Risultati per: L'imaging nella urolitiasi

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 AWP219-AWP219, February 1, 2024. Background:Moyamoya Disease (MMD) is a steno-occlusive arteriopathy associated with transient ischemic attacks, stroke, and cognitive impairments. In adult MMD, normal-appearing deep gray and white matter structures (NADWM) show diffusion changes that are associated with cognitive impairments. Apparent diffusion coefficient [ADC] measures the mean diffusion and is sensitive to these changes. The association of ADC changes in NADWM in pediatric MMD is not clear. Our objective is to determine whether ADC is elevated in NADWM in pediatric MMD patients.Hypothesis:ADC values in NADWM will be elevated in MMD patients compared to controls.Methods:Twenty-nine MMD patients and no stroke and 7 healthy controls (HC) were included in a single center, retrospective study. Diffusion and T1-weighted images were analyzed. We constructed a script implementing a convolutional neural network (CNN) based approach to segment and binarize cortical regions of interest (ROI) and allow extraction of ADC values (units =[x10-6mm2/s]). Segmented ROIs included: 1) all white matter (WM), and NADWM including: 2) thalamus, 3) caudate, 4) putamen, 5) globus pallidus, 6) hippocampus. Mean ADC values were compared for: 1) all ROIs between MMD and controls, and 2) all ROIs in the MMD affected and the contralateral hemispheres within the MMD group.Results:Patients were on average 7.7+5.4 years at MMD diagnosis. In all WM, MMD patients had significantly higher ADC values than controls in the left (mean= 865.7+101.6 versus 762.4+21.6, p=0.01) and right hemispheres (mean= 869.9+104.9 versus 761.0+21.3, p=.01), respectively. In NADGM, there were no significant differences found between the MMD and control groups in any of the NADGM ROIs. In the NADGM of MMD patients, higher ADC values were found in the putamen (mean= 778.2+46.0, p=0.041), hippocampus (mean=1009.5+58.6, p=0.005) and all NAWM (mean= 860.3+57.0, p

Stroke, Volume 55, Issue Suppl_1, Page A128-A128, February 1, 2024. Background and aims:Portable, low-field (LF) MRI has the potential to improve access to expeditious, definitive brain imaging and facilitate diagnosis of acute stroke. Currently available diffusion-weighted imaging (DWI) protocols at LF are limited to a single diffusion direction due to acquisition duration. However, single-direction diffusion has reduced sensitivity for detecting acute ischemic infarcts, particularly small lesions residing in white matter tracts. The purpose of this study was to establish the feasibility of acquiring multi-direction DWI compared with single-direction counterparts on LF-MRI.Methods:Patients presenting with a diagnosis of acute ischemic stroke between July and September 2023 were eligible. Consented patients underwent DWI acquisition on a 0.064T LF-MRI (Mk1.9; Hyperfine Research Inc). Three diffusion directions (x, y, and z) were acquired with abweighting of 900 s/mm2and a single acquisition with ab0 s/mm2. Theb900 images were co-registered to theb0, trace and apparent diffusion coefficient (ADC) maps calculated, and the final images interpolated at 1 mm3.Results:Ten patients presenting to the Massachusetts General Hospital with acute ischemic stroke were consented and imaged within 72 hours of last known well. The total acquisition time was 14 minutes, with all subjects able to tolerate the scan duration. Ischemic lesions as small as 0.1 mL were detectable on the LF-MRI (17.5 +/- 18.2 mL). An example of each diffusion direction individually, the combined trace, and corresponding ADC maps are shown in Figure 1, compared with conventional high-field (HF) diffusion images acquired within 30 minutes of the LF acquisition.Conclusion:Multi-direction DWI imaging is feasible on a 0.064T LF-MRI scanner. Our experience suggests further modifications to the pulse sequence and scanner configuration may facilitate a reduction in acquisition time, improve resolution, or both.

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 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 ATP12-ATP12, February 1, 2024. Background:Increase in mean lesional iron content (≥6%) measurement by QSM and vascular permeability (≥ 40%) assessed by DCEQP MRI have been associated with new bleeding in cavernous angiomas (CA), and are used as monitoring biomarkers in clinical trial of pharmacotherapy in CAs with symptomatic hemorrhage (SH). Plasma metabolites have been associated with CA in unsupervised discovery, and linked mechanistically to the permissive microbiome and angiogenic and inflammatory mechanisms in CAs. To date, their levels change has not been compared to lesional QSM and DCEQP change during prospective monitoring.Methods:Fifty-nine paired plasma samples and MRI sequences were simultaneously acquired in 46 subjects at beginning and end of 1-year epochs in prospective follow-up of cases with CA enrolled in clinical trial after SH. Plasma levels of 14 metabolites previously associated with CA were assayed by liquid-chromatography mass spectrometry, and their changes were compared to changes in mean lesional QSM and DCEQP during the same epochs. Univariate correlations were followed by multivariate analyses combining multiple metabolites levels to minimize Akaike Information Criterion (AIC) or increase R2. Accuracy (AUC on receiver operating curves) and sum of squared error (SSE) are reported for associations achieving statistical significance with FDR correction.Results:Aceltyl.L.carnitine absolute change was correlated with QSM absolute change (p=0.01). Highest accuracy for lesional ΔθΣμ ινχρεασε ≥6% was reported for the absolute change of Arachidonic Acid + LPE.18.0 (AUC 99.7%; SD 0.003; p0.01). Relative change of Arachidonic Acid + Hypoxanthine + Piperine, and absolute change of LPE.18.0 + Pipecolic Acid + Piperine had the highest accuracy (AUC 99.1%; SD 0.008 and 98.0%; 0.013) for lesional DCEQP increase of ≥40%. Relative change in Phenylacetylglutamine and LPE.18.0+Piperine reported the lowest SSE (9.77; 438.33) with respective QSM and DCEQP relative changeConclusion:Changes in circulating metabolites accurately reflect changes in lesional iron content and permeability in CASH during yearly follow-up. Results are a proof of concept that blood tests could replace more complex and costly imaging biomarkers in monitoring CA hemorrhage.

