Trial of Early Minimally Invasive Removal of Intracerebral Hemorrhage.

BACKGROUND: Trials of surgical evacuation of supratentorial intracerebral hemorrhages have generally shown no functional benefit. Whether early minimally invasive surgical removal would result in better outcomes than medical management is not known. METHODS: In this multicenter, randomized trial involving patients with an acute intracerebral hemorrhage, we assessed surgical removal of the hematoma as compared with medical management. Patients who had a lobar or anterior basal ganglia hemorrhage with a hematoma volume of 30 to 80 ml were assigned, in a 1:1 ratio, within 24 hours after the time that they were last known to be well, to minimally invasive surgical removal of the hematoma plus guideline-based medical management (surgery group) or to guideline-based medical management alone (control group). The primary efficacy end point was the mean score on the utility-weighted modified Rankin scale (range, 0 to 1, with higher scores indicating better outcomes, according to patients' assessment) at 180 days, with a prespecified threshold for posterior probability of superiority of 0.975 or higher. The trial included rules for adaptation of enrollment criteria on the basis of hemorrhage location. A primary safety end point was death within 30 days after enrollment. RESULTS: A total of 300 patients were enrolled, of whom 30.7% had anterior basal ganglia hemorrhages and 69.3% had lobar hemorrhages. After 175 patients had been enrolled, an adaptation rule was triggered, and only persons with lobar hemorrhages were enrolled. The mean score on the utility-weighted modified Rankin scale at 180 days was 0.458 in the surgery group and 0.374 in the control group (difference, 0.084; 95% Bayesian credible interval, 0.005 to 0.163; posterior probability of superiority of surgery, 0.981). The mean between-group difference was 0.127 (95% Bayesian credible interval, 0.035 to 0.219) among patients with lobar hemorrhages and -0.013 (95% Bayesian credible interval, -0.147 to 0.116) among those with anterior basal ganglia hemorrhages. The percentage of patients who had died by 30 days was 9.3% in the surgery group and 18.0% in the control group. Five patients (3.3%) in the surgery group had postoperative rebleeding and neurologic deterioration. CONCLUSIONS: Among patients in whom surgery could be performed within 24 hours after an acute intracerebral hemorrhage, minimally invasive hematoma evacuation resulted in better functional outcomes at 180 days than those with guideline-based medical management. The effect of surgery appeared to be attributable to intervention for lobar hemorrhages. (Funded by Nico; ENRICH ClinicalTrials.gov number, NCT02880878.).

Robust quantitative susceptibility mapping via approximate message passing with parameter estimation.

PURPOSE: For quantitative susceptibility mapping (QSM), the lack of ground-truth in clinical settings makes it challenging to determine suitable parameters for the dipole inversion. We propose a probabilistic Bayesian approach for QSM with built-in parameter estimation, and incorporate the nonlinear formulation of the dipole inversion to achieve a robust recovery of the susceptibility maps. THEORY: From a Bayesian perspective, the image wavelet coefficients are approximately sparse and modeled by the Laplace distribution. The measurement noise is modeled by a Gaussian-mixture distribution with two components, where the second component is used to model the noise outliers. Through probabilistic inference, the susceptibility map and distribution parameters can be jointly recovered using approximate message passing (AMP). METHODS: We compare our proposed AMP with built-in parameter estimation (AMP-PE) to the state-of-the-art L1-QSM, FANSI, and MEDI approaches on the simulated and in vivo datasets, and perform experiments to explore the optimal settings of AMP-PE. Reproducible code is available at: https://github.com/EmoryCN2L/QSM_AMP_PE. RESULTS: On the simulated Sim2Snr1 dataset, AMP-PE achieved the lowest NRMSE, deviation from calcification moment and the highest SSIM, while MEDI achieved the lowest high-frequency error norm. On the in vivo datasets, AMP-PE is robust and successfully recovers the susceptibility maps using the estimated parameters, whereas L1-QSM, FANSI and MEDI typically require additional visual fine-tuning to select or double-check working parameters. CONCLUSION: AMP-PE provides automatic and adaptive parameter estimation for QSM and avoids the subjectivity from the visual fine-tuning step, making it an excellent choice for the clinical setting.

