Patterns of Contrast Enhancement in the Brain and Meninges

Prospective comparison of volumetric post-contrast T1-Sampling Perfection with Application optimized Contrasts by using different flip angle Evolutions and Magnetization-Prepared Rapid Acquisition with Gradient Echo in patients with metastatic melanoma

INTRODUCTION

Volumetric turbo spin echo (3D-TSE) T1-weighted imaging techniques such as T1-SPACE (Sampling Perfection with Application optimized Contrasts by using different flip angle Evolutions) improve detection of intracranial metastases (IM) compared to volumetric magnetisation-prepared gradient recalled echo techniques such as MPRAGE (Magnetization-Prepared Rapid Acquisition with Gradient Echo). However, incomplete vascular suppression can produce false positives when using 3D-TSE. Research into 3D-TSE has generally targeted patients with known or suspected IM, but the clinical implications of false positives are greater in patients with lower likelihood of IM. This study examined additional findings identified by T1-SPACE in patients with metastatic melanoma, targeting patients with a lower incidence of IM.

METHODS

Patients with metastatic melanoma and an upcoming brain MRI booking were identified prospectively. Consent for adding post-contrast T1-SPACE to the MRI protocol (which included MPRAGE) was obtained. Imaging was initially assessed without T1-SPACE. Subsequently, T1-SPACE images were examined and additional findings identified were recorded, including their correlation with MPRAGE.

RESULTS

One hundred examinations were performed, 24 having evidence of active IM. T1-SPACE allowed identification of additional lesions in five patients, including two with small solitary IM not identified when first assessing MPRAGE. In 18 examinations, T1-SPACE identified additional equivocal findings, confidently attributed to artefact (most commonly normal vessels) following correlation with MPRAGE.

CONCLUSION

T1-SPACE improves detection of small lesions in patients without known IM, changing patient management. False positives are common but can be clarified with MPRAGE. Combining T1-SPACE and MPRAGE allows both sensitivity and specificity to be optimised.

Influence of measurement mode on the results of glioblastoma multiforme analysis with the FTIR microspectroscopy

Fourier Transform Infrared (FTIR) microspectroscopy is well known for its effectiveness in spectral and biochemical analyses of various materials. It enables to determine the sample biochemical composition by assigning detected frequencies, characteristic for functional groups of main biological macromolecules. In analysis of tissue sections one of two measurement modes, namely transmission and transflection, is usually applied. The first one has relatively straightforward geometry, hence it is considered to be more precise and accurate. However, IR-transparent media are very fragile and expensive. Transflection does not require expensive substrates, but is more prone to disruptive influence of Mie scattering as well as electric field standing wave effect. The excessive comparison of spectra' characteristics, obtained via both measurement modes, was performed in this paper. By the means of Mann-Whitney non-parametrical U test and PCA, the comparison of results obtained with both modes and assessment of usefulness of IR spectra obtained with transmission and transflection modes to differentiate between healthy and GBM-affected tissue, were performed. The main objective of the presented research is to compare the results of FTIR analysis of unfixed biological samples performed with transflection and transmission mode. In frame of the study we demonstrated the discrepancies between results of biochemical analysis performed based on data obtained with transmission and transflection. Such observation suggests that caution should be taken in drawing conclusions from the results obtained with transflection geometry, as its more prone to disruptive effects. Despite that, IR spectra developed with both modes allowed to distinguish GBM area from healthy tissue, which proves their diagnostic potential. Especially, application of the ME-EMSC correction of spectra before PCA enhances the performance of both methods to distinguish the analysed tissue areas.

Shape and texture analyses based on conventional MRI for the preoperative prediction of the aggressiveness of pituitary adenomas

OBJECTIVES

Pituitary adenomas can exhibit aggressive behavior, characterized by rapid growth, resistance to conventional treatment, and early recurrence. This study aims to evaluate the clinical value of shape-related features combined with textural features based on conventional MRI in evaluating the aggressiveness of pituitary adenomas and develop the best diagnostic model.

METHODS

Two hundred forty-six pituitary adenoma patients (84 aggressive, 162 non-aggressive) who underwent preoperative MRI were retrospectively reviewed. The patients were divided into training (n = 193) and testing (n = 53) sets. Clinical information, shape-related, and textural features extracted from the tumor volume on contrast-enhanced T1-weighted images (CE-T1WI), were compared between aggressive and non-aggressive groups. Variables with significant differences were enrolled into Pearson's correlation analysis to weaken multicollinearity. Logistic regression models based on the selected features were constructed to predict tumor aggressiveness under fivefold cross-validation.

RESULTS

Sixty-five imaging features, including five shape-related and sixty textural features, were extracted from volumetric CE-T1WI. Forty-seven features were significantly different between aggressive and non-aggressive groups (all p values < 0.05). After feature selection, four features (SHAPE_Sphericity, SHAPE_Compacity, DISCRETIZED_Q3, and DISCRETIZED_Kurtosis) were put into logistic regression analysis. Based on the combination of these features and Knosp grade, the model yielded an area under the curve value of 0.935, with a sensitivity of 94.4% and a specificity of 82.9%, to discriminate between aggressive and non-aggressive pituitary adenomas in the testing set.

CONCLUSION

The radiomic model based on tumor shape and textural features study from CE-T1WI might potentially assist in the preoperative aggressiveness diagnosis of pituitary adenomas.

KEY POINTS

• Pituitary adenomas with aggressive behavior exhibit rapid growth, resistance to conventional treatment, and early recurrence despite gross resection and may require multiline treatments. • Shape-related features and texture features based on CE-T1WI were significantly correlated with the Ki-67 labeling index, mitotic count, and p53 expression, and the proposed model achieved a favorable prediction of the aggressiveness of PAs with an AUC value of 0.935. • The prediction model might provide valuable guidance for individualized treatment in patients with PAs.

Dual-energy CT imaging of chronic subdural hematoma membranes: technical note

This technical note describes a novel dual-energy CT (DECT) protocol with iodine map reconstruction that will enable visualization of chronic subdural hematoma (CSDH) membranes. We describe the technique and discuss the potential implications for surgical management. The cohort included 36 patients with 50 hematomas. Enhancing external membrane was demonstrated in all the 50 hematomas, incomplete internal membrane in 13, and complete internal membrane in 23 hematomas. A spandrel sign at the transition zone that indicates partial or complete formation of internal membrane was demonstrated in 36 hematomas. KEY POINTS: • Iodine maps from 5-min delayed post-contrast DECT provide spectral contrast difference and facilitate segregation of chronic subdural hematoma membranes. • The ability to image the membranes helps in assessing the degree of organization of the hematoma by providing the information about the membrane thickness, volume, complexity of the membranes, and the proportion of the liquefied component within the hematoma before surgical procedures are undertaken. • Membrane visualization helps in the localization of the transition zone and extension of the membranes over the cerebral lobes helping in the determination of craniotomy location and size, during membranectomy.

Imaging of Central Nervous System Autoimmune, Paraneoplastic, and Neuro-rheumatologic Disorders

OBJECTIVE

This article provides an overview of the imaging modalities used in the evaluation of central nervous system (CNS) autoimmune, paraneoplastic, and neuro-rheumatologic disorders. An approach is outlined for interpreting imaging findings in this context, synthesizing a differential diagnosis based on certain imaging patterns, and choosing further imaging for specific diseases.

