Risultati per: L'imaging nella urolitiasi

Stroke, Volume 55, Issue Suppl_1, Page AWMP61-AWMP61, February 1, 2024. Background:Assessing carotid artery plaques in stenosis is crucial for treatment strategies and safety. Chemical exchange saturation transfer (CEST)-MRI, particularly Amide proton transfer (APT) imaging, shows promise in molecular imaging. This study explores the correlation between APT imaging and histopathological findings of carotid artery plaques in 34 consecutive patients who had carotid endarterectomy. We investigated the utility of CEST-MRI as a preoperative plaque diagnostic tool.Methods:APT imaging evaluated plaques prior to the procedures. APT signal values were derived from concentration maps. Plaques were categorized into Group A (APT signal values ≥ 1.90 E-04) and Group B (APT signal values < 1.90 E-04). Postoperative histopathological assessments were conducted on the excised plaques. Histology slides were categorized following AHA’s classification, distinguishing type VI lesions with intraplaque hemorrhage from non-type VI lesions.Results:Type VI lesions accounted for 64.7% (22 cases), while non-type VI lesions were 35.3% (12 cases). Type VI group showed significantly higher mean APT signal values (2.72 ± 1.96 E-04) compared to non-type VI group (0.70 ± 0.59 E-04) (p < 0.001). Pathologically, Group A had a significantly higher proportion of Type VI lesions (100%) than Group B (45%) (p < 0.01). Symptomatic patients or patients with worsening stenosis rates were significantly higher in Group A (75%) than Group B (36%) (p < 0.01).Conclusion:Elevated APT signals were observed in unstable plaques with intraplaque hemorrhage and in plaques of symptomatic or progressive stenosis patients. CEST-MRI evaluation is valuable for assessing plaque characteristics and activity.

Stroke, Volume 55, Issue Suppl_1, Page ATMP49-ATMP49, February 1, 2024. Background:Red blood cells (RBC)-rich thrombus are more easily retrieved via endovascular procedures while platelet-rich thrombus are more resistant to recanalization. Our aim was to generate a radiomics model able to identify both RBC and platelet-rich thrombus at CT admission in patients undergoing mechanical thrombectomy.Methods:We included consecutive patients that received mechanical thrombectomy due to a large vessel occlusion in which thrombi was obtained. Thrombi obtained during the procedure were hematoxiline-eosine processed and proportions of RBC were determined. Relative proportion of the platelets in the thrombi was quantified by using a immunohistochemical staining recognizing CD61. We considered RBC-rich thrombi those with a content of RBC >30% and platelet-rich thrombi those with a content of CD61 >70%. Thrombi were segmented manually on co-registered non-contrast CT (NCCT) and CT angiography (CTA) at admission (30% was 0.938 (sensitivity 86%, specificity 86%, PPV 84%). Regarding platelet-rich thrombus, the area under the curve for detecting CD61 >70% was 0.89 (sensitivity 83%, specificity 84%, PPV 74%). Feature importance by imaging type for RBC-rich and platelet rich thrombus was 70.33% and 69.8% for NCCT and 29.67% and 30% for CTA, respectively. The most important feature types for RBC-rich thrombus were histograms (51%) and first order (27%) while the most important features for platelet rich-thrombus were histograms (94%) followed by texture (5.94%). No information about shape improved any model.Conclusion:Our radiomics model can reliably identify RBC and platelet-rich thrombi. Fast identification of thrombus histological components on CT at arrival can help to design the preferred therapeutic strategy

