Susceptibility-weighted Imaging Research Articles

Magnetic resonance imaging findings of cerebral venous malformations.

Our study aimed to evaluate the incidence and anatomical locations of cerebral venous malformations (CVMs), their alterations over time, and magnetic resonance imaging (MRI) findings of their relationships with each other in patients who underwent magnetic susceptibility-weighted imaging (SWI) and contrast-enhanced MRI. The drainage pattern of developmental venous anomalies (DVAs), the number of collecting veins, DVA thrombosis, signal-intensity abnormalities, and hemosiderin deposits (nodular, diffuse, or both) related to the DVA, were examined. The alterations over time in cavernomas (type and size) were assessed. The study evaluated 7,826 patients who had 8,957 magnetic SWIand contrast-enhanced brain MRIs. A total of 643 CVMs were detected in 520 patients. The frequencies of DVAs, cavernomas, and capillary telangiectasias were 5.26%, 1.28%, and 0.62%, respectively. Isolated DVAs were detected in 430 (71.5%), cavernomas in 77 (12.8%), and capillary telangiectasias in 52 (8.7%) cases of CVMs. The coexistence of DVA with cavernoma and DVA with capillary telangiectasia was found in 38 (6.3%) and 4 (0.7%) cases, respectively. DVA drainage was largely provided by a single collecting vein. Signal-intensity abnormalities associated with the DVA were observed in 7, and two patients had DVA thrombosis. Hemosiderin deposits were nodular in 14 cases, diffuse in three, and both nodular and diffuse in two. In a follow-up of 11 (7.8%) cavernomas, alterations in the type and size were detected. It is not uncommon for cavernomas to become symptomatic owing to alterations in their nature, size, and type over time, while DVAs rarely become symptomatic. Capillary telangiectasias are vascular malformations that tend to remain stable in terms of clinical and imaging features, and those with supratentorial localization are detected more frequently in the frontal lobe. On magnetic susceptibility sequences, hemosiderin deposits can be seen in the GVA region, not rarely but more frequently in nodular form, as well as in diffuse or nodular or diffuse and nodular forms.

Delayed Magnetic Resonance Imaging of Alzheimer's Disease by Using Poly(2-(methacryloyloxy)ethyl phosphorylcholine)-Functionalized Nanoprobes.

Alzheimer's disease (AD) is one of the most common neurodegenerative diseases, commonly affecting the aged, with pathophysiological changes presenting 15 to 20 years before clinical symptoms. Early diagnosis and intervention are crucial in effectively slowing the progression of AD. In the current study, poly(2-(methacryloyloxy)ethyl phosphorylcholine) (PMPC)-functionalized NaGdF4 nanoparticles (NaGdF4-PMPC) were developed as magnetic resonance imaging (MRI) contrast agents for targeting alpha 7 nicotinic acetylcholine receptors (α7 nAChRs) in AD mice. NaGdF4-PMPC showed excellent biocompatibility, targeting ability, and MRI performance, with the longitudinal molar relaxivity (r1) and transverse molar relaxivity (r2) being 1.21-fold and 1.33-fold higher than those of the clinical contrast agent Gd-DTPA, respectively, resulting in higher-sensitive MR angiography. After intravenous injection, 3D dynamic contrast-enhanced (DCE) MR images with high-resolution vasculature of the mouse brain were obtained. In addition, by using NaGdF4-PMPC, susceptibility-weighted imaging (SWI) signals in AD mouse brains were greatly retained compared to those in healthy mice for 24 h, emphasizing the excellent targeting ability of NaGdF4-PMPC. Furthermore, the CD31, α7 nAChRs, and Thioflavin S staining were also utilized to investigate the relationship among vascular inflammation, α7 nAChRs, and amyloid-β (Aβ) deposition in AD mice. This work highlights a promising targeted imaging strategy for the timely diagnosis of AD.

