Susceptibility-weighted Imaging Research Articles

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.

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.

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

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. 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. 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. 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. 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.

Deep medullary vein abnormalities impact white matter hyperintensity volume through increases in interstitial free water

BackgroundOur intent was to explore the mediating role of interstitial free water (FW) linking deep medullary vein (DMV) score to white matter hyperintensity (WMH) volume.MethodsOur research team conducted a forward-looking analysis of initial clinical and imaging information gathered from 125 patients with cerebral small vessel disease. We identified six anatomic DMV regions on susceptibility weighted imaging (SWI) studies. Each region earned a score of 0–3, determined by the visual conditions of vessels, summing all six to generate a DMV score. We utilized fluid-attenuated inversion recovery (FLAIR) sequences to measure the volume of WMH. Additionally, we employed diffusion tensor imaging (DTI) to assess FW value.ResultsDMV score significantly positively correlated with FW value and with WMH volume (p < 0.05), and value of FW positively correlated with WMH volume (p < 0.05). The indirect effect of DMV score on WMH volume was mediated by FW (β = 0.281, 95% confidence interval [CI]: 0.178–0.388), whether adjusted for age and gender (β = 0.142, 95% CI: 0.058–0.240) or for age, gender and vascular risk factors (β = 0.141, 95% CI: 0.054–0.249).ConclusionDMV score correlate with WMH volume by virtue of FW increases in white matter.

Relationship between radiation dose and cerebral microbleed formation in dogs with intracranial tumors.

Cerebral microbleeds (CMBs) are a possible sequela in human brain tumor patients treated with radiation therapy (RT). No such association is reported in dogs. To investigate whether CMBs occur in dogs after radiotherapy, and if there is an association between number and dose, and an increase over time. Thirty-four client-owned dogs irradiated for primary intracranial neoplasia. ≥2 magnetic resonance imaging (MRI) scans including susceptibility-weighted imaging (SWI) were required. Retrospective, observational, single-center study. Cerebral microbleeds identified on 3 T SWI were counted within the entire brain, and within low- (<20 Gy), intermediate- (20-30 Gy), and high- (>30 Gy) dose regions. A generalized linear mixed-effects model was used to analyze the relationship between the CMBs count and the predictor variables (irradiation dose, time after treatment). Median follow-up time was 12.6 months (range, 1.8-37.6 months). Eighty-three MR scans were performed. In 4/15 dogs (27%, 95% CI, 10%-52%) CMBs were present at baseline. ≥1 CMBs after RT were identified in 21/34 dogs (62%, 95% CI, 45%-77%). With each month, the number of CMBs increased by 14% (95% CI, 11%-16%; P < .001). The odds of developing CMBs in the high-dose region are 4.7 times (95% CI, 3.9-5.6; P < .001) greater compared with the low-dose region. RT is 1 possible cause of CMBs formation in dogs. Cerebral microbleeds are most likely to occur in the peritumoral high-dose volume, to be chronic, and to increase in number over time. Their clinical relevance remains unknown.

Susceptibility-Weighted Imaging for Differentiating Intracranial Calcification and Hemosiderin: A Comparative Study with CT

