Diffusion-weighted Magnetic Resonance Imaging Lesions Research Articles

Multi-modality multi-task model for mRS prediction using diffusion-weighted resonance imaging

This study focuses on predicting the prognosis of acute ischemic stroke patients with focal neurologic symptoms using a combination of diffusion-weighted magnetic resonance imaging (DWI) and clinical information. The primary outcome is a poor functional outcome defined by a modified Rankin Scale (mRS) score of 3–6 after 3 months of stroke. Employing nnUnet for DWI lesion segmentation, the study utilizes both multi-task and multi-modality methodologies, integrating DWI and clinical data for prognosis prediction. Integrating the two modalities was shown to improve performance by 0.04 compared to using DWI only. The model achieves notable performance metrics, with a dice score of 0.7375 for lesion segmentation and an area under the curve of 0.8080 for mRS prediction. These results surpass existing scoring systems, showing a 0.16 improvement over the Totaled Health Risks in Vascular Events score. The study further employs grad-class activation maps to identify critical brain regions influencing mRS scores. Analysis of the feature map reveals the efficacy of the multi-tasking nnUnet in predicting poor outcomes, providing insights into the interplay between DWI and clinical data. In conclusion, the integrated approach demonstrates significant advancements in prognosis prediction for cerebral infarction patients, offering a superior alternative to current scoring systems.

Abstract TMP36: Anatomical Predictors of Gastrostomy Tube Placement After Large Vessel Occlusion Ischemic Stroke

Dysphagia is a common neurologic deficit after ischemic stroke; as a result, patients often require percutaneous endoscopic gastrostomy (PEG) tube placement for safe maintenance of sufficient caloric intake. Right hemispheric strokes have previously been associated with post-stroke dysphagia. We examined whether topographic locations of post-stroke diffusion-weighted MRI (DWI) lesions associated with the need for placement of PEG tube. A registry of 898 patients evaluated for acute treatment of suspected large vessel occlusion (LVO) stroke was used. 65 patients underwent post-stroke PEG placement, and 65 additional patients were selected as propensity matches based on age, baseline NIH Stroke Scale score, and recanalization status. Binary masks of 24-to-72-hour post-stroke DWI lesions were co-registered to standard template space. Voxel-based lesion symptom mapping (V2.6), rewritten to perform logistic regression at each voxel, was used to generate statistical maps of lesion contribution to PEG placement. Uncorrected t-statistic maps demonstrated voxels in the right frontal, parietal, and temporal regions were associated with post-stroke PEG placement. Upon controlling for age and/or recanalization status, lesions in the right parietal lobe were associated with need for PEG. After controlling for lesion volume, this association weakened; once all variables were controlled for, there were no topographical regions associated with PEG placement. In this limited series, there is not a topographic region on post-stroke diffusion MRI that is significantly associated with need for PEG placement in patients with LVO stroke after controlling for appropriate covariates. PEG tube requirement may be a composite outcome, dependent on various inputs notably including lesion volume.

Quantification of new intracerebral lesions on diffusion-weighted magnetic resonance imaging after transcarotid artery revascularization for treatment of carotid artery stenosis

Transcarotid artery revascularization (TCAR) has been used with increasing prevalence for treatment of carotid artery stenosis. TCAR holds potential benefits over traditional carotid endarterectomy (CEA) or transfemoral carotid artery stenting by its nature of being less invasive than CEA but more neuroprotective than transfemoral carotid artery stenting. The purpose of this pilot study is to evaluate the effectiveness of the neuroprotection system of TCAR with flow reversal by quantifying the incidence and degree of new intracerebral lesions using diffusion-weighted magnetic resonance imaging (DW-MRI). This study is the first to evaluate these findings in a real-world, high-risk cohort, who would have been excluded from the ROADSTER and ENROUTE transcarotid neuroprotection system DW-MRI studies. Patients undergoing unilateral TCAR for symptomatic or asymptomatic severe internal carotid artery disease were eligible and prospectively enrolled in the study. All patients had high risk features, including comorbidities or medications, which excluded them from industry-sponsored DW-MRI trials. Patients underwent a preoperative DW-MRI to obtain a baseline intracerebral evaluation within 1 week of the scheduled surgery. The follow-up DW-MRI occurred within 48hours postoperatively. The primary outcome was new, acute postoperative lesion(s) identified on DW-MRI. Secondary outcomes include any major stroke, myocardial infarction, or death during hospitalization. Five consecutive patients underwent TCAR with preoperative and postoperative imaging. All five patients were on dual antiplatelet therapy before their procedure and verified to be therapeutic on these agents. All patients underwent a right-sided TCAR and three were symptomatic as the indication for their procedure. All five patients demonstrated chronic lesions on the preoperative DW-MRI. Technical success was achieved in all five patients, with one operative complication involving a dissection of the common carotid at the access site, which was stented using the TCAR system. Postoperative DW-MRI did not identify any new intracerebral lesions in any patient following the procedure. No patient had a stroke, myocardial infarction, or death during hospitalization. In this real-world, high-risk cohort, TCAR was completed with no evidence of new, postoperative DW-MRI lesions. These data further demonstrate that TCAR with flow reversal is an effective neuroprotective strategy for carotid revascularization. Further study is warranted to evaluate DW-MRI differences between TCAR and CEA.

