Multiphase CT Angiography Research Articles

Time-resolved assessment of cortical venous drainage on multiphase CT angiography in patients with acute ischemic stroke.

Cortical vein opacification is not routinely assessed in patients presenting with acute ischemic stroke (AIS), and the value of temporal assessment of venous outflow is not known. We evaluated the utility of assessing cortical venous drainage over time using multiphase CT angiography (mCTA). Cortical venous drainage was assessed in patients from the Precise and Rapid Assessment of Collaterals Using Multi-Phase CTA in the Triage of Patients With Acute Ischemic Stroke for IA Therapy prospective multicenter cohort study of patients with symptoms of AIS with ICA and/or middle cerebral artery occlusion on baseline mCTA. Opacification of vein of Labbe, sphenoparietal sinus, superficial middle cerebral vein, and vein of Trolard of the affected hemisphere was graded as no (0), partial (1), or full (2) opacification in each mCTA phase. The venous opacification scores for each phase were added to generate a total venous score (TVS) (range 0-24). Primary outcome was 90-day modified Rankin score. Repeated measures analysis was used to assess the effect of phase timing on venous score on outcome. Of 432 patients, 284 (65.7%) had proximal arterial occlusions. Median venous opacification score per phase (range 0-8) was 3 (IQR 1-6) in the first phase and increased in the second and third phases [median (IQR): 6 (5-8) and 8 (6-8), respectively] of the mCTA. In a multivariable analysis adjusting for age, baseline National Institutes of Health Stroke Scale, and Albertastrokeprogram early CT score, a significant association between TVS and 90-day mRS was noted ([adjusted cOR for TVS 6-11: 0.16 (95% CI 0.05-0.51); TVS 12-17: 0.18 (95% CI 0.06-0.57); TVS 18-24: 0.20 (0.06-0.63)]. Repeated measures analysis of venous scores from all three phases showed a significant effect of time/phase on TVS (p < 0.001). This study concludes that venous opacification over time on multiphase CTA is associated with 90-day clinical outcome. There was however no added benefit of venous scoring vis-a-vis arterial collateral assessment in predicting outcome.

Impact of Multiphase Computed Tomography Angiography for Endovascular Treatment Decision-Making on Outcomes in Patients with Acute Ischemic Stroke.

Background and PurposeVarious imaging paradigms are used for endovascular treatment (EVT) decision-making and outcome estimation in acute ischemic stroke (AIS). We aim to compare how these imaging paradigms perform for EVT patient selection and outcome estimation. MethodsProspective multi-center cohort study of patients with AIS symptoms with multi-phase computed tomography angiography (mCTA) and computed tomography perfusion (CTP) baseline imaging. mCTA-based EVT-eligibility was defined as presence of large vessel occlusion (LVO) and moderate-to-good collaterals on mCTA. CTP-based eligibility was defined as presence of LVO, ischemic core (defined on relative cerebral blood flow, absolute cerebral blood flow, and cerebral blood volume maps) <70 mL, mismatch-ratio >1.8, absolute mismatch >15 mL. EVT-eligibility and adjusted rates of good outcome (modified Rankin Scale 0–2) based on these imaging paradigms were compared. ResultsOf 289/464 patients with LVO, 263 (91%) were EVT-eligible by mCTA-criteria versus 63 (22%), 19 (7%) and 103 (36%) by rCBF, aCBF, and CBV-CTP-criteria. CTP and mCTA-criteria were discordant in 40% to 53%. Estimated outcomes were best in patients who met both mCTA and CTP eligibility-criteria and were treated with EVT (62% to 87% good outcome). Patients eligible for EVT by mCTA-criteria and not by CTP-criteria receiving EVT achieved good outcome rates of 53% to 57%. Few patients met CTP-criteria and not mCTA-criteria for EVT. ConclusionsSimpler imaging selection criteria that rely on little else than detection of the occluded blood vessel may be more sensitive and less specific, thus resulting in more patients being offered EVT and arguably benefiting from it.