Background: Magnetic resonance imaging (MRI) is an essential diagnostic modality for evaluating various tissue types, but distinguishing between substances such as calcification and hemosiderin remains challenging due to their similar appearances on conventional MRI sequences. Susceptibility-weighted imaging (SWI) improves tissue contrast by incorporating phase information, potentially enhancing the accuracy of differentiating these substances. This study aims to assess the effectiveness of SWI, specifically the filtered phase image, in comparison with computed tomography (CT), which is considered the gold standard for calcification detection. Methods: A retrospective analysis was conducted on 35 patients, aged 50-80 years, who presented with confirmed cases of intracranial calcification or hemosiderin deposits. MRI was performed on a 1.5-tesla Siemens Essenza Magnetom using SWI sequences, including both phase and magnitude images. CT scans were obtained using a GE Optima 660 scanner. The study focused on 17 cases of calcification identified by both SWI and CT, and 18 cases of hemosiderin deposits detected by SWI. Statistical analysis was performed using Pearson correlation coefficients to evaluate the relationship between MRI and CT measurements. Results: The study revealed a strong correlation between CT and SWI in detecting calcifications, with a significant agreement in the measurement of calcification size. However, while phase and magnitude images demonstrated a strong correlation with one another, the filtered phase image did not show a significant correlation with hemosiderin size, suggesting limitations in its application for detecting hemosiderin deposits. CT scans confirmed calcification with Hounsfield units exceeding 100, while hemosiderin deposits were more effectively identified through SWI, which provided enhanced contrast without the use of ionizing radiation. Conclusion: SWI, particularly the filtered phase image, is a reliable and sensitive tool for detecting intracranial calcification, offering high accuracy compared to CT. While SWI proves effective in distinguishing calcification, further research is needed to optimize its use for detecting hemosiderin deposits. This study underscores the non-ionizing advantages of SWI over CT, advocating for its potential as a safer and equally effective alternative in clinical imaging.

Feasibility of Hologram-Assisted Bilateral Blood-Brain Barrier Opening in Non-Human Primates.

Focused ultrasound (FUS) and microbubbles facilitate blood-brain barrier opening (BBBO) noninvasively, transiently, and safely for targeted drug delivery. Unlike state-of-the-art approaches, in this study, we demonstrate for the first time the simultaneous, bilateral BBBO in non-human primates (NHPs) using acoustic holograms at caudate and putamen structures. The simple and low-cost system with a single-element FUS transducer and 3-D printed acoustic hologram was guided by neuronavigation and a robotic arm. The advantages of holograms are transcranial aberration correction, simultaneous multifocus and high localization, and target-independent transducer positioning, defining a promising alternative for time- and cost-efficient FUS procedures. Holograms were designed with the k-space method by time-reversal techniques. T1-weighted MRI was used for treatment planning, while the computed tomography (CT) scan provided the head tissues acoustic properties. For the BBBO procedure, a robotic arm allowed transducer positioning errors below 0.1 mm and 0.1°. Following positioning, 0.5-0.6-MPa, 513-kHz microbubble-enhanced FUS was applied for 4 min. For BBBO assessment, Post-FUS T1-weighted MRI was acquired, and contrast enhancement indicated bilateral gadolinium extravasation at both caudate or putamen structures. The two BBBO locations were separated by 13.13 mm with a volume of 91.81 mm3 in the caudate, compared with 9.40 mm with a volume of 124.52 mm3 in simulation, while they were separated by 21.74 mm with a volume of 145.38 mm3 in the putamen and compared with 22.32 mm with a volume of 156.42 mm3 in simulation. No neurological damage was observed through T2-weighted and susceptibility-weighted imaging. This study demonstrates the feasibility and safety of hologram-assisted neuronavigation-guided-FUS for BBBO in NHP, providing thus an avenue for clinical translation.

The Sensitivity and Specificity of Susceptibility Weighted Imaging Phase (Swip) in Detecting Intracranial Large Artery Calcium Stenosis Compared to Cone Beam CT

