Susceptibility-weighted imaging: technical aspects and clinical applications, part 2

Feasibility and Potential Diagnostic Value of Noncontrast Brain MRI in Nonsedated Children With Sturge-Weber Syndrome and Healthy Siblings

BACKGROUND

Postcontrast magnetic resonance imaging (MRI), obtained under anesthesia, is often used to evaluate brain parenchymal and vascular abnormalities in young children, including those with Sturge-Weber syndrome. However, anesthesia and contrast administration may carry risks. We explored the feasibility and potential diagnostic value of a noncontrast, nonsedate MRI acquisition in Sturge-Weber syndrome children and their siblings with a wide range of cognitive and behavioral functioning.

METHODS

Twenty children (10 with Sturge-Weber syndrome and 10 healthy siblings; age: 0.7-13.5 years) underwent nonsedate 3-tesla (T) brain MRI acquisition with noncontrast sequences (including susceptibility-weighted imaging) prospectively along with neuropsychology assessment. All images were evaluated for quality, and MRI abnormalities identified in the Sturge-Weber syndrome group were compared to those identified on previous clinical pre- and postcontrast MRI.

RESULTS

Nineteen participants (95%) completed the MRI with good (n = 18) or adequate (n = 1) quality, including all children with Sturge-Weber syndrome and all 5 children ≤5 years of age. The Sturge-Weber syndrome group had lower cognitive functions than the controls, and both groups had several children with behavioral issues, without an apparent effect on the success and quality of the MR images. Susceptibility-weighted imaging detected key venous vascular abnormalities and calcifications and, along with the other noncontrast sequences, provided diagnostic information comparable to previous clinical MRI performed with contrast administration under anesthesia.

CONCLUSION

This study demonstrates the feasibility and the potential diagnostic value of a nonsedate, noncontrast MRI acquisition protocol in young children including those with cognitive impairment and/or behavioral concerns. This approach can facilitate clinical trials in children where safe serial MRI is warranted.

SIPAS: A comprehensive susceptibility imaging process and analysis studio

Quantitative susceptibility mapping (QSM) is a rising MRI-based technology and quite a few QSM-related algorithms have been proposed to reconstruct maps of tissue susceptibility distribution from phase images. In this paper, we develop a comprehensive susceptibility imaging process and analysis studio (SIPAS) that can accomplish reliable QSM processing and offer a standardized evaluation system. Specifically, SIPAS integrates multiple methods for each step, enabling users to select algorithm combinations according to data conditions, and QSM maps could be evaluated by two aspects, including image quality indicators within all voxels and region-of-interest (ROI) analysis. Through a sophisticated design of user-friendly interfaces, the results of each procedure are able to be exhibited in axial, coronal, and sagittal views in real-time, meanwhile ROIs can be displayed in 3D rendering visualization. The accuracy and compatibility of SIPAS are demonstrated by experiments on multiple in vivo human brain datasets acquired from 3T, 5T, and 7T MRI scanners of different manufacturers. We also validate the QSM maps obtained by various algorithm combinations in SIPAS, among which the combination of iRSHARP and SFCR achieves the best results on its evaluation system. SIPAS is a comprehensive, sophisticated, and reliable toolkit that may prompt the QSM application in scientific research and clinical practice.

Magnetic Resonance Imaging (MRI) Evaluation and Classification of Vascular Malformations

Introduction Vascular malformations of the soft tissues are a diverse collection of lesions frequently encountered in clinical practice. Vascular malformations are rare and complex abnormalities that affect both children and young adults. Low-flow malformations are more common in children and often become symptomatic in later years. These malformations are common causes of soft tissue masses in children and can affect any part of the body at any age. Significant advancements in the management of these conditions have been made due to the implementation of a comprehensive binary categorization system, which classifies vascular abnormalities into tumors and malformations based on their clinicopathological characteristics. Imaging, particularly magnetic resonance imaging (MRI), plays a crucial role in the accurate identification, localization, and classification of these lesions, aiding in the development of appropriate treatment plans. Materials and methods This prospective study was conducted at Dr. D. Y. Patil Medical College, Hospital and Research Centre, Pimpri, Pune, from August 2022 to June 2024. Fifty patients of all age groups with clinically suspected soft tissue vascular malformations were included. MRI was performed using a MAGNETOM Vida (3T) Scanner (Siemens Healthcare Private Limited, Mumbai, India), and ultrasound was used as an adjunct. Institutional Ethics Committee clearance and informed consent were obtained. The study employed various MRI sequences, including T1-weighted imaging (T1WI) fast spin echo (FSE), T2-weighted imaging (T2WI) FSE, short tau inversion recovery (STIR), T2-weighted gradient recalled echo (GRE), pre-contrast fat-saturated T1WI, 3D post-contrast T1WI, diffusion-weighted imaging (DWI), and ANGIO TWIST (time-resolved angiography with interleaved stochastic trajectories) ISO. Results The study included 50 patients, with a male predominance of 28 (56%). The mean age was 22.13 years, and the average duration of vascular malformations was 32.94 months. The swelling was present in 43 (86%) of patients, and 35 (70%) had superficial lesions. MRI findings revealed hypointensity on T1 imaging in 40 (80%) patients and hyperintensity on T2 imaging in 49 (98%) cases. STIR sequences showed hyperintensity in all patients. The most common type of vascular malformation was slow-flow 46 (92%), with venous malformations being the most prevalent 39 (78%). Conclusion MRI is a valuable imaging modality for the evaluation and classification of vascular malformations, providing detailed information on lesion extent and involvement of surrounding tissues. The findings support the use of MRI as a primary tool in the assessment of vascular malformations, with ultrasound serving as a useful adjunct in certain cases. Further studies with larger sample sizes are recommended to validate these findings and refine imaging protocols.

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

BACKGROUND

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.

MATERIALS AND METHODS

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.

RESULTS

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.

CONCLUSION

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.

Advanced Magnetic Resonance Imaging for Detection of Liver Fibrosis and Inflammation in Autoimmune Hepatitis: A State-of-the-Art Review

Autoimmune hepatitis is a rare chronic liver disease, associated with a high level of morbidity and high mortality; approximately 40% of patients with severe untreated disease die within 6 months of diagnosis. It should be treated to achieve complete biochemical and histologic resolution of the disease using corticosteroids and immunosuppression to prevent further progression to cirrhosis. The use of invasive liver biopsy is recommended for the staging and assessment of inflammation and fibrosis for treatment decision-making in the face of an unsatisfactory response or clinical remission, including being a determinant for withdrawal of immunosuppression. On the other hand, liver biopsy is invasive, costly, and not free of complications. It also has potential sampling error and poor interobserver agreement. The limitations of liver biopsy highlight the importance of developing new imaging biomarkers that allow accurate and non-invasive assessment of autoimmune hepatitis in terms of liver inflammation and fibrosis, developing the virtual biopsy concept. Therefore, we review the state-of-the-art of Magnetic Resonance Imaging sequences for the noninvasive evaluation of autoimmune hepatitis, including historical advances and future directions.

