Risultati per: L'imaging nella urolitiasi

Stroke, Volume 55, Issue Suppl_1, Page A82-A82, February 1, 2024. Background:Patients with large core strokes have poor clinical outcomes and are frequently not transferred to endovascular thrombectomy (EVT)-capable centers for EVT. We analyzed the association of transfer status and time on neuroimaging changes, clinical outcomes and EVT treatment effect in SELECT2.Methods:Patients enrolled in the SELECT-2 trial were stratified based on transfer status. CT ASPECTS at outside hospital and EVT center were collected if available. Treatment effect was compared by transfer status as well as in transferred patients with outside ASPECTS ≤5. The association of ASPECTS loss during transfer was also quantified. The primary outcome was the distribution of modified Rankin Scale score at 90-day follow-up.Results:Of 352 enrolled patients, 211 (60%) were transferred to EVT capable center and 108(51%) received EVT. 141 presented directly and 72 (51%) received EVT. The median transfer time was 185 (140-234) minutes. Median ASPECTS decreased from outside hospital [5(4-7)] to EVT center [4 (3-5)] with ASPECTS decay rate at 0.31 (0-0.84) points/hour of transfer time, with 50/120 (42%) experienced ASPECTS loss ≥2. Thrombectomy treatment effect was preserved in both directly presenting patients [aGenOR: 2.01 (1.42-2.86)] as well as transferred patients [aGenOR: 1.50 (1.11-2.03)] without significant heterogeneity (P-int=0.14). EVT also demonstrated numerically better functional outcomes in transferred patients with outside ASPECTS of ≤5 (n=65, 35 EVT, aGenOR: 1.77 (0.97-3.23), p=0.068). ASPECTS loss was associated with worse clinical outcomes in EVT [aGenOR: 0.81 (0.71-0.83) per ASPECTS point loss] but not in MM: [aGenOR: 0.89 (0.73-1.08) per ASPECTS point loss].Conclusion:In large core patients, transfer time was associated with ASPECTS decay, resulting in worse outcomes with EVT. Transferred patients however still benefited from EVT, with a trend towards better outcomes in patients with low ASPECTS at outside hospitals. These findings may substantially impact stroke care infrastructure, emphasizing the need for rapid identification of patients suitable for transfer and expedited transport.Clinicaltrials.gov registration:NCT03876457

Stroke, Volume 55, Issue Suppl_1, Page AWP323-AWP323, February 1, 2024. Introduction:Our earlier studies show that the small non-coding RNA, mir20a-3p, is neuroprotective after stroke, and reduces sensory-motor impairments in the acute phase and cognitive decline in the long-term in female rats. Cognitive decline due to vascular diseases, such as stroke, is associated with volume loss in the cortex, the limbic structures and white matter tracts. In this study, we examined the volume of forebrain white matter tracts, cortical and limbic structures in animals with characterized cognitive impairment due to stroke, and the efficacy of microRNA treatment.Methodology:Middle-aged females were subjected to ischemic stroke using endothelin 1, injected adjacent to the left middle cerebral artery (MCA). Mir-20a-3p mimic (n=10) or scrambled oligo (n=8) was administered i.v. 4h, 24h and 70d post stroke. Animals were assessed periodically for cognitive performance up to 100d after stroke using both the cued fear conditioning test and the novel object recognition test (NORT). After perfusion fixation, T2 and diffusion tensor imaging (DTI) magnetic resonance imaging of the brain was performed. Thereafter, brains were processed for Weil myelin staining, followed by quantification of the corpus callosum and internal capsule.Results:Stroke resulted in impairment in both the cued fear conditioning test and the NORT, which was attenuated by mir-20a-3p treatment. Compared to sham (no-stroke) animals, volumetric analysis of DTI scans showed a significant reduction in the volume of substantia nigra (p