Introduction: Intracranial calcifications are common and often associated with advanced stages of atherosclerosis. Studies estimating the prevalence of intracranial calcifications using other imaging modalities are common, however, studies comparing the diagnostic accuracies of cone-beam computed tomography (CBCT) and susceptibility-weighted imaging (SWI) and generated scoring systems for SWI are not well established. Aims: The objectives of the present study are to identify locations of intracranial calcifications; estimate the sensitivity and specificity rates for each intracranial vessel and each modality; estimate the sensitivity and specificity rates for diagnosing each grade of stenosis for each modality; and generate cutoff value for predicting each grade of intracranial stenosis and for each modality; as well as to develop a scoring system for estimating intracranial stenosis using SWI. Material and Methods: The study employs a prospective cross-sectional study design to collect brain data from 146 stroke patients who had initially undergone CBCT and SWI examinations. Data were collected using pro forma from January 2021 to December 2022 at Hospital Pengajar Universiti Putra Malaysia. Results: The results show an estimated prevalence of intracranial calcification of 87.7% and 92.5% for CBCT and SWI respectively. Regarding intracranial calcium grades, the prevalence of minimum – mild, moderate, and severe grade stenosis were 18.5%, 58,9%, and 10.3% respectively for CBCT and 2.7%, 33.8%, and 57.5% for SWI. Further, the results revealed that CBCT attained a sensitivity of 100% for the anterior cerebral artery, 71% for the middle cerebral artery, and 100% for the vertebral artery as well as a specificity of 90%, 80%, and 42% for the anterior cerebral artery, middle cerebral artery, and vertebral artery respectively. However, with the SWI modality, basilar, vertebral, and middle cerebral arteries reached a sensitivity of 90%, 63%, and 87% and a specificity of 82%, 95%, and 59%. Conclusion: In conclusion, both CBCT and SWI demonstrate reliable means of detecting intracranial calcifications and vessel stenosis with SWI outperforming CBCT.

A Novel Detection and Classification Framework for Diagnosing of Cerebral Microbleeds Using Transformer and Language.

The detection of Cerebral Microbleeds (CMBs) is crucial for diagnosing cerebral small vessel disease. However, due to the small size and subtle appearance of CMBs in susceptibility-weighted imaging (SWI), manual detection is both time-consuming and labor-intensive. Meanwhile, the presence of similar-looking features in SWI images demands significant expertise from clinicians, further complicating this process. Recently, there has been a significant advancement in automated detection of CMBs using a Convolutional Neural Network (CNN) structure, aiming at enhancing diagnostic efficiency for neurologists. However, existing methods still show discrepancies when compared to the actual clinical diagnostic process. To bridge this gap, we introduce a novel multimodal detection and classification framework for CMBs' diagnosis, termed MM-UniCMBs. This framework includes a light-weight detection model and a multi-modal classification network. Specifically, we proposed a new CMBs detection network, CMBs-YOLO, designed to capture the salient features of CMBs in SWI images. Additionally, we design an innovative language-vision classification network, CMBsFormer (CF), which integrates patient textual descriptions-such as gender, age, and medical history-with image data. The MM-UniCMBs framework is designed to closely align with the diagnostic workflow of clinicians, offering greater interpretability and flexibility compared to existing methods. Extensive experimental results show that MM-UniCMBs achieves a sensitivity of 94% in CMBs' classification and can process a patient's data within 5 s.

Brain microbleeds resulting from presumed extensive fat emboli in a patient with bone marrow necrosis following a sickle cell disease vaso-occlusive crisis.

Acute manifestations of sickle cell disease (SCD) are numerous and multisystemic.Cerebral fat embolism (CFE) is a rare but serious complication of SCD caused by bone marrow necrosis (BMN) during vaso-occlusive crises (VOC). We present the case of a41-year-old man with SCD who developed severe VOC and multi-organ dysfunction.He subsequently experienced neurological deterioration with decreased consciousness and diffuse encephalopathy on serial electroencephalograms. Bone marrow aspiration confirmed BMN. Brain MRI revealed extensive diffuse leukoencephalopathy, vasogenic and cytotoxic edema in the white matter, patchy edema in the cranial vault bone marrow on fat-suppressed FLAIR sequence (a finding consistent with the confirmed BMN), and multiple cerebral microbleeds on susceptibility-weighted imaging consistent with CFE. The management of acute neurological complications of SCD varies depending on the specific complication. Brain MRI plays a crucial role in the accurate diagnosis of these complications to guide appropriate treatment.

Logistic regression model for predicting risk factors and contribution of cerebral microbleeds using renal function indicators.

