Hypointense Signal Research Articles

Is mitral annular disjunction always dangerous - the brighter side of MAD

Abstract Background Mitral valve prolapse (MVP) is a common problem affecting 1 - 3% of the adults. There have been published several reports of life-threatening ventricular arrhythmias (VA) in patients with MVP (known as arrhythmogenic MVP – AMVP), in which the presence, severity, and possible consequences of mitral annular disjunction (MAD) could have an adverse arrhythmogenic effect. However, the unequivocal arrhythmic potential of MAD is controversial, while MAD presence is described even in healthy hearts without MVP. The purpose of our study was to assess the relationship between MAD and potentially arrhythmogenic morphological parameters of the left ventricle in the non-selected patients referred for CMR examination. Methods Sixty-two patients with MAD detection in CMR (Siemens Magnetom 1.5T Sola i Area; Siemens Syngovia, Medviso Segment Classic) were enrolled into the study. In every patient late gadolinium enhancement (LGE), extracellular volume (ECV) and darkPAP presence (a relatively hypointensive systolic signal of papillary muscles) as potentially arrhythmogenic substrates of VA were analyzed. Additionally, all patients underwent echocardiography (VIVID E94 GE Healthcare) with particular assessment of tissue doppler and speckle tracking analysis parameters. Results Patients with MVP (+) were characterized by higher mitral annular S' velocity, post systolic dispersion (PSD) index, bigger size of MAD in posterior, inferior and lateral walls, and significantly more frequent occurrence of darkPAP (known as modern, intensively studied potentially arrhythmogenic parameter); however, they did not differ in global longitudinal strain (GLS) and LGE presence from MVP (-) patients (Table 1). Patients with darkPAP apperance were significantly more likely to have MVP, Pickelhaube sign occurence, and greater walls covered by MAD, but also a higher level of general ECV. LGE in papillary muscles did not differ both of those groups (Table 2). Conclusions The process of formation of arrhythmia foci in AMVP patients seems to be gradual and consists of many stages. In patients with MVP and MAD occurence, formation of arrhythmogenic substrate precede discrete changes which could be observed in CMR examination.

Brain tissue integrity in neuromyelitis optica spectrum disorder through T1-w/T2-w ratio, MTR and DTI.

The presence of diffuse brain damage in normal-appearing white matter (NAWM) and gray matter (NAGM) in neuromyelitis optica spectrum disorder (NMOSD) remains controversial. We aimed to address this controversy by applying a multiparametric MRI approach. Additionally, the association between MRI metrics and clinical variables was explored. In this cross-sectional study, we prospectively evaluated aquaporin-4-IgG positive NMOSD patients and healthy controls (HC) matched for age and sex. The clinical variables of interest were collected for each participant. The mean values of T1-w/T2-w ratio, magnetization transfer ratio (MTR), fractional anisotropy (FA), axial diffusivity (AD), mean diffusivity (MD), and radial diffusivity (RD) were obtained in NAWM, NAGM, as well as in global and hypointense lesion masks. Global lesions refer to those typically associated with aquaporin-4-IgG positive NMOSD. Hypointense lesions were defined as areas of hypointense signal in both T1-w and fluid-attenuated inversion recovery (FLAIR) images. In total, we included 105 participants (59 NMOSD patients and 46 HC). T1-w/T2-w ratio was lower in NAWM of NMOSD patients versus HC (1.83 ± 0.14 vs 1.89 ± 0.14; p = 0.029), while no significant differences were found in NAWM or NAGM across the other metrics: (p range: 0.079 to 0.973). Hypointense lesions showed lower T1-w/T2-w ratio, MTR, and FA, and higher diffusivity metrics as compared to global lesion masks (p < 0.001). T1-w/T2-w ratio in NAWM was inversely correlated with time to start immunosuppressive therapy (r = - 0.278; p = 0.036) and with MD (r = - 0.325; p = 0.014). Microstructural integrity loss seems to be confined to focal tissue damage in NMOSD. Decreased T1-w/T2-w ratio in NAWM may reflect subclinical water accumulation due to astrocyte and blood-brain barrier dysfunction. Hypointense lesions have shown a severe degree of microstructural damage.