Stroke, Volume 55, Issue Suppl_1, Page A144-A144, February 1, 2024. Introduction:CTP has increasingly been incorporated into the evaluation of all patients with suspected acute ischemic stroke (AIS), including those with minor symptoms. We aimed to assess the incremental value of CTP in acute treatment decision-making among patients with low NIHSS.Methods:We performed a retrospective cohort study of all patients who underwent CTP upon presentation to the ED at three academic, urban hospitals in Philadelphia, PA between January 1, 2022 and December 31, 2022. We collected data on initial NIHSS score, AIS treatment decisions, subsequent neuroimaging, and final diagnosis.Results:There were 531 patients with a median age of 64.5 years (IQR 54-73) and 56% were women. 73% were Black or African American, 20% White, and 4% Asian. Frequency of CTP imaging by initial NIHSS score is presented in the Figure. Among 90 patients (16.9%) with NIHSS≤2, CTP imaging was cited as justification for AIS treatment (thrombolysis, thrombectomy, or both) in 0 (0%, 95% CI: 0-4%). Specifically, among 41 patients (7.7%) with NIHSS≤1, 0 received thrombolysis or thrombectomy, and 12 (29.2%) were ultimately diagnosed with AIS on CT/MRI. Among 49 with NIHSS=2 (9.2%), 2 patients received thrombolysis (based on clinical exam, CTP was normal) and one later underwent thrombectomy based on clinical decompensation with repeat NIHSS=7, and 28.6% had AIS on CT/MRI. Meanwhile, among 33 patients with NIHSS=3, acute treatment was given to 3 and CTP influenced AIS treatment decisions in 2 (6.1%). Among 59 patients with NIHSS=4, acute treatment was given to 4 and CTP influenced decision-making in 3 (5.1%). CTP mismatch ratio was > 1.7 in all 5 patients who received acute treatment and had NIHSS of 3 or 4.Conclusions:CTP is frequently performed in patients with low NIHSS. It had limited impact on acute treatment decisions, notably none among those with NIHSS≤2, suggesting that CTP may be over-utilized in this subset of patients with AIS.

Stroke, Volume 55, Issue Suppl_1, Page ATP141-ATP141, February 1, 2024. Background:Computerized tomography perfusion (CTP) imaging serves as a valuable modality for the assessment of individuals with a large vessel anterior circulation stroke. Current literature proposes that employing CTP imaging in patients within the initial time frame of less than 8 hours, may lead to an overestimation of the projected infarct core, specifically when utilizing cerebral blood flow (CBF) less than 30%. The hypoperfusion intensity ratio (HIR) may result in overestimation. We sought to further investigate the interplay of CTP parameters in patients presenting within 8 hours of symptom onset of stroke, to assess the accuracy of core infarct estimation.Methods:A retrospective cohort study analyzing patients with large vessel anterior occlusion (LVAO) who underwent CTP and mechanical thrombectomy within 24 hours of symptom onset between January 2017 to December 2022. RAPID software estimates the infarct core using CBF

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 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 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 AWP119-AWP119, February 1, 2024. Introduction:Magnetic resonance imaging (MRI) and computed tomography (CT) is useful for the evaluation of the ischemic core and penumbra. The indication for mechanical thrombectomy (MT) for acute ischemic stroke is determined by either or both imaging modalities. The selection of initial imaging modality is differed by the institute, and it is uncertain which imaging modality is superior before MT. In this study, we compared the clinical outcomes after MT by imaging modality in the K-NET registry (Kanagawa intravenous and endovascular treatment of acute ischemic stroke registry).Methods:The K-NET registry is a Japanese multicenter prospective registry study of patients treated with Intravenous thrombolysis with recombinant tissue plasminogen activator, endovascular treatment, or both for acute ischemic stroke. The present study is based on patients’ data in the K-NET registry between January 2018 and June 2021. The inclusion criteria for the current analysis were as follows: (1) pre-modified Rankin score (mRS) 0-2; (2) patients transferred directly to primary stroke centers; (3) treated with MT; and (4) performed only CT or MRI for diagnosis of acute ischemic stroke before MT. The patients who performed both CT and MRI at admission were excluded. Unbalanced cohorts with a nonrandom distribution of patients were accounted for by using propensity score matching.Results:2348 patients were enrolled in the registry during the period, and 753 patients were eligible for inclusion criteria. 498 (249 matched pairs) were included after propensity score-matched analysis. The baseline characteristics were well-balanced between the two groups. There was no difference in the final mTICI grade between the two groups. The time from image to puncture in the MRI group was significantly shorter than the CT group (52min versus 38min), and the time from image to recanalization was also significantly shorter in the MRI group (108min versus 88.5min). The rate of functional independence (90 days mRS 0-2) was higher in the MRI group versus the CT group (54.4% versus 43.8%, p=0.017).Conclusions:The selection of MRI before MT was associated with a shorter time from image to puncture and recanalization and a favorable outcome compared with CT.