The brain and kidneys share similar low-resistance microvascular structures, receiving blood at consistently high flow rates and thus, are vulnerable to blood pressure fluctuations. This study investigates the causative factors of cerebral microbleeds (CMBs), aiming to quantify the contribution of each risk factor by constructing a multivariate model via stepwise regression. A total of 164 hospitalized patients were enrolled from January 2022 to March 2023 in this study, employing magnetic susceptibility-weighted imaging (SWI) to assess the presence of CMBs. The presence of CMBs in patients was determined by SWI, and history, renal function related to CMBs were analyzed. Out of 164 participants in the safety analysis, 36 (21.96%) exhibited CMBs and 128 (78.04%) did not exhibit CMBs, and the median age of the patients was 66 years (range: 49-86 years). Multivariate logistic regression identified hypertension (OR = 13.95%, 95% CI: 4.52, 50.07%), blood urea nitrogen (BUN) (OR = 1.57, 95% CI: 1.06-2.40), cystatin C (CyC) (OR = 4.90, 95% CI: 1.20-22.16), and urinary β-2 microglobulin, (OR = 2.11, 95% CI: 1.45-3.49) as significant risk factors for CMBs. The marginal R-square ( ) was 0.25. Among all determinants, hypertension (47.81%) had the highest weight, followed by UN (11.42%). Quasi-curves plotted using the bootstrap method (999 times) showed good agreement between the predictive model and actual observations. Hypertension, BUN, urinary β-2 microglobulin, CyC were risk factors for CMBs morbidity, and controlling the above indicators within a reasonable range will help to reduce the incidence of CMBs.

Differentiating calcifications from cerebral microbleeds using quantitative susceptibility mapping.

To differentiate cerebral microbleeds (CMBs) and calcifications using quantitative susceptibility mapping (QSM). CMBs were visualized and located using QSM from susceptibility-weighted imaging data collected on a 3-T MR scanner. Calcifications of the pineal gland and the choroid plexus were localized first using CT. All calcifications and CMBs were assessed using QSM to evaluate their magnetic susceptibility. The distribution of the magnetic susceptibility for the CMBs was determined and the CT attenuation was correlated with the mean magnetic susceptibility for the calcifications. A total of 232 hypointense foci were selected from the QSM data: 121 were CMBs and 111 were calcifications. The mean magnetic susceptibility was -214 ± 112 ppb for the calcifications and 392 ± 204 ppb for the CMBs. The minimum value of magnetic susceptibility was 75 ppb for all the CMBs and the maximum value was -52 ppb for all the calcifications. The calcifications were clearly differentiable from the CMBs from the sign alone (p < 0.001). The magnetic susceptibility for the CMBs was 299 ± 133 ppb in the lobar subcortical white matter and 499 ± 220 ppb for deep CMBs in the basal ganglia, thalamus, and brainstem. There was a significant difference in the susceptibility between these two regions (p < 0.001). The sign of the magnetic susceptibility was sufficient to differentiate calcifications and CMBs. The concentration of calcium or iron can be determined from the susceptibility value itself. The deep CMBs had higher susceptibility on average than lobar bleeds. This study's ability to differentiate between CMBs and calcifications using QSM could enhance diagnostic accuracy, guiding more precise treatment decisions for stroke or tumor patients. The sign of magnetic susceptibility is sufficient to differentiate calcifications and CMBs. QSM can successfully differentiate calcifications from microbleeds. The concentration of calcium or iron can be determined from the susceptibility value itself.

HTRA1-related cerebral small-vessel disease causes cerebral microbleeds on the brainstem surface

Background and objectivesCerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy (CARASIL) has recently been known as HTRA1-related cerebral small-vessel disease (CSVD), it is caused by variants in HTRA1. Recently, it has been reported to develop in heterozygotes with some variants of the gene. Multiple prospective studies have reported that the frequency of heterozygous HTRA1 variants developing CSVD is 2 - 6.5 % in CARASIL. Heterozygous variant cases lack unique clinical features, have an older age of onset, and are difficult to detect. Characteristic findings are required to identify such cases. MethodMagnetic resonance imaging (MRI) images of cases that experienced cerebral infarction and carried heterozygous variants in HTRA1 were reviewed. ResultsFour cases of heterozygous HTRA1-related CSVD in two families (Family 1: c.754G > A, p.A252T; three males. Family 2: c.497G > T, p.R166L, one female). In all cases, white matter lesions with lacunar infarcts were observed in the periventricular and basal ganglia, external capsule, and brainstem. Moreover, T2 star weighted image (T2*WI) low presented dot-like lesions were present along the surface of the brainstem, which have only been reported in one homozygous case. Susceptibility-weighted imaging (SWI) was performed in two cases, and the dot-like lesions on T2*WI resembled a pearly tiara along the surface of the brainstem. ConclusionBrainstem surface on T2*WI low showed dot-like lesions, which are not generally observed in patients with stroke and can be characteristic of HTRA1-CSVD associated with heterozygous variant. The pathology requires further investigation for diagnosis.