Plaque morphology effect on periprocedural asymptomatic cerebral embolism in carotid artery stenting using first-generation carotid stents: A diffusion-weighted magnetic resonance imaging study.

Silent cerebral embolism with carotid artery stenting (CAS) may contribute to dementia and cognitive decline. Moreover, clinically silent embolism is an important index of peri-procedural stroke risk. The purpose of this study was to compare the periprocedural asymptomatic cerebral embolism rates of CAS procedures performed for noncalcified and calcified carotid artery plaques using diffusion-weighted magnetic resonance imaging (DW-MRI). Five hundred and seventy clinically uncomplicated patients who underwent CAS at our center from December 2010 to June 2020 (mean [standard deviation, SD] age 69.3 [8.2 years]) were analyzed retrospectively. The patients were divided into 2 groups with noncalcified (268 patients) and calcified (302 patients) plague. Cerebral DW-MRI was performed for the patients before and after CAS and compared. The presence of periprocedural new ipsilateral diffusion limitations detected on cerebral DW-MRI was noted as a significant finding. Ipsilateral diffusion limitations of the non-calcified and calcified plaque groups detected on cerebral DW-MRI were compared. The presence of periprocedural asymptomatic ipsilateral DW-MRI lesions was higher in patients in the noncalcified plaque group (45 [16.8%]) than in patients in the calcified plaque group (31 [10.3%]; P = 0.02). This study demonstrated that the rate of ipsilateral asymptomatic cerebral embolism detected on cerebral DW-MRI was higher in the CAS procedures performed for noncalcified carotid artery plaques than in those performed for calcified plaques.

Association of Iatrogenic Infarcts With Clinical and Cognitive Outcomes in the Evaluating Neuroprotection in Aneurysm Coiling Therapy Trial.

Small iatrogenic brain infarcts are often seen on diffusion-weighted MRI (DWI) following surgical or endovascular procedures, but there are few data on their clinical effects. We examined the association of iatrogenic infarcts with outcomes in the ENACT (Evaluating Neuroprotection in Aneurysm Coiling Therapy) randomized controlled trial of nerinetide in patients undergoing endovascular repair of intracranial aneurysms. In this post hoc analysis, we used multivariable models to evaluate the association of the presence and number of iatrogenic infarcts on DWI with neurologic impairment (NIH Stroke Scale [NIHSS]), functional status (modified Rankin Scale [mRS]), and cognitive and neuropsychiatric outcomes (30-minute test battery) at 1-4 days and 30 days postprocedure. We also related infarct number to a z score-derived composite outcome score using quantile regression. Among 184 patients (median age 56 years [interquartile range (IQR) 50-64]), 124 (67.4%) had postprocedural DWI lesions (median 4, IQR 2-10.5). Nerinetide treatment was associated with fewer iatrogenic infarcts but no overall significant clinical treatment effects. Patients with infarcts had lower Mini-Mental State Examination (MMSE) scores at 2-4 days (median 28 vs 29, adjusted coefficient [acoef] -1.11, 95% CI -1.88 to -0.34, p = 0.005). Higher lesion counts were associated with worse day 1 NIHSS (adjusted odds ratio for NIHSS ≥1: 1.07, 1.02-1.12, p = 0.009), day 2-4 mRS (adjusted common odds ratio [acOR] 1.05, 1.01-1.09, p = 0.005), and day 2-4 MMSE (acoef -0.07, -0.13 to -0.003, p = 0.040) scores. At 30 days, infarct number remained associated with worse mRS (acOR 1.04, 1.01-1.07, p = 0.016) and Hopkins Verbal Learning Test (HVLT) delayed recall scores (acoef -0.21, -0.39 to -0.03, p = 0.020). Patients with infarcts trended towards lower 30-day Digit Symbol Substitution Test (DSST) scores (acoef -3.73, -7.36 to -0.10, p = 0.044). Higher lesion count was associated with worse composite outcome scores at both 1-4 days and 30 days (30-day acoef -0.12, 95% CI -0.21 to -0.03, p = 0.008). Among those with infarcts, day 1 NIHSS and day 2-4 mRS correlated with 30-day NIHSS, DSST, HVLT, and mRS scores, whereas day 2-4 MMSE correlated with 30-day NIHSS and DSST scores (Spearman ρ 0.47, p = 0.001). Iatrogenic brain infarcts were associated with subtle differences in postprocedural (1-4 days) and 30-day outcomes on different measures in this middle-aged cohort, with earlier dysfunction correlating with later differences. Clinical trials registration NCT00728182.