LATEST DEVELOPMENTS

The rapid discovery of new neuronal and glial autoantibodies has revolutionized the autoimmune neurology field and has elucidated imaging patterns characteristic of certain antibody-associated diseases. Many CNS inflammatory diseases, however, lack a definitive biomarker. Clinicians should recognize neuroimaging patterns suggestive of inflammatory disorders, as well as the limitations of imaging. CT, MRI, and positron emission tomography (PET) modalities all play a role in diagnosing autoimmune, paraneoplastic, and neuro-rheumatologic disorders. Additional imaging modalities such as conventional angiography and ultrasonography can be helpful for further evaluation in select situations.

ESSENTIAL POINTS

Knowledge of imaging modalities, both structural and functional, is critical in identifying CNS inflammatory diseases quickly and can help avoid invasive testing such as brain biopsy in certain clinical scenarios. Recognizing imaging patterns suggestive of CNS inflammatory diseases can also facilitate the early initiation of appropriate treatments to diminish morbidity and future disability.

Neuroimaging Patterns of Intracranial Infections: Meningitis, Cerebritis, and Their Complications

Neuroimaging provides rapid, noninvasive visualization of central nervous system infections for optimal diagnosis and management. Generalizable and characteristic imaging patterns help radiologists distinguish different types of intracranial infections including meningitis and cerebritis from a variety of bacterial, viral, fungal, and/or parasitic causes. Here, we describe key radiologic patterns of meningeal enhancement and diffusion restriction through profiles of meningitis, cerebritis, abscess, and ventriculitis. We discuss various imaging modalities and recent diagnostic advances such as deep learning through a survey of intracranial pathogens and their radiographic findings. Moreover, we explore critical complications and differential diagnoses of intracranial infections.

Case report: Autoimmune encephalitis associated with anti-CASPR2 antibody mimicking cerebral infarction

Autoimmune encephalitis associated with antibody against contactin-associated protein-like 2 (CASPR2) varies in its clinical presentation. The disease is difficult to distinguish from some other conditions without testing for anti-CASPR2 antibody in blood serum or cerebrospinal fluid. Cerebral lesions are typically detected by magnetic resonance imaging (MRI) in the medial temporal lobe or hippocampus. Here, we describe a patient with anti-CASPR2 antibody autoimmune encephalitis whose imaging manifestations mimicked infarction in the left frontal lobe. The 48-year-old man reported memory loss, convulsions, and disturbed consciousness one day after drinking wine. The right upper arm showed reduced autonomous movement after painful stimuli, and MRI showed abnormal hyperintensities in the left frontal lobe on T2 and fluid-attenuated inversion recovery sequences, restricted diffusion, and decreased cerebral blood flow, mimicking acute cerebral infarction. Contrast-enhanced T1-weighted MRI showed gyral enhancement involving the cortex and subcortical white matter. Computed tomography angiography did not identify culprit blood vessels. Symptoms did not improve with anti-platelet or lipid-lowering therapy. Screening for serum antibodies associated with autoimmune encephalitis detected antibody against CASPR2, and intravenous immunoglobulin therapy substantially improved symptoms. This case provides the first indication that anti-CASPR2 antibody-associated autoimmune encephalitis can manifest as involvement of the cortex and subcortical white matter in the frontal lobe based on MRI. It emphasizes the need for thorough investigation, including analysis of potential autoimmunity, of patients whose imaging findings mimic ischemic infarction.

Contrast Medium Use in Computed Tomography for Patients Presenting with Headache: 4-year Retrospective Two-Center Study in Central and Western Regions of Ghana

Background

Contrast medium (CM) administration during computed tomography (CT) enhances the accuracy in the detection and interpretation of abnormalities. Evidence from literature also validate the essence of CM in imaging studies. CT, by virtue of its ubiquity, ease of use, speed, and lower financial footprint, is usually the first investigation in cases of headache. Through a multicenter retrospective analysis, we compared findings of contrast-enhanced CT (CECT) to noncontrast-enhanced CT (NCECT) head examinations among patients presenting with headache.

Methods

A multicenter retrospective analysis of four years' CT head examination data at two radiology centers located in Central and Western Regions of Ghana were reviewed. Records of patients who presented with headache as principal complaint between January 2017 and December 2020 were reviewed. A total of 477 records of patients with headache were identified, retrieved and evaluated. A Chi-square test and Fisher exact test were used to compare the CECT and NCECT groups. Binary logistic regression analysis was computed to assess association between CECT and each CT findings. Statistical significance was considered at p < 0.05 with a 95% confidence interval.

Results

A significant proportion of the patients was females (51.8% in CECT and 60% in NCECT). The NCECT group (40.06 ± 14.76 years) was relatively older than the CECT group (38.43 ± 17.64 years). There was a significant difference between the CECT and NCECT in terms of age (p=0.002) and facility CT was performed (p < 0.0001). The rate of abnormalities was higher in CECT (43.5%, 166/382) compared NCECT (37.9%, 36/95). There was no significant association between CT head findings and contrast enhancement.

Conclusion

CECT examination accounted for 5.6% increase in the detection of head abnormalities. Efforts required to establish local standard operation procedures (SOPs) for contrast medium use especially in CT head examinations. Further studies to improve the knowledge of agents, mechanism of action, and safety of contrast media used among practitioners in Ghana is recommended.

Brain metastases: A Society for Neuro-Oncology (SNO) consensus review on current management and future directions

Brain metastases occur commonly in patients with advanced solid malignancies. Yet, less is known about brain metastases than cancer-related entities of similar incidence. Advances in oncologic care have heightened the importance of intracranial management. Here, in this consensus review supported by the Society for Neuro-Oncology (SNO), we review the landscape of brain metastases with particular attention to management approaches and ongoing efforts with potential to shape future paradigms of care. Each coauthor carried an area of expertise within the field of brain metastases and initially composed, edited, or reviewed their specific subsection of interest. After each subsection was accordingly written, multiple drafts of the manuscript were circulated to the entire list of authors for group discussion and feedback. The hope is that the these consensus guidelines will accelerate progress in the understanding and management of patients with brain metastases, and highlight key areas in need of further exploration that will lead to dedicated trials and other research investigations designed to advance the field.

Headache Attributed to Non-vascular Intracranial Disorder: Neoplasms, Infections, and Substance Abuse

Evaluation of headaches warrants a careful history and neurologic assessment to determine the need for further workup and imaging. Identifying patients who are at risk for underlying pathology is important and this includes individuals with known or suspected malignancy and those who are immunocompromised and at increased risk for intracranial infection. While CT is helpful in the acute setting and to screen for intracranial hypertension, MRI is the modality of choice for the evaluation of underlying pathologies. Imaging in substance abuse may show injury related to direct toxicity or secondary to vascular complications.

