Tips and tricks in the diagnosis of intracranial dural arteriovenous fistulas: A pictorial review.

Dural arteriovenous fistulas (DAVFs) are complex vascular abnormalities that account for 10-15% of intracranial vascular malformations. DAVFs are typically encountered in middle-aged adults, with a slightly female predominance. The causative factors are still uncertain; however, abnormal local hemodynamics and neoangiogenesis related to dural sinus or venous thrombosis can contribute to DAVF occurrence. The diagnosis is dependent on a high level of clinical suspicion and high-resolution imaging techniques. Computed tomography and/or magnetic resonance imaging aid in the diagnosis, but conventional angiography remains the most accurate method for the complete characterization and classification of DAVFs. The therapeutic approach can be conservative or more aggressive, based on symptom severity, sequelae risk and patient characteristics. This article is a pictorial review of adult intracranial DAVFs that highlights some tips and tricks for recognizing useful red flags in the suspicion of DAVFs.

Neuromyelitis Optica Spectrum Disorders: Spectrum of MR Imaging Findings and Their Differential Diagnosis.

Neuromyelitis optica (NMO) is an autoimmune demyelinating disorder for which the aquaporin-4 (AQP4) water channels are the major target antigens. Advances in the understanding of NMO have clarified several points of its pathogenesis, clinical manifestations, and imaging patterns. A major advance was the discovery of the AQP4 antibody, which is highly specific for this disorder. Descriptions of new clinical and radiologic features in seropositive patients have expanded the spectrum of NMO, and the term NMO spectrum disorder (NMOSD) has been adopted. NMOSD is now included in a widening list of differential diagnoses. Acknowledgment of NMOSD imaging patterns and their mimicry of disorders has been crucial in supporting early NMOSD diagnosis, especially for unusual clinical manifestations of this demyelinating disease. This pictorial review summarizes the wide imaging spectrum of NMOSD and its differential diagnosis, as well as its historical evolution, pathophysiology, and clinical manifestations. ©RSNA, 2018.

Intracranial vessel wall magnetic resonance imaging features of infectious vasculitis.

Vasculitis is a complication of several infectious diseases affecting the central nervous system, which may result in ischemic and/or hemorrhagic stroke, transient ischemic attack, and aneurysm formation. The infectious agent may directly infect the endothelium, causing vasculitis, or indirectly affect the vessel wall through an immunological mechanism. The clinical manifestations of these complications usually overlap with those of non-infectious vascular diseases, making diagnosis challenging. Intracranial vessel wall magnetic resonance imaging (VWI) enables the evaluation of the vessel wall and the diseases that affect it, providing diagnostic data beyond luminal changes and enabling the identification of inflammatory changes in cerebral vasculitis. This technique demonstrates concentric vessel wall thickening and gadolinium enhancement, associated or not with adjacent brain parenchymal enhancement, in patients with vasculitis of any origin. It permits the detection of early alterations, even before a stenosis occurs. In this article, we review the intracranial vessel wall imaging features of infectious vasculitis of bacterial, viral, and fungal etiologies.

Midline brain-in-brain malformation associated with bilateral perirolandic cortical abnormalities: an image review of this rare disorder.

A midline brain-in-brain malformation was recently reported, but appropriate classification of this malformation remains uncertain. We describe a child with a complex brain malformation that was not restricted to the midline structures, enlarging the neuroanatomical spectrum of this pseudotumoral midline dysplasia associated with corpus callosum dysgenesis, azygos anterior cerebral artery, absent septum pellucidum and bilateral perirolandic cortical abnormalities. The spectrum of fusion of the cerebral hemispheres and associated brain hemispherical abnormalities is not completely understood. Our data are in line with previous arguments that this malformation could be an additional variant in the spectrum of holoprosencephaly.

Hippocampal sclerosis and status epilepticus: cause or consequence? A MRI study.

BACKGROUND: Transient imaging abnormalities, including changes on diffusion-weighted imaging (DWI), may be seen in status epilepticus. These abnormalities can be followed by hippocampal sclerosis. CASE REPORT: We report a 15-year-old lady with focal non convulsive status epilepticus (NCSE) and focal slowing on EEG. DWI exhibited abnormal hyperintense signals in bilateral temporal and insular cortices. After 3 weeks, MRI performed a localizated hippocampal atrophy. CONCLUSION: The MRI findings indicated vasogenic and cytotoxic edema during seizure activity and subsequent loss of brain parenchyma.

Contusion Contrast Extravasation Depicted on Multidetector Computed Tomography Angiography Predicts Growth and Mortality in Traumatic Brain Contusion.