Effect of gadolinium contrast medium administration on susceptibility-weighted imaging of the canine brain

Susceptibility-weighted imaging (SWI) is a gradient echo (GE) MRI sequence. Intravenous administration of gadolinium (Gd) may affect GE images, but its effect on SWI has not been investigated in veterinary medicine. This cross-sectional prospective study evaluated the effects of Gd on SWI. Seventy-one dogs that underwent brain MRI were included and distributed in two groups. Susceptibility-weighted imaging was performed pre- and postcontrast, obtained immediately after Gd administration (Group A: n = 35) or delayed (Group B: n = 36; median delay 19.9 min). Pre- and post-Gd SWI were analyzed for signal intensity changes in the lentiform nuclei of gray matter (GM), in the centrum semiovale of white matter (WM), and in brain lesions. No difference in GM signal intensity was identified in either group between pre- and postcontrast images (Group A, P = .395; Group B, P = .895). In group A, WM signal intensity was lower in pre- than post-Gd sequences (P = .019). Brain lesions were identified in 30/71 (41%) cases; the signal intensity of intracranial lesions was significantly lower in pre- than post-Gd images in both groups (P < .001); the number of lesions influenced the difference in signal intensity in group B (P = .043). Susceptibility artifacts did not change in appearance between pre- and postcontrast images in either the normal brain or in parenchymal lesions. In conclusion, Gd may modify the signal intensity of WM and brain lesions but does not affect the susceptibility artifacts and does not interfere with SWI interpretation.

Multiparametric MRI dataset for susceptibility-based radiomic feature extraction and analysis

Multiple sclerosis (MS) is a progressive demyelinating disease impacting the central nervous system. Conventional Magnetic Resonance Imaging (MRI) techniques (e.g., T2w images) help diagnose MS, although they sometimes reveal non-specific lesions. Quantitative MRI techniques are capable of quantifying imaging biomarkers in vivo, offering the potential to identify specific signs related to pre-clinical inflammation. Among those techniques, Quantitative Susceptibility Mapping (QSM) is particularly useful for studying processes that influence the magnetic properties of brain tissue, such as alterations in myelin concentration. Because of its intrinsic quantitative nature, it is particularly well-suited to be analyzed through radiomics, including techniques that extract a high number of complex and multi-dimensional features from radiological images. The dataset presented in this work provides information about normal-appearing white matter (NAWM) in a cohort of MS patients and healthy controls. It includes QSM-based radiomic features from NAWM and its tracts, and MR sequences necessary to implement the pipeline: T1w, T2w, QSM, DWI. The workflow is outlined in this article, along with an application showing feature reliability assessment.

Advancing MRI with magnetic nanoparticles: a comprehensive review of translational research and clinical trials

The nexus of advanced technology and medical therapeutics has ushered in a transformative epoch in contemporary medicine. Within this arena, Magnetic Resonance Imaging (MRI) emerges as a paramount tool, intertwining the advancements of technology with the art of healing. MRI's pivotal role is evident in its broad applicability, spanning from neurological diseases, soft-tissue and tumour characterization, to many more applications. Though already foundational, aspirations remain to further enhance MRI's capabilities. A significant avenue under exploration is the incorporation of innovative nanotechnological contrast agents. Forefront among these are Superparamagnetic Iron Oxide Nanoparticles (SPIONs), recognized for their adaptability and safety profile. SPION's intrinsic malleability allows them to be tailored for improved biocompatibility, while their functionality is further broadened when equipped with specific targeting molecules. Yet, the path to optimization is not devoid of challenges, from renal clearance concerns to potential side effects stemming from iron overload. This review endeavors to map the intricate journey of SPIONs as MRI contrast agents, offering a chronological perspective of their evolution and deployment. We provide an in-depth current outline of the most representative and impactful pre-clinical and clinical studies centered on the integration of SPIONs in MRI, tracing their trajectory from foundational research to contemporary applications.

MRI in the Evaluation of Cryptogenic Stroke and Embolic Stroke of Undetermined Source

Cryptogenic stroke refers to a stroke of undetermined etiology. It accounts for approximately one-fifth of ischemic strokes and has a higher prevalence in younger patients. Embolic stroke of undetermined source (ESUS) refers to a subgroup of patients with nonlacunar cryptogenic strokes in whom embolism is the suspected stroke mechanism. Under the classifications of cryptogenic stroke or ESUS, there is wide heterogeneity in possible stroke mechanisms. In the absence of a confirmed stroke etiology, there is no established treatment for secondary prevention of stroke in patients experiencing cryptogenic stroke or ESUS, despite several clinical trials, leaving physicians with a clinical dilemma. Both conventional and advanced MRI techniques are available in clinical practice to identify differentiating features and stroke patterns and to determine or infer the underlying etiologic cause, such as atherosclerotic plaques and cardiogenic or paradoxical embolism due to occult pelvic venous thrombi. The aim of this review is to highlight the diagnostic utility of various MRI techniques in patients with cryptogenic stroke or ESUS. Future trends in technological advancement for promoting the adoption of MRI in such a special clinical application are also discussed.

Appropriate incorporation of susceptibility-weighted magnetic resonance imaging into routine imaging protocols for accurate diagnosis of traumatic brain injuries: a systematic review

Traumatic brain injury (TBI) results from physical or traumatic injuries to the brain's surrounding bony structures and associated tissues, which can lead to various sequelae, including simple concussion, acute epidural hematoma, parenchymal contusions, subarachnoid hemorrhage, diffuse axonal injury, and chronic traumatic encephalopathy. Susceptibility-weighted imaging (SWI) has enhanced the accuracy of neuroimaging for these injuries. SWI is based on 3D gradient echo magnetic resonance imaging (MRI) with long echo times and flow compensation. Owing to its sensitivity to deoxyhemoglobin, hemosiderin, iron, and calcium, SWI is extremely informative and superior to conventional MRI for the diagnosis and follow-up of patients with acute, subacute, and prolonged hemorrhage. This systematic review aimed to evaluate and summarize the published articles that report SWI results for the evaluation of TBI and to determine correlations between clinical status and SWI results. Consequently, our analysis also aimed to identify the appropriate MRI sequences to use in the assessment of patients with TBI. We searched the Medline and Embase online electronic databases for relevant papers published from 2012 onwards. We found that SWI had higher sensitivity than gradient echo MRI in detecting and characterizing microbleeds in TBIs and was able to differentiate diamagnetic calcifications from paramagnetic microhemorrhages. However, it is important that future research not only continues to evaluate the utility of SWI in TBIs but also attempts to overcome the limitations of the studies described in this review, which should help validate the conclusions and recommendations from our analysis.

Unveiling the Intricacies: A Comprehensive Review of Magnetic Resonance Imaging (MRI) Assessment of T2-Weighted Hyperintensities in the Neuroimaging Landscape

T2-weighted hyperintensities in neuroimaging represent areas of heightened signal intensity on magnetic resonance imaging (MRI) scans, holding crucial importance in neuroimaging. This comprehensive review explores the T2-weighted hyperintensities, providing insights into their definition, characteristics, clinical relevance, and underlying causes. It highlights the significance of these hyperintensities as sensitive markers for neurological disorders, including multiple sclerosis, vascular dementia, and brain tumors. The review also delves into advanced neuroimaging techniques, such as susceptibility-weighted and diffusion tensor imaging, and the application of artificial intelligence and machine learning in hyperintensities analysis. Furthermore, it outlines the challenges and pitfalls associated with their assessment and emphasizes the importance of standardized protocols and a multidisciplinary approach. The review discusses future directions for research and clinical practice, including the development of biomarkers, personalized medicine, and enhanced imaging techniques. Ultimately, the review underscores the profound impact of T2-weighted hyperintensities in shaping the landscape of neurological diagnosis, prognosis, and treatment, contributing to a deeper understanding of complex neurological conditions and guiding more informed and effective patient care.

Prominent cerebral veins on susceptibility-weighted angiography in acute meningoencephalitis

BACKGROUND AND PURPOSE

We have commonly observed prominent cerebral veins on susceptibility-weighted angiography (SWAN) in acute meningoencephalitis. This study aimed to investigate the clinical significance of these findings.