Efficient Prediction of Ki-67 Proliferation Index in Meningiomas on MRI: From Traditional Radiological Findings to a Machine Learning Approach

Background/aim This study aimed to explore the value of radiological and radiomic features retrieved from magnetic resonance imaging in the prediction of a Ki-67 proliferative index in meningioma patients using a machine learning model. Methods This multicenter, retrospective study included 371 patients collected from two centers. The Ki-67 expression was classified into low-expressed and high-expressed groups with a threshold of 5%. Clinical features and radiological features were collected and analyzed by using univariate and multivariate statistical analyses. Radiomic features were extracted from contrast-enhanced images, followed by three independent feature selections. Six predictive models were constructed with different combinations of features by using linear discriminant analysis (LDA) classifier. Results The multivariate analysis suggested that the presence of intratumoral necrosis (p = 0.032) and maximum diameter (p < 0.001) were independently correlated with a high Ki-67 status. The predictive models showed good performance with AUC of 0.837, accuracy of 0.810, sensitivity of 0.857, and specificity of 0.771 in the internal test and with AUC of 0.700, accuracy of 0.557, sensitivity of 0.314, and specificity of 0.885 in the external test. Conclusion The results of this study suggest that the predictive model can efficiently predict the Ki-67 index of meningioma patients to facilitate the therapeutic management.

Case Report: Atypical Solitary Brain Metastasis: The Role of MR Spectroscopy In Differential Diagnosis

Background

Metastatic brain tumors are typically located at the cerebral hemispheres or the cerebellum and most frequently originate from primary breast or lung tumors. Metastatic lesions are usually associated with blood–brain barrier disruption, solid or ring-like contrast enhancement, and perilesional vasogenic edema on brain imaging. Even in cases where metastases are predominantly cystic, enhancement of the minor solid component can be detected. In contrast, non-enhancing secondary brain tumors were only reported in a patient after antiangiogenic treatment with bevacizumab.

Case report

We report a case of a 54-year-old male who presented with left-sided weakness and multiple seizures. Brain magnetic resonance imaging revealed a T2-weighted heterogeneous solid tumor in the right frontoparietal parasagittal region, with no apparent enhancement on T1-weighted post-contrast images and no evident perilesional edema. Further MRS analysis revealed markedly increased choline and lipid peaks. The patient underwent craniotomy for tumor removal. Histopathology revealed findings consistent with metastatic non-microcellular neuroendocrine lung cancer. positron emission tomography/computed tomography (PET/CT) revealed a stellate lesion within the right upper lung lobe, compatible with primary lung cancer.

Conclusion

Non-enhancing brain metastatic tumors are rarely reported in the literature, usually following antiangiogenic treatment. Here, we report the first ever case of a non-enhancing metastatic brain tumor with no prior history of antiangiogenic treatment, with particular emphasis on the importance of MRS analysis in atypical brain lesions.

SMART syndrome: a case report

INTRODUCTION

Stroke-like migraine attacks after radiation therapy (SMART) syndrome, is a late complication of brain radiotherapy (1). Symptoms are commonly subacute in onset and involve migraine type of headache, seizures, focal neurologic deficits (2). Magnetic resonance imaging (MRI) findings are usually unilateral and posterior predominant cortical-subcortical hyperintensity, swelling and prominent gyriform (cortical and leptomeningeal) gadolinium enhancement in the areas of the brain that underwent irradiation with or without diffusion restriction (1). There is no standard treatment protocol for SMART syndrome. Antiepileptics and corticosteroids are commonly used drugs.

CASE REPORT

A 65 years old woman was diagnosed with breast cancer with brain metastases and treated with more than 50 Gy brain radiotherapy. The patient presented with acute right-sided weakness and numbness, episodic myoclonic jerking of the right arm and leg, and gait instability five months later. MRI and magnetic resonance angiography of the brain with gadolinium revealed left parietooccipital cortical diffusion restriction and accompanying dilatation of the left posterior cerebral artery as new findings. Computed tomography (CT) perfusion revealed increased perfusion in the affected area. The patient was diagnosed with SMART syndrome.

MANAGEMENT AND OUTCOME

The patient was treated with dexamethasone (16 mg/day) and anticonvulsant therapy. Myoclonic seizures had almost completely remitted. However, her cognitive impairment persisted, then the patient was arrested because of aspiration a month later.

DISCUSSION

Besides confirming SMART syndrome, diagnostic investigations are also important to exclude other etiologies. Posterior reversible encephalopathy syndrome, post-ictal changes, meningoencephalitis, and cerebrovascular diseases are radiological differential diagnoses considered (3). Proper and early diagnosis of SMART syndrome is significant in preventing unnecessary aggressive approaches and appropriate treatment to avoid lesions of sequela.

MRI Findings after Recent Image-Guided Lumbar Puncture: The Rate of Dural Enhancement and Subdural Collections

BACKGROUND AND PURPOSE

The rate of abnormal intracranial MR imaging findings including subdural collections and dural enhancement after recent lumbar puncture is not known. The purpose of our study was to examine the intracranial MR imaging findings after recent image-guided lumbar puncture.

MATERIALS AND METHODS

Patients who underwent contrast-enhanced MR imaging of the brain within 7 days of a CT-guided lumbar puncture between January 2014 and April 2021 were included. Contrast-enhanced MR images were reviewed for diffuse dural enhancement, morphologic findings of brain sag, dural venous sinus distension, and subdural collections.

RESULTS

Of the 160 patients who met the inclusion criteria, only 6 patients (3.9%) had new diffuse dural enhancement, though none had dural enhancement when the MR imaging was within 2 days of lumbar puncture. All 6 patients with dural enhancement had small, concurrent subdural collections. Two additional patients had subdural collections, for a total of 5.2% of our population.

CONCLUSIONS

Our study is the first to examine intracranial MR imaging after recent lumbar puncture and has 2 key findings: First, 5.2% of patients had small, bilateral subdural collections after recent lumbar puncture, suggesting that asymptomatic subdural collections after recent lumbar puncture are not atypical and do not require further work-up. Additionally, when MR imaging was performed within 2 days of lumbar puncture, none of our patients had diffuse dural enhancement. This argues against the commonly held practice of performing MR imaging before lumbar puncture to avoid findings of dural enhancement, and should not delay diagnostic work-up.

MRI-based radiomics signature and clinical factor for predicting H3K27M mutation in pediatric high-grade gliomas located in the midline of the brain

OBJECTIVE

To develop a nomogram based on MRI radiomics and clinical features for preoperatively predicting H3K27M mutation in pediatric high-grade gliomas (pHGGs) with a midline location of the brain.

METHODS

The institutional database was reviewed to identify patients with pHGGs with a midline location of the brain who underwent tumor biopsy with preoperative MRI scans between June 2016 and June 2021. A total of 107 patients with pHGGs, including 79 patients with H3K27M mutation, were consecutively included and randomly divided into training and test sets. Radiomics features were extracted from fluid-attenuated inversion recovery (FLAIR), diffusion-weighted (DW) and post-contrast T1-weighted images, and apparent diffusion coefficient (ADC) maps. The minimum redundancy maximum relevance (MRMR) and least absolute shrinkage and selection operator (LASSO) logistic regression were performed for radiomics signature construction. Clinical and radiological features were analyzed to select clinical predictors. A nomogram was then developed by incorporating the radiomics signature and selected clinical predictors.

RESULTS

Nine radiomics features were selected to construct the radiomics signature, which showed a favorable discriminatory ability in training and test sets with an area under the curve (AUC) of 0.95 and 0.92, respectively. Ring enhancement was identified as an independent clinical predictor (p < 0.01). The nomogram, constructed with radiomics signature and ring enhancement, showed good calibration and discrimination in training and testing sets (AUC: 0.95 and 0.90 respectively).

CONCLUSIONS

The nomogram which combined radiomics signature and ring enhancement had a satisfactory ability to predict H3K27M mutation in pHGGs with a midline of the brain.