SHIVA-CMB: a deep-learning-based robust cerebral microbleed segmentation tool trained on multi-source T2*GRE- and susceptibility-weighted MRI

Cerebral microbleeds (CMB) represent a feature of cerebral small vessel disease (cSVD), a prominent vascular contributor to age-related cognitive decline, dementia, and stroke. They are visible as spherical hypointense signals on T2*- or susceptibility-weighted magnetic resonance imaging (MRI) sequences. An increasing number of automated CMB detection methods being proposed are based on supervised deep learning (DL). Yet, the lack of open sharing of pre-trained models hampers the practical application and evaluation of these methods beyond specific data sources used in each study. Here, we present the SHIVA-CMB detector, a 3D Unet-based tool trained on 450 scans taken from seven acquisitions in six different cohort studies that included both T2*- and susceptibility-weighted MRI. In a held-out test set of 96 scans, it achieved the sensitivity, precision, and F1 (or Dice similarity coefficient) score of 0.67, 0.82, and 0.74, with less than one false positive detection per image (FPavg = 0.6) and per CMB (FPcmb = 0.15). It achieved a similar level of performance in a separate, evaluation-only dataset with acquisitions never seen during the training (0.67, 0.91, 0.77, 0.5, 0.07 for the sensitivity, precision, F1 score, FPavg, and FPcmb). Further demonstrating its generalizability, it showed a high correlation (Pearson’s R = 0.89, p < 0.0001) with a visual count by expert raters in another independent set of 1992 T2*-weighted scans from a large, multi-center cohort study. Importantly, we publicly share both the pipeline (https://github.com/pboutinaud/SHiVAi/) and pre-trained models (https://github.com/pboutinaud/SHIVA-CMB/) to the research community to promote the active application and evaluation of our tool. We believe this effort will help accelerate research on the pathophysiology and functional consequences of CMB by enabling rapid characterization of CMB in large-scale studies.

Cerebral amyloid angiopathy-related inflammation (CAA-ri): A case report.

Cerebral amyloid angiopathy-related inflammation (CAA-ri) is a treatable condition characterized by an acute or subacute onset, with its primary pathological hallmark being the deposition of amyloid, predominantly β-amyloid (Aβ), within intracranial microvessels. Despite its potential for treatment, CAA-ri is a rare disorder that is frequently underrecognized by clinicians in practice. This article provides a comprehensive overview of the clinical manifestations and therapeutic approaches associated with CAA-ri, aiming to enhance awareness among healthcare professionals. A 67-year-old male patient who suffered from a sudden decline in cognitive functioning, intermittent headache, and dysphoria underwent brain magnetic resonance imaging, susceptibility weighted imaging, and cerebrospinal fluid analysis and was considered probable CAA-ri. During the course of disease development, the patient suffered from a sudden decline in cognitive functioning, mainly in the form of unresponsiveness, decreased comprehension, and increased repetitive language, accompanied by intermittent headaches and dysphoria. Brain magnetic resonance imaging showed numerous white matter in both hemispheres. Susceptibility weighted imaging showed multiple spots of hypointensity in the bilateral cerebral and cerebellar hemispheres, a hypointensity signal in the left occipital lobe, and extensive zones of hypointensity in bilateral sulci. Cerebrospinal fluid analysis was abnormal with elevated levels of protein and low levels of P-tau, Aβ42, and Aβ1-42/Aβ1-40. The use of glucocorticoids greatly reduced his symptoms. This lends credence to the probable CAA-ri diagnosis. The symptoms can be successfully alleviated by administering methylprednisolone sodium succinate. During the patient's hospitalization, immunosuppressive therapy, primarily consisting of methylprednisolone sodium succinate and methylprednisolone, was administered, resulting in a significant improvement in symptoms. Post-discharge, the patient was monitored regularly, revealing a gradual enhancement in cognitive function without recurrence. Consequently, immunosuppressive therapy was discontinued 1 year following the patient's discharge. CAA-ri is a rare clinical condition, and timely diagnosis and early treatment are very critical for patient prognosis.

Distinguishing Characteristics of Benign Versus Malignant Intraosseous Schwannomas: A Comparative Study.