METHODS

Cerebral veins on SWAN of 98 patients with acute meningoencephalitis diagnosed from February 2016 through October 2020 were classified into three groups according to the degree of venous prominence (mild, 23; moderate, 53; and prominent, 22). Clinical variables and laboratory findings were compared between these groups. The influence of variables on the prediction of prominent cerebral veins was measured by random forest (RF) and gradient boosting machine (GBM).

RESULTS

As cerebral veins became more prominent, cerebrospinal fluid (CSF) glucose level decreased (69.61 ± 29.05 vs. 59.72 ± 22.57 vs. 48.36 ± 20.29 mg/dL, p = .01) and CSF protein level increased (100.73 ± 82.98 vs. 104.73 ± 70.99 vs. 159.12 ± 118.15 mg/dL, p = .03). The etiology of meningoencephalitis, neurological symptoms, and increased intracranial pressure (ICP) signs differed between groups (p < .05). RF and GBM demonstrated that CSF protein level was the variable with the highest power to predict the prominent cerebral vein (mean decrease in node impurity: 4.19, relative influence: 50.66).

CONCLUSION

The presence of prominent cerebral veins on SWAN in acute meningoencephalitis was significantly associated with a low CSF glucose level and a high CSF protein level, as well as ICP. Thus, the visual grade of the cerebral veins on SWAN may be utilized for the management of patients with acute meningoencephalitis.

FLAIR vascular hyperintensity combined with asymmetrical prominent veins in acute anterior circulation ischemic stroke: prediction of collateral circulation and clinical outcome

BACKGROUND

To investigate the value of fluid-attenuated inversion recovery vascular hyperintensity (FVH) within asymmetrical prominent veins sign (APVS) on susceptibility-weighted imaging predicting collateral circulation and prognosis in patients with acute anterior circulation ischemic stroke.

METHOD

Patients with severe stenosis or occlusion of ICA or MCA M1, who underwent MRI within 72 h from stroke onset were reviewed. The Alberta Stroke Program Early CT Score was used to evaluate the volume of infarction on DWI, the degree of FVH and APVS. Spearman correlation analysis was used to evaluate the correlation between FVH and APVS. All patients were divided into the good prognosis group and the poor prognosis group according to the score of the modified ranking scale (mRS) 90 days after the stroke. Logistic regression analysis was used to explore the relationship between FVH and APVS and functional prognosis, while receiver operating characteristic (ROC) curves were plotted to assess the value of FVH and APVS in predicting prognosis.

RESULTS

Spearman correlation analysis revealed moderate positive correlations between FVH and APVS (r = 0.586, P < 0.001). The poor prognosis group had a higher rate of a history of atrial fibrillation, a larger cerebral infarction volume, a higher NIHSS score at admission, and a higher FVH and APVS score compared with the good prognosis group (all P < 0.05). A further logistic regression indicated that the NIHSS score, cerebral infarction volume, FVH and APVS were independent risk factors for a poor functional prognosis. In terms of FVH, APVS, alone and their combination for the diagnosis of poor prognosis, the sensitivity, specificity, area under the ROC curve (AUC), and 95% confidence interval (CI) were 86.8%, 83.3%, 0.899 (95% CI 0.830-0.968); 60.5%, 93.7%, 0.818 (95% CI 0.723-0.912); 86.8%, 89.6%, 0.921 (95% CI 0.860-0.981), respectively.

CONCLUSION

The presence of FVH and APVS can provide a comprehensive assessment of collateral circulation from the perspective of veins and arteries, and the correlation between the two is positively correlated. Both of them were independent risk factors for poor prognosis, their combination is complementary and can improve the predictive value.

Iron quantification in basal ganglia using quantitative susceptibility mapping in a patient with ALS: a case report and literature review

Background

Quantitative susceptibility mapping (QSM) is a magnetic resonance imaging (MRI) technique that can measure the magnetic susceptibility of tissues, which can reflect their iron content. QSM has been used to detect iron accumulation in cortical and subcortical brain regions. However, its application in subcortical regions such as the basal ganglia, particularly the putamen, is rare in patients with amyotrophic lateral sclerosis (ALS).

Case presentation and literature review

We present the case of a 40-year-old male patient with ALS who underwent an MRI for QSM. We compared his QSM images with those of a control subject and performed a quantitative analysis of the magnetic susceptibility values in the putamen regions. We also reviewed the literature on previous QSM studies in ALS and summarized their methods and findings. Our QSM analysis revealed increased magnetic susceptibility values in the bilateral putamen of the ALS patient compared to controls, indicating iron overload. This finding is consistent with previous studies reporting iron dysregulation in subcortical nuclei in ALS. We also discussed the QSM processing techniques used in our study and in the literature, highlighting their advantages and limitations.

Conclusion

This case report demonstrates the potential of QSM as a sensitive MRI biomarker for evaluating iron levels in subcortical regions of ALS patients. QSM can provide quantitative information on iron deposition patterns in both motor and extra-motor areas of ALS patients, which may help understand the pathophysiology of ALS and monitor disease progression. Further studies with larger samples are needed to validate these results and explore the clinical implications of QSM in ALS.

Utility of 3D T1-weighted turbo spin echo black blood sequence for the diagnosis of cerebral venous thrombosis

PURPOSE

Accurate assessment of dural sinus, deep and cortical venous thrombosis on MR imaging is challenging. The aim of this study is to evaluate the accuracy of 3D-T1 turbo spin echo (T1S), sequences in detecting venous thrombosis and comparing it with susceptibility-weighted imaging (SWI), magnetic resonance venography (MRV) and post contrast T1 magnetization-prepared rapid acquisition gradient echo (T1C).

METHODS

A blinded retrospective observational analysis of 71 consecutive patients evaluated for cerebral venous thrombosis (CVT) and 30 control patients was performed. Multimodality reference standard adopted included T1C, SWI with MRV. Sub-analyses in superficial, deep and cortical venous segments were performed in addition to correlation of signal intensity of thrombus with the clinical stage.

RESULTS

A total of 2222 segments in 101 complete MRI examinations were evaluated. Sensitivity/specificity/positive predictive value/negative predictive value/accuracy and precision of T1S for detection of cortical vein thrombosis was 0.994/1/1/0.967/0.995/1, 1/0.874/0.949/1/0.963/0.950 for detection of superficial venous sinus thrombosis and 1/1/1/1/1/1 for deep venous thrombosis. The AUC yield for T1S was 0.997 for cortical, 1 for deep and 0.988 for superficial venous segments.

CONCLUSION

T1S paralleled the accuracy of conventional sequences in the overall detection of CVT but showed superior accuracy in the detection of cortical venous thrombosis. It makes a fitting addition to the CVT MRI protocol in scenarios demanding negation of gadolinium administration.

Susceptibility weighted imaging for qualitative grading of persistent arteriovenous shunting in deep-seated arteriovenous malformations after stereotactic radiation surgery

BACKGROUND AND PURPOSE

To investigate Susceptibility Weighted Imaging (SWI) signal changes in the draining vein of deep-seated arterio-venous malformations (AVMs) following stereotactic radiosurgery (SRS).

