New England Journal of Medicine, Ahead of Print.
Risultati per: L'imaging nella urolitiasi
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Pilot study of paediatric regional lung function assessment via X-ray velocimetry (XV) imaging in children with normal lungs and in children with cystic fibrosis
Introduction
Cystic fibrosis (CF) is a life-limiting autosomal recessive genetic condition. It is caused by mutations in the gene that encodes for a chloride and bicarbonate conducting transmembrane channel. X-ray velocimetry (XV) is a novel form of X-ray imaging that can generate lung ventilation data through the breathing cycle. XV technology has been validated in multiple animal models, including the β-ENaC mouse model of CF lung disease. It has since been assessed in early-phase clinical trials in adult human subjects; however, there is a paucity of data in the paediatric cohort, including in CF. The aim of this pilot study was to investigate the feasibility of performing a single-centre cohort study in paediatric patients with CF and in those with normal lungs to demonstrate the appropriateness of proceeding with further studies of XV in these cohorts.
Methods and analysis
This is a cross-sectional, single-centre, pilot study. It will recruit children aged 3–18 years to have XV lung imaging performed, as well as paired pulmonary function testing. The study will aim to recruit 20 children without CF with normal lungs and 20 children with CF. The primary outcome will be the feasibility of recruiting children and performing XV testing. Secondary outcomes will include comparisons between XV and current assessments of pulmonary function and structure.
Ethics and dissemination
This project has ethical approval granted by The Women’s and Children’s Hospital Human Research Ethics Committee (HREC ID 2021/HRE00396). Findings will be disseminated through peer-reviewed publication and conferences.
Trial registration number
ACTRN12623000109606.
Abstract TP140: Effect of MR-Guided Perfusion Imaging Mismatch Profiles Within 6 Hours on Endovascular Thrombectomy Outcomes
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.
Abstract 128: Multi-Direction Diffusion Weighted Imaging on Portable, Low-Field Magnetic Resonance Imaging
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.
Abstract 38: Temporal Changes in Intracranial Arterial Diseases: A Longitudinal High-Resolution Vessel Wall Imaging Analysis
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.
Abstract WP118: Ischemic Core Volumes and Collateral Status Have Diurnal Fluctuations – A Retrospective Cohort Study of 18137 Patients Using Automated Perfusion Imaging
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
Abstract TP109: Quality Improvement Review and Practical Consideration of Hyperfine Portable Bedside Low-Field Magnetic Resonance Imaging in the Non-ICU Setting
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.
Abstract TMP9: Flair Vascular Hyperintensities as Imaging Biomarker in Pediatric Arterial Ischemic Stroke
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
Abstract TMP53: MR-ASL Imaging Can Predict the Collaterals in Moyamoya Disease
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
Abstract 125: Marked Variation in Perfusion Imaging Definitions of No-Reflow Phenomenon After Thrombectomy
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
Abstract TP131: Computed Tomography Perfusion Imaging Patterns Are Similar Before and After Interfacility Transfer of Ischemic Stroke Patients
Stroke, Volume 55, Issue Suppl_1, Page ATP131-ATP131, February 1, 2024. Background:Large vessel occlusion (LVO) stroke patients are often transferred from regional hospitals to comprehensive stroke centers (CSC) for thrombectomy. The need for repeat imaging at CSCs prior to intervention is unclear. We compared regional hospital and CSC perfusion imaging results for interfacility transfers in a single health system.Methods:We analyzed a cohort of patients in western Michigan who received CT perfusion imaging before and after transfer to a CSC. Perfusion mismatch (MM), core infarct volume (CIV), and favorability of imaging for mechanical thrombectomy (MT) candidacy were compared between the regional and CSC studies. A favorable imaging profile was defined as the presence of LVO, MM volume >10 mL, and MM/CIV ratio of >1.2. Linear regression was used to examine predictors of infarct growth during transfer.Results:Over a 10-month period, 25 patients met inclusion criteria. The median age was 76 (IQR 66-81), 60% were male, median NIHSS was 11 (IQR 2-18), and most patients had occlusion of the internal carotid or middle cerebral arteries (72%). The median time from last known well to initial CT was 250 minutes (IQR 85-620). Regional median MM volume was 52 mL (IQR 8-97), CIV was 0 mL (IQR 0-13), and hypoperfusion intensity ratio (HIR) was 0.25 (IQR 0-0.34). The median time between CTs was 152 minutes (IQR 139-226). The median change in MM volume was -3 mL (IQR -27-3) and median CIV growth rate was 0 mL/hr (IQR 0-2.0). In a multivariable regression model, higher HIR (β=23.2, p=0.012) and minutes between imaging studies (β=0.10, p=0.021) were associated with CIV growth. Sixteen patients (64%) had favorable imaging profiles for MT at the regional hospital. Of these, 15 (93.8%) continued to have a favorable CSC imaging profiles and 9 (56.2%) underwent MT. Of the 9 patients without favorable regional imaging profiles, 1 (11.1%) had a favorable CSC imaging profile and 2 (22.2%) underwent MT.Conclusion:In our sample, regional and CSC perfusion imaging patterns were similar and patients infrequently crossed thresholds for MT candidacy between studies. Initial HIR and longer delays between were independently associated with infarct growth during transfers, however overall infarct growth was very small.