Benign and malignant intraosseous schwannomas are rare, and primarily documented in case reports. This study aims to elucidate the differences in clinical features and imaging manifestations between these tumors. This will help clinicians identify malignant lesions at an early stage, reliable guide treatment decisions, and accurately predict outcomes. Eighteen patients who underwent surgery and got pathological examinations in our hospital from 2012 to 2023 were retrospectively reviewed. Among them, 14 cases were found benign with 4 malignant. In the benign group, patients underwent curettage followed by bone grafting, whereas the malignant group was treated with extensive resection or amputation. Patients' demographics and radiographic features, including gender, age at diagnosis, symptom duration, tumor location, tumor margin, and the ratio of sclerotic margins were documented and compared between these tumors. All imaging was reviewed by two fellowship-trained musculoskeletal radiologists, who also quantified the sclerotic margin ratio. The intraclass correlation coefficient was used to determine inter-observer agreement. The Mann-Whitney U test was applied for continuous clinical variables, and the chi-square test or Fisher's exact test for categorical variables. In our series, the mean age of these patients was 43.1 ± 14.0 years, six patients were male and 12 were female. Pain was the predominant preoperative symptom. The average duration from symptom onset to initial physician visit was 28.5 ± 25.3 months for benign schwannomas and 8.3 ± 4.3 months for malignant schwannomas (p = 0.012). On plain radiographs, 13 (13/14) of benign schwannomas exhibited well-defined margins of bone destruction, compared to 1 (1/4) of malignant schwannomas (p = 0.019). Furthermore, benign schwannomas had a significantly higher sclerotic margin ratio (75.5%) than malignant ones (16.7%) (p = 0.001). No statistically significant difference was found between the two groups in terms of cortical bone destruction (p = 1.0). On MRI, both tumors demonstrated intermediate to slightly hypointense signal intensity on T1-weighted images and heterogeneous high signal intensities on T2-weighted images. Despite their rarity, benign and malignant intraosseous schwannomas should be considered in the differential diagnosis for patients presenting with painful and radiographically lytic bone lesions, especially in the mandible, sacrum, and vertebrae. The ratio of sclerotic margins, which we proposed for the first time, in combination with symptom duration and the clarity of tumor margins, provide valuable diagnostic clues for distinguishing the malignancy of the tumors.

Postmortem MRI signature of Hippocampal Sclerosis of Aging

AbstractBackgroundHippocampal Sclerosis of aging (HS) refers to age‐related selective neuronal loss and gliosis in hippocampal cornu ammonis 1 (CA1) and subiculum that is out of proportion to tau pathology in Alzheimer’s Disease (AD). HS is related to cognitive decline and memory impairments separately from other neurodegenerative pathologies. To date, in vivo imaging biomarkers of HS of aging are non‐existent, and their development would greatly improve diagnosis and prognosis in memory clinics. We therefore aimed to characterize the magnetic resonance imaging (MRI) signature of HS among autopsy confirmed cases of HS.MethodData consisted of same‐subject histological Nissl‐stained slices and postmortem MRI (0.2mm isotropic) acquired from 27 subjects at the University of Pennsylvania and University Castilla‐La Mancha. Based on neuropathological assessment, cases were grouped into HS (N = 5), intermediate to high AD neuropathologic change without HS (N = 10) and limited or no neuropathological burden (N = 12). We manually measured grey matter thickness and GM/WM intensity ratio in select locations across the hippocampal head, body, and tail. We also obtained more global structural measures from hippocampal subfields using an automated postmortem atlas‐based segmentation algorithm.ResultQualitatively, HS is clearly noticeable as cortical thinning and hypointense signal (approximating white matter) on postmortem MRI across the CA1 and subiculum, particularly anteriorly closer to the border between CA1/subiculum (Figure 1). Manual thickness measures showed complete separation between the HS group and the two reference groups across both the hippocampal head and body, and a less pronounced difference in the tail. Global structural measures from automated segmentations corroborated these group differences showing complete separation in CA1 thickness and significant differences in subiculum and the white matter layer of CA1 (Stratum Radiatum Lacunosum Moleculare, SRLM).ConclusionIn MRI, HS is marked by hypointense voxels and cortical thinning across CA1 and subiculum. Both local manual thickness measurements and thickness measures of whole subfields derived from automatic segmentations provided promising results. As a next step, we plan to perform similar measurements on antemortem MRI of the same subjects, with the hopes of making progress toward an in vivo MRI biomarker of HS.