METHODS AND MATERIALS

This is a retrospective study of 32 patients with deep-seated AVMs who were treated with SRS. Pre-SRS treatment and post-SRS treatment MRI were performed at 6, 12, and 24-month intervals. Deep-seated AVMs were classified based on their anatomical location and venous drainage pattern. AVM nidal volume (cm3) was estimated using the ABC/2 method. AV shunting of the AVM draining veins were graded according to its SWI signal intensity: hyperintense (grade III), mixed signal intensity (grade II), hypointense (grade I) and absent (grade 0). Conventional time-of-flight (TOF)-MRA and contrast enhanced (CE)-MRA sequences were performed to document the patency of the vein.

RESULTS

Pre-SRS treatment AVM draining veins were either grade III 18/32 (56%) or grade II 14/32 (44%). Using mixed effects analysis, we demonstrate that each month following the SRS treatment nidal volumes decreased at the rate of 0.51 cm3/per month (CI -0.61 to (-0.40)) p =.00. Following the treatment, there was a clinically significant relationship between the signal and nidal volume: signal 0 corresponded with average nidal volume of 1.81 cm3 (CI 1.40-2.21), signal 1 with nidal volume of 2.06 cm3 (CI 1.69-2.44), signal 2 with nidal volume 2.73 cm3 (CI 2.35-3.11) and signal 3 with nidal volume 3.13 cm3 (CI 2.70-3.56) p = .00.

CONCLUSION

Post-SRS AVM draining veins shows a stepwise regression of the SWI signal grades which can be reliably used as a surrogate to monitor the reduction of AV shunting.

Cerebral microbleeds. Utility of SWI sequences

OBJECTIVES

Define the concept of cerebral microbleeds (CMBs) and describe the most useful MRI sequences for detecting this finding. Review the entities that most frequently present with CMBs and that may benefit from the use of susceptibility-weighted imaging (SWI) sequences.

CONCLUSIONS

SWI is a useful MRI sequence for the detection and characterization of microhemorrhages, venous structures and other sources of susceptibility in imaging. SWI is particularly sensitive to local magnetic field inhomogeneities generated by certain substances and is superior to T2* GRE sequences for this assessment. CMBs may be seen in different neurologic conditions, in certain infrequent clinical contexts and have a key role as a biomarker status in gliomas (ITTS) and as a marker of inflammatory activity in multiple sclerosis.

Technical note: Improved differentiation of calcification from hemosiderin using paramagnetic- and diamagnetic-specific magnetic resonance susceptibility weighted imaging (p-SWI, d-SWI)

INTRODUCTION

Differentiation of calcification and calcium-containing tissue from blood products remains challenging using magnetic resonance imaging (MRI). We developed a novel post-processing algorithm which creates both paramagnetic- and diamagnetic-specific SWI images generated from T2* weighted images using distinct "positive" and "negative" phase masks.

METHODS

10 patients who had undergone clinical MRI scanning of the brain with a rapid echo planar based T2*-weighted EPI-GRE pulse sequence with evidence for either hemosiderin and/or calcifications were retrospectively identified. Complex raw k-space data from individual imaging coils were then extracted, reconstructed, and appropriately combined to produce magnitude and phase images using a phase preserving method. The final reconstructed images included the T2* EPI-GRE magnitude images, p-SWI and d-SWI images. Filtered phase images were also available for review. Correlation with CT scans and MR imaging appearance over time corroborated the composition of the voxels.

RESULTS

Differential "blooming" of diamagnetic and paramagnetic foci was readily identified on the corresponding p-SWI and d-SWI images and provided fast and reliable visual differentiation of diamagnetic from paramagnetic susceptibility effects by ascertaining which of the two images depicted the greatest "blooming" effect. Correlation with the available filtered phase maps was not necessary for differentiation of paramagnetic from diamagnetic image components.

CONCLUSION

Clinical interpretation of SWI images can be further enhanced by creating specific p-SWI and d-SWI image pairs which contain greater visual information than the combination of standard p-SWI images and phase image.

Current and Emerging Techniques in Neuroimaging of Sport-Related Concussion

SUMMARY

Sport-related concussion (SRC) affects an estimated 1.6 to 3.8 million Americans each year. Sport-related concussion results from biomechanical forces to the head or neck that lead to a broad range of neurologic symptoms and impaired cognitive function. Although most individuals recover within weeks, some develop chronic symptoms. The heterogeneity of both the clinical presentation and the underlying brain injury profile make SRC a challenging condition. Adding to this challenge, there is also a lack of objective and reliable biomarkers to support diagnosis, to inform clinical decision making, and to monitor recovery after SRC. In this review, the authors provide an overview of advanced neuroimaging techniques that provide the sensitivity needed to capture subtle changes in brain structure, metabolism, function, and perfusion after SRC. This is followed by a discussion of emerging neuroimaging techniques, as well as current efforts of international research consortia committed to the study of SRC. Finally, the authors emphasize the need for advanced multimodal neuroimaging to develop objective biomarkers that will inform targeted treatment strategies after SRC.

Magnetic resonance imaging protocols in pediatric stroke

Neuroimaging protocols play an important role in the timely evaluation and treatment of pediatric stroke and its mimics. MRI protocols for stroke in the pediatric population should be guided by the clinical scenario and neurologic examination, with consideration of age, suspected infarct type and underlying risk factors. Acute stroke diagnosis and causes in pediatric age groups can differ significantly from those in adult populations, and delay in stroke diagnosis among children is a common problem. An awareness of pediatric stroke presentations and risk factors among pediatric emergency physicians, neurologists, pediatricians, subspecialists and radiologists is critical to ensuring timely diagnosis. Given special considerations related to unique pediatric stroke risk factors and the need for sedation in some children, expert consensus guidelines for the imaging of suspected pediatric infarct have been proposed. In this article the authors review standard and rapid MRI protocols for the diagnosis of pediatric stroke, as well as the key differences between pediatric and adult stroke imaging.

Susceptibility artifact morphology is more conspicuous on susceptibility-weighted imaging compared to T2* gradient echo sequences in the brains of dogs and cats with suspected intracranial disease

Susceptibility-weighted imaging (SWI) has been found to be more reliable in the detection of vessels and blood products than T2*-weighted gradient echo (GE) in several human brain diseases. In veterinary medicine, published information on the diagnostic usefulness of SWI is lacking. The aim of this retrospective observational study was to investigate the value of SWI compared to T2*-weighted GE images in a population of dogs and cats with presumed, MRI-based diagnoses grouped as neoplastic (27), cerebrovascular (14), inflammatory (14), head trauma (5), other pathologies (4), or that were normal (36). Areas of signal void (ASV) were assessed based on shape, distribution, number, and conspicuity. Presence of ASV was found in 31 T2*-weighted GE and 40 SWI sequences; the conspicuity of lesions increased in 92.5% of cases with SWI. A 44.7% increase in the number of cerebral microbleeds (CMBs) was identified within the population using SWI (110) compared to T2*-weighted GE (76). Linear ASV presumed to be abnormal vascular structures, as are reported in humans, were identified in 12 T2*-weighted GE and 19 SWI sequences. In presumed brain tumors, abnormal vascular structures were detected in 11 of 27 (40.7%) cases on T2*-weighted GE and in 16 of 27 (59.3%) cases on SWI, likely representing tumor neovascularization; amorphous ASV interpreted as presumed hemorrhages on T2*-weighted GE were diagnosed as vessels on SWI in five of 27 (18.5%) cases. Since SWI shows ASV more conspicuously than T2*-weighted GE, the authors advocate the use of SWI in veterinary patients.

Conventional MR Imaging in Trauma Management in Pediatrics

Traumatic brain injury (TBI) is a major cause of death and disability in children across the world. The aim of initial brain trauma management of pediatric patients is to diagnose the extent of TBI and to determine if immediate neurosurgical intervention is required. A noncontrast computed tomography is the recommended diagnostic imaging choice for all patients with acute moderate to severe TBI. This article outlines the current use of conventional MR imaging in the management of pediatric head trauma and discusses potential future recommendations.