Color-coded multiphase computed tomography angiography may predict outcome in anterior circulation acute ischemic stroke

PurposeTo evaluate whether arterial and venous color-coded mCTA score may predict clinical outcome in anterior circulation acute ischemic stroke. MethodsConsecutive patients referred to the emergency department with anterior circulation acute ischemic stroke (AIS) were retrospectively reviewed at our center. All patients underwent multimodal brain computed tomography (CT) imaging, including non-contrast CT (NCCT) and multiphase computed tomography angiography (mCTA). Baseline collateral scores of color-coded mCTA, also known as ColorViz, and conventional mCTA were recorded. mCTA was assessed by a 6-point scale whereas color-coded mCTA was assessed by a 3-point scale. In the Color-coded maps, a different color is assigned to intracranial vessels based on the arrival time of the contrast medium and on a per-person adaptive threshold technique. We compared the radiological and clinical features of a group of patients who reached independency (defined as modified Rankin Scale score ≤ 2) with those of patients who did not. A multivariate logistic regression model was then used to assess the potential of color-coded mCTA scores to predict patients' outcome after AIS. ResultsA total of 86 patients (36 M, 50 F) were enrolled in the study. Multivariate logistic regression showed that score 3 at Color-coded mCTA was a good predictor of favorable outcome (p = 0.003). Moreover, NIHSS at onset (p = 0.004) and discharge (p < 0.001) along with ischemic core area (p = 0.011) were significant predictors of favorable prognosis. Conclusionour data confirm that ColorViz is a useful and easily understandable neuroimaging tool that might have a predictive role in assessing the outcome of anterior circulation acute ischemic stroke patients regardless of revascularization therapy.

Risk and Benefit Evaluation: Application of Multiphase Computed Tomography Angiography in Mechanical Thrombectomy for Patients With Acute Ischemic Stroke

The objective of this study was to evaluate the collateral circulation in patients with acute ischemic stroke (AIS) by multiphase computed tomography angiography (mCTA) and explore its application value in the risk and benefit assessment after thrombectomy. Clinical and imaging parameters of AIS patients who underwent thrombectomy were consecutively collected. The 90-day modified Rankin Scale (mRS) score was used as the standard for evaluating the recovery of neurological functions. The receiver operating characteristic curve and correlation analysis were used to evaluate the diagnostic efficacy of collateral circulation in the clinical outcomes at 90 days and the correlation with symptomatic intracerebral hemorrhage (sICH), respectively. Thirty of 58 AIS patients (51.7%) had favorable functional recovery (90-day mRS score, ≤2). Significant differences were observed in age, time from symptom onset to groin puncture, National Institutes of Health Stroke Scale score at admission and 24 hours after thrombectomy, mRS score at discharge, collateral circulation score, and target mismatch between the favorable and unfavorable groups (P < 0.05). The diagnostic efficacy of mCTA collateral score (area under the curve, 0.697; 95% confidence interval, 0.563-0.831) was similar to that of computed tomography perfusion target mismatch (area under the curve, 0.740; 95% confidence interval, 0.609-0.872) (DeLong test, P = 0.575). The collateral circulation score was significantly negatively correlated with sICH (ρ = -0.607, P < 0.001). Patients with sICH had lower collateral circulation scores and higher 90-day mRS scores (P < 0.05). The mCTA collateral score has good application value in the risk and benefit evaluation after mechanical thrombectomy, and it is well suited for routine emergency assessment of AIS patients.

Improved visualization of medium vessel occlusion stroke with time-variant color-coded multiphase CT angiography maps: A technical note

Detecting medium vessel occlusions (MeVOs) is often challenging due to their distal location and small vessel size. Herein we describe an innovative imaging technique for fast and reliable MeVO detection: time-variant color-coded multiphase CTA. Three CTA phases of the intracranial vasculature are color-coded and displayed in a single summation image, which improves visualization of MeVOs through a color indicator effect, thereby substantially facilitating MeVO detection, particularly for readers with limited experience.

Predicting hemorrhagic transformation after thrombectomy in acute ischemic stroke: a multimodal score of the regional pial collateral.