Stroke, Volume 55, Issue Suppl_1, Page A41-A41, February 1, 2024. Background:The optimal imaging modality for treatment selection in the extended stroke window is uncertain. VESTA study (NCT05299034) compared conventional imaging (noncontrast CT + CT angiography) with advanced imaging (adding perfusion) in extended window stroke patients, focusing on EVT selection rate, safety and functional outcome.Methods:From the prospective Catalan Stroke Registry (CICAT, 29 centers) ischemic stroke patients within 6-24h of symptom onset and NIHSS ≥6 (Jan 2019 -Dec 2021) were selected. Imaging modality was decided according to the local site protocol. Images were re-evaluated by a central core lab with full access to each patient’s images. LVO was defined as intracranial ICA, M1 or proximal M2 occlusion. Blinded investigators centrally assessed 90-day functional independence, defined as mRS≤2. We employed a propensity score matching algorithm to adjust for age, sex, NIHSS, established infarct, and time from onset to arrival.Results:We included 1405 patients in the analysis (median age 76y, median NIHSS 11; 48% women). Conventional imaging was performed in 48% of patients, while 52% received advanced imaging. Patients receiving conventional vs. advanced imaging showed lower NIHSS (11 vs. 12, p=0.006), and lower rates of LVO (45% vs. 58%, p

Stroke, Volume 55, Issue Suppl_1, Page ATP207-ATP207, February 1, 2024. Background and purpose:Clinical-imaging mismatch or perfusion imaging mismatch criteria per DAWN (Clinical Mismatch in the Triage of Wake Up and Late Presenting Strokes Undergoing Neurointervention With Trevo) or DEFUSE-3 (Endovascular Therapy Following Imaging Evaluation for Ischemic Stroke), respectively were recommended for case selection for endovascular treatment (EVT) of acute ischemic stroke (AIS) in the late time window outside 6 hours of stroke onset. We aimed to compare the clinical functional outcomes in EVT patients with and without strict perfusion imaging screening criteria in the late time window.Methods:AIS patients with anterior circulation large vessel occlusion (LVO) presenting within 6 to 24h hours after symptom onset were selected from a retrospectively collected thrombectomy cohort database (RESTORE). According to the imaging criteria of DAWN and DEFUSE-3, we compared proportions of patients with a favorable functional outcome (defined as a modified Rankin Scale [mRS] score of 0-2) at 90 days between the DAWN or DEFUSE-3 patients (D/D) and the non-DAWN or DEFUSE-3 (non-D/D) patients.Results:Among 265 adult patients with anterior circulation LVO who received EVT within 6 to 24 hours after symptom onset, 142 patients met either DAWN or DEFUSE-3 imaging criteria. D/D group independently predicted favorable functional outcome at 90 days (50.7% vs. 35.0%, aOR 0.514; 95% CI 0.273-0.966, p=0.039) adjusted for age, sex, previous stroke, hypertension, atrial fibrillation, coronary heart disease, pre-EVT collateral score, successful recanalization, onset to CT time.Conclusions:In AIS patients with anterior circulation LVO in the late time window, our real world data support the guideline that DAWN or DEFUSE-3 imaging criteria are strongly recommended for EVT case selection.

Stroke, Volume 55, Issue Suppl_1, Page AWP118-AWP118, February 1, 2024. Introduction:Circadian rhythms have recently been shown to influence stroke incidence and progression of infarct. We aimed to describe the diurnal variations in the incidence and perfusion profiles of patients with ischemic stroke using a large, multi-center, automated imaging database.Methods:The RAPID Insights database was queried from 02/01/2016 to 01/31/2022 for patients with perfusion imaging and automated detection of an ischemic stroke due to a presumed large vessel occlusion. Exclusion criteria included: patient age ≤25, mismatch volume of 10s]/[Tmax >6s]), where a higher HIR suggests poorer collateral status. All perfusion parameters were analyzed on a 24-hour continuous cycle. Statistical significance was tested using a sinusoidal regression analysis.Results:A total of 18,137 cases were analyzed. The peak incidence of ischemic stroke occurred around noon. A sinusoidal pattern was present, with larger ischemic core volumes and higher HIR during the night compared to the day: peak ischemic core volume of 23.40 cc occurred with imaging performed at 3:56 AM (p