Papilledema and venous stasis in patients with cerebral venous and sinus thrombosis

BACKGROUND

Cerebral venous and sinus thrombosis (CVST) can cause increased intracranial pressure, often leading to papilledema. In this study, we investigated the association between papilledema and venous stasis on susceptibility weighted imaging (SWI) in CVST.

METHODS

Patients with CVST between 2008 and 2020 were reviewed. Patients without fundoscopic examination or SWI were excluded in this study. Venous stasis was evaluated and scored for each cerebral hemisphere: each hemisphere was divided into 5 regions according to the venous drainage territories (superior sagittal sinus, Sylvian veins, transverse sinus and vein of Labbé, deep cerebral veins, and medullary veins) and 1 point was added if venous prominence was confirmed in one territory on SWI. The venous stasis score on SWI between cerebral hemispheres with and without papilledema was compared.

RESULTS

Eight of 19 patients with CVST were excluded because of the absence of fundoscopic examination or SWI. Eleven patients (26.5 ± 2.1 years) were included in this study. Papilledema was identified in 6 patients: bilateral papilledema in 4 patients and unilateral papilledema in 2 patients. The venous stasis score on SWI was significantly higher (P = 0.013) in the hemispheres with papilledema (median, 4.0; 95% CI, 3.038-4.562) than in the hemispheres without papilledema (median, 2.5; 95% CI, 0.695-2.805).

CONCLUSIONS

This study shows that higher score of venous stasis on SWI is associated with papilledema. Therefore, the venous stasis on SWI may be an imaging surrogate marker of increased intracranial pressure in patients with CVST.

Susceptibility phase imaging of deep gray matter: Presenting the effects of slice orientation

Susceptibility-weighted image (SWI) is a T2* gradient echo sequence, which is highly sensitive to substances that have magnetic properties. The phase and magnitude of SWI can play an important role in the diagnosis of several diseases. The phase data is highly affected by spatial variations in the main magnetic field of the magnetic resonance imaging (MRI) scanner. The axial acquisition is the frequent plane alignment while acquiring SWI in diagnostic imaging. Clinical requirements often lead to changing of the alignment angles due to variability in patient positioning and anatomy. For many patients undergoing brain MRI, the line of the anterior and posterior commissure AC-PC can vary in direction with respect to the transverse plane of the MRI system. We investigated whether there exist significant effect on phase data of SWI, and this is due to oblique orientation. The obtained results showed significant differences in phase values between axial and anatomically alignments.

MRI features of pediatric atypical teratoid rhabdoid tumors and medulloblastomas of the posterior fossa

BACKGROUND

Atypical teratoid rhabdoid tumor (AT/RT) occurs at a younger age and is associated with a worse prognosis than medulloblastoma; however, these two tumor entities are mostly indistinguishable on neuroimaging. The aim of our study was to differentiate AT/RT and medulloblastoma based on their clinical and MRI features to enhance treatment planning and outcome prediction.

METHODS

From 2005-2021, we retrospectively enrolled 16 patients with histopathologically diagnosed AT/RT and 57 patients with medulloblastoma at our institute. We evaluated their clinical data and MRI findings, including lesion signals, intratumoral morphologies, and peritumoral/distal involvement.

RESULTS

The age of children with AT/RT was younger than that of children with medulloblastoma (2.8 ± 4.9 [0-17] vs. 6.5 ± 4.0 [0-18], p < 0.001), and the overall survival rate was lower (21.4% vs. 66.0%, p = 0.005). Regarding lesion signals on MRI, AT/RT had a lower ADC_min (cutoff value ≤544.7 × 10^-6  mm² /s, p < 0.001), a lower ADC ratio (cutoff value ≤0.705, p < 0.001), and a higher DWI ratio (cutoff value ≥1.595, p < 0.001) than medulloblastoma. Regarding intratumoral morphology, the "tumor central vein sign" was mostly exclusive to medulloblastoma (24/57, 42.1%; AT/RT 1/16, 6.3%; p = 0.007). Regarding peritumoral invasion on T2WI, AT/RT was more prone to invasion of the brainstem (p < 0.001) and middle cerebellar peduncle (p < 0.001) than medulloblastoma.

CONCLUSIONS

MRI findings of a lower ADC value, more peritumoral invasion, and absence of the "tumor central vein sign" may be helpful to differentiate AT/RT from medulloblastoma. These distinct MRI findings together with the younger age of AT/RT patients may explain the worse outcomes in AT/RT patients.

Multimodal MRI diagnosis and transvenous embolization of a basicranial emissary vein dural arteriovenous fistula: A case report

A dural arteriovenous fistula (DAVF) is an abnormal linkage connecting the arterial and venous systems within the intracranial dura mater. A basicranial emissary vein DAVF drains into the cavernous sinus and the ophthalmic vein, similar to a cavernous sinus DAVF. Precise preoperative identification of the DAVF location is a prerequisite for appropriate treatment. Treatment options include microsurgical disconnection, endovascular transarterial embolization (TAE), transvenous embolization (TVE), or a combination thereof. TVE is an increasingly popular approach for the treatment of DAVFs and the preferred approach for skull base locations, due to the risk of cranial neuropathy caused by dangerous anastomosis from arterial approaches. Multimodal magnetic resonance imaging (MRI) can provide anatomical and hemodynamic information for TVE. The therapeutic target must be precisely embolized in the emissary vein, which requires guidance via multimodal MRI. Here, we report a rare case of successful TVE for a basicranial emissary vein DAVF, utilizing multimodal MRI assistance. The fistula had vanished, pterygoid plexus drainage had improved, and the inferior petrosal sinus had recanalized, as observed on 8-month follow-up angiography. Symptoms and signs of double vision, caused by abduction deficiency, disappeared. Detailed anatomic and hemodynamic assessment by multimodal MRI is the key to guiding successful diagnosis and treatment.

Quantitative susceptibility mapping improves cerebral microbleed detection relative to susceptibility-weighted images

BACKGROUND AND PURPOSE

Cerebral microbleed (CMB) detection impacts disease diagnosis and management. Susceptibility-weighted imaging (SWI) MRI depictions of CMBs are used with phase images (SWIP) to distinguish blood from calcification, via qualitative intensity evaluation (bright/dark). However, the intensities depicted for a single lesion can vary within and across consecutive SWIP image planes, impairing the classification of findings as a CMB. We hypothesize that quantitative susceptibility mapping (QSM) MRI, which maps tissue susceptibility, demonstrates less in- and through-plane intensity variation, improving the clinician's ability to categorize a finding as a CMB.

METHODS

Forty-eight patients with acute intracranial hemorrhage who received multi-echo gradient echo MRI used to generate both SWI/SWIP and morphology-enabled dipole inversion QSM images were enrolled. Five hundred and sixty lesions were visually classified as having homogeneous or heterogeneous in-plane and through-plane intensity by a neuroradiologist and two diagnostic radiology residents using published rating criteria. When available, brain CT scans were analyzed for calcification or acute hemorrhage. Relative risk (RR) ratios and confidence intervals (CIs) were calculated using a generalized linear model with log link and binary error.