Stroke, Volume 55, Issue Suppl_1, Page ATMP79-ATMP79, February 1, 2024. Introduction:Incident intracerebral hemorrhage (ICH) is an uncommon medical event that can lead to devastating outcomes, including death. Small vessel disease (SVD), as measured by cerebral microbleeds (CMBs) and white matter hyperintensities (WMH), has been associated with risk factors and might be a predictor of incident ICH. CMBs result from irregularities in brain vessel structure due to chronic hypertension and cerebral amyloid angiopathy. These microhemorrhages are a possible risk factor for ICH.Methods:A cohort of ARIC (Atherosclerosis Risk in Communities) participants underwent 3T MRI at visit 5 (2011-2013). CMBs were assessed using a T2* gradient echo. CMBs are homogenous hypointense lesions ≤10 mm in diameter. WMH volumes were derived from FLAIR images using an automated program to measure the volumetric burden of leukoaraiosis. During 10 years of follow-up, incident ICH was noted in 7 (0.4%) out of 1,656 participants were dichotomized based on the presence of CMB and the median of WMH volume.Results:ARIC subjects (n=1656, mean age=76±5 years; 40% men; 26% African American race) underwent MRI. CMBs were present in 385 (23.25%) patients out of 1656. ICH occurred in 0.16% and 1.30% of patients without CMBs and with CMBs, respectively. Kaplan Meier (KM) survival analysis between CMBs and ICH was significant (logrank p=0.002). Cox Regression yielded a significant crude hazards ratio (HR 8.7, 95% CI 1.7-44.7, p=0.010). Adjustment for age, gender, race, and hypertension was also significant (HR 9.9, 95% CI 1.9-52.0, p=0.07). KM survival analysis between WMH median (11.68 cm3) and ICH was significant (logrank p=0.006). Figure 1 displays the KM curves of those with and without CMBs and the incidence of ICH as well as those below and above WMH median and incidence of ICH.Conclusion:CMBs and WMH detected by MRI appear to be an important predictor for the occurrence of incident ICH. Further research is needed to observe if MRI could be used to screen subjects at high-risk for elevated risk of incident ICH.

Stroke, Volume 55, Issue Suppl_1, Page ANS1-ANS1, February 1, 2024. Background:Comprehensive Stroke Program identified increased thrombolytic door to needle times [DTN-t] for stroke alert patients [SA]. To increase numbers treated with [w/] mechanical thrombectomy [MT], the decision was made to perform additional multimodal neuroimaging [AMN] w/initial imaging for all SA & before thrombolytic. Prior to this, the Vision, Aphasia, Neglect [VAN] Large Vessel Occlusion [LVO] screening tool was used to triage for AMN. When compared to LVO screen triage, AMN for all SA demonstrated an overall increase in neuroimaging without increasing sensitivity of MT triage [Patterson et al, 2023].Purpose:Evaluate impact of AMN w/initial imaging for all SA on timely administration of thrombolytic.Method:Retrospective review of 220 SA receiving thrombolytic over 24-months was conducted, w/38 excluded for documented valid delay reasons & 156 receiving AMN before thrombolytic. The NIHSS was evaluated for components of the LVO screening tool to determine VAN [+] or [-]. For VAN [-] SA time required for AMN was subtracted from DTN-t & adjusted times assigned [A-DTN-t]. The group was divided into all SA, NIHSS 0-5 & NIHSS ≥6 & compared to determine impact on DTN-t.Results:A-DTN-t using LVO screen triage resulted in fewer AMN prior to DTN-t with a 5% increase in DTN-t ≤45 minutes [m] in all groups. For DTN-t ≤30m there was a 5% increase in all SA & in NIHSS ≥6, w/a 2% increase in NIHSS 0-5.Conclusion:Clinical Practice Guidelines state thrombolytic therapy is time-dependent & most beneficial when not delayed for AMN. Performing AMN w/initial imaging & before thrombolytic for all SA resulted in delayed administration of thrombolytic without increasing sensitivity of MT triage when compared to utilizing LVO screen triage.