Stroke, Volume 55, Issue Suppl_1, Page AWMP91-AWMP91, February 1, 2024. Introduction:The association of extent of ischemic injury on various imaging modalities and EVT efficacy and safety in patients with large ischemic core remains unexplored. We analyzed ischemic injury estimates on structural and perfusion imaging modalities and their association with time and EVT treatment effect.Methods:In SELECT2, all patients received non contrast CT and CT perfusion/MR diffusion. Baseline ischemic injury was estimated using ASPECTS, CTP/MRI with RAPID processing, manual delineation of CT hypodensity and composite core [the larger of the CT hypodensity and CTP/MRI core volumes], Figure 1A. We assessed how these estimates compared to one another, which correlated best with the outcomes and described EVT treatment effect across their strata.Results:Of 352 patients, 16 were excluded for missing mRS/imaging data. 170/336 (51%) received EVT. The median (IQR) CT-ASPECTS was 4 (3-5), CT-hypodensity 86 (49-114) mL, CTP/MRI core 73 mL (46-107). 60% had CT hypodensity > CTP/MRI core volume. CTP core was larger in 81% within 0-3 hours that inverted to 86% patients with larger CT hypodensity in 21-24 hours of LKW [Figure 1B]. Composite core (101 [72-138] ml) had best fit for mRS (Bayesian Information Criteria for mRS shift: ASPECTS – 448, CT hypodensity – 443, CTP core – 434, Composite core – 429 with lower the better). Treatment effect estimates favored EVT across strata (≥70 ml, ≥100ml & ≥150 ml) for CT hypodensity, CTP/MRI core and composite core as well as ASPECTS 3,4 and 5. For a given volume probability of independent ambulation with EVT decreased with age and time to reperfusion.Conclusions:CT perfusion and CT hypodensity were complementary and most prognostic when used together, in conjunction with age and time to reperfusion. Thrombectomy benefit was preserved across ischemic volumes and ASPECTS. These findings can assist clinicians in assessing the likely outcome of thrombectomy for individual patients.Trial Registration: NCT03876457

Stroke, Volume 55, Issue Suppl_1, Page AWP120-AWP120, February 1, 2024. Introduction:FDA approval of Hyperfine has led to interest in using low-field Magnetic Resonance Imaging (MRI) in acute ischemic stroke (AIS). Portable MRI (pMRI) has practical advantages over high-field MRI (hMRI), and prior studies have evaluated pMRI predominantly in the ICU settings. We sought to determine performance of pMRI on floor level AIS patients.Methods:We retrospectively reviewed floor status AIS patients who had pMRI obtained during their hospitalization. We reviewed pMRI for ability to visualize confirmed infarcts on hMRI. hMRI was considered gold standard. Incomplete or technically limited scans were excluded. Our institutional pMRI (Hyperfine) is 0.064 Tesla and our protocol sequences include diffusion-weighted imaging (DWI), Apparent diffusion coefficient, and fluid-attenuated inversion recovery (scan time 24 minutes). Infarct size was measured based upon maximum longitudinal axis on MRI DWI.Results:Among 12 AIS patients, the mean age was 58.5 years (range, 25 to 88) and 7 (58.3%) were female. Mean time from hMRI to pMRI was 46.2 hours (range, -0.9 to 126.9 hrs). Mean Time from LKN to pMRI was 3.6 days (range, 0.87 to 7.8 days). In most 9/12 (75%) patients, pMRI demonstrated acute infarcts (7/12 pMRI scans demonstrated all infarcts seen on hMRI, while 2/12 pMRI scans identified some but not all infarcts). Three 3 (25%) pMRI DWI were negative. On 12 hMRI scans, 15 infarct lesions were demonstrated. Infarct distribution was as follows: cortical (9), deep (1), medullary (1), thalamus (3), and cerebellar (1). Among the 15 infarcts demonstrated on hMRI, 10/15 (67%) were also visible on pMRI. The mean size of infarcts that were not visible on pMRI was 7.7 mm, compared to pMRI visible infarct mean size of 21.7mm (p 0.0436). The smallest infarct that was visible on the pMRI was 7.7mm.Conclusions:pMRIs performed reasonably well on floor-level AIS patients and was able to detect the majority of acute infarcts seen on hMRI. There was a correlation between infarct size and visibility on pMRI, with pMRI performing better on larger sized infarcts. Understanding limitation of pMRI will allow clinical teams to maximize patient selection for use in AIS population.

