Intracranial arterial disease (ICAD) is a heterogeneous condition characterized by distinct pathologies, including atherosclerosis. Advances in magnetic resonance technology have enabled the visualization of intracranial arteries using high-resolution vessel wall imaging (HR-VWI). This review summarizes the anatomical, embryological, and histological differences between the intracranial and extracranial arteries. Next, we review the heterogeneous pathophysiology of ICAD, including atherosclerosis, moyamoya or RNF213 spectrum disease, intracranial dissection, and vasculitis. We also discuss how advances in HR-VWI can be used to differentiate ICAD etiologies. We emphasize that one should consider clinical presentation and timing of imaging in the absence of pathology-radiology correlation data. Future research should focus on understanding the temporal profile of HR-VWI findings and developing quantitative interpretative approaches to improve the decision-making and management of ICAD.

Purpose: Cutting balloon-percutaneous transluminal angioplasty (CB-PTA) is a feasible treatment option for in-stent restenosis (ISR) after carotid artery stenting (CAS). However, the longterm durability and safety of CB-PTA for ISR after CAS have not been well established. Materials and Methods: We retrospectively reviewed medical records of patients with ISR after CAS who had been treated with CB-PTA from 2012 to 2021 in our center. Detailed information of baseline characteristics, periprocedural and long-term outcomes, and follow-up imaging was collected. Results: During 2012–2021, a total of 301 patients underwent CAS. Of which, CB-PTA was performed on 20 lesions exhibiting severe ISR in 18 patients following CAS. No patient had any history of receiving carotid endarterectomy or radiation therapy. These lesions were located at the cervical segment of the internal carotid artery (n=16), proximal external carotid artery (n=1), and distal common carotid artery (n=1). The median time interval between initial CAS and detection of ISR was 390 days (interquartile range 324–666 days). The follow-up period ranged from 9 months to 9 years with a median value of 21 months. Four patients (22.2%) were symptomatic. The average of stenotic degree before and after the procedure was 79.2% and 34.7%, respectively. Out of the 18 patients receiving CB-PTA, 16 (88.9%) did not require additional stenting, and 16 (88.9%) did not experience recurrent ISR during the follow-up period. Two patients who experienced recurrent ISR were successfully treated with CB-PTA and additional stenting. No periprocedural complication was observed in any case. Conclusion Regarding favorable periprocedural and long-term outcomes in our single-center experience, CB-PTA was a feasible and safe option for the treatment of severe ISR after CAS.

Background: and PurposeInterhospital transfer is an essential practical component of regional stroke care systems. To establish an effective stroke transfer network in South Korea, an interactive transfer system was constructed, and its workflow metrics were observed. Methods: In March 2019, a direct transfer system between primary stroke hospitals (PSHs) and comprehensive regional stroke centers (CSCs) was established to standardize the clinical pathway of imaging, recanalization therapy, transfer decisions, and exclusive transfer linkage systems in the two types of centers. In an active case, the time metrics from arrival at PSH (“door”) to imaging was measured, and intravenous thrombolysis (IVT) and endovascular treatment (EVT) were used to assess the differences in clinical situations. Results: The direct transfer system was used by 27 patients. They stayed at the PSH for a median duration of 72 min (interquartile range [IQR], 38–114 min), with a median times of 15 and 58 min for imaging and subsequent processing, respectively. The door-to-needle median times of subjects treated with IVT at PSHs (n=5) and CSCs (n=2) were 21 min (IQR, 20.0–22.0 min) and 137.5 min (IQR, 125.3–149.8 min), respectively. EVT was performed on seven subjects (25.9%) at CSCs, which took a median duration of 175 min; 77 min at the PSH, 48 min for transportation, and 50 min at the CSC. Before EVT, bridging IVT at the PSH did not significantly affect the door-to-puncture time (127 min vs. 143.5 min, p=0.86). Conclusions The direct and interactive transfer system is feasible in real-world practice in South Korea and presents merits in reducing the treatment delay by sharing information during transfer.

Background: and Purpose Lesions on diffusion-weighted imaging (DWI) occasionally appear on follow-up magnetic resonance imaging (MRI) among initially DWI-negative but clinically suspicious stroke patients. We established the prevalence of positive conversion in DWI-negative stroke and determined the clinical factors associated with it. Methods: This retrospective, observational, single-center study included 5,271 patients hospitalized due to stroke/transient ischemic attack (TIA) in a single university hospital during 2010 to 2017. Patients without initial DWI lesions underwent follow-up DWI imaging as a routine practice. Adjusted hazard ratios (aHRs) for recurrent stroke risk according to positive conversion were determined using Cox proportional hazard regression. Adjusted odds ratios (aORs) and 95% confidence intervals (CIs) for positive conversion among initially DWI-negative patients were estimated. Results: In total, 694 (13.2%) patients (mean±standard deviation age, 62.9±13.7 years; male, 404 [58.2%]) were initially DWI-negative. Among them, 22.5% had positive-conversion on follow-up DWI. Positive conversion was associated with a higher risk of recurrent stroke (aHR, 3.12; 95% CI, 1.56 to 6.26). Early neurologic deterioration (aOR, 15.1; 95% CI, 5.71 to 47.66), atrial fibrillation (aOR, 6.17; 95% CI, 3.23 to 12.01), smoking (aOR, 3.76; 95% CI, 2.19 to 6.63), pre-stroke dependency (aOR, 1.62; 95% CI, 1.15 to 2.27), objective hemiparesis (aOR, 4.39; 95% CI, 1.90 to 10.32), longer symptom duration (aOR, 2.17; 95% CI, 1.57 to 3.08), high cholesterol (aOR, 4.70; 95% CI, 1.78 to 12.77), National Institutes of Health Stroke Scale score (aOR, 1.44; 95% CI, 1.08 to 1.91), and high systolic blood pressure (aOR, 1.01; 95% CI, 1.00 to 1.02) were associated with a higher incidence of lesions with delayed appearance. Regarding the location of lesions on follow-up DWI, 34.6% and 21.2% were in the cortex and brainstem, respectively. Conclusions In DWI-negative stroke/TIA, positive conversion is associated with a higher risk of recurrent stroke. DWI-negative stroke with factors related to positive conversion may require follow-up MRI for a definitive diagnosis.