This study aims to analyze the multimodal score of the regional pial collateral in predicting hemorrhagic transformation (HT) after mechanical thrombectomy in acute ischemic stroke (AIS). On the basis of different brain regions and multiphase computed tomography angiography (mCTA), we evaluated the pial arterial filling status in extent, delay, and contrast washout. The prediction models of HT and symptomatic intracerebral hemorrhage (sICH) were established using mCTA (model-H1 and model-S1), CT perfusion (CTP, model-H2 and model-S2), and comprehensive parameters (model-H3 and model-S3). The receiver operating characteristic curve was used to analyze the prediction performance of each model. Among the 102 patients with AIS who received thrombectomy, 36 (35.3%) developed HT, and 15 (14.7%) of whom had sICH. In model-H1 and model-S1, washout independently influenced HT (OR, 95%CI 0.398, 0.249-0.634) and sICH (OR, 95%CI 0.552, 0.342-0.892). In model-H2, the relative surface permeability independently influenced HT (OR, 95%CI 1.217, 1.082-1.370). Model-H3 and model-S3 improved the prediction performance (areas under the curve: HT, 0.957; sICH, 0.938). The correlation coefficients between relative cerebral blood volume and the three modes of pial arterial filling status were higher than those of other CTP parameters. The 90-day modified Rankin scale score in the sICH group was significantly increased (P < 0.05). The multimodal regional pial collateral score has good value in the risk assessment of HT and sICH in patients with AIS after mechanical thrombectomy. The combination of multiple parameters can improve diagnostic performance.

High Triglyceride Glucose Index Is Associated with Poor Outcomes in Ischemic Stroke Patients after Reperfusion Therapy

Introduction: The triglyceride glucose index (TyG index) is a simple and reliable surrogate marker of insulin resistance (IR) that can predict functional outcomes and mortality after acute ischemic stroke (AIS). However, it is unclear whether the TyG index is associated with functional outcomes in patients with stroke who receive reperfusion therapy. Thus, we aimed to explore the prognostic value of the TyG index for the clinical outcomes of patients with AIS who underwent reperfusion therapy. Methods: We retrospectively assessed patients with AIS, with occlusion of either the middle cerebral artery or internal carotid artery, who were evaluated using multiphase computed tomography angiography (mCTA) and received reperfusion therapy. The TyG index was calculated as “ln [fasting glucose level (mg/dL) × triglyceride level (mg/dL)]/2.” Collateral status was evaluated using mCTA based on the University of Calgary Scale. Clinical outcomes included 3-month functional outcomes, early neurological deterioration, recanalization status, and hemorrhagic transformation. Results: In all, 183 subjects (age 69.5 ± 12.4 years; men, 59.0%) were enrolled. The median initial National Institutes of Health Stroke Scale score was 15.0 (interquartile range [IQR] 11–18). The median TyG index was 4.8 (IQR, 4.6–5.1), and 158 patients had TyG levels >4.49, which represents the presence of IR. On univariate analysis, a higher TyG index was associated with both early neurological deterioration (18.4 vs. 0.0%, p = 0.041) and a 3-month poor functional outcome (mRS3-6) (61.4 vs. 32.0%, p = 0.011). After adjusting for multiple variables, including age, sex, type of reperfusion therapy, recanalization status, initial stroke severity, type of stroke, and history of hypertension and diabetes, high TyG index remained an independent predictor of a poor 3-month functional outcome (adjusted OR, 5.22; p = 0.014). However, TyG levels were not significantly associated with collateral status (p = 0.756). Conclusions: IR, represented by a high TyG index, may predict poor 3-month functional outcomes in patients with AIS who undergo reperfusion therapy.

Hyperintense Vessels on Magnetic Resonance Imaging Correlate with Arteries in the Delayed Phase of Multiphase Computed Tomography Angiography

Hyperintense Vessels on Magnetic Resonance Imaging Correlate with Arteries in the Delayed Phase of Multiphase Computed Tomography Angiography

Detection of Perfusion Deficits in Multiphase Computed Tomography Angiography-A Stroke Imaging Technique Based on Iodine Mapping on Spectral Computed Tomography: Initial Findings.