Image characteristics of retained medullary cord in secondary neurulation arrest: an observational study

Retained medullary cord (RMC) is a recently defined term denoting closed spinal dysraphism arising from the failure of regression in secondary neurulation. Despite the acknowledgment of this condition, there needs to be more literature elucidating the radiologic manifestations of RMC. This study aimed to describe the MR imaging findings of RMC. A retrospective analysis was conducted on spinal MRI scans of pediatric patients with surgically confirmed RMC, from January 2014 to August 2023. The investigation focused on evaluating the following image characteristics: level and morphology of the cord-like structure (C-LS), the signal intensity in the far distal C-LS, nerve root-like structures originating from the C-LS, intradural fatty lesions, and arachnoid cysts. This study included 38 patients (19 girls, mean age 7.3 months) who showed a low-lying cord in all cases. The morphology of C-LS was either smooth tapered (50%) or hourglass with fusiform cystic dilatation (50%). The C-LS exhibited aberrant T2 hypointense signal compared to the juxta-proximal level. T2 hypointense signal vestigial nerves emanating from the C-LS and intradural fatty masses were observed (89.5%). Sacral arachnoid cysts in extradural location were identified in eight patients. The characteristic MR features of RMC revealed an extremely low-lying distal C-LS with smooth tapering or hourglass-shaped cystic dilatation of the caudal part, accompanied by an intradural fatty stalk and the aberrant signal vestigial nerve. This study suggests those radiologic findings can be RMC instead of the previously called terminal syrinx with low-lying conus.

Extracutaneous Lesions in Patients with Focal Scleroderma of Craniofacial Localization: a Retrospective Cross-Sectional Study

Background. Focal scleroderma is rare, acquired disease characterized by inflammation, sclerosis, skin and underlying tissues atrophy, with no lesions to internal organs. However, craniofacial localized scleroderma (CLS) can lead to neurological, ophthalmic, and maxillofacial changes. Extracutaneous lesions at limited scleroderma remain poorly studied despite its high prevalence. Objective. The aim of the study is to characterize brain anomalies revealed at neuroimaging and to analyze their incidence in pediatric patients with focal scleroderma, as well as to describe comorbid neurological and ophthalmic disorders. Methods. Descriptive retrospective cross-sectional study included 33 pediatric patients who underwent hospital treatment at dermatology and allergology department of National Medical Research Center of Children’s Health with diagnosis of focal scleroderma from 2016 to 2024. All patients were examined by neurologist and ophthalmologist during hospitalization, as well as magnetic resonance imaging (MRI) was performed. The incidence of neurological, ophthalmic, and radiological signs was evaluated in the studied patients as well as their correlations within the data analysis. Results. 33 pediatric patients from 3 to 17 years old were studied. The number of boys and girls was not significantly different (p=0.46). MRI neuroimaging changes were revealed in 17 of 33 patients (51.5%). 12 patients (36.4%) had isolated disorders, 5 (15.1%) — multiple (two or more types) according to MRI data. Neurological disorders were reported in 8 out of 33 patients (24%). Ophthalmic disorders — in 10 out of 33 (30.3%). The study has revealed correlation indicating that the presence of epilepsy in CLS is associated with changes in the brain structure according to MRI (hyperintensive signal at T2-weighted image and FLAIR) (p=0,022). Also, such changes as hypointense signal during T2-VI are correlated with tension headache (p=0.03). No correlation between ophthalmic changes and neuroimaging changes was revealed. Conclusion. Significant number of pediatric patients with CLS have wide range of ophthalmic and neurological manifestations, including neuroimaging abnormalities. Precise and timely diagnosis of these symptoms is crucial for determining treatment intervention.

A rare occurrence of enchondroma with pathological fracture of proximal femur in an adult female: A case report

Enchondroma occurrence in the proximal femur is a very uncommon condition. We report a 40-year-old female with a history of accidental slip and fall, sustained injury to her left lower limb, and was unable to bear weight on the injured leg since the fall. Anteroposterior radiograph of the pelvis with bilateral hips shows a well-defined lytic lesion in the neck of the femur with some calcified matrix and no periosteal reaction with the left femoral subtrochanteric fracture. Magnetic resonance imaging scan revealed hypointense signals on T1 and hyperintense signals on T2 sequence over the proximal femur as well as left subtrochanteric femur fracture. After preanesthetic evaluation, bone curettage with excision biopsy with open reduction and internal fixation with long proximal femoral nail and bolts and iliac crest bone graft was done. A biopsy sample sent for histopathological examination reveals enchondroma. Complete weight bearing was started after four months. No recurrence was noted on follow up.

Absence of the Susceptibility Vessel Sign with Cancer-Associated Hypercoagulability-Related Stroke.