Resting-State Brain Temperature: Dynamic Fluctuations in Brain Temperature and the Brain-Body Temperature Gradient.

BACKGROUND: While fluctuations in healthy brain temperature have been investigated over time periods of weeks to months, dynamics over shorter time periods are less clear. PURPOSE: To identify physiological fluctuations in brain temperature in healthy volunteers over time scales of approximately 1 hour. STUDY TYPE: Prospective. SUBJECTS: A total of 30 healthy volunteers (15 female; 26 ± 4 years old). SEQUENCE AND FIELD STRENGTH: 3 T; T1-weighted magnetization-prepared rapid gradient-echo (MPRAGE) and semi-localized by adiabatic selective refocusing (sLASER) single-voxel spectroscopy. ASSESSMENTS: Brain temperature was calculated from the chemical shift difference between N-acetylaspartate and water. To evaluate within-scan repeatability of brain temperature and the brain-body temperature difference, 128 spectral transients were divided into two sets of 64-spectra. Between-scan repeatability was evaluated using two time periods, ~1-1.5 hours apart. STATISTICAL TESTS: A hierarchical linear mixed model was used to calculate within-scan and between-scan correlations (Rw and Rb , respectively). Significance was determined at P ≤ .05. Values are reported as the mean ± standard deviation. RESULTS: A significant difference in brain temperature was observed between scans (-0.4 °C) but body temperature was stable (P = .59). Brain temperature (37.9 ± 0.7 °C) was higher than body temperature (36.5 ± 0.5 °C) for all but one subject. Within-scan correlation was high for brain temperature (Rw  = 0.95) and brain-body temperature differences (Rw  = 0.96). Between scans, variability was high for both brain temperature (Rb  = 0.30) and brain-body temperature differences (Rb  = 0.41). DATA CONCLUSION: Significant changes in brain temperature over time scales of ~1 hour were observed. High short-term repeatability suggests temperature changes appear to be due to physiology rather than measurement error. EVIDENCE LEVEL: 2 TECHNICAL EFFICACY: Stage 1.

Assessment of Complex Flow Patterns in Patients With Carotid Webs, Patients With Carotid Atherosclerosis, and Healthy Subjects Using 4D Flow MRI.

BACKGROUND: Carotid webs (CaWs) are fibromuscular projections in the internal carotid artery (ICA) that cause mild luminal narrowing (<50%), but may be causative in up to one-third of seemingly cryptogenic strokes. Understanding hemodynamic alterations caused by CaWs is imperative to assessing stroke risk. Time-Average Wall Shear Stress (TAWSS) and Oscillatory Shear Index (OSI) are hemodynamic parameters linked to vascular dysfunction and thrombosis. PURPOSE: To test the hypothesis: "CaWs are associated with lower TAWSS and higher OSI than mild atherosclerosis or healthy carotid bifurcation." STUDY TYPE: Prospective study. POPULATION: A total of 35 subjects (N = 14 bifurcations with CaW, 11F, age: 49 ± 10, 10 mild atherosclerosis 6F, age: 72 ± 9, 11 healthy 9F, age: 42 ± 13). FIELD STRENGTH/SEQUENCE: 4D flow/STAR-MATCH/3D TOF/3T MRI, CTA. ASSESSMENT: 4D Flow velocity data were analyzed in two ways: 1) 3D ROI in the ICA bulbar segment (complex flow patterns are expected) was used to quantify the regions with low TAWSS and high OSI. 2) 2D planes were placed perpendicular to the centerline of the carotid bifurcation for detailed analysis of TAWSS and OSI. STATISTICAL TESTS: Independent-samples Kruskal-Wallis-H test with 0.05 used for statistical significance. RESULTS: The percent surface area where low TAWSS was present in the ICA bulb was 12.3 ± 8.0% (95% CI: 7.6-16.9) in CaW subjects, 1.6 ± 1.9% (95% CI: 0.2-2.9) in atherosclerosis, and 8.5 ± 7.7% (95% CI: 3.6-13.4) in healthy subjects, all differences were statistically significant (ƞ2 = 0.3 [95% CI: 0.05-0.5], P-value CaW vs. healthy = 0.2). OSI had similar values in the CCA between groups (ƞ2 = 0.07 [95% CI: 0.0-0.2], P-value = 0.5), but OSI was significantly higher downstream of the bifurcation in CaW subjects compared to atherosclerosis and normal subjects. OSI returned to similar values between groups 1.5 diameters distal to the bifurcation (ƞ2 = 0.03 [95% CI: 0.0-0.2], P-value = 0.7). CONCLUSION: Lower TAWSS and higher OSI are present in the ICA bulb in patients with CaW when compared to patients with atherosclerotic or healthy subjects. EVIDENCE LEVEL: 2 TECHNICAL EFFICACY: Stage 2.