Stroke, Volume 55, Issue Suppl_1, Page ATP109-ATP109, February 1, 2024. Introduction:The Hyperfine portable low-field Magnetic Resonance Imaging (MRI) scanner (0.064 Tesla) was FDA approved in 2020. The use of portable low-field MRI (pMRI) has been best studied in ICU settings, although there has been interest in expanding this technology in floor level status stroke patients.Methods:We report our experience launching pMRI in our academic comprehensive stroke program in the non-ICU setting. From September 2021 to March 2022, 24 pMRI scans were performed (2 volunteers, 22 floor-status stroke patients). Our institutional pMRI protocol includes localizer, DWI, ADC, and FLAIR (24 minutes scan time). Good head position (GHP) was defined as the vertex of the head abutting the top of the helmet insert. Complete scans were defined as including all sequences and Partial scan included DWI/ADC.Results:Among 24 scans, most 17/24 (70.8%) were Complete and 2 scans were aborted after only localizer images. Six scans were Partial, due to patient discomfort in 4 (“feeling hot” [2], neck/back pain [2]), and technical issues with machine in 2. Among 22 scans that were Partial or Complete, 6 scans had poor head positioning. We noted that although there was initial GHP, the head could shift out due to gravity or patient self-adjustment due to discomfort. To combat the shift issue, the bed was placed in slight reverse Trendelenburg. We also implemented wedge padding for the lower back that improved comfort. After scan # 11, re-training was performed to include GHP updates. Before re-training, 6/11 (45.5%) had GHP, and afterwards, 11/11 (100%) had GHP. Our quality review also noted that artifact on the DWI/ADC mimicking restricted diffusion could be seen in the internal capsule and corpus callosum, and clinical teams were educated on this.Conclusions:The use of low-field pMRI in non-ICU settings is feasible. Our institutional QI experience suggests that patient selection and technical skill in GHP is a consideration. After adjusting our protocol, the rate of GHP increased from 45% to 100%. Clinical teams also need to be aware of artifact mimicking restricted diffusion in areas of tightly bound white matter tracks. Further studies are warranted to better maximize pMRI and understand the logistical barriers to successful implementation.

Stroke, Volume 55, Issue Suppl_1, Page A36-A36, February 1, 2024. Background and Objectives:This study aimed to investigate the association between high-resolution magnetic resonance imaging (HR-MRI) characteristics and recurrent ipsilateral stroke in patients with symptomatic intracranial atherosclerotic steno-occlusive disease (ICAS).Methods:This multicenter, observational study recruited first-ever acute ischemic stroke patients attributed to ICAS ( >50% stenosis or occlusion) within 7 days after onset. Participants were assessed by multi-parametric MRI including diffusion-weighted imaging, three-dimension time-of-flight magnetic resonance angiography, and three-dimensional T1-weighted HR-MRI. The patients were recommended to receive best medical therapy and were systematically followed up for 12 months. The association between HR-MRI characteristics and the time to recurrent ipsilateral stroke was investigated by univariable and multivariable analysis.Results:Two hundred and fifty-five consecutive patients were enrolled from 15 centers. The cumulative 12-month ipsilateral recurrence incidence was 4.1% (95% confidence interval [CI]: 1.6-6.6%). The plaque length (5.69±2.21 mm vs. 6.67±4.16 mm), plaque burden (78.40±7.37% vs. 78.22±8.32%), degree of stenosis (60.25±18.95% vs. 67.50±22.09%) and remodeling index (1.07±0.27 vs. 1.03±0.35) on HR-MRI did not exhibit discernible difference between patients with and without recurrent ipsilateral stroke. Patients with recurrent ipsilateral stroke exhibited higher rates of intraplaque hemorrhage (IPH) (30.0% vs. 6.5%) and eccentric plaque (90.0% vs. 48.2%), and lower occurrence of occlusive thrombus (10.0% vs. 23.7%). In the multivariable Cox regression analysis, IPH (hazard ratio: 7.05, 95% CI: 1.53-32.41, p=0.012) was significantly associated with recurrent ipsilateral stroke after adjustment.Discussion:We found IPH is significantly associated with recurrent ipsilateral stroke. Our results suggest IPH has potential value in the selection of patients for aggressive treatment strategies.