The susceptibility vessel sign, a hypointense signal on MR T2-weighted gradient-recalled echo images, is associated with erythrocyte-predominant thrombi, which are often present in cardioembolism. In contrast, cancer-associated hypercoagulability (CAH)-related stroke, which is presumably caused by fibrin-predominant thrombi, is associated with the absence of the susceptibility vessel sign. We hypothesized that the prevalence of the susceptibility vessel sign may be helpful in distinguishing CAH-related stroke from cardioembolism. This study attempted to validate this hypothesis and investigated the usefulness of the susceptibility vessel sign in differentiating CAH-related stroke from cardioembolism. We retrospectively studied patients with both CAH-related stroke (CAH group) and cardioembolism (cardioembolism group) who had major cerebral artery occlusion on MRA that was performed within 6 hours of stroke onset. All patients visited our department from 2015 to 2021. CAH-related stroke was defined as the following: 1) complication of active cancer, 2) pretreatment D-dimer value of >3 μg/mL, 3) multiple vascular territory infarctions, and 4) lack of any other specifically identified causes of stroke. We compared susceptibility vessel sign positivity rates within each group. Multivariable logistic regression analysis was used to assess the association between the absence of the susceptibility vessel sign and CAH-related stroke. Of 691 patients with CAH-related stroke or cardioembolism, major cerebral artery occlusion was observed in 10 patients in the CAH group and 198 patients in the cardioembolism group. The absence of the susceptibility vessel sign was identified in 55 of 208 patients and was significantly more frequent in the CAH group versus the cardioembolism group (90% versus 24%, P < .05). For predicting CAH-related stroke, the absence of the susceptibility vessel sign demonstrated a sensitivity of 90% (95% CI, 59%-99%), specificity of 78% (95% CI, 71%-83%), a positive predictive value of 18% (95% CI, 10-31), a negative predictive value of 99% (95% CI, 96%-99%), and a likelihood ratio of 4.06. Multivariable logistic regression analysis revealed that the absence of the susceptibility vessel sign was independently associated with CAH-related stroke (OR, 43; 95% CI, 6.8-863; P < .01). The absence of the susceptibility vessel sign was more frequent in CAH-related stroke than in cardioembolism. These findings could potentially be helpful for clinical management and differentiating cardioembolism and CAH-related stroke.

In Vivo visualization of white matter fiber tracts in the brainstem using low flip angle double echo 3D gradient echo imaging at 3T

BackgroundWhite matter (WM) fiber tracts in the brainstem communicate with various regions in the cerebrum, cerebellum, and spinal cord. Clinically, small lesions, malformations, or histopathological changes in the brainstem can cause severe neurological disorders. A direct and non-invasive assessment approach could bring valuable information about the intricate anatomical variations of the white matter fiber tracts and nuclei. Although tractography from diffusion tensor imaging has been commonly used to map the WM fiber tracts connectivity, it is difficult to differentiate the complex WM tracts anatomically. Both high field MRI methods and ultrahigh-field MRI methods at 7T and 11.7 T have been used to enhance the contrast of WM fiber tracts. Despite their promising results, it is still challenging to achieve wide clinical adoption at 3T. In this study, we explored a clinically feasible method using a proton density weighted (PDW) 3D gradient echo (GRE) sequence to directly image the WM fiber tracts in the brainstem at 3T in vivo. MethodsWe optimized a 3D high resolution, double echo, short TR, PDW GRE sequence on 5 healthy volunteers using a clinical 3T scanner to visualize the complicated anatomy of WM fiber tracts in the brain stem. Tissue properties including T1, proton density and T2* from in vivo quantitative MRI data were used for simulations to determine the optimal flip angle for the sequence. The visualization of multiple WM fiber tracts in the brainstem was assessed qualitatively and quantitatively using relative contrast and contrast-to-noise ratio (CNR). To improve the CNR, the final images were created by averaging over all echoes from two consecutive scans at the optimal flip angle. The results were compared to anatomical atlases and histology sections to identify the major fiber tracts. All the identified major fiber tracts were labeled on axial, sagittal and coronal slices. ResultsThe WM fiber tracts were found to have distinct hypointense signal throughout the brainstem and most of the major WM fiber tracts, such as the corticospinal tract, medial lemniscus, medial longitudinal fasciculus, and central tegmental tract, in the brainstem up to and including the thalamus were identified in all subjects. Both qualitative and quantitative evaluations showed that the 3° scan offered the best contrast for WM fiber tracts for a TR of 20 ms. The average over the first two echo times and two consecutive 3° scans gave a CNR of 47.8 ± 6.2 for the pyramidal tracts in particular and CNRs values greater than 6.5 ± 2.4 for the rest of the fiber tracts. ConclusionsAll the major fiber tracts in the brainstem could be visualized. Given the reasonably short scan time of 10 min at 3T, double echo PDW GRE sequence is a very practical approach for clinical adoption.