Traumatic brain injury (TBI) is the main cause of death in trauma victims and causes high rates of disability and neurological sequelae. Approximately 38-65% of traumatic brain contusions (TBC) demonstrate hemorrhagic expansion on serial computed tomography (CT) scans. Thus far, however, no single variable can accurately predict the hemorrhage expansion of a TBC. Our purpose was to evaluate contrast extravasation (CE) as a predictor of expansion, mortality, and poor outcome in TBC in a Brazilian cohort. After Institutional Review Board approval, we used multidetector CT angiography (MDCTA) to study 121 consecutive patients (106 men, 87.6%) with ages varying from 10 to 85 years. Informed consent was obtained from all subjects. The clinical and imaging findings were correlated with the findings on the initial MDCTA using either the Fisher exact test or Student t test and a multivariate logistic regression model. Of the persons who presented CE in TBC, 21.8% died (in-hospital mortality), whereas in the absence of this sign, the mortality rate was 7.6% (p = 0.014). In addition, expansion of the hemorrhagic component of the TBC was detected in 61.1% of the CE-positive patients, whereas expansion was only observed in 10% of the CE-negative patients (p < 0.001). Poor outcome was observed in 24.2% of the patients in the CE-negative group, but in the presence of CE, 72.7% evolved with poor outcome (p < 0.001). The CE was a strong independent predictor of expansion, poor outcome, and increased risk of in-hospital mortality in our series of patients with TBC.

Granulomatous diseases of the central nervous system.

Infectious diseases of the central nervous system (CNS), particularly those accompanied by the formation of granulomas, are a constant diagnostic challenge in some specific regions of the world, above all in developing countries. The pattern of image seen on CT or MR scan is the result of the inter-relations between the individual characteristics of the infectious agent and the capacity of each host to mount an appropriate inflammatory response to that specific type of aggression, inside one particular compartment of the CNS. Taking these parameters into account we will discuss the several patterns of image found in parasitic, bacterial, and fungal granulomatous infections.

Evidence of acute ischemic tissue change in transient global amnesia in magnetic resonance imaging: case report and literature review.

Transient global amnesia is a benign syndrome of sudden-onset alteration of behavior with temporary dysfunction of anterograde and recent retrograde memory. Its neural substrates remain uncertain. Possible causes include ischemia, migraine, and epilepsy. The authors report a case of a 62-year-old man with a transient attack of memory disturbance, suggestive of transient global amnesia, in which magnetic resonance imaging performed 48 hours after onset showed left mesial temporal lobe signal changes on diffusion-weighted imaging and fluid-attenuated inversion recovery images. The findings and a literature review lend further support to the ischemic pathogenesis of transient global amnesia as a possible etiology, and underscore the role of diffusion-weighted imaging in the diagnosis of this condition.

Dementia in motor neuron disease: Reviewing the role of MRI in diagnosis.

The superimposed clinical features of motor neuron disease (MND) and frontotemporal dementia (FTD) comprise a distinct, yet not fully understood, neurological overlap syndrome whose clinicopathological basis has recently been reviewed. Here, we present a review of the clinical, pathological and genetic basis of MND-FTD and the role of MRI in its diagnosis. In doing so, we discuss current techniques that depict the involvement of the selective corticospinal tract (CST) and temporal lobe in MND-FTD.

As características clínicas sobreposta da doença do neurônio motor (DNM) e demência frontotemporal (DFT) compreendem um distinto ainda não totalmente compreendido, base neurológica síndrome de sobreposição clínico-patológico foi recentemente revisto. Aqui, apresentamos uma revisão das bases clínicas, patológicas e genética de DNM-DFT e o papel da ressonância magnética no diagnóstico STI. Ao fazê-lo, discutimos as técnicas atuais que retratam o envolvimento do trato corticoespinhal seletiva (TCS) e lobo temporal em DNM-DFT.

Incidental demyelinating inflammatory lesions in asymptomatic patients: a Brazilian cohort with radiologically isolated syndrome and a critical review of current literature.

Despite the definition of specific diagnostic criteria to identify radiologically isolated syndrome (RIS) suggestive of multiple sclerosis, its natural history remains incompletely understood. We retrospectively analyzed a Brazilian cohort of 12 patients to clarify their features and to emphasize the role of imaging predictors in clinical conversion. We demonstrated that, although some individuals did not exhibit progression over a lengthy follow-up period (16.7%), most patients will progress clinically or radiologically in the initial years of the follow-up (83.3%). Infratentorial and spinal cord involvement, as well as the total number of lesions, were more relevant predictors of progression than gadolinium enhancement. Further studies remain necessary to define the risk of conversion in males and to clarify the cognitive abilities of RIS patients. This study may provide an improved understanding of the natural course and evolution of incidental magnetic resonance imaging lesions, and further assists with the management of RIS in clinical practice.

Diffusion MR imaging for monitoring treatment response.

The objective of this article was to emphasize the use of diffusion-weighted imaging in the diagnosis and follow-up of several major disease contexts, as established in recent literature. In some of these diseases the diffusion changes are correlated with the clinical deficit and are potentially useful for early diagnosis and longitudinal evaluation, as well as in the context of pharmacologic trials. Diffusion magnetic resonance is a major advance in the continuing evolution of MR imaging. It provides contrasts and characterization between tissues at a cellular level that may imply differences in function as well as framework and have contributed to a better understanding of the pathophysiological mechanisms of several diseases.

Idiopathic inflammatory demyelinating disorders of the central nervous system in children.