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 ATP150-ATP150, February 1, 2024. Introduction:Ischemic stroke is a leading cause of death and disability in the US, with 20-40% of cases, classified as cryptogenic or with an unexplained cause. Detection of one cause, paroxysmal atrial fibrillation (AF), is critical to ensuring optimal treatment with direct oral anticoagulant (DOAC). Currently, the most reliable AF detection strategy is use of an insertable cardiac monitor (ICM). However, earlier detection of occult cardioembolic patterns using MRI may promote earlier decisions for DOAC use. The overall goal of this study is to determine if MRI lesion patterns are predictive of AF detection by ICM.Methodology:Cases of consecutive patients (1/1/2015 – 12/31/2017) with MRI-confirmed stroke performed 48h from time last known well and prior to endovascular treatment were retrospectively analyzed. The primary outcome, presence of occult atrial fibrillation, was detected by ICM placement within 90 days and follow-up within 180 days from stroke. Four imaging patterns were tested as predictors of AF: i) acute stroke lesion involving multiple vascular territories (MVT, i.e. right or left carotid and/or posterior circulation), ii) MVT plus wedge-shaped cortical infarct or chronic stroke on FLAIR, iii) MVT involving 3 territories, and iv) MVT in 3 territories plus chronic FLAIR lesion. Adjustment variables were based on univariate logistic regression predictors of AF at P ≤0.1000.Results:Of the 101 cases in this analysis, the median age was 63 years and 49.5% male. Stroke in multiple vascular territories MVT was present in 22/101 (22%) at baseline. The total AF 6-month detection rate was 36/101 (36%). The imaging pattern most predictive of AF was pattern ii, MVT plus chronic FLAIR with an unadjusted odds ratio (OR) of 3.47, 95% CI of 0.3442-2.1731, P=.0073. The adjusted OR (age ≥ 55, history of stroke, and history of TIA,) was 3.26, 95% CI: 1.0358-11.1860,P=.0480.Conclusion:The presence of acute lesions in MVT and a chronic FLAIR lesion may be a biomarker of occult cardioembolic source that could be used early after the onset of stroke to determine optimal DOAC use for secondary prevention and potential risk reduction of stroke recurrence from suspected but unproven cardioembolic source.Funding:Lone Star Stroke Research Consortium

Stroke, Volume 55, Issue Suppl_1, Page ATP52-ATP52, February 1, 2024. Background:Delays in IV thrombolytic and thrombectomy treatments are associated with worse outcomes after ischemic stroke. The objective of our study was to compare door-to-CT imaging times among Code Stroke patients who presented by private vehicle and were evaluated by a physician in the emergency department (ED) either in the triage hallway or the emergency department room.Methods:We prospectively collected real-time data on Code Stroke patients presenting by private vehicle to a primary stroke center from May 1, 2022 through September 18, 2022. A Code Stroke was activated for all patients presenting to the emergency room with positive BE-FAST symptoms occurring within 24 hours from last known normal time. Patients were evaluated by a physician either in the triage hallway or an ED room prior to CT imaging. We compared baseline demographic data, NIHSS scores and door-to-CT times in patients evaluated by the physician in the ED triage hallway versus the ED room.Results:Of 55 patients who presented to the ED by private vehicle during the study period, the mean age was 54 ± 15 years, 53% were female and 45% non-white. The median NIHSS score was 1 [IQR 0-4]. There were 27 (49%) patients who underwent physician evaluation in the triage hallway and the remaining went into a patient room before going to CT. The median NIHSS scores for evaluations in the room were higher than in the triage hallway (2 vs 0, p=0.037). Overall, median time from door-to-CT was 11 minutes for patients who went directly from the triage hallway to CT and 21 minutes for patients who were roomed prior to CT (p=0.005).Conclusions:This study found that Code Stroke patients presenting by private vehicle and evaluated by an emergency physician in the triage hallway saved 10 minutes in door-to-CT time compared with physician evaluation in a room.

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 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 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