KEY POINTS

• Conventional MRI features were not powerful enough to predict H3K27M mutation status in pediatric high-grade gliomas (pHGGs) with a midline location of the brain. • An MRI-based radiomics signature showed satisfactory ability to predict H3K27M mutation status of pHGGs located in the midline of the brain. • Associating the radiomics signature with clinical factors improved predictive performance.

The potential of advanced MR techniques for precision radiotherapy of glioblastoma

As microscopic tumour infiltration of glioblastomas is not visible on conventional magnetic resonance (MR) imaging, an isotropic expansion of 1-2 cm around the visible tumour is applied to define the clinical target volume for radiotherapy. An opportunity to visualize microscopic infiltration arises with advanced MR imaging. In this review, various advanced MR biomarkers are explored that could improve target volume delineation for radiotherapy of glioblastomas. Various physiological processes in glioblastomas can be visualized with different advanced MR techniques. Combining maps of oxygen metabolism (CMRO₂), relative cerebral blood volume (rCBV), vessel size imaging (VSI), and apparent diffusion coefficient (ADC) or amide proton transfer (APT) can provide early information on tumour infiltration and high-risk regions of future recurrence. Oxygen consumption is increased 6 months prior to tumour progression being visible on conventional MR imaging. However, presence of the Warburg effect, marking a switch from an infiltrative to a proliferative phenotype, could result in CMRO₂ to appear unaltered in high-risk regions. Including information on biomarkers representing angiogenesis (rCBV and VSI) and hypercellularity (ADC) or protein concentration (APT) can omit misinterpretation due to the Warburg effect. Future research should evaluate these biomarkers in radiotherapy planning to explore the potential of advanced MR techniques to personalize target volume delineation with the aim to improve local tumour control and/or reduce radiation-induced toxicity.

Diffuse Leptomeningeal Glioneuronal Tumour with 9-Year Follow-Up: Case Report and Review of the Literature

In 2016, the World Health Organisation Classification (WHO) of Tumours was updated with diffuse leptomeningeal glioneuronal tumour (DLGNT) as a provisional unit of mixed neuronal and glial tumours. Here, we report a DLGNT that has been re-diagnosed with the updated WHO classification, with clinical features, imaging, and histopathological findings and a 9-year follow-up. A 16-year-old girl presented with headache, vomiting, and vertigo. Magnetic resonance imaging (MRI) demonstrated a hyperintense mass with heterogenous enhancement in the right cerebellopontine angle and internal auditory canal. No leptomeningeal involvement was seen. The histological examination revealed neoplastic tissue of moderate cellularity formed mostly by oligodendrocyte-like cells. Follow-up MRI scans demonstrated cystic lesions in the subarachnoid spaces in the brain with vivid leptomeningeal enhancement. Later spread of the tumour was found in the spinal canal. On demand biopsy samples were re-examined, and pathological diagnosis was identified as DLGNT. In contrast to most reported DLGNTs, the tumour described in this manuscript did not present with diffuse leptomeningeal spread, but later presented with leptomeningeal involvement in the brain and spinal cord. Our case expands the spectrum of radiological features, provides a long-term clinical and radiological follow-up, and highlights the major role of molecular genetic testing in unusual cases.

Current Understanding of Exosomal MicroRNAs in Glioma Immune Regulation and Therapeutic Responses

Exosomes, the small extracellular vesicles, are released by multiple cell types, including tumor cells, and represent a novel avenue for intercellular communication via transferring diverse biomolecules. Recently, microRNAs (miRNAs) were demonstrated to be enclosed in exosomes and therefore was protected from degradation. Such exosomal miRNAs can be transmitted to recipient cells where they could regulate multiple cancer-associated biological processes. Accumulative evidence suggests that exosomal miRNAs serve essential roles in modifying the glioma immune microenvironment and potentially affecting the malignant behaviors and therapeutic responses. As exosomal miRNAs are detectable in almost all kinds of biofluids and correlated with clinicopathological characteristics of glioma, they might be served as promising biomarkers for gliomas. We reviewed the novel findings regarding the biological functions of exosomal miRNAs during glioma pathogenesis and immune regulation. Furthermore, we elaborated on their potential clinical applications as biomarkers in glioma diagnosis, prognosis and treatment response prediction. Finally, we summarized the accessible databases that can be employed for exosome-associated miRNAs identification and functional exploration of cancers, including glioma.

Brain metastases: An update on the multi-disciplinary approach of clinical management

IMPORTANCE

Brain metastasis (BM) is the most common malignant intracranial neoplasm in adults with over 100,000 new cases annually in the United States and outnumbering primary brain tumors 10:1.

OBSERVATIONS

The incidence of BM in adult cancer patients ranges from 10-40%, and is increasing with improved surveillance, effective systemic therapy, and an aging population. The overall prognosis of cancer patients is largely dependent on the presence or absence of brain metastasis, and therefore, a timely and accurate diagnosis is crucial for improving long-term outcomes, especially in the current era of significantly improved systemic therapy for many common cancers. BM should be suspected in any cancer patient who develops new neurological deficits or behavioral abnormalities. Gadolinium enhanced MRI is the preferred imaging technique and BM must be distinguished from other pathologies. Large, symptomatic lesion(s) in patients with good functional status are best treated with surgery and stereotactic radiosurgery (SRS). Due to neurocognitive side effects and improved overall survival of cancer patients, whole brain radiotherapy (WBRT) is reserved as salvage therapy for patients with multiple lesions or as palliation. Newer approaches including multi-lesion stereotactic surgery, targeted therapy, and immunotherapy are also being investigated to improve outcomes while preserving quality of life.

CONCLUSION

With the significant advancements in the systemic treatment for cancer patients, addressing BM effectively is critical for overall survival. In addition to patient's performance status, therapeutic approach should be based on the type of primary tumor and associated molecular profile as well as the size, number, and location of metastatic lesion(s).

Cerebrospinal fluid analysis is associated with enhancement on MRI in bacterial and tuberculous meningitis: A retrospective observational study

OBJECTIVE

Along with cerebrospinal fluid (CSF) analysis, enhancement on contrast-enhanced MRI is useful to diagnose meningitis. However, the conditions for its appearance have not been clarified. This study aimed to investigate the association between CSF parameters and enhancement on contrast-enhanced head or spinal MRI in patients with bacterial meningitis (BM) or tuberculous meningitis (TM).

METHODS

A total of 12 patients with BM and 23 patients with TM who underwent both CSF analysis and contrast-enhanced MRI were included. The correlation between CSF analysis and MRI findings has been examined using receiver operating characteristic (ROC) analysis.

RESULTS

Contrast enhancement was found in 7 and 10 patients with BM and TM, respectively. Both CSF analysis and MRI were useful to distinct between BM and TM, and the enhancement implied the severity of them. In patients with BM, higher CSF protein and lower CSF glucose were associated with enhancement on MRI, while not only CSF protein and glucose but also leukocyte and lymphocyte counts were associated with it in TM. CSF adenosine deaminase (ADA) did not show discriminant ability of the MRI findings.

CONCLUSIONS

CSF analysis is associated with enhancement on contrast-enhanced MRI both in BM and TM. Our findings indicate the importance of CSF analysis in assessing the need to perform contrast-enhanced MRI, which may be useful in diagnosis, distinction, and estimation of prognosis in those patients.