Hippocampal subfield involvement in patients with transient global amnesia.

Transient global amnesia (TGA) is a rare neurological disorder causing a transient disturbance of episodic long-term memory. Its etiology remains yet to be identified; the only consistently reported findings in patients with TGA are small hyperintense lesions in the hippocampus on diffusion-weighted magnetic resonance imaging (DWI). The aim of this study was to define whether these lesions are subfield specific, as suggested previously. High-resolution multiplanar reformation T1 and DWI of the hippocampus were acquired in 25 patients after TGA with a total of 43 hippocampal lesions. Hippocampal subfields were determined using the FreeSurfer software and the location of the DWI lesions was transformed to the T1 images after data co-registration. Additionally, hippocampal subfield volumes in each patient were calculated and compared with that of 20 healthy controls. Hippocampal lesions were most frequently detected in the cornu ammonis area 1 (CA1) subfield (30.2%), the hippocampal tail (28.0%), and the subiculum (21.0%); however, lesions were also found in other subfields. There was no significant difference between patients and controls concerning the volumes of the hippocampal subfields. Contrasting previous assumptions, we found DWI hyperintense lesions not to be restricted to the CA1 subfield. The visualization of focal hippocampal lesions on diffusion imaging located to several different hippocampal subfields suggests a potential pathophysiology of TGA independent of microstructural hippocampal anatomy and subfield-specific vulnerability.

Randomized Controlled Trial of Conventional Versus MicroNet-Covered Stent in Carotid Artery Revascularization.

The aim of this study was to compare procedure-related ipsilateral cerebral embolism with a conventional (Acculink, Abbott Vascular) versus a MicroNet-covered (CGuard, InspireMD) stent in carotid artery stenting (CAS). The MicroNet-covered stent may reduce periprocedural cerebral embolism in CAS, but level 1 evidence is lacking. A total of 100 consecutive patients were randomized 1:1 to filter-protected CAS using the Acculink or the CGuard device. The study was powered for its primary endpoint of at least 50% reduction in ipsilateral diffusion-weighted magnetic resonance imaging lesion average volume 48 hours postprocedure (blinded external core laboratory analysis). The baseline characteristics of the study groups were similar. Eighty-two (total volume = 18,212mm3) diffusion-weighted magnetic resonance imaging postprocedural cerebral lesions occurred in 26 Acculink-treated patients and 45 lesions (total volume = 3,930mm3; 78.4% reduction) in 25 CGuard-treated patients. New cerebral lesion average volume was 171 mm3 vs 73mm3 (P=0.017) per affected patient and 222 mm3 vs 84mm3 (P=0.038) per lesion (Acculink vs CGuard). In lesion-affected patients, the average sum of lesion volumes was 701 mm3 vs 157mm3 (P=0.007). The Acculink significantly increased the risk for multiple (≥5) cerebral lesions (relative risk: 7.8; 95% CI:1.3-14.9; P=0.021). At 30days, new permanent (fluid-attenuated inversion recovery) lesion prevalence was 3:1 (P<0.001), with total permanent lesion volume 7,474 mm3 vs 574mm3 (92.3% reduction with the CGuard). There were 6 vs 0 new ipsilateral lesions (P=0.030) and 2 versus 0 strokes. The MicroNet-covered stent significantly reduced periprocedural and abolished postprocedural cerebral embolism in relation to a conventional carotid stent. This is consistent with the MicroNet-covered stent's sustained embolism prevention, translating into cerebral protection not only during but also after CAS. The present findings may influence decision making in carotid revascularization. (The SIBERIA Trial [Acculink™ Versus CGuard™]; NCT03488199).

Sensitivity of diffusion-weighted magnetic resonance imaging in transient global amnesia as a function of time from symptom onset.