The purpose of this study was to explore a novel method for brain tissue differentiation using quantitative analysis of multiphase computed tomography (CT) angiography (MP-CTA) on spectral CT, to assess whether it can distinguish underperfused from normal tissue, using CT perfusion (CTP) as reference. Noncontrast CT and MP-CTA images from 10 patients were analyzed in vascular regions through measurements of Hounsfield unit (HU) at 120 kV, HU at 40 keV, and iodine density. Regions were categorized as normal or ischemic according to CTP. Hounsfield unit and iodine density were compared regarding ability to separate normal and ischemic tissue, the difference in maximum time derivative of the right over left hemisphere ratio. Iodine density had the highest maximum time derivatives and generated the largest mean separation between normal and ischemic tissue. The method can be used to categorize tissue as normal or underperfused. Using iodine quantification seems to give a more distinct differentiation of perfusion defects compared with conventional HU.

Matrix metallopeptidase 9 and placental growth factor may correlate with collateral status based on whole-brain perfusion combined with multiphase computed tomography angiography

ABSTRACT Objective The aim of this study was to find out the relationship between serum biomarkers and cerebral collateral status in acute ischemic stroke with cerebral large artery atherosclerosis. Methods We enrolled patients with ischemic stroke due to large artery atherosclerosis within 7 days of symptom onset, age 18–80 years, from August 2016 to December 2017. Twelve biomarkers representing different pathophysiological mechanisms were tested after admission. Whole-brain perfusion combined with multiphase computed tomography angiography was performed to assess cerebral collateral structure and function. Results Fifty-two patients completed the test of candidate biomarkers and recruited in this study. The mean age was 55.0 (11.1) years, 42 (80.8%) patients were male, 20 (38.5%) had poor collateral, 36 (69.2%) patients had anterior circulation stenosis or occlusion. Compared with poor collateral group, the level of MMP-9 (135,475.00 pg/ml vs. 103,612.00 pg/ml, p = 0.040) and PGF (5.75 pg/ml vs. 3.46 pg/ml, p = 0.046) was significantly higher in good collateral group. The adjusted OR (95%CI) of MMP-9 and PGF were 5.533 (1.10–27.74, p = 0.038), 7.73 (1.41–42.39, p = 0.018), respectively. sTie-2 level had a positive correlation with proportion of Tmax 4–6 (r = 0.302, p = 0.033) and HMW-KGN had negative correlation with proportion of Tmax 6–8 (r = −0.338, p = 0.02). After adjustment, the correlation of sTie-2 level and proportion of Tmax 4–6 was statistically significant (p = 0.003), and correlation of HMW-KGN and Tmax6-8 was not statistically significant (p = 0.056). Discussion Serum PGF and MMP-9 levels may correlate with collateral status based on MP-CTA in acute ischemic stroke patients with cerebral large artery atherosclerosis. Higher PGF and MMP-9 concentration associated with good collateral status.

Effects of multiphase versus single-phase CT angiography for the detection of distal cerebral vessel occlusion.

The goal of this study was to determine whether the benefits of multiphase CTA (mCTA) over single-phase CTA (sCTA) for the detection of proximal cerebrovascular occlusions similarly extend to the distal cerebral vasculature. Four attending radiologists, two neuroradiologists and two emergency radiologists, contributed as readers to this retrospective study. For each reader, two sessions were conducted, one using sCTA and one using mCTA. During each session, the reader interpreted the studies of 104 patients who underwent imaging for suspicion of acute ischemic stroke, resulting in a total of 832 interpretations. Changes in diagnostic accuracy, time to render final decision, and reported levels of reader confidence were quantitatively assessed. Further analysis comparing the effects for neuroradiologists versus emergency radiologists was additionally conducted. Using mCTA resulted in a significant 5.0% absolute increase in sensitivity (91.6% vs. 96.6%, p = .004) and an insignificant increase in specificity (99.5% vs. 99.7%, p = .39). A significant reduction in reading time (66.7s vs. 59.6s, p = .001) and an increase in diagnostic confidence (2.26 vs. 2.58, p < .001) were observed. Using sCTA, higher sensitivity was achieved by neuroradiologists than emergency radiologists (96.0% vs. 86.9%, p = .002); using mCTA resulted in an absolute increase in sensitivity of 0.9% (97.4%, p = .44) for neuroradiologists and 9.6% (96.5%, p < .001) for emergency radiologists, eliminating significant differences between the groups (p = 0.57). The use of mCTA results in increased sensitivity and negative predictive value, decreased reading time, increased diagnostic confidence, and the elimination of differences in accuracy between neuroradiologists and emergency radiologists.

