contrast enhancement, and remodeling index.

Results:

HRVWI done in 21 patients with PACNS yielded abnormality in 20 (95.2%) who were included in the analysis. The mean age at presentation was 42.55 ± 9.48 years and 14 (70%) were males. The median number of vessels involved were four (range 2–12). The commonest vessels affected were proximal middle cerebral artery (70%) and internal carotid artery (55%). Vessel wall thickening was concentric, eccentric, and absent in 12 (60%), 1 (5%), and 7 (35%) patients, respectively. Vessel wall enhancement was diffuse in 17 (85%), eccentric in 1 (5%), and absent in 2 (10%) patients. One patient had T2W hyperintense stenotic lesion. Remodeling index was negative in 11 (55%) patients.

Conclusion:

Distinctive vessel wall appearances were observed by HRVWI in PACNS, concentric vessel wall thickening and enhancement being more frequent. Hence, HRVWI can be considered as an additional noninvasive imaging modality in the diagnosis of PACNS.

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

BACKGROUND AND PURPOSE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

ACR Appropriateness Criteria® Cerebrovascular Diseases-Aneurysm, Vascular Malformation, and Subarachnoid Hemorrhage

Cerebrovascular disease is a broad topic. This document focuses on the imaging recommendations for the varied clinical scenarios involving intracranial aneurysms, vascular malformations, and vasculitis, which all carry high risk of morbidity and mortality. Additional imaging recommendations regarding complications of these conditions, including subarachnoid hemorrhage and vasospasm, are also covered. While each variant presentation has unique imaging recommendations, the major focus of this document is neurovascular imaging techniques. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

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.