Diffuse leptomeningeal glioneuronal tumor with high-grade features masquerading as tubercular meningitis—a case report

Background

Diffuse leptomeningeal glioneuronal tumor (DLGNT) has been recently described in the literature. The complete neuroimaging spectrum and histopathological characteristics of this entity are yet to be elucidated. In an endemic region, diffuse leptomeningeal enhancement on neuroimaging with associated communicating hydrocephalus is usually suggestive of infective meningitis and the patients are started on empirical anti-microbial therapy. However, it is important to consider other differential diagnosis of leptomeningeal enhancement in such cases, particularly if the clinical condition does not improve on anti-microbial therapy. An early diagnosis of a neoplastic etiology may be of particular importance as the treatment regimens vary considerably depending on the underlying disease condition.

Case presentation

In this case report, we describe a case of DLGNT with high-grade histopathological features which was initially managed as tubercular meningitis based on the initial neuroimaging findings. Due to worsening of the clinical course and subsequent imaging findings at follow-up, a diagnosis of DLGNT was considered and subsequently proven to be DLGNT with features of anaplasia on histopathological examination of leptomeningeal biopsy specimen.

Conclusion

This case highlights the importance of recognizing certain subtle finding on MRI which may help in an early diagnosis of DLGNT which is crucial for appropriate treatment.

Distinguishing Intramedullary Spinal Cord Neoplasms from Non-Neoplastic Conditions by Analyzing the Classic Signs on MRI in the Era of AI

Intramedullary lesions can be challenging to diagnose given the wide range of possible pathologies. Each lesion has unique clinical and imaging features, which are best evaluated on magnetic resonance imaging. Radiological imaging is unique with rich, descriptive patterns and classic signs-which are often metaphorical. In this review, we present a collection of classic MRI signs, ranging from neoplastic to non-neoplastic lesions, within the spinal cord. The differential diagnosis (DD) of intramedullary lesions can be narrowed down by careful analysis of the classic signs and pattern of involvement in the spinal cord. Furthermore, the signs are illustrated memorably with emphasis on the pathophysiology, mimics and pitfalls. Artificial intelligence (AI) algorithms, particularly deep learning, have made remarkable progress in image recognition tasks. The classic signs and related illustrations can enhance a pattern recognition approach in diagnostic radiology. Deep learning can potentially be designed to distinguish neoplastic from non-neoplastic processes by pattern recognition of the classic MRI signs.

Passive targeting of high-grade gliomas via the EPR effect: a closed path for metallic nanoparticles?

Passive tumor targeting via the enhanced permeability and retention (EPR) effect has long been considered the most effective mechanism for the accumulation of nanoparticles inside solid tumors. However, several studies have demonstrated that the EPR effect is largely dependent on the tumor type and location. Particularly complex is the situation in brain tumors, where the presence of the blood-brain tumor barrier (BBTB) adds an extra limiting factor in reaching the tumor interstitium. However, it remains unclear whether these restraints imposed by the BBTB prevent the EPR effect from acting as an efficient tumor targeting mechanism for metallic nanoparticles. In this work, we have studied the EPR effect of metallic magnetic nanoparticles (MMNPs) in a glioblastoma (GBM) model by parametric MRI. Our results showed that only MMNPs ≤50 nm could reach the tumor interstitium, whereas larger MMNPs were unable to cross the BBTB. Furthermore, even for MMNPs around 30-50 nm, the amount of them found within the tumor was scarce and restricted to the vicinity of large tumor vessels, indicating that the BBTB strongly limits the passive accumulation of metallic nanoparticles in brain tumors. Therefore, active targeting becomes the most reasonable strategy to target metallic nanoparticles to GBMs.

The Clinical Significance of the Hyperintense Acute Reperfusion Marker Sign in Subacute Infarction Patients

Purpose: The hyperintense acute reperfusion marker (HARM) is characterized by the delayed enhancement of the subarachnoid or subpial space observed on postcontrast fluid-attenuated inversion recovery (FLAIR) images, and is considered a cerebral reperfusion marker for various brain disorders, including infarction. In this study, we evaluated the cerebral distribution patterns of HARM for discriminating between an enhancing subacute infarction and an enhancing mass located in the cortex and subcortical white matter. Materials and methods: We analyzed consecutive patients who experienced a subacute ischemic stroke, were hospitalized, and underwent conventional brain magnetic resonance imaging including postcontrast FLAIR within 14 days from symptom onset, as well as those who had lesions corresponding to a clinical sign detected by diffusion-weighted imaging and postcontrast T1-weighted imaging between May 2019 and May 2021. A total of 199 patients were included in the study. Of them, 94 were finally included in the subacute infarction group. During the same period, 76 enhancing masses located in the cortex or subcortical white matter, which were subcategorized as metastasis, malignant glioma, and lymphoma, were analyzed. We analyzed the overall incidence of HARM in subacute ischemic stroke cases, and compared the enhancement patterns between cortical infarctions and cortical masses. Results: Among 94 patients with subacute stroke, 78 patients (83%) presented HARM, and among 76 patients with subcortical masses, 48 patients (63%) presented peripheral rim enhancement. Of 170 subcortical enhancing lesions, 88 (51.8%) showed HARM, and 78 (88.6%) were determined to be subacute infarction. Among 94 patients with subacute stroke, 48 patients (51%) had diffusion restrictions, and HARM was found in 39 patients (81.2%). Of the 46 patients (49%) without diffusion restriction, 39 patients (84.8%) showed HARM. Conclusions: The presence of HARM was significantly associated with subacute infarctions. For the masses, a peripheral rim enhancement pattern was observed around the mass rather than the cerebral sulci on postcontrast FLAIR.

Delayed FDG PET Provides Superior Glioblastoma Conspicuity Compared to Conventional Image Timing

Background: Glioblastomas are malignant, often incurable brain tumors. Reliable discrimination between recurrent disease and treatment changes is a significant challenge. Prior work has suggested glioblastoma FDG PET conspicuity is improved at delayed time points vs. conventional imaging times. This study aimed to determine the ideal FDG imaging time point in a population of untreated glioblastomas in preparation for future trials involving the non-invasive assessment of true progression vs. pseudoprogression in glioblastoma.

Methods: Sixteen pre-treatment adults with suspected glioblastoma received FDG PET at 1, 5, and 8 h post-FDG injection within the 3 days prior to surgery. Maximum standard uptake values were measured at each timepoint for the central enhancing component of the lesion and the contralateral normal-appearing brain.

Results: Sixteen patients (nine male) had pathology confirmed IDH-wildtype, glioblastoma. Our results revealed statistically significant improvements in the maximum standardized uptake values and subjective conspicuity of glioblastomas at later time points compared to the conventional (1 h time point). The tumor to background ratio at 1, 5, and 8 h was 1.4 ± 0.4, 1.8 ± 0.5, and 2.1 ± 0.6, respectively. This was statistically significant for the 5 h time point over the 1 h time point (p > 0.001), the 8 h time point over the 1 h time point (p = 0.026), and the 8 h time point over the 5 h time point (p = 0.036).

Conclusions: Our findings demonstrate that delayed imaging time point provides superior conspicuity of glioblastoma compared to conventional imaging. Further research based on these results may translate into improvements in the determination of true progression from pseudoprogression.