The hypointense pulvinar sign on susceptibility weighed magnetic resonance imaging: A visual biomarker for iron deposition in epilepsy

Objective Our study aimed to investigate potential alterations in iron deposition within pulvinar, using susceptibility weighted imaging (SWI) MRI in epilepsy patients through a biomarker termed the “hypointense pulvinar sign.” Methods A full-text radiological information system search of radiological reports was performed for the term “epilepsy” between 2014 and 2022. Only patients with the diagnosis of epilepsy were included. SWI was assessed by two readers recording lateralization of an asymmetrically more hypointense pulvinar. Cohen’s kappa for inter-rater reliability was calculated. Fisher’s exact test was performed to assess for significance between groups. Results Our epilepsy cohort comprised 105 patients with following diagnoses: 45 intra-axial tumor, 13 meningioma, 13 MRI negative, 12 encephalomalacia, seven siderosis, six cavernoma, five arteriovenous malformation, two acute demyelinating encephalomyelitis, one tuberous sclerosis, one giant aneurysm. The hypointense pulvinar sign was correct in 44% of cases. Notably, right hemispheric lesions exhibited a significantly higher proportion of correct hypointense pulvinar signs compared to the left hemisphere (46% vs 24%; p = 0.044). Inter-rater reliability was substantial at 0.62 ( p < 0.001). Only two of 21 (10%) of healthy controls demonstrated a hypointense pulvinar sign, which was significantly different from the epilepsy cohort ( p < 0.01). Conclusions The hypointense pulvinar sign has proven to be a reproducible, simple to use biomarker for iron deposition in epilepsy which could be considered for inclusion into multimodal precision medicine models.

Exploring the Causal Relationship Between Inflammatory Cytokines and MRI-Derived Brain Iron: A Mendelian Randomization Study.

The association between inflammation and brain iron deposition is widely acknowledged. However, the precise causal impact of peripheral inflammatory cytokines on changes in brain iron content remains uncertain. The study utilized an available genome-wide association study (GWAS) summary associated with inflammatory cytokines from The Cardiovascular Risk in Young Finns Study and the FINRISK surveys. The GWAS data for brain iron markers were obtained from the UK Biobank. We assessed the iron content of each brain region using susceptibility-weighted magnetic resonance imaging, utilizing both quantitative susceptibility mapping and T2* measurements. The primary outcomes were susceptibility (χ) and T2*, which serve as indices of iron deposition. To investigate the causal relationship between exposure and outcome, we primarily employed inverse variance weighting, MR Egger, weighted median, simple mode, and weighted mode methods, collectively enhancing the robustness of our results. The results of MR analyses demonstrate that our study unveiled that nerve growth factor-β, hepatocyte growth factor, interleukin-1 (IL-1), IL-8, macrophage inflammatory protein 1α, and tumor necrosis factor-α were associated with elevated brain iron content in the regions of left hippocampus, putamen, left thalamus, right pallidum, right hippocampus, left amygdala, respectively. Furthermore, our investigation provides evidence for a negative relationship between IL-1, IL-17, monocyte chemotactic protein-3, tumor necrosis factor-β, and brain iron content in distinct regions. Our findings suggest a causal association between circulating inflammatory cytokines and brain iron deposition across various brain regions. This provides new insights into the immunopathogenesis of neurodegenerative diseases and potential preventive strategies targeting iron metabolism.

Susceptibility-Weighted Imaging: Technical Aspects and Clinical Applications, Part 1.

Susceptibility-Weighted Imaging: Technical Aspects and Clinical Applications, Part 1.

Rapid submillimeter QSM and R2* mapping using interleaved multishot 3D-EPI at 7 and 3 Tesla.

To explore the high signal-to-noise ratio (SNR) efficiency of interleaved multishot 3D-EPI with standard image reconstruction for fast and robust high-resolution whole-brain quantitative susceptibility (QSM) and mapping at 7 and 3T. Single- and multi-TE segmented 3D-EPI is combined with conventional CAIPIRINHA undersampling for up to 72-fold effective gradient echo (GRE) imaging acceleration. Across multiple averages, scan parameters are varied (e.g., dual-polarity frequency-encoding) to additionally correct for -induced artifacts, geometric distortions and motion retrospectively. A comparison to established GRE protocols is made. Resolutions range from 1.4 mm isotropic (1 multi-TE average in 36 s) up to 0.4 mm isotropic (2 single-TE averages in approximately 6 min) with whole-head coverage. Only 1-4 averages are needed for sufficient SNR with 3D-EPI, depending on resolution and field strength. Fast scanning and small voxels together with retrospective corrections result in substantially reduced image artifacts, which improves susceptibility and mapping. Additionally, much finer details are obtained in susceptibility-weighted image projections through significantly reduced partial voluming. Using interleaved multishot 3D-EPI, single-TE and multi-TE data can readily be acquired 10 times faster than with conventional, accelerated GRE imaging. Even 0.4 mm isotropic whole-head QSM within 6 min becomes feasible at 7T. At 3T, motion-robust 0.8 mm isotropic whole-brain QSM and mapping with no apparent distortion in less than 7 min becomes clinically feasible. Stronger gradient systems may allow for even higher effective acceleration rates through larger EPI factors while maintaining optimal contrast.