Stroke, Volume 55, Issue Suppl_1, Page ATP140-ATP140, February 1, 2024. Background:The treatment of acute ischemic stroke (AIS) aims to achieve early vascular recanalization and reperfusion of the penumbra. However, the effect of early penumbral imaging within 6 hours on clinical outcomes remains unclear.Objective:The objective of this study was to determine the effect of magnetic resonance-guided (MR-guided) perfusion imaging within 6 hours after symptom onset on endovascular thrombectomy outcomes in AIS patients.Methods:We prospectively collected the clinical information of consecutive AIS patients undergoing endovascular thrombectomy based on MR-guided perfusion imaging within 6 hours after symptom onset from AISRNA and EVTRNA studies. The primary outcome was defined as the poor outcome (mRS > 2 within 90 days). The perfusion-weighted imaging/diffusion-weighted imaging (PWI/DWI) mismatch was assessed by an automated software.Results:We enrolled 84 patients (25 in the mismatch ≤ 1.8 group and 59 in the mismatch > 1.8 group). Significant difference was found between the mismatch >1.8 group and the mismatch≤1.8 group for the incidence of disabling stroke (mRS > 2) within 90 days (40.7% vs. 68.0%, OR: 3.099, 95% CI: 1.154-8.323, P =0.025). Intracranial hemorrhage occurred in 8 patients (13.6%) in the mismatch > 1.8 group and 10 patients in the mismatch ≤ 1.8 group (40.0%) (P = 0.010). The risk of severe cerebral edema was 2/59 (3.4%) vs. 7/25 (28.0%) (P = 0.004). These findings remained stable after adjustment.Conclusion:MR-guided perfusion imaging mismatch profiles within 6 hours after symptom onset may be feasible to improve clinical outcomes and reduce clinically ineffective reperfusion after endovascular thrombectomy.

Stroke, Volume 55, Issue Suppl_1, Page A130-A130, February 1, 2024. Objective:To investigate the anatomical and physiological impact of intracerebral hemorrhage (ICH) on the mechanical CST distortion measured using serial MRI and its relation to functional recovery.Introduction:ICH causes CST (motor pathway for arm movement) deformation/displacement leading to disruption of brain-arm neuronal communication. Limited knowledge exists about the degree and anatomical disruption of CST and long-term recovery of the arm impairment and how temporal resolution of the hematoma/edema volume impacts recovery. Here we applied serial quantitative MRI to establish an association between the CST displacement (CSTD) and arm recovery.Methods:We imaged 12 patients with subcortical bleed on day-2 and 90, who underwent routine care. Using DTI, the change in CSTD at the level of posterior limb of internal capsule (PLIC) was calculated by the distance shift between the patient’s pre (determined a standard brain template, registered to DTI images) and post-ICH CST location. A centroid (the medians of a volume at 3 intersecting coordinates) at each PLICs was determined and the distance between the two centroids was recorded. ICH severity and arm impairment were measured on NIHSS and Fugl-Meyer assessment for Upper Extremity (FM-UE) scores.Results:We enrolled 9M/3F, with an average age of 512.1±8.3y who were serially imaged. The hematoma volume (18.6±28.1 to 4.5±4.9mL) and NIHSS (14.0±5 to 5.0±3) significantly (p