The objective was to systematically evaluate the sensitivity of diffusion-weighted magnetic resonance imaging (DW-MRI) for transient global amnesia (TGA) across various time frames compared to the reference-standard clinical criteria. All indexed publications related to TGA and MRI through June 2020 were retrieved by a medical librarian. Two independent reviewers identified original research studies of adults with a clinical diagnosis of TGA using Caplan and Hodges and Warlow criteria (reference standard) who were evaluated with DW-MRI. Pooled estimates and its 95% confidence intervals (CI) for the proportion of acute TGA patients with positive DW-MRI (i.e., sensitivity) were obtained using random-effects meta-analysis for various time frames. Quality assessment was performed using the revised Quality of Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool. After screening 665 reports, we identified 81 potentially relevant studies. Twenty-three studies representing 1688 patients met eligibility criteria, but not all studies had data available for meta-analysis. The pooled sensitivity (also described as positivity rate) of DW-MRI was 15.6% (95% CI=2.6%-35.0%) between 0 and 12h from symptom onset, 23.1% (95% CI=6.1%-45.7%) at 0-24h, 72.8% (95% CI=40.8%-96.3) at 12-24h, 68.8% (95% CI=44.8%-88.8%) at 24-36h, 72.4% (95% CI=59.8%-83.5%) at 36-48h, 82.8% (95% CI=54.7%-99.6%) at 48-60h, 66.9% (95% CI=47.5%-83.9%) at 60-72h, and 72.0% (95% CI=30.1%-100.0%) at 72-96h. There was significant concern for risk of bias in the QUADAS-2 domains of patient selection and index test, yielding a low level of certainty in the pooled estimates. DW-MRI lesions are uncommon in patients with TGA early after symptom onset, but the sensitivity (i.e., positivity rate) of DW-MRI increases with time. Despite the limited quality of existing evidence, obtaining an early DW-MRI in patients with clinical diagnosis of TGA in the acute setting is likely a low-yield test.

The Utility of Diffusion-Weighted MRI Lesions to Compare the Effects of Different Heparinization Schemes in Intracranial Aneurysms Treated by Endovascular Intervention.

Objective: Heparinization is applied to prevent ischemic complications in the endovascular treatment of intracranial aneurysms, but there is no unified heparinization scheme. Diffusion-weighted imaging (DWI) can be used to evaluate ischemia after endovascular therapy for intracranial aneurysms. The goal of this study is to apply DWI to evaluate the effects of different heparinization schemes on intracranial aneurysms treated with endovascular therapy.Methods: We retrospectively reviewed 141 patients with 149 aneurysms treated with endovascular interventions from July 2019 to April 2020 at our center, including 96 aneurysms treated with local heparinization and 53 aneurysms treated with systemic heparinization. We collected the basic information of the patients, including age, sex, comorbidities, and aneurysm characteristics, and associated treatment data. New ischemic lesions detected by DWI were categorized belonging to four types. Multivariate logistic regression was used to compare the effects of different heparinization schemes on intracranial aneurysms treated with endovascular therapy.Results: There were no significant differences in age, sex, hypertension, diabetes, and aneurysm size or location between the two groups. The incidence and distribution types of DWI abnormalities in the local heparinization groups and systemic heparinization groups were not significantly different (P > 0.05). There was a correlation between the laser engraving stent and postoperative DWI abnormalities (P < 0.003). Multivariate logistic regression analysis showed that the laser engraving stent was significantly correlated with postoperative DWI abnormalities (odds ratio, 4.71; 95% CI: 1.51–14.58; P = 0.007).Conclusion: Compared with systemic heparinization, local heparinization does not increase the incidence of DWI abnormalities after endovascular treatment, and its application in this group of patients is safe and effective.

Diffusion MRI Reversibility in Ischemic Stroke Following Thrombolysis: A Meta-Analysis.

Diffusion-weighted magnetic resonance imaging (DWI) detects early infarction in acute stroke. With the substantial progress in stroke therapies, the frequency of posttreatment DWI reversibility in modern stroke cohorts is currently unknown. The purpose of this study was to perform a systematic literature review examining the relationship between characteristics of patients with ischemic stroke and DWI reversibility following treatment with lytic therapy. A systematic review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, yielding a total of 422 unique articles. Studies that were nonclinical or did not report data pertaining to DWI reversibility in the context of an acute stroke series were excluded. Characteristics regarding presentation, diagnosis, intervention, and the timing of DWI reversibility were collected for each study. After full-text review, 10 studies were identified as meeting inclusion criteria. The number of patients with DWI reversal ranged from .9% to 50%, whereas the extent of reversal ranged from 1.8% to 72.7%. Studies reporting on younger patients describe greater rates of reversibility following stroke treatment. These data suggest that early DWI signal may not represent the definitive DWI burden in recanalized populations. However, substantial heterogeneity exists regarding the rate of DWI reversal following recanalization. Additional studies are needed to elucidate the relationship among time to treatment, early reversal rates, and clinical outcomes. Physicians should use caution when basing clinical decisions on DWI lesion volumes, as these likely change to some degree with recanalization.

The usefulness of Time-of-Flight MR angiography in detection of intraplaque hemorrhage in patients with acute ischemic stroke with symptomatic carotid stenosis.