RESULTS

QSM showed unambiguous lesion signal intensity three times more frequently than SWIP (RR = 0.3235, 95% CI 0.2386-0.4386, p<.0001). The probability of QSM depicting homogeneous lesion intensity was three times greater than SWIP for small (RR = 0.3172, 95% CI 0.2382-0.4225, p<.0001), large (RR = 0.3431, 95% CI 0.2045-0.5758, p<.0001), lobar (RR = 0.3215, 95% CI 0.2151-0.4805, p<.0001), cerebellar (RR = 0.3215, 95% CI 0.2151-0.4805, p<.0001), brainstem (RR = 0.3100, 95% CI 0.1192-0.8061, p = .0163), and basal ganglia (RR = 0.3380, 95% CI 0.1980-0.5769, p<.0001) lesions.

CONCLUSIONS

QSM more consistently demonstrates interpretable lesion intensity compared to SWIP as used for distinguishing CMBs from calcification.

Lymphomas of Central Nervous System

Central nervous system (CNS) lymphoma consists of primary central nervous system lymphoma (PCNSL) and secondary CNS involvement by systemic lymphoma. This chapter focuses on the former. PCNSL is a relative rare disease, accounting for approximately 2.4-4.9% of all primary CNS tumors. It is an extra-nodal variant of non-Hodgkin's lymphoma (NHL), confined to the brain, leptomeninges, spinal cord, and eyes, with no systemic involvement. Recently, elderly patients (≥ 60 years) are increasing. Histologically, B cell blasts, which originate from late germinal center exit B cell, are growing and homing in CNS. Immunohistochemically, these cells are positive for PAX5, CD19, CD20, CD22, and CD79a. PCNSL shows relatively characteristic appearances on CT, MR imaging, and PET. Treatment first line of PCNSL is HD-MTX-based chemotherapy with or without rituximab and irradiation. Severe side-effect of this treatment is delayed onset neurotoxicity, which cause of cognitive impairment. Therefore, combined chemotherapy alone or chemotherapy with reduced-dose irradiation is more recommended for elderly patients. There is no established standard care for relapse of the PCNSLs. Temsirolimus, lenalidomide, temozolomide, and Bruton's tyrosine kinase (BTK) inhibitor ibrutinib are candidates for refractory patients. The prognosis of PCNSL has significantly improved over the last decades (median OS: 26 months, 5-year survival: 31%). Younger than 60 age and WHO performance status less than < or = 1 are associated with a significantly better overall survival.

A Compendium on Perinatal Autopsy in Neonats

Professionals who work in perinatal care must understand the advantages and disadvantages of perinatal autopsy since they are an essential tool for determining fetal and neonatal mortality. Perinatal is the period five months before one month after birth, while prenatal is before birth. The traditional prenatal autopsy is still the gold standard for establishing the cause of death and providing an accurate report, notwithstanding the development of new technology. The ideal locations for a prenatal autopsy are tertiary institutes that offer these procedures. It emphasizes the need for systematic histopathologic sampling, rigorous record-keeping, technological adaptation, and wise laboratory test use. When a laboratory does a microbiologic examination with a focus on the genital tract and neonatal problems, it is very beneficial. Karyotyping needs to be selective and works best when there are many aberrations if resources are to be saved. A perinatal autopsy is insufficient without examining the placenta, and severe lesions should be distinguished from deformities and abnormalities brought on by fetal death. In addition to providing epidemiology teams and auditing committees with high-quality data, the pathologist's role in perinatal medicine also includes participating in the multidisciplinary management of fetal abnormalities identified during pregnancy, monitoring the patterns of iatrogenic disease, and aiding the perinatal grief management process. Investigations into complicated multiple pregnancies, hydrops, bone dysplasias, and unexpected intrauterine fetal deaths provide unique obstacles and diagnostic difficulties. There hasn't been any research that contrasts postmortem computed tomography with postmortem x-rays in pregnant women, as far as we know. Histological analysis of many perinatal autopsies revealed healthy developing tissues. Only a tiny percentage of histological abnormalities can be expected in fetal anomaly terminations. On prenatal imaging, many organ abnormalities are commonly anticipated. A thorough database search was done in Pubmed, Medline, and Scopus using the phrases "fetal abnormalities," "karyotyping," "fetal abnormality," "postmortem," and "perinatal autopsy."

Blood in the Brain on Susceptibility-Weighted Imaging

Intraparenchymal brain hemorrhage is not uncommon and results from a wide variety of causes ranging from trauma to tumor. Many a time, it is not possible to determine the exact cause of non-traumatic hemorrhage on conventional magnetic resonance imaging (MRI). Susceptibility-weighted imaging (SWI) is a high-resolution (3D) gradient-echo sequence. It is extremely sensitive to the inhomogeneity of the local magnetic field and highly useful in identifying the small amount of hemorrhage, which may be inapparent on other MR pulse sequences. In this review, we present different pattern of an intra-parenchymal brain hemorrhage on SWI with emphasis on differential diagnosis.

Cerebral Superficial Siderosis

Superficial siderosis (SS) of the central nervous system constitutes linear hemosiderin deposits in the leptomeninges and the superficial layers of the cerebrum and the spinal cord. Infratentorial (i) SS is likely due to recurrent or continuous slight bleeding into the subarachnoid space. It is assumed that spinal dural pathologies often resulting in cerebrospinal fluid (CSF) leakage is the most important etiological group which causes iSS and detailed neuroradiological assessment of the spinal compartment is necessary. Further etiologies are neurosurgical interventions, trauma and arteriovenous malformations. Typical neurological manifestations of this classical type of iSS are slowly progressive sensorineural hearing impairment and cerebellar symptoms, such as ataxia, kinetic tremor, nystagmus and dysarthria. Beside iSS, a different type of SS restricted to the supratentorial compartment can be differentiated, i.e. cortical (c) SS, especially in older people often due to cerebral amyloid angiopathy (CAA). Clinical presentation of cSS includes transient focal neurological episodes or “amyloid spells”. In addition, spontaneous and amyloid beta immunotherapy-associated CAA-related inflammation may cause cSS, which is included in the hemorrhagic subgroup of amyloid-related imaging abnormalities (ARIA). Because a definitive diagnosis requires a brain biopsy, knowledge of neuroimaging features and clinical findings in CAA-related inflammation is essential. This review provides neuroradiological hallmarks of the two groups of SS and give an overview of neurological symptoms and differential diagnostic considerations.

Clinical significance of asymmetric venous vasculature on minimum-intensity projection in patients with moyamoya disease

This study analyzed the clinical significance and characteristics of asymmetric venous blood flow in patients with Moyamoya disease (MMD) using minimum intensity projection (minIP) susceptibility-weighted imaging. The minIP views of 30 patients diagnosed with MMD were retrospectively analyzed using clinical features, brain magnetic resonance angiography, electroencephalography, and brain single-photon emission computed tomography (SPECT). Simultaneously, differences between patients with acute cerebral infarction and non-MMD causes were analyzed. Twelve (40.0%) of the 30 patients had asymmetrical venous flow, which is usually seen in patients with acute cerebral infarction (P = .146). They also had significantly higher Suzuki stages than symmetric patients (P = .014), with five (41.7%) and three (25.0%) of them in stages 4 and 5, respectively. When the Suzuki stages of both hemispheres were different, more veins were found in the stenotic hemisphere (88.9%). Brain SPECT showed more severe hypoperfusion on the side with prominent vascularity in the minIP view (100.0%). Additionally, asymmetric blood flow was observed in 66.7% of the patients with cerebral infarction caused by MMD, whereas only 11.1% of the children with cerebral infarction caused by non-MMD had asymmetry (P = .005). Patients with MMD showed asymmetric hypointensity of the cortical veins with a minIP appearance. The venous structure showed greater signal loss on SWI and was more prominent in the hemisphere where stenosis was advanced or infarction occurred in other examinations. Cerebral infarction in patients with MMD tended to occur with asymmetrically prominent venous patterns with damaged areas in minIP images, which had distinct characteristics from those of patients without MMD.