Endovascular recanalization therapy (ERT) has been a standard of care for patients with acute ischemic stroke due to large artery occlusion (LAO) within 6 hours after onset since the five landmark ERT trials up to 2015 demonstrated its clinical benefit. Recently, two randomized clinical trials demonstrated that ERT, even in the late time window up to 16 hours or 24 hours after last known normal time, improved the outcome of patients who had a target mismatch defined as either clinical-core mismatch or perfusion-core mismatch, which prompted the update of national guidelines in several countries. Accordingly, to provide evidence-based and up-to-date recommendations for ERT in patients with acute LAO in Korea, the Clinical Practice Guidelines Committee of the Korean Stroke Society decided to revise the previous Korean Clinical Practice Guidelines of Stroke for ERT. For this update, the members of the writing group were appointed by the Korean Stroke Society and the Korean Society of Interventional Neuroradiology. After thorough reviewing the updated evidence from two recent trials and relevant literature, the writing members revised recommendations, for which formal consensus was achieved by convening an expert panel composed of 45 experts from the participating academic societies. The current guidelines are intended to help healthcare providers, patients, and their caregivers make their well-informed decisions and to improve the quality of care regarding ERT. The ultimate decision for ERT in a particular patient must be made in light of circumstances specific to that patient.

PURPOSE: Although endovascular treatment is currently thought to only be suitable for patients who have pial arterial filling scores >3 as determined by multiphase computed tomography angiography (mpCTA), a cut-off score of 3 was determined by a study, including patients within 12 hours after symptom onset. We aimed to investigate whether a cut-off score of 3 for endovascular treatment within 6 hours of symptom onset is an appropriate predictor of good functional outcome at 3 months. MATERIALS AND METHODS: From April 2015 to January 2016, acute ischemic stroke patients treated with mechanical thrombectomy within 6 hours of symptom onset were enrolled into this study. Pial arterial filling scores were semi-quantitatively assessed using mpCTA, and clinical and radiological parameters were compared between patients with favorable and unfavorable outcomes. Multivariate logistic regression analysis was then performed to investigate the independent association between clinical outcome and pial collateral score, with the predictive power of the latter assessed using C-statistics. RESULTS: Of the 38 patients enrolled, 20 (52.6%) had a favorable outcome and 18 had an unfavorable outcome, with the latter group showing a lower mean pial arterial filling score (3.6±0.8 vs. 2.4±1.2, P=0.002). After adjusting for variables with a P-value of <0.1 in univariate analysis (i.e., age and National Institutes of Health Stroke Scale score at admission), pial arterial filling scores higher than a cut-off of 2 were found to be independently associated with favorable clinical outcomes (P=0.012). C-statistic analysis confirmed that our model had the highest prediction power when pial arterial filling scores were dichotomized at >2 vs. ≤2. CONCLUSION: A pial arterial filling cut-off score of 2 as determined by mpCTA appears to be more suitable for predicting clinical outcomes following endovascular treatment within 6 hours of symptom onset than the cut-off of 3 that had been previously suggested.
Angiography ; Humans ; Logistic Models ; National Institutes of Health (U.S.) ; Stroke ; Thrombectomy

Endovascular recanalization therapy (ERT) has been a standard of care for patients with acute ischemic stroke due to large artery occlusion (LAO) within 6 hours after onset, since five landmark ERT trials conducted by 2015 demonstrated its clinical benefit. Recently, two randomized clinical trials demonstrated that ERT, even in the late time window of up to 16 hours or 24 hours after last known normal time, improved the outcome of patients who had a target mismatch, defined as either clinical-core mismatch or perfusion-core mismatch, which prompted the update of national guidelines in several countries. Accordingly, to provide evidence-based and up-to-date recommendations for ERT in patients with acute LAO in Korea, the Clinical Practice Guidelines Committee of the Korean Stroke Society decided to revise the previous Korean Clinical Practice Guidelines of Stroke for ERT. For this update, the members of the writing group were appointed by the Korean Stroke Society and the Korean Society of Interventional Neuroradiology. After thoroughly reviewing the updated evidence from two recent trials and relevant literature, the writing members revised recommendations, for which formal consensus was achieved by convening an expert panel composed of 45 experts from the participating academic societies. The current guidelines are intended to help healthcare providers, patients, and their caregivers make well-informed decisions and to improve the quality of care regarding ERT. The ultimate decision for ERT in a particular patient must be made in light of circumstances specific to that patient.
Arteries ; Caregivers ; Cerebral Infarction ; Consensus ; Health Personnel ; Humans ; Korea ; Mechanical Thrombolysis ; Reperfusion ; Standard of Care ; Stroke ; Writing