ObjectiveCarotid intraplaque hemorrhage (IPH) is a well-known risk indicator of thromboembolism, but it is not easy to rapidly detect IPH in acute symptomatic carotid disease. The aim of this study was to assess the utility of time-of-flight (TOF) magnetic resonance angiography (MRA) in the detection of IPH and evaluate the degree of stenosis and stroke patterns in patients with acute symptomatic carotid disease.MethodsWe retrospectively identified consecutive patients with acute symptomatic carotid disease who were admitted within 12 h after stroke onset. Fifty-nine patients underwent TOF MRA at admission and were categorized according to the presence or absence of intraplaque high signal intensity (HSI). The severity of carotid stenosis and diffusion-weighted magnetic resonance imaging lesion patterns were evaluated.ResultsIntraplaque HSI was detected in 28.8% of the enrolled patients (17/59). Mild-to-moderate symptomatic carotid stenosis was more frequent in the intraplaque HSI-positive group (70.6%) than in the intraplaque HSI-negative group (42.8%) (p = 0.015). The patients with intraplaque HSI more frequently exhibited a disseminated small infarction pattern (76.5% in the intraplaque HSI-positive group, 47.6% in the -negative group), and did not exhibit a border-zone infarction pattern (0% in the positive group, 16.7% in the negative group).ConclusionsTOF MRA may be a useful noninvasive and rapid tool to detect IPH in patients with acute symptomatic carotid disease. IPH was common in those with a lower degree of carotid stenosis and manifested as a disseminated small infarction pattern. Intraplaque HSI on TOF MRA in acute symptomatic carotid disease may help to determine the mechanism of stroke and establish early treatment plans.

Texture analysis of diffusion-weighted magnetic resonance imaging to identify atypically enhanced small hepatocellular carcinoma and dysplastic nodules under the background of cirrhosis

Objective: To investigate the value of texture analysis based on diffusion-weighted magnetic resonance imaging (DWI) in the differential diagnosis of atypically enhanced small hepatocellular carcinoma (sHCC) and dysplastic nodules (DNs) in liver cirrhosis. Methods: Data of 59 cases with atypical enhancement and solitary cirrhotic nodule (≤2 cm) confirmed by dynamic contrast enhanced MRI and surgical pathology specimen were analyzed retrospectively. Among them, 37 cases were of atypically enhanced sHCC and 22 cases of DNS. The DWI signal characteristics of the lesions were analyzed to measure the average apparent diffusion coefficient (ADC) value of the lesions, and the ADC ratio of the lesion to the liver parenchyma. MaZda software was used to manually draw the region of interest to extract the texture parameters of DWI lesions. The three sets (combination of Fisher coefficient, classification of error probability combined with average correlation coefficient and interactive information) were used to select the thirty optimal texture parameters. Raw data analysis (RDA), principal component analysis (PCA), linear discriminant analysis (LDA) and non-linear discriminant analysis (NDA) were performed for texture classification. The difference of ADC value and ADC ratio between sHCC and DNS group was compared by independent sample t-test, and χ2 test was used to compare the count data (or rate). ROC curve analysis was used to evaluate the diagnostic efficiency. Results: The sensitivity, specificity and accuracy of DWI high-signal in the identification of atypically enhanced sHCC and DNs were 94.6% (35/37), 68.2% (15/22), and 84.7% (50/59), respectively. The ADC ratio of atypically enhanced sHCC was significantly lower than DNs, and the difference was statistically significant (t = 2.99, P = 0.002). The sensitivity, specificity, and accuracy for the diagnosis of atypically enhanced sHCC were 73.0% (27/37), 72.7% (16/22) and 72.9% (43/59), respectively. The sensitivity, specificity and accuracy of DWI texture analysis in diagnosing atypically enhanced sHCC were 94.6% (35/37), 95.5% (21/22) and 94.9% (56/59).The diagnostic efficiency of DWI texture analysis (AUC = 0.94) was significantly higher than DWI high-signal (AUC = 0.81) and ADC ratio (AUC = 0.72). Conclusion: The texture analysis based on DWI can identify atypically enhanced sHCC and dysplastic nodules under the background of cirrhosis, and its efficacy is better than qualitative and quantitative DWI.

Temporal evolution and spatial distribution of quantitative T2 MRI following acute ischemia reperfusion injury.

Determining mechanisms of secondary stroke injury related to cerebral blood flow and the severity of microvascular injury contributing to edema and blood-brain barrier breakdown will be critical for the development of adjuvant therapies for revascularization treatment. To characterize the heterogeneity of the ischemic lesion using quantitative T2 imaging along with diffusion-weighted magnetic resonance imaging (DWI) within five hours of treatment. Quantitative T2 magnetic resonance imaging was acquired within 5 h (baseline) and at 24 h (follow-up) of stroke treatment in 29 patients. Dynamic contrast enhanced permeability imaging was performed at baseline in a subgroup of patients. Absolute volume change and lesion percent change was determined for the quantitative T2, DWI, and absolute volume change sequences. A Gaussian process with RRELIEFF feature selection algorithm was used for prediction of relative quantitative T2 and DWI lesion growth, baseline and follow-up quantitative T2/DWI lesion ratios, and also NIHSS at 24 h and change in NIHSS from admission to 24 h. In n = 27 patients, median (interquartile range) lesion percent change was 114.8% (48.9%, 259.1%) for quantitative T2, 48.2% (-12.6%, 179.6%) for absolute volume change, and 62.7% (26.3%, 230.9%) for DWI, respectively. Our model, consisting of baseline NIHSS, CT ASPECTS, and systolic blood pressure, showed a strong correlation with quantitative T2 percent change (cross correlation R2 = 0.80). There was a strong predictive ability for quantitative T2/DWI lesion ratio at 24 h using baseline NIHSS and last seen normal to 24 h magnetic resonance imaging time (cross correlation R2 = 0.93). Baseline dynamic contrast enhanced permeability was moderately correlated to the baseline quantitative T2 values (rho = 0.38). Quantitative T2 imaging provides critical information for development of therapeutic approaches that could ameliorate microvascular damage during ischemia reperfusion.