Evaluating performance and quality of a fast multi-contrast scan in routine brain MRI.

Neuromix is a fast, motion robust multi-contrast sequence capable of providing all diagnostic contrasts in ∼3.5 minutes. However, more evaluation is needed across the various contrasts compared to gold standard, optimized sequences routinely used in the clinic. The goal of this study was to prospectively determine how NeuroMix performs in the clinical setting compared to routine clinical MRI. NeuroMix and routine clinical MRI sequences were acquired on a 3 Tesla clinical scanner for 39 patients clinically indicated for brain MRI. Three radiologists were asked to assess the diagnostic confidence of NeuroMix compared to the routine MRI using a series of questions. Signal-to-noise and contrast-to-noise ratios (SNR and CNR) were assessed for NeuroMix. Fleiss' free-marginal multirater kappa was calculated for the qualitative assessment performed by the radiologists. Radiologists were comfortable substituting or reading some of the NeuroMix sequences in place of the corresponding conventional sequence for some contrasts, including diffusion-weighted imaging, single-shot T2, and susceptibility-weighted imaging. The image quality, SNR, and CNR allowed the radiologists to visualize anatomy and pathology on NeuroMix images. There was no significant difference between coefficient of variation for the apparent diffusion coefficient maps (p=.084). Analysis revealed both positives and some pitfalls of NeuroMix. However, these results indicate Neuromix as having the capability to be a backup sequence in case artifacts are present in routine sequences, or potentially a replacement for some contrasts altogether.

Prevalence and Clinical Implications of Hemosiderin Deposits in Recent Small Subcortical Infarcts.

A quarter of ischemic strokes are of lacunar clinical subtype and have an underlying recent small subcortical infarct (RSSI), but their long-term outcomes remain poorly characterized. Hemosiderin deposits (HDs) have been noted in RSSIs at chronic stages and might mimic primary hemorrhage. We characterized HDs' morphology, frequency, and clinical relevance. Participants with RSSIs were identified from a prospective longitudinal study and evaluated on 3T MRI including susceptibility-weighted imaging (SWI) from stroke diagnosis to 12 months. We categorized HDs in RSSIs on SWI at all available time points into 4 types (spots, smudge, rim, cluster) and assessed their associations with demographic factors, stroke-related factors, and image markers with adjusted logistic regression. HDs were observed in 43 (55.0%) of 108 participants within 3 months and 83 (76.9%) of 108 within 12 months after stroke onset. The mean time to first detection of HDs was 87 (interquartile range 53-164) days. A "rim" pattern (similar to late appearance of primary hemorrhage) occurred in at least 26.5% of RSSIs at all follow-up time points, mainly those located in the lentiform/internal capsule (50.0%) or thalamus (36.4%). Infarct volume (odds ratio [OR] 1.003, 95% CI 1.001-1.006; p = 0.004) and the total small vessel disease (SVD) score at baseline (OR 2.50, 95% CI 1.28-4.86, p = 0.007) independently predicted HDs at 12 months. HDs were positively associated with more lacunes (OR 1.60, 95% CI 1.13-2.26, p < 0.01), but not the Fazekas score, number of microbleeds, basal ganglia mineral deposit score, or clinical outcomes. HDs occur commonly in RSSIs and may be associated with infarct volume and SVD score. Hemosiderin "rim" is common in RSSIs, urging caution to avoid mistaking ischemic RSSI for primary hemorrhage in subacute and chronic stages.

MRI differentiation of CNS fungal infections: correlating imaging features with microbiological and histopathological findings.