Rate of Leptomeningeal Enhancement in Pediatric Myelin Oligodendrocyte Glycoprotein Antibody-Associated Encephalomyelitis

INTRODUCTION

Myelin oligodendrocyte glycoprotein antibodies (MOG-abs) are associated with demyelinating diseases. Leptomeningeal enhancement occurs in 6% of adult MOG-abs patients but rates in pediatric MOG-abs patients are unknown.

METHODS

Retrospective review of pediatric MOG-abs patients was performed.

RESULTS

Twenty-one patients (7 boys, 14 girls) were included with an average age of 8.6 years (range 2-15 years). Seven of 21 (33%) pediatric MOG-abs patients had leptomeningeal enhancement. Two patients' relapses were manifested by leptomeningeal enhancement alone and another patient presented with seizures, encephalopathy, and aseptic meningitis without demyelinating lesions. Cerebrospinal fluid pleocytosis was seen in both leptomeningeal (4/7 patients) and nonleptomeningeal enhancement (10/14 patients). Interestingly, 3 patients with leptomeningeal enhancement had normal cerebrospinal fluid white blood cell count. Cortical edema was more likely in patients with leptomeningeal enhancement (P = .0263).

CONCLUSION

We expand the clinical spectrum of anti-MOG antibody-associated disorder. Patients with recurrent leptomeningeal enhancement without demyelinating lesions should be tested for MOG antibodies.

Deep Learning With Data Enhancement for the Differentiation of Solitary and Multiple Cerebral Glioblastoma, Lymphoma, and Tumefactive Demyelinating Lesion

Objectives

To explore the MRI-based differential diagnosis of deep learning with data enhancement for cerebral glioblastoma (GBM), primary central nervous system lymphoma (PCNSL), and tumefactive demyelinating lesion (TDL).

Materials and Methods

This retrospective study analyzed the MRI data of 261 patients with pathologically diagnosed solitary and multiple cerebral GBM (n = 97), PCNSL (n = 92), and TDL (n = 72). The 3D segmentation model was trained to capture the lesion. Different enhancement data were generated by changing the pixel ratio of the lesion and non-lesion areas. The 3D classification network was trained by using the enhancement data. The accuracy, sensitivity, specificity, and area under the curve (AUC) were used to assess the value of different enhancement data on the discrimination performance. These results were then compared with the neuroradiologists’ diagnoses.

Results

The diagnostic performance fluctuated with the ratio of lesion to non-lesion area changed. The diagnostic performance was best when the ratio was 1.5. The AUCs of GBM, PCNSL, and TDL were 1.00 (95% confidence interval [CI]: 1.000–1.000), 0.96 (95% CI: 0.923–1.000), and 0.954 (95% CI: 0.904–1.000), respectively.

Conclusions

Deep learning with data enhancement is useful for the accurate identification of GBM, PCNSL, and TDL, and its diagnostic performance is better than that of the neuroradiologists.

Longitudinal Sodium MRI of Multiple Sclerosis Lesions: Is there Added Value of Sodium Inversion Recovery MRI

BACKGROUND

Sodium enhancement has been demonstrated in multiple sclerosis (MS) lesions.

PURPOSE

To investigate sodium MRI with and without an inversion recovery pulse in acute MS lesions in an MS relapse and during recovery.

STUDY TYPE

Prospective.

SUBJECTS

Twenty-nine relapsing-remitting MS patients with an acute relapse were included.

FIELD STRENGTH/SEQUENCE

A 3D density-adapted radial sodium sequence at 3 T using a dual-tuned (²³ Na/¹ H) head coil.

ASSESSMENT

Full-brain images of the tissue sodium concentration (TSC1, n = 29) and a sodium inversion recovery sequence (SIR1, n = 20) at the beginning of the anti-inflammatory therapy and on medium-term follow-up visits (days 27-99, n = 12 [TSC], n = 5 [SIR]) were measured. Regions of interest (RoIs) with contrast enhancement (T₁ CE+) and without change in T1-weighted imaging (FL + T1n) were normalized (nTSC and nSIR). To gain insight on the origin of the TSC enhancement at time point 1, it is investigated whether the nTSC enhancement of the lesions is accompanied by a change of the respective nSIR. Potential prognostic value of nSIR1 is examined referring to the nTSC progression. STATISTICAL TESTS: nTSC and nSIR were compared regarding the type of lesion and the time point using a one-way ANOVA. Pearson's correlation coefficient was calculated for nTSC over nSIR and for nTSC1-nTSC2 over nSIR1. A P-value <0.05 was considered statistically significant.

RESULTS

At the first measurement, all lesion types showed increased nTSC, while nSIR was decreased in the FL + T₁ n and the T₁ CE+ lesions in comparison to the normal-appearing white matter. For acute lesions, the difference between nTSC at baseline and nTSC at time point 2 showed a significant correlation with the baseline nSIR.

DATA CONCLUSION

At time point 1, nTSC is increased, while nSIR is unchanged or decreased in the lesions. The mean sodium IR signal at baseline correlates with recovery or progression of an acute lesion.

EVIDENCE LEVEL

2 TECHNICAL EFFICACY: Stage 4.

Meningeal B Cell Clusters Correlate with Submeningeal Pathology in a Natural Model of Multiple Sclerosis

Multiple sclerosis (MS) is an idiopathic demyelinating disease in which meningeal inflammation correlates with accelerated disease progression. The study of meningeal inflammation in MS has been limited because of constrained access to MS brain/spinal cord specimens and the lack of experimental models recapitulating progressive MS. Unlike induced models, a spontaneously occurring model would offer a unique opportunity to understand MS immunopathogenesis and provide a compelling framework for translational research. We propose granulomatous meningoencephalomyelitis (GME) as a natural model to study neuropathological aspects of MS. GME is an idiopathic, progressive neuroinflammatory disease of young dogs with a female bias. In the GME cases examined in this study, the meninges displayed focal and disseminated leptomeningeal enhancement on magnetic resonance imaging, which correlated with heavy leptomeningeal lymphocytic infiltration. These leptomeningeal infiltrates resembled tertiary lymphoid organs containing large B cell clusters that included few proliferating Ki67+ cells, plasma cells, follicular dendritic/reticular cells, and germinal center B cell-like cells. These B cell collections were confined in a specialized network of collagen fibers associated with the expression of the lympho-organogenic chemokines CXCL13 and CCL21. Although neuroparenchymal perivascular infiltrates contained B cells, they lacked the immune signature of aggregates in the meningeal compartment. Finally, meningeal B cell accumulation correlated significantly with cortical demyelination reflecting neuropathological similarities to MS. Hence, during chronic neuroinflammation, the meningeal microenvironment sustains B cell accumulation that is accompanied by underlying neuroparenchymal injury, indicating GME as a novel, naturally occurring model to study compartmentalized neuroinflammation and the associated pathology thought to contribute to progressive MS.

Challenges and advances for the treatment of renal cancer patients with brain metastases: From immunological background to upcoming clinical evidence on immune-checkpoint inhibitors

The introduction of checkpoint inhibitors (ICIs) in renal cell carcinoma (RCC) treatment landscape, resulted in improvements in overall survival (OS) in metastatic patients. Brain metastases (BMs) are a specific metastatic site of interest representing a predictive factor of poor prognosis. Patients with BMs were usually excluded from prospective clinical trials in the past. Despite recent evidence suggest the efficacy and safety of ICIs, the BMs treatment remains a challenge; the immunotherapy responsiveness seems to be multifactorial and dependent on several factors, such as the genetic intratumor heterogeneity and the immunosuppressive role of the brain tumor microenvironment. This review, starting from the immunological background in RCC BMs, provide an overview of the upcoming evidence from clinical trials, address the issues related to the neuroradiological immunotherapy response evaluation and, with a look to the future, describes how the epigenetic modulation of immune evasion could represent a background for new therapeutic strategies.