Hypoperfusion Index Ratio as a Surrogate of Collateral Scoring on CT Angiogram in Large Vessel Stroke.

Background: This study was to evaluate the correlation of the hypoperfusion intensity ratio (HIR) with the collateral score from multiphase computed tomography angiography (mCTA) among patients with large vessel stroke. Method: From February 2019 to May 2020, we retrospectively reviewed the patients with large vessel strokes (intracranial carotid artery or proximal middle cerebral artery occlusion). HIR was defined as a Tmax > 10 s lesion volume divided by a Tmax > 6 s lesion volume, which was calculated by automatic software (Syngo.via, Siemens). The correlation between the HIR and mCTA score was evaluated by Pearson’s correlation. The cutoff value predicting the mCTA score was evaluated by receiver operating characteristic analysis. Result: Ninety-four patients were enrolled in the final analysis. The patients with good collaterals had a smaller core volume (37.3 ± 24.7 vs. 116.5 ± 70 mL, p < 0.001) and lower HIR (0.51 ± 0.2 vs. 0.73 ± 0.13, p < 0.001) than those with poor collaterals. A higher HIR was correlated with a poorer collateral score by Pearson’s correlation. (r = −0.64, p < 0.001). The receiver operating characteristic (ROC) analysis suggested that the best HIR value for predicting a good collateral score was 0.68 (area under curve: 0.82). Conclusion: HIR is a good surrogate of collateral circulation in patients with acute large artery occlusion.

Abstract P471: Ipsilateral Asymmetrical Internal Cerebral Vein on Multiphasic Computed Tomography for Acute Anterior Circulation Ischemic Stroke Thrombectomy is an Independent Predictor of Poor Functional Outcome

Background: National Institute of health stroke scale(NIHSS) and collateral circulation are well-established predictors for functional outcomes of endovascular thrombectomy (EVT) patients in acute ischemic stroke (AIS), nonetheless additional prognostic markers can improve the prediction of stroke outcomes. The inflow and drainage into the internal cerebral veins (ICV) can be seen consistently on multiphasic computed tomography angiography (mCTA). Thus, we hypothesize that asymmetry of ICV in the mCTA in large vessel occlusion AIS can be used as an adjunctive predictor of functional outcomes and complications. Method: We enrolled 185 consecutive anterior circulation AIS patients who underwent EVT that presented to our hospital between 2017 and 2019. The collateral circulation was defined by the university of Calgary mCTA collateral flow assessment in stroke. The ICV on the ipsilateral occlusion side was compared with the contralateral side according to a binary scale: 1 (less than contralateral or absent) or 2(equal or greater than contralateral). The primary outcome was modified Rankin scale at 3 months (mRS), and secondary outcomes included symptomatic intracranial hemorrhage and mortality. Result: Among 185 patients, 53% were men, the median age 70 years (range 29-91) and the median NIHSS score on arrival (NIHSS OA) was 19 (range 4-34). 82 patients (44.3%) had good functional outcomes at 3 months. Ipsilateral asymmetry in all three stages of mCTA were statistically significantly associated with good functional outcomes. The 1 st delay phase of mCTA showed the strongest association. On multivariate analysis, high NIHSS OA (OR 1.09, 95% CI 1.02-1.15, P = 0.007), good mCTA collateral score (OR 0.30, 95% CI .16- .53, P &lt; .001), ipsilateral asymmetrical ICV on the 1 st delay phase of mCTA (OR 2.64, 95% CI 1.17-5.96, P = 0.01) were independent predictors of poor functional outcome. Ipsilateral asymmetry was not associated with mortality or symptomatic intracranial hemorrhage on multivariate analysis. Conclusion: Ipsilateral assymetrical ICV is a novel radiological marker associated with functional outcomes after thrombectomy even after correction for the collateral circulation. Further studies should be done to validate this finding in different datasets.

