Arsany Hakim

Adrenal and Extra-adrenal Myelolipomas - A Comparative Case Report

Myelolipoma is an uncommon benign tumour composed of mature fat tissue and haematopoietic elements and is most commonly found in the adrenal gland. We report a case, which was discovered incidentally on chest X-ray, of a rare occurrence of multifocal extra-adrenal myelolipoma in the thoracic paravertebral region. This was further investigated with multi-detector computed tomography and magnetic resonance imaging. The presumed diagnosis, of extra-adrenal myelolipoma, was histologically confirmed via tissue sample obtained by computed tomography guided biopsy. We compare the adrenal and extra-adrenal entities from the perspective of published literature and also review the cases, published in Pubmed, of extra-adrenal myelolipomas in order to summarize the different locations of this lesion.

Pyogenic brain abscess with atypical features resembling glioblastoma in advanced MRI imaging

Differentiation between infectious and neoplastic brain processes is crucial for treatment planning. Advanced magnetic resonance imaging techniques, such as diffusion, perfusion, susceptibility weighted imaging, and magnetic resonance spectroscopy, enhance the imaging differences between these two pathologies. However, despite the utilization of these advanced techniques, the pathologic process may be confound by atypical findings. Here, we report a case of an autistic patient with multiple brain lesions with diffusion weighted imaging, susceptibility weighted imaging, and perfusion patterns resembling features of a multicentric glioblastoma, which were confirmed surgically, neuropathologically, and bacteriologically as brain abscesses. We discuss the differentiation of these different entities in the light of advanced magnetic resonance imaging techniques.

Clinical evaluation of the iterative metal artefact reduction algorithm for post-operative CT examination after maxillofacial surgery

OBJECTIVES Metal artefacts present challenges to both radiologists and clinicians during post-operative imaging. Such artefacts reduce the diagnostic effectiveness of CT scans and mask findings that could be vital for patient management. Thus, a powerful artefact reduction tool is necessary when imaging patients with metal implants. Our aim was to test the recently introduced iterative metal artefact reduction (iMAR) algorithm in patients with maxillofacial implants. METHODS Images from 17 patients with diverse maxillofacial metal implants who had undergone CT scans were qualitatively and quantitatively analyzed before and after metal artefact reduction with iMAR. RESULTS After iMAR application, images exhibited decreased artefacts and improved image quality, leading to detection of lesions that were previously masked by artefacts. The application of iMAR did not affect image quality in regions distant from the metal implants. CONCLUSIONS The application of iMAR to CT examinations of patients with maxillofacial metal implants leads to artefact reduction, improvement of image quality and increased diagnostic utility. Routine implementation of iMAR during imaging of patients with metal hardware implants could add diagnostic value to their CT examinations.

Brush sign in Sturge-Weber syndrome

Dear Editors, We read with great interest the pictorial review by Linscott et al [1], “Imaging patterns of venous-related brain injury in children,” which offers a clear and valuable summary of these patterns. Furthermore, we would like to share with the readers of Pediatric Radiology an imaging pattern related to SturgeWeber syndrome – the brush sign. The brush sign was first described by Morita et al. [2] in 2008 in a T2*-weighted sequence in the context of acute stroke and was defined as asymmetrical visualization of the subependymal and medullary veins in the deep white matter (Fig. 1). This phenomenon was attributed to BOLD (blood-oxygen-level-dependent) effect due to an increase in intravenous deoxyhemoglobin in cases with major vessel occlusion, reflecting an increased oxygen extraction fraction. Later, Horie et al. [3] identified the brush sign in susceptibility-weighted imaging (SWI) of patients with Moyamoya disease and used this sign to assess disease severity by determining the number of conspicuous deep medullary veins. Again, this phenomenon was attributed to increased oxygen extraction as well as to the chronic state of cerebral vasodilation in these patients. Sturge-Weber syndrome is a sporadic condition associated with vascular malformation of the skin, eye and brain that classically includes facial port-wine stain and ipsilateral pial venular angioma. Abnormal development of the cortical veins is a typical feature, and disease progression has been linked to progressive venous occlusion and resulting venous stasis, for which aspirin is recommended by some clinicians [4]. Engorgement of the medullary veins is commonly seen and was previously described in conventional angiography and MRI [5, 6]. This enlargement resembles the brush sign (Fig. 1) and can be detected in T1-W contrast-enhanced imaging (as in girl with known in Linscott et al. [1]) and is also delineated clearly in SWI sequences, which enhance the abnormal neurovasculature and therefore improve the detection of the prominent deep veins [7]. These collateral channels develop early in the disease and, to a certain extent, are efficient in preventing damage to the adjacent cortex [8], as they can be appreciated in imaging before cortical hypometabolism develops [8]. Furthermore, the development of collaterals may also increase as the disease progresses, as seen in a case presented by Mentzel et al. [9], who demonstrated an increase in medullary veins in a follow-up MRI in a neonate in comparison with the initial exam. In conclusion, Sturge-Weber syndrome should be added to the list of diseases causing the brush sign. It develops due to engorgement of the medullary and subependymal veins serving as collateral channels from the cortex to the deep venous system resulting from the progressive occlusion of the abnormal cortical veins, and an increase in local deoxyhemoglobin concentration caused by hypoxia due to venous stasis. To determine whether this sign can facilitate assessment of disease severity, according to the number or the degree of engorgement of conspicuous deep medullary veins, or whether it can be used to monitor therapy (e.g., effect of aspirin), further studies with serial MRI and clinical correlation are required. * Arsany Hakim arsany_hakim@yahoo.com

Association of anemia and hemoglobin decrease during acute stroke treatment with infarct growth and clinical outcome.