Dark papillary muscles sign is a new prognostic indicator in patients with dilated cardiomyopathy: A multi-center study

ObjectivesThe prognostic value of left ventricular (LV) papillary muscle anomalies in dilated cardiomyopathy (DCM) patients is unclear. The objective of this study was to evaluate the prognostic significance of LV papillary muscle anomalies in DCM patients using cardiac magnetic resonance (CMR). Methods369 DCM patients who underwent CMR at two Chinese medical facilities from January 2019 to June 2023 were retrospectively and consecutively included in total. The various features of the LV papillary muscles were taken into consideration: thickness, attachment, supernumerary papillary muscles, angles, and signal intensity. The end-systolic signal hypointensity of both papillary muscles in early post-contrast cine CMR images was identified as Dark-Paps. Major adverse cardiac events (MACEs) were assessed, and all patients were followed up. Results119 patients (32.2 %) had Dark-Paps and 141 patients (38.2 %) experienced MACE during a median follow-up of 22 months. According to Kaplan-Meier curve analysis, patients who had Dark-Paps had a lower survival rate free from MACE (log-rank, p < 0.001). Dark-Paps maintained an independent predictor of MACE in a multivariate model that included left ventricular ejection fraction (LVEF) and late gadolinium enhancement (LGE) extent (HR: 3.49; p < 0.001). Furthermore, adding Dark-Paps to the multivariate model greatly enhanced the prognostic role of endpoint events (C-statistic improvement: 0.652–0.777, Delong test: p < 0.001). ConclusionDark-Paps is a potent independent indicator of major adverse cardiac events in dilated cardiomyopathy patients. In addition, Dark-Paps can provide additional prognostic value over the multivariable baseline clinical model.

Contrast-enhanced magnetic resonance neurography for diagnosing brachial plexopathy: improved visualization and additional imaging features

Contrast-enhanced magnetic resonance neurography (CE-MRN) holds promise for diagnosing brachial plexopathy by enhancing nerve visualization and revealing additional imaging features in various lesions. This study aims to validate CE-MRN’s efficacy in improving brachial plexus (BP) imaging across different patient cohorts. Seventy-one subjects, including 19 volunteers and 52 patients with BP compression/entrapment, injury, and neoplasms, underwent both CE-MRN and plain MRN. Two radiologists assessed nerve visibility, with inter-reader agreement evaluated. Quantitative parameters such as signal intensity (SI), contrast-to-noise ratio (CNR), and contrast ratio (CR) of the C7 nerve were measured. Both qualitative scoring and quantitative metrics were compared between CE-MRN and plain MRN within each patient group. Patient classification followed the Neuropathy Score Reporting and Data System (NS-RADS), summarizing additional imaging features for each brachial plexopathy type. Inter-reader agreement for qualitative assessment was strong. CE-MRN significantly enhanced BP visualization and nerve-tissue contrast across all cohorts, particularly in volunteers and patients with injuries. It also uncovered additional imaging features such as hypointense signals in ganglia, compressed nerve sites, and neoplastic enhancements. CE-MRN effectively mitigated muscle edema and vascular contamination, enabling precise classification of BP injuries. Overall, CE-MRN consistently enhances BP visualization and provides valuable imaging features for accurate diagnosis.

An Algorithmic Approach to MR Imaging of Hypomyelinating Leukodystrophies.

Hypomyelinating leukodystrophies (HLDs) are a heterogeneous group of white matter diseases characterized by permanent deficiency of myelin deposition in brain. MRI is instrumental in the diagnosis and recommending genetic analysis, and is especially useful as many patients have a considerable clinical overlap, with the primary presenting complains being global developmental delay with psychomotor regression. Hypomyelination is defined as deficient myelination on two successive MR scans, taken at least 6 months apart, one of which should have been obtained after 1 year of age. Due to subtle differences in MRI features, the need for a systematic imaging approach to diagnose and classify hypomyelinating disorders is reiterated. The presented article provides an explicit review of imaging features of a myriad of primary and secondary HLDs, using state of the art genetically proven MR cases. A systematic pattern-based approach using MR features and specific clinical clues is illustrated for a quick yet optimal diagnosis of common as well as rare hypomyelinating disorders. The major MR features helping to narrow the differential diagnosis include extent of involvement like diffuse or patchy hypomyelination with selective involvement or sparing of certain white matter structures like optic radiations, median lemniscus, posterior limb of internal capsule and periventricular white matter; cerebellar atrophy; brainstem, corpus callosal or basal ganglia involvement; T2 hypointense signal of the thalami; and presence of calcifications. The authors also discuss the genetic and pathophysiologic basis of HLDs and recent methods to quantify myelin in vivo using advanced neuroradiology tools. The proposed algorithmic approach provides an improved understanding of these rare yet important disorders, enhancing diagnostic precision and improving patient outcomes. EVIDENCE LEVEL: 4 TECHNICAL EFFICACY: Stage 5.