Supratentorial Cerebral Arterial Territories for Computed Tomograms: A Mapping Study in 1160 Large Artery Infarcts

We recently generated a high-resolution supratentorial vascular topographic atlas using diffusion-weighed MRI in a population of large artery infarcts. These MRI-based topographic maps are not easily applicable to CT scans, because the standard-reference-lines for axial image orientation (i.e., anterior-posterior commissure line versus orbito-meatal line, respectively) are ‘not parallel’ to each other. Moreover, current, widely-used CT-based vascular topographic diagrams omit demarcation of the inter-territorial border-zones. Thus, we aimed to generate a CT-specific high-resolution atlas, showing the supratentorial cerebrovascular territories and the inter-territorial border-zones in a statistically rigorous way. The diffusion-weighted MRI lesion atlas is based on 1160 patients (67.0 ± 13.3 years old, 53.7% men) with acute (<1-week) cerebral infarction due to significant (>50%) stenosis or occlusion of a single large cerebral artery: anterior, middle, or posterior cerebral artery. We developed a software package enabling the transformation of our MR-based atlas into a re-oriented CT space corresponding to the axial slice orientations used in clinical practice. Infarct volumes are individually mapped to the three vascular territories on the CT template-set, generating brain maps showing the voxelwise frequency of infarct by the affected parent vessel. We then mapped the three vascular territories collectively, generating a dataset of Certainty-Index (CI) maps to reflect the likelihood of a voxel being a member of a specific vascular territory. Border-zones could be defined by using either relative infarct frequencies or CI differences. The topographic vascular territory atlas, revised for CT, will allow for easier and more accurate delineation of arterial territories and borders on CT images.

Big Data Approaches to Phenotyping Acute Ischemic Stroke Using Automated Lesion Segmentation of Multi-Center Magnetic Resonance Imaging Data.

Background and Purpose- We evaluated deep learning algorithms' segmentation of acute ischemic lesions on heterogeneous multi-center clinical diffusion-weighted magnetic resonance imaging (MRI) data sets and explored the potential role of this tool for phenotyping acute ischemic stroke. Methods- Ischemic stroke data sets from the MRI-GENIE (MRI-Genetics Interface Exploration) repository consisting of 12 international genetic research centers were retrospectively analyzed using an automated deep learning segmentation algorithm consisting of an ensemble of 3-dimensional convolutional neural networks. Three ensembles were trained using data from the following: (1) 267 patients from an independent single-center cohort, (2) 267 patients from MRI-GENIE, and (3) mixture of (1) and (2). The algorithms' performances were compared against manual outlines from a separate 383 patient subset from MRI-GENIE. Univariable and multivariable logistic regression with respect to demographics, stroke subtypes, and vascular risk factors were performed to identify phenotypes associated with large acute diffusion-weighted MRI volumes and greater stroke severity in 2770 MRI-GENIE patients. Stroke topography was investigated. Results- The ensemble consisting of a mixture of MRI-GENIE and single-center convolutional neural networks performed best. Subset analysis comparing automated and manual lesion volumes in 383 patients found excellent correlation (ρ=0.92; P<0.0001). Median (interquartile range) diffusion-weighted MRI lesion volumes from 2770 patients were 3.7 cm3 (0.9-16.6 cm3). Patients with small artery occlusion stroke subtype had smaller lesion volumes ( P<0.0001) and different topography compared with other stroke subtypes. Conclusions- Automated accurate clinical diffusion-weighted MRI lesion segmentation using deep learning algorithms trained with multi-center and diverse data is feasible. Both lesion volume and topography can provide insight into stroke subtypes with sufficient sample size from big heterogeneous multi-center clinical imaging phenotype data sets.

The Relationship between Diffusion-Weighted Magnetic Resonance Imaging Lesions and 24-Hour Rhythm Holter Findings in Patients with Cryptogenic Stroke.