Pituitary Incidentalomas: Best Practices and Looking Ahead.

Pituitary Incidentalomas (PI) are pituitary lesions serendipitously identified on imaging. PIs have become common in clinical practice because of increased use of imaging and radiologic advances. The most frequently incidentally detected lesions in adults are pituitary adenomas, followed by cystic lesions, and rarely other types of tumors and infiltrative and inflammatory disorders. Biochemical screening for hyperprolactinemia and acromegaly is needed in all patients with PI, whereas testing for hyposecretion is recommended for lesions larger than 6.0 mm. Most PIs are small nonfunctioning adenomas or cysts, which can be conservatively managed. For larger lesions, a multidisciplinary approach including endocrinology, neurosurgery, and neuro-ophthalmology is required. For incidentally detected lactotroph, somatotroph, and corticotroph adenomas, disease-specific management guidelines apply. Prospective studies are needed to enhance our understanding of the long-term course and response to treatment.

Implementation of Automated Pipeline for Resting-State fMRI Analysis with PACS Integration.

In recent years, the quantity and complexity of medical imaging acquisition and processing have increased tremendously. The explosion in volume and need for advanced imaging analysis have led to the creation of numerous software programs, which have begun to be incorporated into clinical practice for indications such as automated stroke assessment, brain tumor perfusion processing, and hippocampal volume analysis. Despite these advances, there remains a need for specialized, custom-built software for advanced algorithms and new areas of research that is not widely available or adequately integrated in these "out-of-the-box" solutions. The purpose of this paper is to describe the implementation of an image-processing pipeline that is versatile and simple to create, which allows for rapid prototyping of image analysis algorithms and subsequent testing in a clinical environment. This pipeline uses a combination of Orthanc server, custom MATLAB code, and publicly available FMRIB Software Library and RestNeuMap tools to automatically receive and analyze resting-state functional MRI data collected from a custom filter on the MR scanner output. The processed files are then sent directly to Picture Archiving and Communications System (PACS) without the need for user input. This initial experience can serve as a framework for those interested in simple implementation of an automated pipeline customized to clinical needs.

Automated Registration and Color Labeling of Serial 3D Double Inversion Recovery MR Imaging for Detection of Lesion Progression in Multiple Sclerosis.

Automated co-registration and subtraction techniques have been shown to be useful in the assessment of longitudinal changes in multiple sclerosis (MS) lesion burden, but the majority depend on T2-fluid-attenuated inversion recovery sequences. We aimed to investigate the use of a novel automated temporal color complement imaging (CCI) map overlapped on 3D double inversion recovery (DIR), and to assess its diagnostic performance for detecting disease progression in patients with multiple sclerosis (MS) as compared to standard review of serial 3D DIR images. We developed a fully automated system that co-registers and compares baseline to follow-up 3D DIR images and outputs a pseudo-color RGB map in which red pixels indicate increased intensity values in the follow-up image (i.e., progression; new/enlarging lesion), blue-green pixels represent decreased intensity values (i.e., disappearing/shrinking lesion), and gray-scale pixels reflect unchanged intensity values. Three neuroradiologists blinded to clinical information independently reviewed each patient using standard DIR images alone and using CCI maps based on DIR images at two separate exams. Seventy-six follow-up examinations from 60 consecutive MS patients who underwent standard 3 T MR brain MS protocol that included 3D DIR were included. Median cohort age was 38.5 years, with 46 women, 59 relapsing-remitting type MS, and median follow-up interval of 250 days (interquartile range: 196-394 days). Lesion progression was detected in 67.1% of cases using CCI review versus 22.4% using standard review, with a total of 182 new or enlarged lesions using CCI review versus 28 using standard review. There was a statistically significant difference between the two methods in the rate of all progressive lesions (P < 0.001, McNemar's test) as well as cortical progressive lesions (P < 0.001). Automated CCI maps using co-registered serial 3D DIR, compared to standard review of 3D DIR alone, increased detection rate of MS lesion progression in patients undergoing clinical brain MRI exam.