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 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 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 A38-A38, February 1, 2024. Introduction:Temporal changes of intracranial arterial disease (ICAD) in patients with ischemic stroke in high-resolution vessel wall imaging (HR-VWI) have not been elucidated.Methods:We recruited consecutive ICAD-related ischemic stroke patients admitted between June 2016 and June 2019 and had subsequent HR-VWI follow-ups. On HR-VWI, we manually segmented the lumen area (LA), total vessel area (TVA), and enhancing area (EA) of the culprit lesion’s most stenotic part in the perpendicular section on T1-weighted, proton density, and post-contrast T1-weighted sequences. We defined the area stenosis as [1-LA/TVA]х100 (%) and the enhancing proportion as EA/TVAх100 (%). Enhancement ratio of the enhancing lesion was also quantified. Three raters independently quantified the imaging using ITK-SNAP with acceptable inter-rater reliability.Results:A total of 208 patients (age 57±14, male 58%) with 469 HR-VWIs (2-6 scans per patient) were included. The causes of ICAD were atherosclerosis (69%), dissection (24%), vasculitis (3%), moyamoya disease (1%), and other causes (2%). The median follow-up duration was 9.0 months (interquartile range: 3.9-13.2 months), and the maximum follow-up duration was 41.3 months. Among patients with atherosclerosis, area stenosis aggravated, stable, and improved in 7%, 77%, and 16%, respectively, with an overall rate of 0.23 ± 0.07% improvement per month. Among patients with dissection, area stenosis aggravated, stable, and improved in 2%, 49%, and 49%, respectively, with an overall rate of 2.11 ± 0.26% improvement per month (Figure,P-for-difference < 0.01). The temporal changes of the enhancing proportion and enhancement ratio were different between atherosclerosis and dissection (Figure,P< 0.01).Conclusions:ICAD lesions had dynamic changes over time; the temporal changes of atherosclerosis and dissection are distinct. Serial HR-VWI can offer insights for a more accurate diagnosis of the underlying pathologies of ICADs.

Stroke, Volume 55, Issue Suppl_1, Page ATMP53-ATMP53, February 1, 2024. Introduction:Digital subtraction angiography (DSA) is the gold standard investigation for the diagnosis and prognostication of moyamoya disease (MMD). Magnetic resonance arterial spin labelling (MR-ASL) is a newer non-invasive technique that can predict the perfusion reliably. Our study aims at prediction of collaterals with MR-ASL in addition to parenchymal perfusion deficit.Methodology:It is an observational single centre cohort study where consecutive MMD patients with both DSA and MR-ASL done within 3 months of each other were included in the study. Images were reviewed by 2 radiologists independently. MMD severity was graded using Suzuki staging and collaterals were graded using DSA and MR-ASL in 7 different regions [4 areas in basal ganglia level – basal ganglia, M1, A1 and P1], 3 areas at superficial cortical level above basal ganglia [M2, A2, P2]. DSA collateral grading used was: grade 0 – no collaterals visible (absence of any capillary blush) with perfusion deficit, grade 1 – mild to moderate collaterals with some perfusion deficit, grade 2 – extensive collaterals with no perfusion deficit, grade 3 – normal antegrade flow. Collateral grading used on MR-ASL was: grade 0 – no or minimal ASL signal; grade 1 – moderate ASL signal with arterial transit artefact (ATA), grade 2 – high ASL signal with ATA, grade 3 – normal perfusion without ATA.Results:Of the 46 MMD patients (males – 22), 92 hemispheres were included. 4 hemispheres were excluded as the patient underwent revascularisation in the corresponding hemisphere. Among the remaining 88 hemispheres, 7 were normal on angiography. At various Suzuki grades, the degree of collaterals graded on ASL changed according to Suzuki staging (p

Stroke, Volume 55, Issue Suppl_1, Page ATP147-ATP147, February 1, 2024. Background:White matter disease is a common phenomenon in patients with sickle cell disease, that has been linked to cognitive impairment. However, there is no standardized approach for quantification of the cerebral disease burden. The Fazekas score is widely used to quantify the burden of white matter disease in chronic small vessel disease. However, its utility in sickle cell disease has not yet been established. We aimed to assess its, interrater reliability in this patient population.Methods:A patient cohort was compiled for the purpose of a research ethics board (REB) approved retrospective study of consecutive adult patients with sickle cell disease, each of whom underwent MRI/MRA between the year 2017 and 2019. All MRI/MRA studies were performed on 3-Tesla MRI. Two neuroradiologists independently assessed the axial FLAIR MRI brain sequence, for all patients, with the sole focus of assigning a Fazekas score (0-3) to each study, as a means of quantifying the burden of ischemic white matter lesions. The neuroradiologists were blinded to the scoring assigned by their counterpart and to the clinical information. Cohen’s weighted Kappa was used as a measure of agreement between readers.Results:Ninety patients with a median age of 31 and 45/90 (50%) women were included. The expected agreement was 74.65%, with an observed agreement of 94.44% between readers, with a weighted Kappa of 0.7808.Conclusion:On the basis of this study, there is good inter-rater reliability of Fazekas scoring on axial FLAIR MRI brain sequence in patients with sickle cell disease, even though the underlying pathophysiology of white matter lesions in this patient population might vary compared to individuals with chronic small vessel disease. The Fazekas is a promising measure that could easily be integrated in systematic evaluation of cerebrovascular lesions of adults with sickle cell disease.

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 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 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.