Background and purpose Anemia is associated with worse outcome in stroke, but the impact of anemia with intravenous thrombolysis or endovascular therapy has hardly been delineated. The aim of this study was to analyze the role of anemia on infarct evolution and outcome after acute stroke treatment. Methods 1158 patients from Bern and 321 from Los Angeles were included. Baseline data and 3 months outcome assessed with the modified Rankin Scale were recorded prospectively. Baseline DWI lesion volumes were measured in 345 patients and both baseline and final infarct volumes in 180 patients using CT or MRI. Multivariable and linear regression analysis were used to determine predictors of outcome and infarct growth. Results 712 patients underwent endovascular treatment and 446 intravenous thrombolysis. Lower hemoglobin at baseline, at 24h, and nadir until day 5 predicted poor outcome (OR 1.150–1.279) and higher mortality (OR 1.131–1.237) independently of treatment. Decrease of hemoglobin after hospital arrival, mainly induced by hemodilution, predicted poor outcome and had a linear association with final infarct volumes and the amount and velocity of infarct growth. Infarcts of patients with newly observed anemia were twice as large as infarcts with normal hemoglobin levels. Conclusion Anemia at hospital admission and any hemoglobin decrease during acute stroke treatment affect outcome negatively, probably by enlarging and accelerating infarct growth. Our results indicate that hemodilution has an adverse effect on penumbral evolution. Whether hemoglobin decrease in acute stroke could be avoided and whether this would improve outcome would need to be studied prospectively.

Anomalies and Normal Variants of the Cerebral Arterial Supply: A Comprehensive Pictorial Review with a Proposed Workflow for Classification and Significance.

Cerebral arteries may exhibit a wide range of variation from normal anatomy, which can be incidentally discovered during imaging. Knowledge of such variants is crucial to differentiate them from pathologies, to understand the etiology of certain pathologies directly related to a vascular variant, and to depict the changes in collateral circulation in patients with certain variants. Detection of particular variants may lead to the discovery of other nonvascular or vascular anomalies, especially aneurysms, and may also affect planning of endovascular or neurosurgical interventions. In this review, we summarize the variants and anomalies of cerebral arteries seen on cross‐sectional imaging classified by a morphological approach and categorize their significance from a clinical perspective. This structured review is intended to serve as a guide for daily use in clinical practice.

Rebound After Fingolimod and a Single Daclizumab Injection in a Patient Retrospectively Diagnosed With NMO Spectrum Disorder—MRI Apparent Diffusion Coefficient Maps in Differential Diagnosis of Demyelinating CNS Disorders

Objective: Differential diagnosis of neuromyelitis optica spectrum disorders (NMOSD) and multiple sclerosis (MS) or mimics can be challenging, especially in patients with atypical presentations and negative serostatus for aquaporin-4 antibodies (AQP4-Ab). This brief research report describes magnetic resonance imaging (MRI) findings focusing on quantitative apparent diffusion coefficient (ADC) histogram analysis as a potential tool to differentiate NMOSD from MS. Methods: Longitudinal MRI data obtained during routine clinical examinations were retrospectively analyzed in a patient with histologically determined cerebral NMOSD, a patient with an acute tumefactive MS lesion, and a patient with ischemic stroke. Histogram analyses of ADC maps were evaluated. Results: A patient diagnosed with MS experienced a severe rebound after fingolimod withdrawal and a single daclizumab injection. Cerebral NMOSD manifestation was confirmed by brain biopsy. However, the patient did not fulfill consensus criteria for NMOSD and was AQP4-Ab negative. Comparison of ADC histogram analyses of this patient with those from a patient with MS and one with ischemic stroke revealed differential ADC characteristics: namely a more pronounced and prolonged ADC leftward shift in inflammatory than in ischemic pathology, even more accentuated in NMOSD versus MS. Conclusion: ADC map histograms and ADC threshold values for different conditions may be useful for differentiation of large inflammatory brain lesions and further studies are merited.

Using an orbit shield during volume perfusion CT: is it useful protection or an obstacle?

AIM To evaluate the image quality and artefacts resulting from in-plane orbit shielding during computed tomography (CT) perfusion and to assess the possibility of artefact reduction using the iterative metal artefact reduction (iMAR) algorithm. MATERIALS AND METHODS Twenty-eight perfusion CT examinations obtained from 20 patients using orbit shields were included in this study. Source images and perfusion maps were analysed retrospectively to detect the type and extent of artefacts. Original images were compared with images processed using the iMAR algorithm. The extent of artefacts was categorised into three groups: orbital/frontal, middle fossa, and posterior fossa. Types of artefacts in source images were categorised as noise, streak, beam hardening, or a combination of those, and types of artefacts in perfusion maps were categorised as: noise, image distortion, areas with missing colour codes, or incorrect colour-coding. RESULTS All source images evaluated showed artefacts related to orbit shielding and 85.7% reached the posterior fossa. In 92.8% of scans, perfusion maps showed artefacts, mostly as incorrect colour codes. Of the perfusion maps with artefacts, 92.3% reached the posterior fossa. After application of the iMAR algorithm, an increase in the extent of artefacts was observed in 93% of perfusion maps, and no improvement of image quality was noted. CONCLUSION Orbit shields cause significant artefacts if used for in-plane shielding during whole-brain CT perfusion, and render areas at the level of the shield undiagnosable. Usage of an orbit shield during whole-brain CT perfusion is not recommended, so alternative methods for reducing the radiation dose are advisable.