Endovascular recanalization therapy (ERT) has been a standard of care for patients with acute ischemic stroke due to large artery occlusion (LAO) within 6 hours after onset, since five landmark ERT trials conducted by 2015 demonstrated its clinical benefit. Recently, two randomized clinical trials demonstrated that ERT, even in the late time window of up to 16 hours or 24 hours after last known normal time, improved the outcome of patients who had a target mismatch, defined as either clinical-core mismatch or perfusion-core mismatch, which prompted the update of national guidelines in several countries. Accordingly, to provide evidence-based and up-to-date recommendations for ERT in patients with acute LAO in Korea, the Clinical Practice Guidelines Committee of the Korean Stroke Society decided to revise the previous Korean Clinical Practice Guidelines of Stroke for ERT. For this update, the members of the writing group were appointed by the Korean Stroke Society and the Korean Society of Interventional Neuroradiology. After thoroughly reviewing the updated evidence from two recent trials and relevant literature, the writing members revised recommendations, for which formal consensus was achieved by convening an expert panel composed of 45 experts from the participating academic societies. The current guidelines are intended to help healthcare providers, patients, and their caregivers make well-informed decisions and to improve the quality of care regarding ERT. The ultimate decision for ERT in a particular patient must be made in light of circumstances specific to that patient.
Arteries ; Caregivers ; Cerebral Infarction ; Consensus ; Health Personnel ; Humans ; Korea ; Mechanical Thrombolysis ; Reperfusion ; Standard of Care ; Stroke ; Writing

BACKGROUND AND PURPOSE: To investigate the number and characteristics of patients eligible for endovascular treatment (EVT) determined using three different selection methods: clinical-core mismatch, target mismatch, and collateral status. METHODS: Using the data of consecutive patients from two prospectively maintained registries of university medical centers, the number and characteristics of patients according to the three selection methods were investigated and their correlation was analyzed. Patients with anterior circulation stroke due to occlusion of the middle cerebral and/or internal carotid artery and a National Institute of Health Stroke Scale (NIHSS) score of ≥6 points, who arrived within 8 hours or between 6 and 12 hours of symptom onset and underwent magnetic resonance imaging prior to EVT, were included. Collateral status was assessed using magnetic resonance perfusion-derived collateral flow maps. RESULTS: Three hundred thirty-five patients were investigated; the proportions of patients who were eligible and ineligible for EVT in all three selection methods were both small (n=85, 25.4%; n=54, 16.1%, respectively). The intercorrelation among the three selection methods was low (κ=0.235). The baseline NIHSS score and onset-to-selection time interval were associated with the presence of clinical-core mismatch, while the penumbra/core volume ratio and onset-to-selection time interval were related to target mismatch; none of these variables were associated with collateral status. The infarct core volume was associated with favorable profiles in all three selection methods. CONCLUSIONS: Although the application of individual selection methods resulted in favorable outcomes after EVT in clinical trials, there is a significant discrepancy in EVT eligibility depending on the selection method used.
Academic Medical Centers ; Carotid Artery, Internal ; Humans ; Magnetic Resonance Imaging ; Methods ; Prospective Studies ; Registries ; Stroke

Recent clinical trials demonstrated the clinical benefit of endovascular treatment (EVT) in patients with acute ischemic stroke due to large vessel occlusion. These trials confirmed that good outcome after EVT depends on the time interval from symptom onset to reperfusion and that in-hospital delay leads to poor clinical outcome. However, there has been no universally accepted in-hospital workflow and performance benchmark for rapid reperfusion. Additionally, wide variety in workflow for EVT is present between each stroke centers. In this consensus statement, Korean Society of Interventional Neuroradiology and Korean Stroke Society Joint Task Force Team propose a standard workflow to reduce door-to-reperfusion time for stroke patients eligible for EVT. This includes early stroke identification and pre-hospital notification to stroke team of receiving hospital in pre-hospital phase, the transfer of stroke patients from door of the emergency department to computed tomography (CT) room, warming call to neurointervention team for EVT candidate prior to imaging, neurointervention team preparation in parallel with thrombolysis, direct transportation from CT room to angiography suite following immediate decision of EVT and standardized procedure for rapid reperfusion. Implementation of optimized workflow will improve stroke time process metrics and clinical outcome of the patient treated with EVT.
Advisory Committees ; Angiography ; Benchmarking ; Consensus* ; Emergency Service, Hospital ; Humans ; Joints ; Reperfusion ; Stroke* ; Transportation