Microhemorrhages in diquat-induced encephalopathy identified using susceptibility-weighted imaging

Introduction Intracerebral bleeding that predominantly affects the pons, midbrain, cerebral peduncle, basal ganglia, and thalamus may occur in severe diquat poisoning. We employed magnetic resonance-susceptibility-weighted imaging to highlight the presence of microhemorrhages in a patient with diquat poisoning. Case summary: A 15-year-old female patient presented with kidney and liver damage after ingesting diquat. Three days later, she developed coma. She received seven sessions of hemoperfusion and was discharged with residual cognitive impairment and right limb muscle weakness after 66 days of hospitalization. Images: Cranial computed tomography on day 5 and magnetic resonance imaging on day 8 revealed swelling in the pons, midbrain, and thalamus without evidence of hemorrhage. However, susceptibility-weighted imaging on day 8 demonstrated multiple punctate low signals, suggesting the presence of microhemorrhages. Conclusion Susceptibility-weighted imaging is a useful technique for detecting microhemorrhages in patients with diquat-induced encephalopathy, as microhemorrhages are often not detectable on computed tomography or conventional magnetic resonance imaging.

Comparing the imaging characteristics of middle-aged patients with multiple sclerosis and CADASIL: A retrospective cross-sectional study

BackgroundFew studies have quantitatively analyzed the imaging disparities between multiple sclerosis (MS) and cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). We aimed to compare the imaging characteristics of MS and CADASIL in middle-aged patients. Materials and MethodsThis retrospective study used a single-center database and included patients aged 40–60 years with MS and CADASIL who underwent the designated imaging protocol including 3D T1-weighted imaging and fluid attenuated inversion recovery (FLAIR), diffusion tensor imaging and susceptibility-weighted imaging between January 2018 and March 2023. Patients with MRI-detected macrobleeds were excluded. ResultsA total of 27 patients with MS (mean age, 46.7 years ± 4.4, 8 men) and 30 patients with CADASIL (mean age, 51.6 years ± 5.8, 14 men) were included. No significant differences were observed in the Fazekas grades of white matter lesions (WMLs). Patients with CADASIL exhibited greater external capsule involvement (56.7% vs.18.5 %; p = 0.006), whereas the MS group had more lesions in the corpus callosum (81.5% vs. 53.3 %, p = 0.02) and brainstem (74.1% vs. 46.7 %, p = 0.04). The CADASIL group exhibited a higher incidence of microbleeds (12.07 vs. 0.11, p = 0.001). The WMLs in the MS group exhibited a lower T1 lesion/cerebrospinal fluid signal index (2.206 vs. 2.882, p < 0.001). A value of ≤2.57 demonstrated a sensitivity of 92.6 % and a specificity of 90.0 % in differentiating MS. Patients with MS had a thinner corpus callosum (7.18 mm vs 7.86 mm, p = 0.04), while patients with CADASIL showed significantly higher mean diffusivity (0.8776 × 10–3 vs. 0.7637 × 10–3 mm2/s, p = 0.03) and lower fractional anisotropy (0.7581 vs. 0.8389, p = 0.04) in the splenium of the corpus callosum. ConclusionMiddle-aged patients with MS and CADASIL showed comparable Fazekas grades for WMLs. However, lesion distribution, T1 signal characteristics, and splenic diffusivity changes can help differentiate between MS and CADASIL.