Carotid Web Phenotype Is Uncommonly Associated With Classic Fibromuscular Dysplasia: A Retrospective Observational Study.

BACKGROUND AND PURPOSE: Carotid web (CaW) is an intimal form of fibromuscular dysplasia (FMD) involving the carotid bulb which has been increasingly recognized as a potential cause of recurrent ischemic strokes. It is overlooked as a separate entity and often dismissed if no coexistent signs of classic FMD changes are observed. We aim to evaluate the frequency of classic FMD in high-yield vascular territories in patients with symptomatic CaW. METHODS: This was a retrospective analysis of a symptomatic CaW database of 2 comprehensive stroke centers (spanning September 2014-October 2020). The diagnosis of a CaW during a stroke workup was defined as the presence of a shelf-like linear filling defect in the posterior aspect of the carotid bulb on computed tomography angiography in patients with acute ischemic stroke or transient ischemic attack of undetermined cause after a thorough evaluation. Neck computed tomography angiography and renal conventional angiography images were independently evaluated by two readers blinded to the laterality and clinical details to inspect the presence of underlying classic FMD. RESULTS: Sixty-six patients with CaW were identified. Median age was 51 years (interquartile range, 42-57), and 74% were women. All patients had neck computed tomography angiography (allowing for bilateral vertebral and carotid evaluation), whereas 47 patients had additional digital subtraction angiography (which evaluated 47 carotids ipsilateral to the stroke and 10 contralateral carotids). Internal carotid artery classic FMD changes were noted in only 6 out of 66 (9%) in the ipsilateral carotids. No contralateral carotid or vertebral artery classic FMD changes were observed. Renal artery catheter-based angiography was obtained in 16 patients/32 arteries and only 1 patient/2 renal arteries demonstrated classic FMD changes. CONCLUSIONS: CaW phenotype is uncommonly associated with classic FMD changes. Coexistent classic FMD does not constitute a useful marker to corroborate or exclude CaW diagnosis.

The "vestibular neuromatrix": A proposed, expanded vestibular network from graph theory in post-concussive vestibular dysfunction.

Convergent clinical and neuroimaging evidence suggests that higher vestibular function is subserved by a distributed network including visuospatial, cognitive-affective, proprioceptive, and integrative brain regions. Clinical vestibular syndromes may perturb this network, resulting in deficits across a variety of functional domains. Here, we leverage structural and functional neuroimaging to characterize this extended network in healthy control participants and patients with post-concussive vestibular dysfunction (PCVD). Then, 27 healthy control subjects (15 females) and 18 patients with subacute PCVD (12 female) were selected for participation. Eighty-two regions of interest (network nodes) were identified based on previous publications, group-wise differences in BOLD signal amplitude and connectivity, and multivariate pattern analysis on affective tests. Group-specific "core" networks, as well as a "consensus" network comprised of connections common to all participants, were then generated based on probabilistic tractography and functional connectivity between the 82 nodes and subjected to analyses of node centrality and community structure. Whereas the consensus network was comprised of affective, integrative, and vestibular nodes, PCVD participants exhibited diminished integration and centrality among vestibular and affective nodes and increased centrality of visual, supplementary motor, and frontal and cingulate eye field nodes. Clinical outcomes, derived from dynamic posturography, were associated with approximately 62% of all connections but best predicted by amygdalar, prefrontal, and cingulate connectivity. No group-wise differences in diffusion metrics or tractography were noted. These findings indicate that cognitive, affective, and proprioceptive substrates contribute to vestibular processing and performance and highlight the need to consider these domains during clinical diagnosis and treatment planning.