Abstract 41: Conventional vs Advanced Imaging for the Selection of Stroke Therapy in the Extended Window (VESTA Study)
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
Abstract 28: Patients Randomised to Glenzocimab Suffered Less Haemorrhagic Transformation at 24 Hours Compared to Placebo: AI-Imaging Sub-Analysis of the ACTIMIS Trial
Stroke, Volume 55, Issue Suppl_1, Page A28-A28, February 1, 2024. Introduction:ACTIMIS (NCT03803007) was a randomized phase 1b/2a clinical trial evaluating glenzocimab, a monoclonal antibody fragment targeting platelet receptor glycoprotein VI in patients with acute ischemic stroke treated by thrombolysis. Primary analysis demonstrated a reduction in intracranial hemorrhage occurrence stroke-related mortality. In this sub-analysis, volumetric imaging biomarkers were used to assess efficacy of glenzocimab.Methods:In the phase 2a study, patients were randomized (1:1) with 1000mg glenzocimab or placebo. CT or MRI was acquired at baseline with CT at 24 hours and MRI at 7 days for safety and efficacy analysis. Baseline and follow up imaging were processed as post-hoc analysis using AI core lab software (Brainomix, Oxford, UK). Automated output was reviewed for accuracy by an expert clinician (DC) blinded to treatment allocation.Results and Conclusions:Follow up imaging data were available from 103/106 patients (51 glenzocimab, 52 placebo) at 24 hours. Of these, 54 underwent mechanical thrombectomy (MT, 27 glenzocimab, 27 placebo). Day-7 imaging was available for 9 fewer placebo patients and 1 glenzocimab patient. All except 2 patients (1 placebo, 1 glenzocimab) with missing data at Day-7 died during the study. Preliminary analysis showed smaller volume of hemorrhagic transformation (HT) in the glenzocimab group at 24 hours compared to placebo and a trend towards smaller volume of ischemic injury. Exploratory analysis also highlighted an interaction effect between risk of HT following MT and glenzocimab (lower risk in patients treated with glenzocimab). The full results of the imaging sub-analysis of the ACTIMIS study will be presented at the conference and discussed in the context of current literature.
Abstract WP323: Late-Stage Degeneration Due to Middle-Cerebral Artery Occlusion Observed in White Matter Tracts and Specific Forebrain Regions in Middle-Aged Female Rats is Attenuated by mir20a-3p Treatment: A Magnetic Resonance-Diffusion Tensor Imaging and Conventional Morphometry Study
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
Abstract TP186: The Presence of Low Signal on T2*-Weighted Gradient Echo Magnetic Resonance Imaging Before MT Should Be Not Associated With Hemorrhagic Complications
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.
Abstract 89: Portable, Low-Field Magnetic Resonance Imaging: Determining Mismatch Following Acute Ischemic Stroke
Stroke, Volume 55, Issue Suppl_1, Page A89-A89, February 1, 2024. Background and Aims:Treatment options for acute ischemic stroke (AIS) are uniquely dependent on the time of stroke onset. Intravenous thrombolysis must be administered within 4.5 hours of symptoms commencing, yet a subset of patients wake-up with symptoms and time of onset is unknown. Mismatch between fluid-attenuated inversion recovery (FLAIR) and diffusion-weighted imaging (DWI) MRI can be used to qualify wake-up strokes for thrombolysis. This has been shown to lead to improved functional outcomes in multicenter trials (WAKE-UP, MR-WITNESS). However, access to MRI is a barrier to differential diagnosis and subsequent treatment. Recent advances in portable, low-field MRI (LF-MRI) offer a solution to increase access to MRI technologies and circumvent the limitations of conventional systems. As such, in this pilot study, we sought to establish the utility of portable LF-MRI to identify DWI-FLAIR mismatch following AIS.Methods:Patients with a diagnosis of AIS presenting to Emergency Department or Intensive Care Unit of the Yale New Haven Hospital or Massachusetts General Hospital from January 2020 to June 2023 underwent DWI and FLAIR acquisition on a 0.064T MRI (Hyperfine Research Inc.) at