Spontaneous Intracranial Hypotension

PURPOSE OF REVIEW

Spontaneous intracranial hypotension is a disorder caused by spinal CSF leakage. This article reviews the clinical presentation, diagnosis, and treatment of spontaneous intracranial hypotension.

RECENT FINDINGS

The hallmark symptom of spontaneous intracranial hypotension is acute orthostatic headache; however, clinical presentations can be heterogeneous. New evidence shows that lumbar puncture is not always necessary or sufficient to establish the diagnosis. Some patients may have normal opening pressure, which suggests that insufficiency of CSF volume (hypovolemia) rather than CSF pressure might be the underlying mechanism. Several neuroimaging modalities can aid in diagnosis and localization of the CSF leakage, including brain MRI, spinal MRI, CT myelography, digital subtraction myelography, and radionuclide cisternography. Complications, such as subdural hematoma, can lead to a change in the headache pattern and potentially life-threatening consequences. Conservative treatments, such as fluid supplementation, can provide temporary relief; however, epidural blood patches, especially targeted ones, are more effective and definitive. For patients with refractory spontaneous intracranial hypotension, surgical repair of spinal CSF leakages should be considered.

SUMMARY

Brain and spinal MRIs are important for the diagnosis and treatment of patients with spontaneous intracranial hypotension. Early treatment with epidural blood patches may be considered to shorten the disease duration and minimize the potential risk of complications.

Exploring MRI Characteristics of Brain Diffuse Midline Gliomas With the H3 K27M Mutation Using Radiomics

Objectives

To explore the magnetic resonance imaging (MRI) characteristics of brain diffuse midline gliomas with the H3 K27M mutation (DMG-M) using radiomics.

Materials and Methods

Thirty patients with diffuse midline gliomas, including 16 with the H3 K27M mutant and 14 with wild type tumors, were retrospectively included in this study. A total of 272 radiomic features were initially extracted from MR images of each tumor. Principal component analysis, univariate analysis, and three other feature selection methods, including variance thresholding, recursive feature elimination, and the elastic net, were used to analyze the radiomic features. Based on the results, related visually accessible features of the tumors were further evaluated.

Results

Patients with DMG-M were younger than those with diffuse midline gliomas with H3 K27M wild (DMG-W) (median, 25.5 and 48 years old, respectively; p=0.005). Principal component analysis showed that there were obvious overlaps in the first two principal components for both DMG-M and DMG-W tumors. The feature selection results showed that few features from T2-weighted images (T2WI) were useful for differentiating DMG-M and DMG-W tumors. Thereafter, four visually accessible features related to T2WI were further extracted and analyzed. Among these features, only cystic formation showed a significant difference between the two types of tumors (OR=7.800, 95% CI 1.476-41.214, p=0.024).

Conclusions

DMGs with and without the H3 K27M mutation shared similar MRI characteristics. T2W sequences may be valuable, and cystic formation a useful MRI biomarker, for diagnosing brain DMG-M.

Pitfalls in the diagnosis of subdural hemorrhage - Mimics and uncommon causes

PURPOSE

Subdural hemorrhage (SDH), the accumulation of blood between the dura and arachnoid mater, is one of the most commonly encountered traumatic findings in emergency radiology setting. The purpose of this essay is to review the pitfalls in the diagnosis of SDH including a) mimics on CT imaging and b) etiology other than accidental trauma. We describe several entities that closely mimic SDH on non-contrast CT scans. A knowledge of these mimics is essential in the emergency setting since overdiagnosis of SDH can lead to unnecessary hospital admissions, potentially invasive procedures, or even delay in necessary treatment. The mimics of SDH on non-contrast head CT include: PATHOLOGIC ENTITIES IATROGENIC MIMICS ANATOMIC/PHYSIOLOGIC MIMICS ARTIFACTUAL MIMICSWe also briefly review non-accidental and non-traumatic causes of SDH. Although, the most common cause of SDH is accidental trauma, other routinely encountered causes of SDH include coagulopathy, non-accidental trauma, cranial surgery, vascular malformations etc. CONCLUSION: Clinicians dealing with SDH in the emergency setting should consider SDH mimics and less common etiologies of SDH in order to facilitate appropriate patient management.

MRI of Emergent Intracranial Infections and Their Complications

Acute intracranial infections of the central nervous system and skull base are uncommon but time sensitive diagnoses that may present to the emergency department. As symptoms are frequently nonspecific or lack typical features of an infectious process, a high index of suspicion is required to confidently make the diagnosis, and imaging may not only serve as the first clue to an intracranial infection, but is often necessary to completely characterize the disease process and exclude any confounding conditions. Although computed tomography is typically the initial imaging modality for many of these patients, magnetic resonance imaging offers greater sensitivity and specificity in diagnosing intracranial infections, characterizing the full extent of infection, and identifying potential complications. The aim of this article is to serve as a review of the typical and most important imaging manifestations of these infections that can be encountered in the emergent setting.

Overcoming the Elusiveness of Neurosarcoidosis: Learning from Five Complex Cases

The involvement of the central nervous system in sarcoidosis can manifest with a variety of neurological symptoms, and most of them can be nonspecific. The diagnosis of neurosarcoidosis (NS) can therefore be very challenging without a tissue biopsy. Both computed tomography (CT) and magnetic resonance imaging (MRI) are important imaging modalities in the diagnosis of NS, and MRI is the modality of choice due to its superior soft-tissue contrast resolution. We present a case series of NS with interesting neuroimaging features, complex neurological presentations, and clinical courses. We identify five cases presenting with clinically isolated neurosarcoidosis (CINS) without any other signs or symptoms of systemic disease which were diagnosed as NS on biopsy. In the first case, we describe a patient with an intramedullary cervical spinal cord lesion. In the second case we describe a patient presenting with inflammatory changes and enhancement in the orbit. The third case demonstrates a lesion with calcification around the region of the foramen of Monro. The fourth case shows multiple ring-enhancing lesions. Lastly, the fifth case exhibits unusual findings with both optic neuritis and a cerebellar nodule. We aim to describe the complicated clinical course with neurological workup, neuro-imaging, and eventual diagnosis and treatment of these challenging cases to highlight the variable presentations of NS. This case series will remind clinicians that NS should always be in the differential diagnosis when a patient presents with nonspecific neurological symptoms with unusual neuroimaging findings.