A probabilistic Bayesian approach to recover R2*$$ {R}_{2\ast } $$ map and phase images for quantitative susceptibility mapping.

PURPOSE: Undersampling is used to reduce the scan time for high-resolution three-dimensional magnetic resonance imaging. In order to achieve better image quality and avoid manual parameter tuning, we propose a probabilistic Bayesian approach to recover R2∗$$ {R}_2^{\ast } $$ map and phase images for quantitative susceptibility mapping (QSM), while allowing automatic parameter estimation from undersampled data. THEORY: Sparse prior on the wavelet coefficients of images is interpreted from a Bayesian perspective as sparsity-promoting distribution. A novel nonlinear approximate message passing (AMP) framework that incorporates a mono-exponential decay model is proposed. The parameters are treated as unknown variables and jointly estimated with image wavelet coefficients. METHODS: Undersampling takes place in the y-z plane of k-space according to the Poisson-disk pattern. Retrospective undersampling is performed to evaluate the performances of different reconstruction approaches, prospective undersampling is performed to demonstrate the feasibility of undersampling in practice. RESULTS: The proposed AMP with parameter estimation (AMP-PE) approach successfully recovers R2∗$$ {R}_2^{\ast } $$ maps and phase images for QSM across various undersampling rates. It is more computationally efficient, and performs better than the state-of-the-art l1$$ {l}_1 $$ -norm regularization (L1) approach in general, except a few cases where the L1 approach performs as well as AMP-PE. CONCLUSION: AMP-PE achieves better performance by drawing information from both the sparse prior and the mono-exponential decay model. It does not require parameter tuning, and works with a clinical, prospective undersampling scheme where parameter tuning is often impossible or difficult due to the lack of ground-truth image.

Associations among civilian mild traumatic brain injury with loss of consciousness, posttraumatic stress disorder symptom trajectories, and structural brain volumetric data.

Posttraumatic stress disorder (PTSD) is prevalent and associated with significant morbidity. Mild traumatic brain injury (mTBI) concurrent with psychiatric trauma may be associated with PTSD. Prior studies of PTSD-related structural brain alterations have focused on military populations. The current study examined correlations between PTSD, acute mTBI, and structural brain alterations longitudinally in civilian patients (N = 504) who experienced a recent Criterion A traumatic event. Participants who reported loss of consciousness (LOC) were characterized as having mTBI; all others were included in the control group. PTSD symptoms were assessed at enrollment and over the following year; a subset of participants (n = 89) underwent volumetric brain MRI (M = 53 days posttrauma). Classes of PTSD symptom trajectories were modeled using latent growth mixture modeling. Associations between PTSD symptom trajectories and cortical thicknesses or subcortical volumes were assessed using a moderator-based regression. mTBI with LOC during trauma was positively correlated with the likelihood of developing a chronic PTSD symptom trajectory. mTBI showed significant interactions with cortical thickness in the rostral anterior cingulate cortex (rACC) in predicting PTSD symptoms, r = .461-.463. Bilateral rACC thickness positively predicted PTSD symptoms but only among participants who endorsed LOC, p < .001. The results demonstrate positive correlations between mTBI with LOC and PTSD symptom trajectories, and findings related to mTBI with LOC and rACC thickness interactions in predicting subsequent chronic PTSD symptoms suggest the importance of further understanding the role of mTBI in the context of PTSD to inform intervention and risk stratification.

Automated Processing of Head CT Perfusion Imaging for Ischemic Stroke Triage: A Practical Guide to Quality Assurance and Interpretation.