The "Hypointense Focal Brain" on susceptibility-weighted imaging as a sign of venous congestion in cranial dural arteriovenous fistulas.

Cranial dural arteriovenous fistulas (dAVFs) are complex neurovascular malformations accounting for approximately 10%-15% of all intracranial arteriovenous malformations. The objective is to investigate the utility of susceptibility-weighted imaging (SWI) in identifying "hypointense focal brain" as an additional helpful sign of venous congestion in cranial dAVFs. A retrospective review of patients diagnosed with cranial dAVFs between January 2015 and June 2023 was conducted, and SWI was used to identify the "hypointense focal brain" sign within the venous drainage region of the dAVF. The "hypointense focal brain" on SWI was identified as a low-intensity signal within the venous drainage region, indicative of venous congestion. The presence of this imaging sign was assessed by two neuroradiologists and signal intensity measurements were performed to support the presence of the sign. The study included six patients with cranial dAVFs exhibiting cortical venous retrograde drainage and the "hypointense focal brain" on SWI. Follow-up imaging post-treatment revealed resolution or improvement of the hypointense signal, confirming its association with venous congestion. Signal intensity measurements further supported the presence of this imaging sign in pre-treatment scans. The study's findings demonstrate the presence of a reversible "hypointense focal brain" sign on SWI in patients with cranial dAVFs and CVR, which can be useful as an additional imaging sign for venous congestion.

The value of susceptibility weighted imaging for immediate assessing the hyperacute outcome of MRgFUS ablation for uterine fibroids: a preliminary study

Purpose To investigate the value of susceptibility weighted imaging (SWI) for assessing the hyperacute outcome of ablation of uterine fibroids immediately after magnetic resonance-guided focused ultrasound (MRgFUS) treatment. Methods This retrospective imaging study included patients who underwent SWI and contrast-enhanced (CE) MR within 15 min of MRgFUS ablation for uterine fibroids. Two readers independently assessed the SWI features of ablative lesions and their association with the non-perfused volume (NPV) ratio. The intraclass correlation coefficient (ICC) and diagnostic value of SWI findings were calculated. Results A total of 27 uterine fibroids from 21 participants (mean age 40.1 ± 7.2 years) were analyzed. 51.9% (14/27) leiomyomas had NPV ratio ≥90%. In post-ablation SWI images, the interobserver ICC for the relative signal intensity and hypointense peripheral rim were 0.613 and 0.843, respectively (both p < .001). There was a significant difference in the prevalence of hypointense peripheral rim in leiomyomas with NPV ratio ≥90% and < 90% (p < .01), while the prevalence of relative signal intensity showed no significant difference (p > .05). When using the complete hypointense peripheral rim as a diagnostic criterion to identify NPV ratio ≥ 90%, readers 1 and 2 showed diagnostic sensitivity, specificity, and accuracy of 85.7%, 76.9%, 81.5%, and 78.6%, 76.9%, 77.8%, respectively. Conclusion Identifying a complete hypointense peripheral rim on SWI may be a potential imaging marker for assessing the hyperacute outcome of uterine fibroids ablation by MRgFUS, specifically in determining whether the NPV ratio is ≥90%.