Blood–Brain Barrier Disturbances and Potential Complications of Endovascular Management in Stroke—Technical Note with Limited Review

Contrast enhancement (CE), contrast extravasation (CX), hemorrhagic transformation (HT), and cerebral hyperperfusion syndrome (CHS) in patients who have suffered ischemic stroke and have undergone revascularization. There are a handful of articles addressing these pathologies separately. But there is scant literature available combining them together, as the underlying pathophysiology involves disturbances of blood–brain barrier (BBB). We have reviewed literature and proposed a common mechanism for these events. We systematically searched PubMed, LibGen, Cochrane, and Sci-Hub databases for the studies published online regarding CE, CX, HT, and CHS after endovascular treatment for stroke. This review was conducted based on the PRISMA guidelines. The following medical search terms were used for the online search: contrast enhancement, contrast extravasation, hemorrhagic transformation, cerebral hyperperfusion syndrome, endovascular treatment, contrast staining, postprocedural attenuation, carotid stenting, intra-arterial thrombolysis, and stroke. We did a limited review of literature by analyzing the relevant articles and research papers published to date. We have randomly included prototype cases of CE, CX, HT, and CHS which we have encountered in our Interventional Department from our own database. In compliance with PRISMA guidelines, we screened 33 articles dealing with CE, 32 with CX, 26 articles that addressed CE and CX both, 53 articles dealing with HT, and 42 articles dealing with CHS. Overall, 88 articles were filtered on studying the abstract. Further, 15 more had to be excluded as reasoned in the flowchart, and finally 71 articles were included in our study, as again shown in the flowchart. We studied and discussed these articles and research papers in relation to pathophysiology, predisposing factors, preventive measures, and current treatment protocols. BBB disruption is the primary event in CE, CX, HT, and CHS with varying severity. Minimizing dose of contrast, optimum timing of revascularization and dose of thrombolytic, judicious selection of mechanical thrombectomy cases, and strict control of blood pressure in postrevascularization period are recommended preventive measures. High-index of clinical suspicion, early imaging to detect, and following-up the same on sequential imaging are key to avoid severe forms of HT and CHS.

Long-term acrylamide exposure exacerbates brain and lung pathology in a mouse malaria model

The consumption of dietary acrylamide (ACR), a carcinogen, results in the dysfunction of various organs and the immune system. However, the impact of ACR exposure on the progression of infectious diseases is unknown. This study investigated the effect of ACR on the progression of malaria infection using a mouse model of malaria. C57BL/6 mice were continuously treated with ACR at a dose of 20 mg/kg bodyweight/day for six weeks (long-term exposure) or phosphate-buffered saline (PBS). Next, the mice were infected with the rodent malaria parasite, Plasmodium berghei NK65 (PbNK). Parasitemia and survival rate were analyzed in the different treatment groups. Magnetic resonance imaging (MRI) and histopathological analyses were performed to evaluate the effect of ACR exposure on the morphology of various organs. Long-term ACR exposure exacerbated PbNK-induced multiorgan dysfunction. MRI and histopathological analysis revealed signs of encephalomeningitis and acute respiratory distress syndrome in the PbNK-infected long-term ACR exposure mice, which decreased the survival rate of mice, but not in the PbNK-infected long-term PBS exposure group. These findings enhance our understanding of the impact of ACR on the progression of infectious diseases, such as malaria.

Asymmetric pathological pachymeningeal enhancement: A new imaging feature for cerebral venous thrombosis

PURPOSE

Cerebral venous thrombosis (CVT) has various clinical presentations and has a median onset delay of 7 days. So it is important to find more identifiable early imaging manifestations for CVT.

METHOD

This was a retrospective study. Patients with CVT (CVT group, n = 26) diagnosed by conventional imaging techniques (magnetic resonance imaging and/or digital subtraction angiogram) and patients with symptomatic intracranial atherosclerosis (control group, n = 30) were included. Magnetic resonance black-blood thrombus imaging (MRBTI) technique had been performed in both groups. The CVT group was divided into 3 groups based on the duration of clinical onset: ≤7 days (group 1), between 7 and 30 days (group 2), and >30 days (group 3). Pathological pachymeningeal enhancement and its characteristics were analyzed between the CVT group and the control group.

RESULTS

Pathological pachymeningeal enhancement was found in 14 CVT patients (54 %) and none in control group (P value = 0.000). The bilateral pathological pachymeningeal enhancement was involved in 10 CVT patients, 6 patients were asymmetric, and 4 patients had ipsilateral enhancement. Asymmetric pathological pachymeningeal enhancement was 71 % and predominantly located on the thrombosed sinus side. Strong enhancement was found in the venous sinus wall beside the thrombus. Pathological pachymeningeal enhancement percentages of three subgroups were 75 % in group 1, 55 % in group 2, and 29 % in group 3 and had no statistical differences (p value = 0.198).

CONCLUSIONS

Current findings suggest asymmetrical pathological pachymeningeal enhancement was associated was CVT and may be a new imaging feature for CVT.

Hemichorea-Hemiballismus as a Presentation of Cerebritis from Intracranial Toxoplasmosis and Tuberculosis

Background

There is limited literature documenting hemichorea-hemiballism (HCHB) resulting from co-infection of toxoplasmosis and tuberculosis (TB) in acquired immunodeficiency syndrome (AIDS). Toxoplasmic abscess is the most common cause while TB is a rare etiology.

Case Description

We describe a 24-year-old male with AIDS-related HCHB as the presentation of cerebritis on the right subthalamic nucleus and cerebral peduncle from intracranial toxoplasma and TB co-infection. Antimicrobials and symptomatic therapy were given. Marked improvement was seen on follow-up.

Discussion

HCHB may be the initial presentation of intracranial involvement of this co-infection in the setting of AIDS and is potentially reversible with timely management.

Highlights

Hemichorea-hemiballismus (HCHB) may be an initial presentation of intracranial involvement of concomitant toxoplasmosis and tuberculosis causing focal cerebritis in the contralateral subthalamic nucleus and cerebral peduncle, particularly in the setting of human immunodeficiency virus infection.Acquired immunodeficiency syndrome-related HCHB is potentially reversible with timely diagnosis and treatment.

High-resolution MRI demonstrates that more than 90% of small intracranial melanoma metastases develop in close relationship to the leptomeninges

BACKGROUND

Despite classic teaching that intracranial metastases typically arise at the gray-white matter junction, small intracranial melanoma metastases (IMM) are frequently observed at the interface between the cortex and leptomeninges (ie, "corticomeningeal interface"), suggesting possible leptomeningeal origin.

METHODS

MRI brain examinations of melanoma patients treated at a specialist oncology center from July 2015 to June 2017 were retrospectively reviewed. The MRI examination on which IMM were first visible was identified, utilizing 1 mm volumetric postcontrast imaging prior to local therapy. Individual metastases (up to 10 per patient) were assessed for the presence of leptomeningeal contact, as well as their number, size, and morphology. Lesions ≥10 mm in long axis were excluded, in order to examine early metastatic disease.

RESULTS

Seventy-five patients had evidence of IMM. Fifteen patients had only lesion(s) measuring ≥10 mm at diagnosis, leaving 60 patients. One hundred ninety-two individual metastases were examined (median 2 per patient; interquartile range, 1-4), 174 (91%) demonstrating leptomeningeal contact. A nodular morphology was observed in 154 of 192 (82%), 32 (17%) were ovoid but elongated along the cortex, and 6 (3%) were linear. Only 3 patients (5%) also exhibited a "classic" linear leptomeningeal disease appearance.

CONCLUSIONS

Most IMM measuring between 2 and 9 mm in diameter are corticomeningeal nodules. These data raise the hypothesis that deeper parenchymal extension of IMM occurs secondarily. If the leptomeninges provide a preferential site for establishment of IMM, further investigation of the underlying biology of this phenomenon may provide opportunities for novel therapeutic strategies for patients with IMM.