Recent successful trials of thrombectomy launched a shift to imaging-based patient selection for stroke intervention. Many centers have adopted CT perfusion imaging (CTP) as a routine part of stroke workflow, and the demand for emergent CTP interpretation is growing. Fully automated CTP postprocessing software that rapidly generates standardized color-coded CTP summary maps with minimal user input and with easy accessibility of the software output is increasingly being adopted. Such automated postprocessing greatly streamlines clinical workflow and CTP interpretation for radiologists and other frontline physicians. However, the straightforward interface overshadows the computational complexity of the underlying postprocessing workflow, which, if not carefully examined, predisposes the interpreting physician to diagnostic errors. Using case examples, this article aims to familiarize the general radiologist with interpreting automated CTP software data output in the context of contemporary stroke management, providing a discussion of CTP acquisition and postprocessing, a stepwise guide for CTP quality assurance and troubleshooting, and a framework for avoiding clinically significant pitfalls of CTP interpretation in commonly encountered clinical scenarios. Interpreting radiologists should apply the outlined approach for quality assurance and develop a comprehensive search pattern for the identified pitfalls, to ensure accurate CTP interpretation and optimize patient selection for reperfusion.

Brain Imaging in Patients With Dementia Visiting U.S. Emergency Departments.

OBJECTIVE. This article aimed to assess changing use of brain imaging tests among patients with Alzheimer disease and vascular dementia who visited U.S. emergency departments (EDs) between 2006 and 2014. MATERIALS AND METHODS. Using the largest publicly available all-payer ED database, the Nationwide Emergency Department Sample, we identified a weighted cohort of 427,705 individuals with Alzheimer disease and 33,743 individuals with vascular dementia who visited U.S. EDs between 2006 and 2014. Logistic regression analyses were performed to identify factors associated with use. RESULTS. Between 2006 and 2014, ED visits among patients with Alzheimer disease and vascular dementia declined by 24.7% and 20.3%, respectively. However, there was a significant increase in utilization rates of head CT (from 4.4% to 11.1% in patients with Alzheimer disease and from 1.5% to 2.9% in patients with vascular dementia) and brain MRI (from 0.04% to 0.5% in patients with Alzheimer disease and 0.0% to 0.1% in those with vascular dementia) in the same time period. Among patients with Alzheimer disease, age, median income in patient ZIP code, day of the week of the ED visit, hospital teaching status, and hospital geographic region were significant predictors of imaging use. Among patients with vascular dementia, insurance type and hospital classification (urban vs rural) were significant predictors of imaging use. CONCLUSION. Despite declining ED visits, ED brain imaging in patients with Alzheimer disease and vascular dementia has increased. Various patient-specific and hospital-specific factors contribute to differential utilization rates.

Imaging Appearance of Ballistic Wounds Predicts Bullet Composition: Implications for MRI Safety.

OBJECTIVE. The purpose of this article was to determine whether the radiographic and CT appearance of ballistic projectiles predicts their composition and to characterize the translational, rotational, and temperature effects of a 1.5-T MRI magnetic field on representative bullets. MATERIALS AND METHODS. Commercially available handgun and shotgun ammunition representing projectiles commonly encountered in a clinical setting was fired into ballistic gelatin as a surrogate for human tissue, and radiographs and CT images of these gelatin blocks were obtained. MR images of unfired bullets suspended in gelatin blocks were also obtained using T1- and T2-weighted sequences. Magnetic attractive force, rotational torque, and heating effects of unfired bullets were assessed at 1.5 T. RESULTS. Fired bullets were separated into ferromagnetic and nonferromagnetic groups based on the presence of a debris trail and deformation of the primary projectile in the gelatin blocks. Whereas ferromagnetic bullets showed mild torque forces and marked imaging artifacts at 1.5 T, nonferromagnetic bullets did not have these effects. Heating above the Food and Drug Administration limit of 2°C was not observed in any of the projectiles tested. CONCLUSION. Patients with ballistic embedded fragments are frequently denied MRI because the bullet composition cannot be determined without shell casings. We found that radiography and CT can be used to identify nonferromagnetic projectiles that are safe for MRI. We also present an algorithm for determining the triage of patients with retained bullets.