Abstract P334: Multiphase Computed Tomography Angiography-Perfusion for Quantitative Measurement of Ischemic Volumes

Introduction: Proficiency required to execute CT perfusion (CTP) protocols is a limiting factor in its use in acute stroke. We propose to calculate perfusion parametric maps and measure ischemic volumes using readily available non-contrast CT (NCCT) and multiphase CT angiography (mCTA) images. Materials and Methods: Twenty-five patients presenting with acute ischemic stroke were included in this study. Our proposed dynamic sequence (multiphase CT angiography-perfusion, mCTA-P) consisted of the NCCT as the pre-contrast baseline and three phases of mCTA, which corresponded to the peak arterial, peak venous, and late venous phases at 8 s intervals. CTP was acquired after mCTA and consisted of 22 dynamic images acquired over 60 s at 2.8 s intervals. A prototype model-based deconvolution algorithm (CT Perfusion 4D, GE Healthcare) was used to calculate cerebral blood flow (CBF) and Tmax maps for each series. Infarct was classified as voxels that satisfied both a time-dependent relative CBF threshold and Tmax &gt; 8 s while penumbral voxels satisfied either threshold but not both. Results: Median (interquartile range) 24-hour follow-up infarct volume was 18.6 (4.7 to 34.3) ml and median stroke onset-to-CTP time was 124.0 (70.5 to 201.5) min. Bland-Altman analysis revealed good agreement between CTP and mCTA-P volume measurements as mean differences (limits of agreement) were -1.0 (-14.9 to 12.9) ml for infarct and 8.4 (-42.4 to 59.1) ml for penumbra. Intraclass correlation (95% confidence interval, p &lt; 0.05) between CTP and mCTA-P volumes were 0.72 (0.46 to 0.87) for infarct and 0.68 (0.41 to 0.85) for penumbra, indicating good to moderate reliability. Conclusion: Quantitative perfusion can be estimated from NCCT and mCTA without introducing additional scan time, radiation dose, and contrast injections associated with CTP. Our technique allows assessments of early ischemic changes and collaterals to be augmented with quantitative perfusion measurements of ischemic volumes.

Embolization for acute gastrointestinal bleeding

Purpose: To retrospectively evaluate the clinical success and complication rates following interventional embolization for treatment of acute gastrointestinal bleeding (GIB) at a tertiary care centre. The secondary purpose was to evaluate results of practice change whereby multiphase CT angiography was requested prior to conventional angiograms.&#x0D; Methods: A retrospective chart review and analysis of 38 patients undergoing Interventional Radiology guided embolization for acute GIB was performed. Clinical success was defined as patient stability 30 days’ post embolization and complications included subsequent bleeding requiring endoscopy, surgery or additional embolization, or death.&#x0D; Results: Overall clinical success rate was 86.8% (33/38). Complications included 14 patients (36.8%) experiencing continued bleeding, 6 patients (15.8%) requiring repeat endoscopic evaluation, 8 patients (21.1%) requiring surgery, 3 patients (7.9%) requiring repeat embolization, and 4 deaths (10.5%). These results were not inferior to clinical success rates reported in the literature for GIB regardless of location. Positive predictive value for multiphase CT angiogram was 92.3% and the negative predictive value was 57.1%.&#x0D; Conclusions: Interventional angiography and embolization is an effective treatment for GIB with the most common complication being recurrent bleeding which may require additional endoscopic evaluation, surgical intervention or additional embolization. Clinical success and complication rates at this centre are similar to those reported in the literature. Continued evaluation of the utility of multiphase CT angiography prior to conducting embolization should be considered to determine its impact on rates of negative angiogram studies.

Multiphase CT Angiography: A Useful Technique in Acute Stroke Imaging—Collaterals and Beyond

Multiphase CTA offers several important advantages over the traditional single-phase CTA technique in acute ischemic stroke, including improved detection of large-vessel occlusion, improved characterization of collateral status, improved tolerance of patient motion and poor hemodynamics, and higher interrater reliability. These benefits are gleaned at little additional cost in terms of time, risk to the patient, and capital expense. Existing data suggest that there are important benefits to using multiphase CTA in lieu of single-phase CTA in the initial vessel assessment of patients with acute stroke.

Inadvertent subclavian artery catheter insertion

A 79-year-old woman was admitted for severe dehydration leading to acute renal failure. A 14F dialysis catheter was inserted into the right internal jugular vein under ultrasound guidance. Despite the lack of clinical evidence of bleeding or hematoma, chest radiography showed that the catheter was awkwardly bent (A, arrows), and its misplacement was confirmed by blood gas analysis. Subsequently, multiphase computed tomography angiography was performed, which revealed that the catheter had passed through the internal jugular vein (B/Cover, left) and had been misplaced into the subclavian artery (B/Cover, right).