Clinical validation of Wave-CAIPI susceptibility-weighted imaging for routine brain MRI at 1.5 T

OBJECTIVES

Wave-CAIPI (Controlled Aliasing in Parallel Imaging) enables dramatic reduction in acquisition time of 3D MRI sequences such as 3D susceptibility-weighted imaging (SWI) but has not been clinically evaluated at 1.5 T. We sought to compare highly accelerated Wave-CAIPI SWI (Wave-SWI) with two alternative standard sequences, conventional three-dimensional SWI and two-dimensional T2*-weighted Gradient-Echo (T2*w-GRE), in patients undergoing routine brain MRI at 1.5 T.

METHODS

In this study, 172 patients undergoing 1.5 T brain MRI were scanned with a more commonly used susceptibility sequence (standard SWI or T2*w-GRE) and a highly accelerated Wave-SWI sequence. Two radiologists blinded to the acquisition technique scored each sequence for visualization of pathology, motion and signal dropout artifacts, image noise, visualization of normal anatomy (vessels and basal ganglia mineralization), and overall diagnostic quality. Superiority testing was performed to compare Wave-SWI to T2*w-GRE, and non-inferiority testing with 15% margin was performed to compare Wave-SWI to standard SWI.

RESULTS

Wave-SWI performed superior in terms of visualization of pathology, signal dropout artifacts, visualization of normal anatomy, and overall image quality when compared to T2*w-GRE (all p < 0.001). Wave-SWI was non-inferior to standard SWI for visualization of normal anatomy and pathology, signal dropout artifacts, and overall image quality (all p < 0.001). Wave-SWI was superior to standard SWI for motion artifact (p < 0.001), while both conventional susceptibility sequences were superior to Wave-SWI for image noise (p < 0.001).

CONCLUSIONS

Wave-SWI can be performed in a 1.5 T clinical setting with robust performance and preservation of diagnostic quality.

KEY POINTS

• Wave-SWI accelerated the acquisition of 3D high-resolution susceptibility images in 70% of the acquisition time of the conventional T2*GRE. • Wave-SWI performed superior to T2*w-GRE for visualization of pathology, signal dropout artifacts, and overall diagnostic image quality. • Wave-SWI was noninferior to standard SWI for visualization of normal anatomy and pathology, signal dropout artifacts, and overall diagnostic image quality.

Cortical lesions, central vein sign, and paramagnetic rim lesions in multiple sclerosis: Emerging machine learning techniques and future avenues

The current diagnostic criteria for multiple sclerosis (MS) lack specificity, and this may lead to misdiagnosis, which remains an issue in present-day clinical practice. In addition, conventional biomarkers only moderately correlate with MS disease progression. Recently, some MS lesional imaging biomarkers such as cortical lesions (CL), the central vein sign (CVS), and paramagnetic rim lesions (PRL), visible in specialized magnetic resonance imaging (MRI) sequences, have shown higher specificity in differential diagnosis. Moreover, studies have shown that CL and PRL are potential prognostic biomarkers, the former correlating with cognitive impairments and the latter with early disability progression. As machine learning-based methods have achieved extraordinary performance in the assessment of conventional imaging biomarkers, such as white matter lesion segmentation, several automated or semi-automated methods have been proposed as well for CL, PRL, and CVS. In the present review, we first introduce these MS biomarkers and their imaging methods. Subsequently, we describe the corresponding machine learning-based methods that were proposed to tackle these clinical questions, putting them into context with respect to the challenges they are facing, including non-standardized MRI protocols, limited datasets, and moderate inter-rater variability. We conclude by presenting the current limitations that prevent their broader deployment and suggesting future research directions.

A case of childhood unilateral relapsing primary angiitis of the central nervous system

The patient was a 17-year-old girl with transient right-sided weakness and dysesthesia associated with headache and nausea. Head magnetic resonance imaging (MRI) revealed white matter lesions confined to the left hemisphere. Initially, multiple sclerosis was suspected, and methylprednisolone (mPSL) pulse therapy was administered, followed by fingolimod hydrochloride. However, on day 267, the patient again experienced transient hypesthesia. Cranial MRI showed expansion of the highly infiltrated areas of the left hemisphere on fluid-attenuated inversion recovery (FLAIR) and T2 weighted image, accompanied by edema. Multiple contrasting areas were also observed. Susceptibility-weighted imaging demonstrated several streaks and some corkscrew-like appearances with low signals from the white matter to the cortex, suggestive of occluded or dilated collateral vessels. Multiple dotted spots indicating cerebral microbleeds (MBs) were also observed. A brain biopsy revealed lymphocytic, non-granulomatous inflammation in and around the vessels. Vascular occlusion and perivascular MBs were prevalent. The patient was diagnosed with relapsing primary angiitis of the central nervous system (PACNS), and immunosuppressive treatment was initiated, mPSL 1000 mg/day pulse therapy. The patient's clinical symptoms and neuroradiological abnormalities gradually improved. She is now receiving oral prednisolone (6 mg/day) and mycophenolate mofetil (1750 mg/day). This case corresponds to unilateral relapsing, which has recently been reported as a specific clinicopathological subtype of PACNS.

Reduced white matter venous density on MRI is associated with neurodegeneration and cognitive impairment in the elderly

High-resolution susceptibility weighted imaging (SWI) provides unique contrast to small venous vasculature. The conspicuity of these mesoscopic veins, such as deep medullary veins in white matter, is subject to change from SWI venography when venous oxygenation in these veins is altered due to oxygenated blood susceptibility changes. The changes of visualization in small veins shows potential to depict regional changes of oxygen utilization and/or vascular density changes in the aging brain. The goal of this study was to use WM venous density to quantify small vein visibility in WM and investigate its relationship with neurodegenerative features, white matter hyperintensities (WMHs), and cognitive/functional status in elderly subjects (N = 137). WM venous density was significantly associated with neurodegeneration characterized by brain atrophy (β = 0.046± 0.01, p < 0.001), but no significant association was found between WM venous density and WMHs lesion load (p = 0.3963). Further analysis of clinical features revealed a negative trend of WM venous density with the sum-of-boxes of Clinical Dementia Rating and a significant association with category fluency (1-min animal naming). These results suggest that WM venous density on SWI can be used as a sensitive marker to characterize cerebral oxygen metabolism and different stages of cognitive and functional status in neurodegenerative diseases.

Paramagnetic rims are a promising diagnostic imaging biomarker in multiple sclerosis

BACKGROUND

White matter lesions (WMLs) on brain magnetic resonance imaging (MRI) in multiple sclerosis (MS) may contribute to misdiagnosis. In chronic active lesions, peripheral iron-laden macrophages appear as paramagnetic rim lesions (PRLs).

OBJECTIVE

To evaluate the sensitivity and specificity of PRLs in differentiating MS from mimics using clinical 3T MRI scanners.

METHOD

This retrospective international study reviewed MRI scans of patients with MS (n = 254), MS mimics (n = 91) and older healthy controls (n = 217). WMLs, detected using fluid-attenuated inversion recovery MRI, were analysed with phase-sensitive imaging. Sensitivity and specificity were assessed for PRLs.