Statistical learning of blunt cerebrovascular injury risk factors using the elastic net.

PURPOSE: To compare logistic regression to elastic net for identifying and ranking clinical risk factors for blunt cerebrovascular injury (BCVI). MATERIALS AND METHODS: Consecutive trauma patients undergoing screening CTA at a level 1 trauma center over a 2-year period. Each internal carotid artery (ICA) and vertebral artery (VA) was independently graded by 2 neuroradiologists using the Denver grading scale. Unadjusted odds ratios were calculated by univariate and adjusted odds ratios by multiple logistic regression with FDR correction. We applied logistic regression with the elastic net penalty and tenfold cross-validation. RESULTS: Total of 467 patients; 73 patients with BCVI. Maxillofacial fracture, basilar skull fracture, and GCS had significant unadjusted odds ratios (OR) for ICA injury and C-spine fracture, spinal ligamentous injury, and age for VA injury. Only transverse foramen fracture had significant adjusted OR for VA injury, with none for ICA injury, after FDR correction. Using elastic net, ICA injury variables included maxillofacial fracture, basilar skull fracture, GCS, and carotid canal fracture. For VA injury, these included cervical spine transverse foramen fracture, ligamentous injury, C1-C3 fractures, posterior element fracture, and vertebral body fracture. CONCLUSION: Elastic net statistical learning methods identified additional risk factors and outperformed multiple logistic regression for BCVI. Elastic net allows the study of a large number of variables, and is useful when covariates are correlated.

Cerebral MR oximetry during acetazolamide augmentation: Beyond cerebrovascular reactivity in hemodynamic failure.

BACKGROUND: Oxygen extraction fraction (OEF) elevation predicts increased ischemic stroke incidence among patients with carotid steno-occlusive disease, and can be estimated from quantitative susceptibility mapping (QSM) MRI. PURPOSE: To explore QSM oximetry during acetazolamide (ACZ) challenge, hypothesizing that detectable OEF alterations will reflect hemodynamic compromise in unilateral cerebrovascular disease (CVD) patients. STUDY TYPE: Retrospective. SUBJECTS: Fourteen unilateral CVD patients, and 24 healthy controls (HC). FIELD STRENGTH/SEQUENCE: Multiecho gradient echo (GRE) and T1 -weighted images at 3T. ASSESSMENT: We constructed QSM images and R2* maps from multiecho GRE images. QSM-OEF maps were generated from the susceptibility difference between venous blood and background brain tissue. Intrasubject diseased/contralateral hemisphere OEF ratios in the middle cerebral artery (MCA) territories were calculated. Intravascular susceptibility in the straight sinus (SS) and MCA was also measured. STATISTICAL TESTS: The result significance was determined using t-tests and Pearson's correlation. RESULTS: Mean and standard deviation for the patient diseased/contralateral OEF ratios were 1.15 ± 0.14 at baseline and 1.23 ± 0.17 post-ACZ. Disease group R2* ratios were 0.95 ± 0.05 at baseline and 1.03 ± 0.08 post-ACZ. Left/right OEF and R2* ratios for the HC group were 0.98 ± 0.06 and 0.99 ± 0.038, respectively. Susceptibility (ppb) in the SS and MCA in patients was 162.63 ± 35.4 and -22.33 ± 13.70, respectively, at baseline, 124.56 ± 37.43 and -19.27 ± 23.14 post-ACZ. The HC group SS and MCA susceptibility was 146.10 ± 24.79 and -19.59 ± 12.37, respectively. Patient group OEF ratios were greater than 1.0 before and after ACZ challenge (P < 0.01 and < 0.001, respectively, one-sample t-test), and were greater than HC ratios (P < 0.001 unpaired t-test). OEF and R2* ratios increased from baseline to post-ACZ (P = 0.024, 0.004, respectively, paired t-test). Detectable blood oxygenation change was confirmed by finding SS susceptibility decreased from baseline to post-ACZ (P < 0.001, paired t-test), while MCA susceptibility did not change significantly (P = 0.67, paired t-test). DATA CONCLUSION: These results suggest QSM is sensitive to dynamic OEF modulation during hemodynamic augmentation. LEVEL OF EVIDENCE: 3 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2019;50:175-182.