Background and objectives: Cranial magnetic resonance imaging findings of patients considered to be cryptogenic stroke may be useful in determining the clinical and prognostic significance of arrhythmias, such as atrial premature beats and atrial run attacks, that are frequently encountered in rhythm Holter analysis. This study was conducted to investigate the relationship between short atrial runs and frequent premature atrial contractions detected in Holter monitors and infarct distributions in cranial magnetic resonance imaging of patients diagnosed with cryptogenic stroke. Materials and Methods: We enrolled the patients with acute ischemic stroke whose etiology were undetermined. We divided the patients in two groups according to diffusion-weighted magnetic resonance imaging as single or multiple vascular territory acute infarcts. The demographic, clinical, laboratory, echocardiographic, and rhythm Holter analyses were compared. Results: The study investigated 106 patients diagnosed with cryptogenic stroke. Acute cerebral infarctions were detected in 31% of the investigated patients in multiple territories and in 69% in a single territory. In multivariate logistic regression analysis, the total premature atrial contraction count (OR = 1.002, 95% CI: 1.001–1.004, p = 0.001) and short atrial run count (OR = 1.086, 95% CI: 1.021–1.155, p = 0.008) were found as independent variables that could distinguish between infarctions in a single or in multiple vascular territories. Conclusions: Rhythm Holter monitoring of patients with infarcts detected in multiple vascular territories showed significantly higher premature atrial contractions and short atrial run attacks. More effort should be devoted to the identification of cardioembolic etiology in cryptogenic stroke patients with concurrent acute infarcts in the multiple vascular territories of the brain.

Association between high sensitivity C-reactive protein (hs-CRP) levels and the risk of major adverse cardiovascular events (MACE) and/or microembolic signals after carotid angioplasty and stenting.

Background:To evaluate the association between pre/post-procedural high sensitive C-reactive protein (hs-CRP) level and hs-CRP difference, and the risk of major adverse cardiovascular events (MACE) or new diffusion-weighted MRI lesions after carotid angioplasty and stenting (CAS).Methods:In this study, conducted in 2016 in Shiraz (Iran), patients who underwent diagnostic angiography and CAS were recruited. CAS was performed with distal embolic protection device on patients with both standard and high risk of endarterectomy. Pre/post-procedural hs-CRP, and hs-CRP difference were determined by immunoenzymometric assay method.Results:A total of 50 patients with diagnostic angiography and 60 patients with CAS were enrolled. No death, myocardial infarction, ischemic or hemorrhagic stroke, and need to revascularization occurred during the 30-days of the post-procedural period. Accordingly, the statistical evaluation in associating MACE and hs-CRP levels was impossible. Angioplasty was associated with higher frequency of elevated post-procedural hs-CRP in comparison to angiography (P=0.003). The higher age, symptomatic lesions, negative history of hypertension, and hs-CRP difference had significant association with the presence of new DWI lesions in univariate analysis (all P<0.05). Angioplasty of left carotid bulb and post-procedural hs-CRP levels was very close to the level of significance (P=0.06). But only left sided lesions had positive association (P=0.037) and hypertension had negative association (P=0.037) in multivariate regression analysis. There were significant association between post-procedural hs-CRP level (P=0.02) and hs-CRP difference (P=0.003), and the number of new lesions; and the hs-CRP difference and the accumulated lesion surface area (P=0.009).Conclusion:Post-procedural hs-CRP and hs-CRP difference may predict embolic complications of CAS.

Peri-procedural brain lesions prevention in CAS (3PCAS): Randomized trial comparing CGuard™ stent vs. Wallstent™

BackgroundAim of this study was to evaluate peri-procedural incidence of new diffusion-weighted-magnetic-resonance-imaging (DWMRI) brain lesions in CAS patients treated by carotid mesh stent (CGuard™) or closed-cell stent (Wallstent™). MethodsConsecutive patients with asymptomatic carotid stenosis ≥ 70% were submitted to preoperative DW-MRI scan, to exclude the presence of preoperative silent cerebral lesions. Patients were randomized to CGuard or Wallstent. DWMRI was performed immediately after the intervention and at 72-hour postoperatively. Moreover, pre and postoperative Mini-Mental-State-Examination Test (MMSE) and a Montreal-Cognitive-Assessment (MoCA) test were conducted, and S100β and NSE neurobiomarkers were measured at 5-time points (preoperatively, 2, 12, 24, and 48 h postoperatively). ResultsFrom January 2015 to October 2016, sixty-one consecutive eligible patients were submitted to preoperative DWMRI scan. Three patients were excluded because of preoperative silent cerebral lesions. In 29 CGuard patients, 1 developed a minor stroke and 8 silent new lesions were observed in the 72 h-DWMRI (31%): 4 lesions were ipsilateral, and 4 lesions were contra or bilateral. In 29 Wallstent patients, 7 clinically-silent new lesions were found in the 72 h-DWMRI (24.1%; p = 0.38). In 4 cases lesions were ipsilateral and in 3 cases contra or bilateral. S100B values doubled at 48 h in 24 patients, and among them 12 presented new DWMRI lesions. 48-h S100B increase was significantly related to 72-h DWMRI lesions (p = 0.012). ConclusionsIn our experience both stents showed an acceptable rate of subclinical neurological events with no significant differences at 72-hour DWMRI between groups. Bilateral/contralateral lesions suggest that periprocedural neurological damage may have extra-carotid sources.