The study aims to evaluate the magnetic resonance (MR) features of central nervous system (CNS) fungal infections and determine the associations between these findings and the type of fungus. Our main objective was to assess whether imaging can serve as a predictor for identifying the specific group of fungi responsible for the infection using microbiology and histopathology as a benchmark. A retrospective analysis was done on 50 patients with proven CNS fungal infections. Fungal type was determined and grouped according to microbial classifications into four subtypes: hyalohyphomycetes, mucorales, yeasts and dematiaceous molds. MR findings were compared with histopathology/microbiology and associations between fungal groups were sought. A total of 37 males and 13 females with a mean age of 39.3 years were included in the study. Aspergillus spp. infection (48%) was the most common. Most patients (54%) had an underlying risk factor for the infection. Pseudo-tumoral mass-like behavior was observed with Aspergillus, and the presence of meningitis was associated with yeast infections (p < 0.001). Of the 19 abscesses, 9 (47.3%) showed a dual rim sign on susceptibility-weighted imaging (SWI), and 10 (52.6%) showed intracavitary dot-like foci of dropouts on SWI. Both findings were statistically significant with dematiaceous molds (p = 0.04 and p = 0.009, respectively). Although radiological characteristics are non-specific and can overlap with each type of fungi, our study shows that certain MR features can help radiologists point towards the causative type. More specifically, dot-like foci of susceptibility point towards abscesses caused by dematiaceous molds possibly owing to melanin pigment and metal chelation properties.

Unveiling connections between venous disruption and cerebral small vessel disease using diffusion tensor image analysis along perivascular space (DTI-ALPS): A 7-T MRI study.

Cerebral venous disruption is one of the characteristic findings in cerebral small vessel disease (CSVD), and its disruption may impede perivascular glymphatic drainage. And lower diffusivity along perivascular space (DTI-ALPS) index has been suggested to be with the presence and severity of CSVD. However, the relationships between venous disruption, DTI-ALPS index, and CSVD neuroimaging features remain unclear. To investigate the association between venous integrity and perivascular diffusion activity, and explore the mediating role of DTI-ALPS index between venous disruption and CSVD imaging features. In this cross-sectional study, 31 patients (mean age, 59.0 ± 9.9 years) were prospectively enrolled and underwent 7-T magnetic resonance (MR) imaging. DTI-ALPS index was measured to quantify the perivascular diffusivity. The visibility and continuity of deep medullary veins (DMVs) were evaluated based on a brain region-based visual score on high-resolution susceptibility-weighted imaging. White matter hyperintensity (WMH) and perivascular space (PVS) were assessed using qualitative and quantitative methods. Linear regression and mediation analysis were performed to analyze the relationships among DMV scores, DTI-ALPS index, and CSVD features. The DTI-ALPS index was significantly associated with the parietal DMV score (β = -0.573, p corrected = 0.004). Parietal DMV score was associated with WMH volume (β = 0.463, p corrected = 0.013) and PVS volume in basal ganglia (β = 0.415, p corrected = 0.028). Mediation analyses showed that DTI-ALPS index manifested a full mediating effect on the association between parietal DMV score and WMH (indirect effect = 0.115, Pm = 43.1%), as well as between parietal DMV score and PVS volume in basal ganglia (indirect effect = 0.161, Pm = 42.8%). Cerebral venous disruption is associated with glymphatic activity, and with WMH and PVS volumes. Our results suggest cerebral venous integrity may play a critical role in preserving perivascular glymphatic activity; while disruption of small veins may impair the perivascular diffusivity, thereby contributing to the development of WMH and PVS enlargement.

Multiple Susceptibility-Weighted Imaging Hypointensities in Intravascular Large B-Cell Lymphoma.

Multiple Susceptibility-Weighted Imaging Hypointensities in Intravascular Large B-Cell Lymphoma.

A Minimalist Iron Oxide Nanoprobe for the High-Resolution Depiction of Stroke by Susceptibility-Weighted Imaging.

The precise mapping of collateral circulation and ischemic penumbra is crucial for diagnosing and treating acute ischemic stroke (AIS). Unfortunately, there exists a significant shortage of high-sensitivity and high-resolution in vivo imaging techniques to fulfill this requirement. Herein, a contrast enhanced susceptibility-weighted imaging (CE-SWI) using the minimalist dextran-modified Fe3O4 nanoparticles (Fe3O4@Dextran NPs) are introduced for the highly sensitive and high-resolution AIS depiction under 9.4 T for the first time. The Fe3O4@Dextran NPs are synthesized via a simple one-pot coprecipitation method using commercial reagents under room temperature. It shows merits of small size (hydrodynamic size 25.8nm), good solubility, high transverse relaxivity (r2) of 51.3 mM-1s-1 at 9.4 T, and superior biocompatibility. The Fe3O4@Dextran NPs-enhanced SWI can highlight the cerebral vessels readily with significantly improved contrast and ultrahigh resolution of 0.1mm under 9.4 T MR scanner, enabling the clear spatial identification of collateral circulation in the middle cerebral artery occlusion (MCAO) rat model. Furthermore, Fe3O4@Dextran NPs-enhanced SWI facilitates the precise depiction of ischemia core, collaterals, and ischemic penumbra post AIS through matching analysis with other multimodal MR sequences. The proposed Fe3O4@Dextran NPs-enhanced SWI offers a high-sensitivity and high-resolution imaging tool for individualized characterization and personally precise theranostics of stroke patients.