Idiopathic inflammatory demyelinating disorders of the central nervous system usually present with a typical morphologic pattern in adults, with multiple sclerosis as the predominant disorder. However, the variety of disorders in children has an odd range of features that have piqued the interest of researchers. Information concerning this group of diseases, both in vivo and in different age groups, has particularly progressed with the advent of magnetic resonance imaging in the last few decades. In this article, we provide an overview of the applicability of imaging for idiopathic inflammatory demyelinating disorders of the central nervous system in children. In addition to pediatric multiple sclerosis, this review addresses other related disorders, such as acute disseminated encephalomyelitis, pediatric neuromyelitis optica, recurrent optic neuritis, and relapsing transverse myelitis.

Pyramidal tract degeneration in multiple system atrophy: the relevance of magnetization transfer imaging.

The clinical features of multiple system atrophy (MSA) include four domains: autonomic failure/urinary dysfunction, Parkinsonism, cerebellar ataxia, and corticospinal tract dysfunction. Although the diagnosis of definite MSA requires pathological confirmation, magnetic resonance imaging (MRI) studies have been shown to contribute to the diagnosis of MSA. Although pyramidal tract dysfunction is frequent in MSA patients, signs of pyramidal tract involvement are controversially demonstrated by MRI. We evaluated the pyramidal involvement in 10 patients (7 women) with clinically probable MSA, detecting the presence of spasticity, hyperreflexia, and Babinski sign, as well as demonstrating degeneration of the pyramidal tract and primary motor cortex by MRI in all of them. Our article also discusses key radiological features of this syndrome. In MSA, pyramidal tract involvement seems to be more frequent than previously thought, and the clinicoradiological correlation between pyramidal tract dysfunction and degeneration may contribute to the understanding of the clinical hallmarks of MSA. MRI may also add information regarding the differential diagnosis of this syndrome.

Focal transient lesion in the splenium of the corpus callosum in three non-epileptic patients.

INTRODUCTION: We analyzed the imaging features of transient focal lesions in the splenium of the corpus callosum (SCC) in non-epileptic patients receiving antiepileptic drugs (AEDs). METHODS: We identified signal abnormalities in the SCC in three non-epileptic patients, all of them receiving AEDs. We examined two of these patients with multiplanar magnetic resonance (MR) imaging using 1.0-T equipment including fluid-attenuated inversion recovery (FLAIR), T2-weighted (TSE) and T1-weighted (SE) sequences before and after injection of contrast agent. The third patient was studied using 1.5-T equipment with the same sequences. Additionally, a T1 SE sequence with a magnetization transfer contrast pulse off resonance (T1 SE/MTC), diffusion-weighted imaging (EPI-DWI) and apparent diffusion coefficient (ADC) maps were obtained. RESULTS: We observed an identical pattern of imaging abnormalities in all patients characterized by round lesions, hyperintense on FLAIR and hypointense on T1 SE images, located in the central portion of the SCC. One lesion showed homogeneous gadolinium enhancement and perilesional vasogenic edema. This particular lesion showed restricted diffusion confirmed on the ADC map. This pattern was considered consistent with focal demyelination. Follow-up MR examinations showed complete disappearance or a clear reduction in lesion size. All patients had been treated with AEDs, but they did not show any clinical signs of toxicity, interhemispheric symptoms, or abnormal neurological findings (including seizures). CONCLUSION: We believe that our MR findings might be interpreted as transient lesions related to AED toxicity. They presumably resulted from focal demyelination in the central portion of the SCC.

Comparative analysis of MR sequences to detect structural brain lesions in tuberous sclerosis.

BACKGROUND: Tuberous sclerosis (TS) is a neurocutaneous genetically inherited disease with variable penetrance characterized by dysplasias and hamartomas affecting multiple organs. MR is the imaging method of choice to demonstrate structural brain lesions in TS. OBJECTIVE: To compare MR sequences and determine which is most useful for the demonstration of each type of brain lesion in TS patients. MATERIALS AND METHODS: We reviewed MR scans of 18 TS patients for the presence of cortical tubers, white matter lesions (radial bands), subependymal nodules, and subependymal giant cell astrocytoma (SGCA) on the following sequences: (1) T1-weighted spin-echo (T1 SE) images before and after gadolinium (Gd) injection; (2) nonenhanced T1 SE sequence with an additional magnetization transfer contrast medium pulse on resonance (T1 SE/MTC); and (3) fluid-attenuated inversion recovery (FLAIR) sequence. RESULTS: Cortical tubers were found in significantly (P<0.05) larger numbers and more conspicuously in FLAIR and T1 SE/MTC sequences. The T1 SE/MTC sequence was far superior to other methods in detecting white matter lesions (P<0.01). There was no significant difference between the T1 SE/MTC and T1 SE (before and after Gd injection) sequences in the detection of subependymal nodules; FLAIR sequence showed less sensitivity than the others in identifying the nodules. T1 SE sequences after Gd injection demonstrated better the limits of the SGCA. CONCLUSION: We demonstrated the importance of appropriate MRI sequences for diagnosis of the most frequent brain lesions in TS. Our study reinforces the fact that each sequence has a particular application according to the type of TS lesion. Gd injection might be useful in detecting SGCA; however, the parameters of size and location are also important for a presumptive diagnosis of these tumors.