RESULTS

At least one PRL was found in 22.9% of MS and 26.1% of clinically isolated syndrome (CIS) patients. Only one PRL was found elsewhere. The identification of ⩾1 PRL was the optimal cut-off and had high specificity (99.7%, confidence interval (CI) = 98.20%-99.99%) when distinguishing MS and CIS from mimics and healthy controls, but lower sensitivity (24.0%, CI = 18.9%-36.6%). All patients with a PRL showing a central vein sign (CVS) in the same lesion (n = 54) had MS or CIS, giving a specificity of 100% (CI = 98.8%-100.0%) but equally low sensitivity (21.3%, CI = 16.4%-26.81%).

CONCLUSION

PRLs may reduce diagnostic uncertainty in MS by being a highly specific imaging diagnostic biomarker, especially when used in conjunction with the CVS.

Computer-Aided Extraction of Select MRI Markers of Cerebral Small Vessel Disease: A Systematic Review

Cerebral small vessel disease (CSVD) is a major vascular contributor to cognitive impairment in ageing, including dementias. Imaging remains the most promising method for in vivo studies of CSVD. To replace the subjective and laborious visual rating approaches, emerging studies have applied state-of-the-art artificial intelligence to extract imaging biomarkers of CSVD from MRI scans. We aimed to summarise published computer-aided methods for the examination of three imaging biomarkers of CSVD, namely cerebral microbleeds (CMB), dilated perivascular spaces (PVS), and lacunes of presumed vascular origin. Seventy classical image processing, classical machine learning, and deep learning studies were identified. Transfer learning and weak supervision techniques have been applied to accommodate the limitations in the training data. While good performance metrics were achieved in local datasets, there have not been generalisable pipelines validated in different research and/or clinical cohorts. Future studies could consider pooling data from multiple sources to increase data size and diversity, and evaluating performance using both image processing metrics and associations with clinical measures.

High-resolution susceptibility-weighted imaging of clots in cerebral venous thrombosis

PURPOSE

To distinguish cerebral venous clots from patent dural sinuses, cortical veins, and calvarium on high-resolution susceptibility-weighted imaging, since there is lack of a well-designed study in the literature.

METHODS

A retrospective review of 51 consecutive cases and 27 controls was performed with susceptibility-weighted imaging independently by two investigators. MR venography along with MR sequences other than the susceptibility-weighted imaging served as the reference standard.

RESULTS

There were 29 males and 49 females in the age range of 1 month to 70 years (mean 27 ± 19.8 years). Substantial (k 0.84 to 1.0) to good (k 0.60 to 0.75) inter-rater agreement was observed on the magnitude images for the demonstration of clots in all venous segments, excluding left sigmoid sinus, jugular bulb, and internal jugular vein (k 0.43 to 0.56). Comparatively magnitude images demonstrated better sensitivity (0.83 (0.54-1.13) to 1.0), specificity (0.92 (0.85-0.99) to 1.0), and negative predictive value (0.98 (0.94-1.02) to 1.0) for the detection of clots across all venous segments. Magnitude images showed positive predictive value ranging from 0.83 (0.66-1.0) to 1.0 for clots anywhere from the anterior aspect of superior sagittal sinus to bilateral transverse sinuses. For the detection of clots from bilateral sigmoid sinuses to internal jugular veins, magnitude images showed relatively better positive predictive value ranging from 0.57 (0.20-0.94) to 0.75 (0.45-1.06) in comparison to the processed magnitude and minimum intensity pixel images.

CONCLUSION

Susceptibility-weighted imaging can successfully distinguish majority of clots from patent dural sinuses, cortical veins, and calvarium with excellent inter-rater agreements.

An Integrated Approach on the Diagnosis of Cerebral Veins and Dural Sinuses Thrombosis

(1) Objective: This review paper aims to discuss multiple aspects of cerebral venous thrombosis (CVT), including epidemiology, etiology, pathophysiology, and clinical presentation. Different neuroimaging methods for diagnosis of CVT, such as computer tomography CT/CT Venography (CTV), and Magnetic Resonance Imaging (MRI)/MR Venography (MRV) will be presented. (2) Methods: A literature analysis using PubMed and the MEDLINE sub-engine was done using the terms: cerebral venous thrombosis, thrombophilia, and imaging. Different studies concerning risk factors, clinical picture, and imaging signs of patients with CVT were examined. (3) Results: At least one risk factor can be identified in 85% of CVT cases. Searching for a thrombophilic state should be realized for patients with CVT who present a high pretest probability of severe thrombophilia. Two pathophysiological mechanisms contribute to their highly variable clinical presentation: augmentation of venular and capillary pressure, and diminution of cerebrospinal fluid absorption. The clinical spectrum of CVT is frequently non-specific and presents a high level of clinical suspicion. Four major syndromes have been described: isolated intracranial hypertension, seizures, focal neurological abnormalities, and encephalopathy. Cavernous sinus thrombosis is the single CVT that presents a characteristic clinical syndrome. Non-enhanced CT (NECT) of the Head is the most frequently performed imaging study in the emergency department. Features of CVT on NECT can be divided into direct signs (demonstration of dense venous clot within a cerebral vein or a cerebral venous sinus), and more frequently indirect signs (such as cerebral edema, or cerebral venous infarct). CVT diagnosis is confirmed with CTV, directly detecting the venous clot as a filling defect, or MRI/MRV, which also realizes a better description of parenchymal abnormalities. (4) Conclusions: CVT is a relatively rare disorder in the general population and is frequently misdiagnosed upon initial examination. The knowledge of wide clinical aspects and imaging signs will be essential in providing a timely diagnosis.

Brain pathological changes during neurodegenerative diseases and their identification methods: How does QSM perform in detecting this process?

The presence of iron is essential for many biological processes in the body. But sometimes, for various reasons, the amount of iron deposition in different areas of the brain increases, which leads to problems related to the nervous system. Quantitative susceptibility mapping (QSM) is one of the newest magnetic resonance imaging (MRI)-based methods for assessing iron accumulation in target areas. This Narrative Review article aims to evaluate the performance of QSM compared to other methods of assessing iron deposition in the clinical field. Based on the results, we introduced related basic definitions, some neurodegenerative diseases, methods of examining iron deposition in these diseases, and their advantages and disadvantages. This article states that the QSM method can be introduced as a new, reliable, and non-invasive technique for clinical evaluations.

Diagnostic utility of T2*-weighted GRE in migraine with aura attack. The cortical veins sign

OBJECTIVE

To evaluate the frequency, distribution, and clinical associations of the dilated appearance of cerebral cortical veins, termed cortical veins sign on T2*-weighted gradient recalled-echo (T2*-GRE) in the acute setting of migraine with aura attack in adult patients.

METHODS

We conducted a retrospective analysis of 60 consecutive patients admitted for acute neurological symptoms with a final diagnosis of migraine with aura (42%) or probable migraine with aura (58%) who underwent emergency brain magnetic resonance imaging and 60 non-migrainous control adults. The cortical veins sign was defined as a marked hypo-intensity and/or an apparent increased diameter of at least one cortical vein. We examined the prevalence, the spatial distribution, and the associations of cortical veins sign with clinical characteristics of migraine with aura.

RESULTS

We detected the cortical veins sign in 25 patients (42%) with migraine with aura, compared to none in the control group (p < 0.0001). The spatial distribution of cortical veins sign was characterised by the predominantly bilateral and posterior location. Presence of cortical veins sign was associated with increased severity of aura (p = 0.05), and shorter delay to MRI (p = 0.02).

CONCLUSION

In the setting of acute neurological symptoms, the presence of cortical veins sign is frequent in patients with migraine with aura and can be detected with good reliability. This imaging marker may help clinicians identify underlying migraine with aura.