Toward Automated Detection of Microbleeds with Anatomical Scale Localization Using Deep Learning

Cerebral Microbleeds (CMBs) are chronic deposits of small blood products in the brain tissues, which have explicit relation to various cerebrovascular diseases depending on their anatomical location, including cognitive decline, intracerebral hemorrhage, and cerebral infarction. However, manual detection of CMBs is a time consuming and error-prone process because of their sparse and tiny structural properties. The detection of CMBs is commonly affected by the presence of many CMB mimics that cause a high false-positive rate (FPR), such as calcifications and pial vessels. This paper proposes a novel 3D deep learning framework that not only detects CMBs but also identifies their anatomical location in the brain (i.e., lobar, deep, and infratentorial regions). For the CMBs detection task, we propose a single end-to-end model by leveraging the 3D U-Net as a backbone with Region Proposal Network (RPN). To significantly reduce the false positives within the same single model, we develop a new scheme, containing Feature Fusion Module (FFM) that detects small candidates utilizing contextual information and Hard Sample Prototype Learning (HSPL) that mines CMB mimics and generates additional loss term called concentration loss using Convolutional Prototype Learning (CPL). For the anatomical localization task, we exploit the 3D U-Net segmentation network to segment anatomical structures of the brain. This task not only identifies to which region the CMBs belong but also eliminates some false positives from the detection task by leveraging anatomical information. We utilize Susceptibility-Weighted Imaging (SWI) and phase images as 3D input to efficiently capture 3D information. The results show that the proposed RPN that utilizes the FFM and HSPL outperforms the baseline RPN and achieves a sensitivity of 94.66% vs. 93.33% and an average number of false positives per subject (FPavg) of 0.86 vs. 14.73. Furthermore, the anatomical localization task enhances the detection performance by reducing the FPavg to 0.56 while maintaining the sensitivity of 94.66%.

Automatic segmentation and diameter measurement of deep medullary veins.

As one of the pathogenic factors of cerebral small vessel disease, venous collagenosis may result in the occlusion or stenosis of deep medullary veins (DMVs). Although numerous DMVs can be observed in susceptibility-weighted MRI images, their diameters are usually smaller than the MRI resolution, making it difficult to segment them and quantify their sizes. We aim to automatically segment DMVs and measure their diameters from gradient-echo images. A neural network model was trained for DMV segmentation based on the gradient-echo magnitude and phase images of 20 subjects at 7 T. The diameters of DMVs were obtained by fitting measured complex images with model images that accounted for the DMV-induced magnetic field and point spread function. A phantom study with graphite rods of different diameters was conducted to validate the proposed method. Simulation was carried out to evaluate the voxel-size dependence of measurement accuracy for a typical DMV size. The automatically segmented DMV masks had Dice similarity coefficients of 0.68 ± 0.03 (voxel level) and 0.83 ± 0.04 (cluster level). The fitted graphite-rod diameters closely matched their true values. In simulation, the fitted diameters closely matched the true value when voxel size was ≤ 0.45 mm, and 92.2% of DMVs had diameters between 90 μm and 200 μm with a peak at about 120 μm, which agreed well with an earlier ex vivo report. The proposed methods enabled efficient and quantitative study of DMVs, which may help illuminate the role of DMVs in the etiopathogenesis of cerebral small vessel disease.

Chronic active lesions preferentially localize in watershed territories in multiple sclerosis.

