Quantitative susceptibility mapping (QSM) is a novel magnetic resonance imaging (MRI) technique for quantifying the spatial distribution of magnetic susceptibility within an object or tissue. Recently, QSM has been widely used to study various dominant magnetic susceptibility sources in the brain, including iron and calcium. In addition, the method enables mapping of the cerebral metabolic rate of oxygen, which could act as a new metabolic biomarker for diseases that involve disruption of the brain's oxygen supply. Thus, the clinical applications of QSM are wide-reaching and hold great promise as imaging biomarkers for studying several neurological diseases. This review aims to summarize the physical concepts and potential clinical applications of QSM in neuroimaging. Evidence Level: 5 Technical Efficacy: Stage 2

BACKGROUND AND PURPOSE: Very few data are available with regard to high-resolution intracranial vessel wall imaging characteristics of Moyamoya disease and their relation to ischemic stroke risk. We investigated the high resolution imaging characteristics of MMD and its correlation with recent ischemic events. MATERIALS AND METHODS:Patients with Moyamoya disease confirmed by DSA, including patients after revascularization, were enrolled. All the patients underwent high-resolution intracranial vessel wall imaging. Vessel wall thickening, enhancement, and the remodeling index of the bilateral distal ICA and proximal MCA were noted. The patients were followed up at 3 months and 6 months after high-resolution intracranial vessel wall imaging and the association of ischemic events with imaging characteristics was assessed. RESULTS:Twenty-nine patients with Moyamoya disease were enrolled. The median age at symptom onset was 12 years (range, 1-51 years). A total of 166 steno-occlusive lesions were detected by high-resolution intracranial vessel wall imaging. Eleven lesions with concentric wall thickening (6.6%) were noted in 9 patients. Ten concentric contrast-enhancing lesions were observed in 8 patients, of which 3 patients (4 lesions) showed grade II enhancement. The presence of contrast enhancement (P 4 .01) and wall thickening (P # .001) showed a statistically significant association with ischemic events within 3 months before and after the vessel wall imaging. Grade II enhancement showed a statistically significant (P 4 .02) association with ischemic events within 4 weeks of high-resolution intracranial vessel wall imaging. The mean 6 standard deviation outer diameter of the distal ICA (right, À3.3 6 0.68 mm; left, 3.4 6 0.60 mm) and the remodeling index (right, 0.71 6 0.13; left, 0.69 6 0.13) were lower in Moyamoya disease. CONCLUSIONS:High-resolution intracranial vessel wall imaging characteristics of concentric wall thickening and enhancement are relatively rare in our cohort of patients with Moyamoya disease. The presence of wall thickening and enhancement may predict future ischemic events in patients with Moyamoya disease. ABBREVIATIONS: ACA 4 anterior cerebral artery; HRVWI 4 high-resolution intracranial vessel wall imaging; MMD 4 Moyamoya disease; PCA 4 posterior cerebral artery; SD 4 standard deviation Indicates open access to non-subscribers at www.ajnr.org http://dx.

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The clinical phenotype of autism spectrum disorder and epilepsy (ASD-E) is a common neurological presentation in various genetic disorders, irrespective of the underlying pathophysiological mechanisms. Here we describe the demographic and clinical profiles, coexistent neurological conditions, type of seizures, epilepsy syndrome, and EEG findings in 11 patients with ASD-E phenotype with proven genetic etiology. The commonest genetic abnormality noted was CDKL5 mutation (3), MECP2 mutation (2), and 1p36 deletion (2). The median age of onset of clinical seizures was 6 months (range, 10 days to 11 years). The most common seizure type was focal onset seizures with impaired awareness, observed in 7 (63.6%) patients followed by epileptic spasms in 4 (30.8%), generalized tonic-clonic and atonic seizures in 3 (27.3%) patients each and tonic seizures in 2 (18.2%) patients and myoclonic seizures in 1 (9.1%) patient. Focal and multifocal interictal epileptiform abnormalities were seen in 6 (54.6%) and 5 (45.5%) patients, respectively. Epileptic encephalopathy and focal epilepsy were seen in 7 (63.6%) and 4 (36.4%) patients, respectively. The diagnostic yield of genetic testing was 44% (11 of 25 patients) and when variants of unknown significance and metabolic defects were included, the yield increased to 60% (15 of 25 patients). We conclude that in patients with ASD-E phenotype with an underlying genetic basis, the clinical seizure type, epilepsy syndrome, and EEG patterns are variable. Next-generation exome sequencing and chromosomal microarray need to be considered in clinical practice as part of evaluation of children with ASD-E phenotype.

The ongoing COVID-19 pandemic has forced every radiology set-up to evolve and formulate guidelines for day-to-day functioning. The sub-speciality of neuroradiology, both diagnostic and neuro-intervention, forms a very important part of any radiology or ‘neuro-care’ set-up. The present document is a consensus statement of the Indian Society of Neuroradiology, prepared after reviewing the available data and working experience. It scientifically tries to answer many questions faced by neuroradiologists everyday in practice. It encompasses simple things such as which patients need to be imaged, what precautions are essential, the work-flows, cleaning of radiology equipment, how to carry out neuro-interventions in COVID-suspect patients, and what procedures/tests to avoid, or their alternatives, to minimise the spread of COVID infection both to the patients and health care personnel. As radiology set-ups can be large, every sub-speciality may have certain precautions which will not be covered in general guidelines, and this document tries to answer those for neuroradiologists. Carefully evolved Standards of Operating Procedure (SOPs) and guidelines are the need of the hour to guide in providing uninterrupted and adequate services to the needy without compromising the safety of the specialised work force and facilities involved.