Stroke, Volume 55, Issue Suppl_1, Page ATMP9-ATMP9, February 1, 2024. Background:FLAIR vascular hyperintensities (FVH) are high signal intensities on MRI resulting from sluggish flow through collateral vessels in patients with acute arterial ischemic stroke (AIS). Data from adults suggest they may be a marker of penumbra. In this first investigation of FVH in children, I measured the prevalence and identified risk factors for FVH in pediatric patients with AIS.Methods:Retrospective review of patients prospectively enrolled in the CHOP Stroke Registry from 2006-2022. Patients with AIS age 29 days to 18 years with MRI within 72 hours of last known well were included. Children with pre-existing strokes, vasculopathy, prior brain surgery, radiation, or vascular compression from intracranial mass were excluded. MRIs were assessed by a blinded reviewer and adjudicated by a neuroradiologist for presence of LVO, FVH score, modASPECTS score, and AIS lesion volume. Clinical data were abstracted from chart review. Independent sample t-test compared FVH score and LVO presence. Pearson’s correlation assessed the relationship between total FVH score and age, stroke size, modASPECTS, and pedNIHSS scores. Multivariable logistic regression evaluated predictors of significant FVH (score >= 3) and included time to MRI, large vessel occlusion, modASPECTS, pedNIHSS, stroke size, and age as independent variables.Results:83 patients met inclusion criteria. Median time to MRI was 26 hours (95% CI 26-33). FVH were present in 45 patients (54%). Mean FVH score was higher in patients with LVO (5.22 ± 0.64) compared to those without (1.21 ± 0.24;p= 0.00). There was a positive correlation between total FVH score and age (p < 0.05), stroke size (p < 0.0001), modASPECTS (p < 0.0000), and pedNIHSS (p < 0.0002). In the multivariate logistic regression, only older age (OR 1.50, 95% CI 1.12-2.01, p < 0.006) and presence of LVO (OR 0.002, 95% CI 4.85x10-5-0.08, p

Stroke, Volume 55, Issue Suppl_1, Page ATMP14-ATMP14, February 1, 2024. Introduction:Endovascular thrombectomy (EVT) is the standard of care for patients with ischemic stroke and large vessel occlusion (LVO). Intracranial vascular imaging is required to determine the presence of an LVO. Although patients can be eligible for EVT up to 24h after last seen normal (LSN), current imaging protocols focus on the first 6h from LSN. We evaluated the use of intracranial vascular imaging in patients with ischemic stroke as a function of time since LSN in Ontario, Canada.Methods:We analyzed data from the Ontario Stroke Registry which performed primary data collection evaluating care and outcomes in 13,828 patients hospitalized with stroke across Ontario in the fiscal year 2019/20. This sampling strategy included 93.3% of all strokes in a province of 14.5 million residents. We used modified Poisson regression models to evaluate the association between time from LSN to first hospital presentation (75% completed and full results will be presented at the ISC. Of 8,482 patients with ischemic stroke, 6,345 (74.8%) presented within 24h of LSN (n=3,811

Stroke, Volume 55, Issue Suppl_1, Page ATP186-ATP186, February 1, 2024. Background:In patients with acute ischemic stroke with the large vessel occlusion (LVO), the presence of low signal including microbleeds on T2*-weighted gradient echo magnetic resonance imaging (T2*-positive) which suggestive of an old cerebral hemorrhage before mechanical thrombectomy (MT) may be associated with hemorrhagic change after MT, but the significance of this finding is unclear.Methods:Patients with acute stroke with LVO underwent T2* before MT. Patients were classified into two groups as T2*-positive and T2*-negative. We compared hemorrhagic change after MT, outcome at discharge and clinical characteristics between two groups. The occurrence of hemorrhagic change was assessed on CT after MT. Patients outcomes were classified into two group; good outcome as modified Rankin Scale (mRS) 0-2 and poor outcome as mRS 5-6, respectively. Clinical characteristics and imaging factors associated with any ICH after MT were evaluated by multivariate regression analysis.Results:348 patients (median age, 78 years; men, 60.1%; median NIHSS score, 16) were enrolled. The site of occlusion was the ICA (n=92, 26.4%), M1 (n=168, 48.3%), M2 (n=49, 14.1%) and BA(n=29, 8.3%). T2*-positive and T2*-negative were found in 73 (21.0%) and 275 (79.0%), respectively. There were no differences in age, history of hypertension, diabetes, atrial fibrillation and stroke, TOAST type, DWI-ASPECTS, NIHSS, use of tPA, or TICI≧2B rate between the two groups. Any ICH after MT was 28 (38.4%) in T2*-positive and 96 (34.9%) in T2*-negative (P=0.585). PH and SAH were 7 (9.6%) and 2 (2.7%) in T2*-positive and 40 (14.9%) and 25 (9.1%) in T2*-negative (P=0.337, and P=0.085), respectively. Poor outcome was 27 (37.0%) in T2*-positive and 65 (23.6%) in T2*-negative (P=0.025), respectively. Multivariate regression analysis demonstrated that T2*-positive was not associated with any ICH (odds ratio, 0.884; confidence interval, 0.473-1.654; P=0.700).Conclusions:In patients with acute ischemic stroke with LVO, low signal on T2* before MT should not be associated with hemorrhagic change after MT.