Paramagnetic rim lesions (PRLs) are a biomarker of chronic active lesions (CALs), and an important driver of neurological disability in multiple sclerosis (MS). The reason subtending some acute lesions evolvement into CALs is not known. Here we ask whether a relatively lower oxygen content is linked to CALs. In this prospective cross-sectional study, 64 people with multiple sclerosis (PwMS), clinically isolated syndrome and radiologically isolated syndrome underwent a 7.0 Tesla (7 T) brain magnetic resonance imaging (MRI). The scanning protocol included a T2-w fluid-attenuated inversion recovery (FLAIR), and a single echo gradient echo from which susceptibility-weighted imaging (SWI) was derived. WM lesions were identified on the T2-w-FLAIR whilst PRLs were identified on the SWI sequence. T2-lesions were classified as PRLs and rimless lesions (PRLs-). We registered a universal vascular atlas to each subject's T2-w-FLAIR and classified each T2-lesions according to its location into watershed- (ws), non-watershed- (nws), and mixed-lesion (m). Ws-lesions were defined as lesions that were fully located in a region between the territories of two major arteries. Out of 1,975 T2-lesions, 88 (4.5%) were PRLs. Ws-regions had a higher number (p = 0.005) and proportion (p < 0.001) of PRLs- compared to nws-regions. Ws-PRL- were larger compared to nws-ones (p = 0.009). The number (p = 0.043) and proportion (p < 0.001) of PRLs was higher in ws-regions compared to nws-ones. Ws-PRLs were not significantlylarger than nws-ones (p = 0.195). We propose the novel concept of a link between arterial vascularization and chronic activity in MS by demonstrating a preferential localization of CALs in ws-territories.

A Wearable, Steerable, Transcranial Low-Intensity Focused Ultrasound System.

Transcranial low-intensity focused ultrasound (LIFU) offers unique opportunities for precisely neuromodulating small and/or deep targets within the human brain, which may be useful for treating psychiatric and neurological disorders. This article presents a novel ultrasound system that delivers focused ultrasound through the forehead to anterior brain targets and evaluates its safety and usability in a volunteer study. The ultrasound system and workflow are described, including neuronavigation, LIFU planning, and ultrasound delivery components. Its capabilities are analyzed through simulations and experiments in water to establish its safe steering range. A cohort of 20 healthy volunteers received a LIFU protocol aimed at the anterior medial prefrontal cortex (amPFC), using imaging and questionnaires to screen for adverse effects. Additional development after the study also analyzes the effect of the skull and sinus cavities on delivered ultrasound energy. Simulations and hydrophone readings agreed with <5% error, and the safe steering range was found to encompass a 1.8 cm × 2.5 cm × 2 cm volume centered at a depth 5 cm from the surface of the skin. There were no adverse effects evident on qualitative assessments, nor any signs of damage in susceptibility-weighted imaging scans. All participants tolerated the treatment well. The interface effectively enabled the users to complete the workflow with all participants. In particular, the amPFC of every participant was within the steering limits of the system. A post hoc analysis showed that "virtual fitting" could aid in steering the beams around subjects' sinuses. The presented system safely delivered LIFU through the forehead while targeting the amPFC in all volunteers, and was well-tolerated. With the capabilities validated here and positive results of the study, this technology appears well-suited to explore LIFU's efficacy in clinical neuromodulation contexts.

Automated quantification of cerebral microbleeds in susceptibility-weighted MRI: association with vascular risk factors, white matter hyperintensity burden, and cognitive function.

To train and validate a deep learning (DL)-based segmentation model for cerebral microbleeds (CMB) on susceptibility-weighted MRI; and to find associations between CMB, cognitive impairment, and vascular risk factors. Participants in this single-institution retrospective study underwent brain MRI to evaluate cognitive impairment between January-September 2023. For training the DL model, the nnU-Net framework was used without modifications. The DL model's performance was evaluated on independent internal and external validation datasets. Linear regression analysis was used to find associations between log-transformed CMB numbers, cognitive function (mini-mental status examination [MMSE]), white matter hyperintensity (WMH) burden, and clinical vascular risk factors (age, sex, hypertension, diabetes, lipid profiles, and body mass index). Training of the DL model (n = 287) resulted in a robust segmentation performance with an average dice score of 0.73 (95% CI, 0.67-0.79) in an internal validation set, (n = 67) and modest performance in an external validation set (dice score = 0.46, 95% CI, 0.33-0.59, n = 68). In a temporally independent clinical dataset (n = 448), older age, hypertension, and WMH burden were significantly associated with CMB numbers in all distributions (total, lobar, deep, and cerebellar; all P <.01). MMSE was significantly associated with hyperlipidemia (β = 1.88, 95% CI, 0.96-2.81, P <.001), WMH burden (β = -0.17 per 1% WMH burden, 95% CI, -0.27-0.08, P <.001), and total CMB number (β = -0.01 per 1 CMB, 95% CI, -0.02-0.001, P = .04) after adjusting for age and sex. The DL model showed a robust segmentation performance for CMB. In all distributions, CMB had significant positive associations with WMH burden. Increased WMH burden and CMB numbers were associated with decreased cognitive function. CMB = cerebral microbleed; DL = deep learning, DSC = dice similarity coefficient; MMSE = mini-mental status examination; SVD = small vessel disease; SWI = susceptibility-weighted image; WMH = white matter hyperintensity.