A Multicenter Survey of Acute Stroke Imaging Protocols for Endovascular Thrombectomy.

PurposeIdentifying current practices in acute stroke imaging is essential for establishing optimal imaging protocols. We surveyed and assessed the current status of acute stroke imaging for endovascular thrombectomy (EVT) at tertiary hospitals throughout South Korea.Materials and MethodsAn electronic questionnaire on imaging protocols for EVT in patients with acute ischemic stroke was e-mailed to physicians at 42 registered tertiary hospitals, and their responses were collected between February and March 2020.ResultsOf the 36 hospitals participating in the survey, 69% (25/36) adopted computed tomography (CT)-based protocols, whereas 31% (11/36) adopted magnetic resonance (MR)-based protocols. Non-enhanced CT (NECT) was the initial imaging study at 28%, NECT with CT angiography (CTA) at 36%, and NECT with CTA and CT perfusion (CTP) at 33% of hospitals. Perfusion imaging was performed at 61% (22/36), CTP at 44% (16/36), and MR perfusion at 17% (6/36) of hospitals. Multiphase CTA was performed at 67%, single-phase CTA at 11%, time-of-flight MR angiography (MRA) at 8%, contrast-enhanced MRA at 8%, and both at 6% of hospitals. For late time window stroke, 50% of hospitals used identical imaging protocols to those for early time window stroke, 39% used additional MR imaging (MRI), and 6% converted the imaging strategy from CT to MRI. Post-processing programs were used at 28% (10/36), and RAPID software at 14% (5/36) of hospitals, respectively. Most hospitals (92%) used the same imaging protocols for posterior and anterior circulation strokes.ConclusionOur multicenter survey demonstrated considerable heterogeneity in acute stroke imaging protocols across South Korean tertiary hospitals, suggesting that hospitals refine their imaging protocols according to hospital-specific conditions.

Diagnostic performance of single-phase CT angiography in detecting large vessel occlusion in ischemic stroke: A systematic review

PurposeTo systematically review the diagnostic performance of single-phase CT angiography (CTA) in detecting intracranial large vessel occlusion (LVO). MethodMEDLINE and Embase were searched for studies investigating the diagnostic performance of single-phase CTA in detecting LVO. Study quality was assessed. Sensitivity and specificity were calculated and meta-analyzed with a bivariate random-effects model. Heterogeneity was assessed with a chi-squared test. ResultsEleven studies were included. High risk of bias with regard to “patient selection”, “reference standard”, and “flow and timing” was present in 4, 1, and 2 studies, respectively. In 7 studies, it was unclear whether reference tests were interpreted blinded to CTA readings. There was variability in types of vessel segments analyzed, resulting in heterogeneous sensitivity and specificity (P < 0.05). Two studies provided data for the proximal anterior circulation (distal intracranial carotid artery, A1-, A2-, M1- and M2-segments), with pooled sensitivity of 88.4 % (95 % CI: 62.2–97.2 %) and pooled specificity of 98.5 % (95 % CI: 33.2–100 %). One study suggested that multiphase CTA improved agreement between nonexperts and an expert in detecting A1-, A2-, M1-, M2-, and M3-segment occlusions compared to single-phase CTA (ĸ = 0.72−0.76 vs. ĸ = 0.32−0.45). No other included study reported added value of advanced CTA (CT perfusion, 4D-CTA, or multiphase CTA) compared to single-phase CTA in detecting proximal anterior circulation LVO. ConclusionThere is lack of high-quality studies on the diagnostic performance of single-phase CTA for LVO detection in the proximal anterior circulation. The added value of advanced CTA techniques in detecting proximal anterior circulation LVO is not completely clear yet.

Imaging criteria across pivotal randomized controlled trials for late window thrombectomy patient selection

BackgroundThe DAWN and DEFUSE-3 trials showed the benefit of endovascular treatment (EVT) in acute ischemic stroke patients presenting beyond 6 hours from last known well (LKW) and selected by perfusion...