Integrated Approach in Evaluating the Results of Cosmetic Procedures Using Ultrasonography and Magnetic Resonance Tomography (Clinical Study)

Aim. To investigate the capabilities of comprehensive assessment using ultrasound and magnetic resonance imaging (MRI) of the results of cosmetic procedures.Materials and Methods. A study of the soft tissues of the anterior abdominal wall of a 43-year-old woman complaining of skin atony and postpartum stretch marks using highresolution ultrasound and MRI.Results. At ultrasonography in the projection of injection of polylactic acid and calcium hydroxyapatite preparations and radiofrequency treatment, an increase in echogenicity of hypodermis with the presence of acoustic shadow was noted. On MRI at the level of derma and hypoderma of periumbilical region in the projection of radiofrequency treatment, injections of preparations based on polylactic acid on the left, calcium hydroxyapatite on the right in 3 months after subdermal injection, areas of hyperintense MR-signal in T2 weight image (WI) and STIR programs, hypointense in T1 WI, without diffusion limitation on DWI b=1000 were determined. In SWI mode, the focus of hypointense MR signal of rounded shape with clear and smooth contours was visualized on the right side of the image.Conclusion. The clinical study demonstrates the possibilities of an integrated approach in evaluating the results of cosmetic procedures using ultrasonography and MRI.

MRI-based microthrombi detection in stroke with polydopamine iron oxide

In acute ischemic stroke, even when successful recanalization is obtained, downstream microcirculation may still be obstructed by microvascular thrombosis, which is associated with compromised brain reperfusion and cognitive decline. Identifying these microthrombi through non-invasive methods remains challenging. We developed the PHySIOMIC (Polydopamine Hybridized Self-assembled Iron Oxide Mussel Inspired Clusters), a MRI-based contrast agent that unmasks these microthrombi. In a mouse model of thromboembolic ischemic stroke, our findings demonstrate that the PHySIOMIC generate a distinct hypointense signal on T2*-weighted MRI in the presence of microthrombi, that correlates with the lesion areas observed 24 hours post-stroke. Our microfluidic studies reveal the role of fibrinogen in the protein corona for the thrombosis targeting properties. Finally, we observe the biodegradation and biocompatibility of these particles. This work demonstrates that the PHySIOMIC particles offer an innovative and valuable tool for non-invasive in vivo diagnosis and monitoring of microthrombi, using MRI during ischemic stroke.

I saw the “shrimp sign”: Cerebellar progressive multifocal leukoencephalopathy

The shrimp sign is characterized by a well-defined lesion in the deep cerebellar white matter, with hyperintense signal on T2- and hypointense signal on T1-weighted imaging, abutting and outlining the dentate nucleus, unilaterally or bilaterally. This sign has high sensitivity and specificity for cerebellar progressive multifocal leukoencephalopathy (PML) within the correct clinical scenario. In this article, we present a case of cerebellar PML in a woman living with human immunodeficiency virus, who was not using antiretroviral therapy, and presented the shrimp sign on brain MRI.

Clinical Implications of Alternating Hypointense Bands on OCT Angiography in Retinal Vascular Occlusive Disease

PurposeTo demonstrate the relationship between alternating hypointense signal bands on optical coherence tomography-angiography (OCTA), real-time fluorescein angiography (FA), and structural OCT findings in patients with retinal vascular occlusive disease (RVOD). DesignRetrospective, consecutive case series. SubjectsConsecutive patients with a clinical diagnosis of acute RVOD and alternating bands of hypointense OCTA flow signal on en face projections. MethodsComplete ophthalmic examination and multimodal imaging, including color fundus photography (CFP), real-time FA, SD-OCT, and OCTA performed with different instruments having different scan speeds and acquisition protocols. Main Outcome MeasurementsThe primary outcomes were: Hypointense OCTA band characteristics (number, width, orientation, and location), OCTA acquisition characteristics (speed and scan direction), and FA findings including delayed arteriovenous (AV) transit and pulsatile flow. Secondary outcomes were: Structural OCT changes including retinal fluid, paracentral acute maculopathy lesion (PAMM), and a prominent middle limiting membrane (p-MLM) sign. ResultsOCTA-hypointense bands were detected in the superficial and deep vascular plexuses in 9 eyes of 9 patients with either partial CRAO or nonischemic RVO. When obtained on the same device, hypointense bands were thinner and more numerous at lower (100 kHz) scan speeds compared with higher (200 kHz) scan speeds. Band orientation was parallel to the OCTA scan direction, and their extent correlated with the area of delayed AV transit on FA. Structural OCT showed multiple PAMM lesions in 78% of cases and a p-MLM sign centered in the fovea in 44% of cases. ConclusionsOCTA-hypointense bands are a novel biomarker in RVOD indicating delayed AV transit and pulsatile filling without the need for dye angiography. Structural OCT often shows PAMM in these eyes, and less commonly, a p-MLM sign.