Update on management of cerebral venous thrombosis.

This review intends to systematize the diagnostic and treatment approach to cerebral venous thrombosis (CVT), highlighting key studies that have been recently published. In light of the recent pandemic, new risk factors for CVT have emerged. Contrast-enhanced MRI and susceptibility-weighted imaging have been shown to offer increased sensitivity for detecting cortical vein thrombosis.Dabigatran seems to be as effective and well tolerated as warfarin for long-term anticoagulation. Partial venous recanalization often occurs in patients treated with anticoagulation only, as early as 8 days after treatment onset. For patients with CVT and impending brain herniation, two-thirds of those who undergo decompressive craniectomy survive, with one-third being functionally independent 6 months after diagnosis. CVT is an unusual type of cerebrovascular disease that mostly affects women of fertile age. Risk factors should be identified and addressed. Diagnosis relies on confirmation of venous sinus and/or vein thrombosis, usually by CT venography or MRI. Anticoagulation is the cornerstone of treatment. Despite the lack of high-quality evidence, endovascular treatment is often considered in severe cases. Special populations require tailored approaches. About 80% achieve mRS 0-1, but residual symptoms often affect quality of life and the ability to return to work.

Comparative Efficacy of MRI and CT in Traumatic Brain Injury: A Systematic Review.

Traumatic brain injury (TBI) is a leading cause of mortality and long-term disability worldwide, and accurate imaging is essential for effective diagnosis, management, and prognosis. This systematic review evaluates the diagnostic capabilities of magnetic resonance imaging (MRI) compared to computed tomography (CT) in assessing TBI across various severities. Through a comprehensive search strategy, studies were selected that directly compared MRI and CT in TBI diagnosis, incorporating advanced MRI techniques such as susceptibility-weighted imaging and fluid-attenuated inversion recovery. The findings confirm that while CT is indispensable in acute settings for the rapid identification of life-threatening conditions such as hemorrhage and skull fractures, MRI offers superior sensitivity for detecting subtle lesions, microbleeds, and diffuse axonal injury. MRI techniques, including magnetic resonance spectroscopy, demonstrated the ability to detect metabolic changes in normal-appearing white matter, which were predictive of long-term neurological outcomes. Additionally, the integration of biomarkers, such as imaging modalities, showed the potential to improve diagnostic accuracy and reduce unnecessary CT scans. Despite the limitations related to study heterogeneity and the exclusion of non-English studies, this review underscores the complementary roles of MRI and CT in TBI management, suggesting that a combined approach can provide the most thorough assessment and improve patient outcomes. Future research should focus on large-scale trials to further refine the clinical application of these imaging modalities.

Phenotyping in vivo chronic inflammation in multiple sclerosis by combined 11C-PBR28 MR-PET and 7T susceptibility-weighted imaging

Background: 11C-PBR28 positron emission tomography (PET), targeting the translocator protein, and paramagnetic rim lesions (PRL) have emerged as promising imaging markers of MS chronic inflammation. No consensus on which is the optimal marker exists. Objectives: To investigate the ability of 11C-PBR28 PET and PRL assessment to identify chronic inflammation in white matter (WM) MS lesions and their relation to neurological impairment. Methods: Based on 11C-PBR28 uptake, brain WM lesions from 30 MS patients were classified as PET active or inactive. The PRL presence was assessed on 7T phase reconstructions, T1/T2 ratio was calculated to measure WM microstructural integrity. Results: Less than half (44%) of non-PRL WM lesions were active on 11C-PBR28 imaging either throughout the lesion (whole active) or at its periphery. PET peripherally active lesions and PRL did not differ in T1/T2 ratio and 11C-PBR28 uptake. A positive correlation was observed between PRL and active PET lesion count. Whole active PET lesion volume was the strongest predictor (β = 0.97, p < 0.001) of increased Expanded Disability Status Scale scores. Conclusion: 11C-PBR28 imaging reveals more active WM lesions than 7T PRL assessment. Although PRL and PET active lesion counts are related, neurological disability is better explained by PET whole active lesion volume.