Stroke, Volume 55, Issue Suppl_1, Page AWMP43-AWMP43, February 1, 2024. Introduction:Global access to mechanical thrombectomy for large vessel occlusion (LVO) stroke is low and disparate between regions. Comparative global data on time metrics for imaging and endovascular treatment (EVT) performance, as well as the reasons for excluding EVT, are lacking.Methods:This is a cross-sectional study using quality metrics from the Res-Q registry on patients presenting directly to the hospital with acute ischemic stroke from January 1, 2022, to December 31, 2022, in countries with 200 or more cases. We used descriptive statistical methods to study the time metrics of interest including door to imaging and door to puncture. Additionally, reasons for not performing thrombectomy in patients with LVO were collected (Table 1).Results:Among the 153,181 patients from 912 hospitals across 67 countries enrolled in the Res-Q registry, 125,390 had an acute ischemic stroke. After excluding secondary transfers (n=26,648), patients with missing or erroneous data (n=42,232), and countries with less than 200 cases (n=1,626), data from a total of 54,884 patients from 631 hospitals across 30 countries were analyzed. CT angiography (CTA) was performed in 24,215 (44.1%) patients and EVT was done in 3,649 (6.6%) patients. For patients who had simultaneous CT+CTA, the median door-to-CTA time was 27.5 min (IQR 22.5-33.9) and the median door-to-puncture time was 98.5 (IQR 79.8-129.3) minutes. The most prevalent specific reason for excluding EVT in patients with LVO on CTA/MRA was the presentation in the late time window (42.0%). Only 11 (36.7%) countries achieved a median door-to-puncture time within 90 minutes (Table 1).Conclusions:The performance of acute imaging for LVO detection and time metrics for EVT appear to be disparate between countries and warrant further study. Additional data from global stroke care quality registries are needed to set benchmarks, compare regional stroke systems of care, and identify gaps to mobilize resources appropriately.

Stroke, Volume 55, Issue Suppl_1, Page A125-A125, February 1, 2024. Introduction:The no-reflow phenomenon (persistent microvascular hypoperfusion despite macrovascular angiographic reperfusion) represents an explanation to poor outcome despite successful thrombectomy. There remains no universally-accepted definition to standardise future studies. We aim to compare the clinical features and outcomes of patients identified as having no-reflow using different perfusion MRI/CT definitions.Methods:We performed a pooled analysis of thrombectomy patients who underwent 24-hour follow-up perfusion MRI or CTs in the EXTEND-IA, EXTEND-IA TNK part 1 and 2 RCT. Presence of no-reflow was defined according to four definitions identified from a meta-analysis of 13 studies (Definition A = eTICI2c-3 and >15% asymmetry in CBV or CBF within the infarct on follow-up perfusion MRI/CT; definition B = mTICI2c-3 and >40% CBF asymmetry, definition C = mTICI2b-3 and presence of a Tmax >6s lesion; Definition D = mTICI2b-3 and >90% reduction of baseline Tmax >6s lesion). Receiver Operating Characteristics (ROC) analysis was performed with the outcome variable being poor functional outcome at 90 days (mRS≥3).Results:Of 325 patients analysed, the prevalence of no-reflow varied between definitions from 1.9 to 29.3% (p