Effects of salvianolic acid on cerebral perfusion in patients after acute stroke: A single‑center randomized controlled trial

Hypoperfusion following acute stroke is common in the infarct core and periphery tissues. The present study evaluated the efficacy of salvianolic acid (SA) on the cerebral perfusion of patients who had suffered from acute stroke using perfusion-weighted magnetic resonance imaging (PWI) to examine the blood perfusion of the affected brain tissue prior to and following treatment. Patients who were admitted to PLA 153 Central Hospital within 72 h of acute stroke symptom onset and had a Glasgow coma scale ≥5 were randomized into two groups: SA and control groups. Patients in the SA group were administered SA 0.13 g/day for 14 days. PWI was performed for all patients at admission and post-treatment. The National Institutes of Health Stroke Scale (NIHSS) and modified Rankin Scale (mRS) were applied to assess neurological function at admission and 3 months post treatment. A total of 159 patients were enrolled (85 patients in the SA group and 74 patients in the control group). A total of 62 patients in the SA group and 51 patients in the control group exhibited hypoperfusion in the ipsihemisphere of the diffusion-weighted magnetic resonance imaging (DWI) lesion. In addition, relative cerebral blood volume (rCBV), a ratio of the signal value of the region of interest in the same hemisphere of the DWI lesion to that of its mirror in the PWI CBV map, decreased significantly following treatment with SA compared with the control group in patients with hypoperfusion (P=0.02), which were indicated by PWI images at admission, in the DWI lesions or the surrounding areas. Additionally, there was no significant difference in patients with normal perfusion at admission in rCBV in DWI lesions or its surrounding area between the two groups at day 15. However, a significant improvement in NIHSS (P=0.001) and mRS (P=0.005) was indicated in the SA group compared with the control at day 90. The present study indicated that SA may improve the neurological dysfunction of patients with acute stroke, which may be explained by the increased perfusion of hypoperfused brain tissues.

Cerebral embolic protection in thoracic endovascular aortic repair

BackgroundStroke occurs in 3% to 8% and silent cerebral infarction in >60% of patients undergoing thoracic endovascular aortic repair (TEVAR). We investigated the utility of a filter cerebral embolic protection device (CEPD) to reduce diffusion-weighted magnetic resonance imaging (DW-MRI) detected cerebral injury and gaseous and solid embolization during TEVAR. MethodsPatients anatomically suitable underwent TEVAR with CEPD, together with intraoperative transcranial Doppler to detect gaseous and solid high-intensity transient signals (HITSs), pre- and postoperative DW-MRI, and clinical neurologic assessment ≤6 months after the procedure. ResultsTen patients (mean age, 68 years) underwent TEVAR with a CEPD. No strokes or device-related complications developed. The CEPD added a median of 7 minutes (interquartile range [IQR], 5-16 minutes) to the procedure, increased the fluoroscopy time by 3.3 minutes (IQR, 2.4-3.9 minutes), and increased the total procedural radiation by 2.2%. The dose area product for CEPD was 1824 mGy·cm2 (IQR, 1235-3392 mGy·cm2). The average contrast volume used increased by 23 mL (IQR, 24-35 mL). New DW-MRI lesions, mostly in the hindbrain, were identified in seven of nine patients (78%). The median number was 1 (IQR, 1-3), with a median surface area of 6 mm2 (IQR, 3-16 mm2). A total of 2835 HITSs were detected in seven patients: 91% gaseous and 9% solid. The maximum number of HITSs were detected during CEPD manipulation: 142 (IQR, 59-146; 95% gaseous and 5% solid). The maximum number of HITSs during TEVAR occurred during stent deployment: 82 (IQR, 73-142; 81% gas and 11% solid). Solid HITSs were associated with an increase in surface area of new DW-MRI lesions (rs = 0.928; P = .01). Increased gaseous HITSs were associated with new DW-MRI lesions (rs = 0.912; P = .01), which were smaller (<3 mm; r = 0.88; P = .02). Embolic debris was captured in 95% of the filters. The median particle count was 937 (IQR, 146-1687), and the median surface area was 2.66 mm2 (IQR, 0.08-9.18 mm2). ConclusionsThe use of a CEPD with TEVAR appeared to be safe and feasible in this first pilot study and could serve as a useful adjunct to reduce cerebral injury. The significance of gaseous embolization and its role in cerebral injury in TEVAR warrants further investigation.