Carotid Webs in Cryptogenic Ischemic Strokes: A Matched Case-Control Study.

BACKGROUND: Young individuals with symptomatic carotid webs may be predisposed to ischemic strokes. However, evidence remains scarce. This investigation reports the frequency of carotid webs among patients with cryptogenic strokes compared to a control group. METHODS: Consecutive cryptogenic ischemic strokes and trauma patients were identified. Additional inclusion criteria required age 18-60 years and availability of head/neck computed tomography (CT) angiography. CT angiogram (CTA) neck images were evaluated independently by 2 fellowshiptrained specialists. A carotid web was defined by a shelf-like, linear filling defect in the posterior internal carotid artery bulb. RESULTS: Of 1877 patients presenting with ischemic strokes in 2015-2017, 165 were diagnosed with cryptogenic strokes, 51 of whom met the inclusion criteria of age and CTA availability. Fifty one trauma cases were matched for age and sex. After imaging analysis, 13 carotid webs (25%) were identified in the 51 cryptogenic stroke group versus 0 (0%; P < .001) in trauma subjects. Thirty-nine of the 51 cryptogenic ischemic stroke patients were found with carotid anterior distribution infarcts, of which 9 (23%) were found with ipsilateral carotid webs. There were more proximal large vessel occlusions in the cryptogenic patients with carotid webs, compared to those without (P = .04). All carotid webs led to less than 30% degree of stenosis. CONCLUSIONS: Carotid webs were found at a significantly higher frequency in patients with cryptogenic ischemic strokes compared to controls, indicating a potentially thrombogenic nature of these lesions in young patients. Additionally, intracranial large vessel occlusions were more common in patients with symptomatic carotid webs, presenting with ipsilateral strokes.

Carotid Web (Intimal Fibromuscular Dysplasia) Has High Stroke Recurrence Risk and Is Amenable to Stenting.

BACKGROUND AND PURPOSE: Carotid webs have been increasingly recognized as a cause of recurrent stroke, but evidence remains scarce. We aim to report the clinical outcomes and first series of carotid stenting in a cohort of patients with strokes from symptomatic carotid webs. METHODS: Prospective and consecutive data of patients <65 years old with cryptogenic stroke admitted within September 2014 to May 2017. Carotid web was defined by a shelf-like/linear filling defect in the posterior internal carotid artery bulb by computed tomographic angiography. RESULTS: Twenty-four patients were identified (91.6% strokes/8.4% transient ischemic attacks [TIAs]). Median age was 46 (41-59) years, 61% were female, and 75% were black. Median National Institutes of Health Stroke Scale score was 10.5 (3.0-16.0) and ASPECTS (Alberta Stroke Program Early CT Score) was 8 (7-8). There were no parenchymal hemorrhages, and 96% of patients were independent at 3 months. All webs caused <50% stenosis. In patients with bilateral webs (58%), median ipsilateral web length was larger than contralateral (3.1 [3.0-4.5] mm versus 2.6 [1.85-2.9] mm; P=0.01), respectively. Twenty-nine percent of patients had thrombus superimposed on the symptomatic carotid web. A recurrent stroke/TIA involving the territory of the previously symptomatic web occurred in 7 (32%; 6 strokes/1 TIA) patients: 3 <1 week, 2 1 year of follow-up. Two recurrences occurred on dual antiplatelet therapy, 3 on antiplatelet monotherapy, 1 within 24 hours of thrombolysis, and 1 off antithrombotics. Median follow-up was 12.2 (8.0-18.0) months. Sixteen (66%) patients were stented at a median 12.2 (7.0-18.7) days after stroke with no periprocedural complications. No recurrent strokes/TIAs occurred in stented individuals (median follow-up of 4 [2.4-12.0] months). CONCLUSIONS: Carotid web is associated with high recurrent stroke/TIA risk, despite antithrombotic use, and is amenable to carotid stenting.