The use of cerebral computed tomographic angiography as an ancillary investigation to support a clinical diagnosis of death using neurological criteria: a consensus guideline.

This multidisciplinary consensus statement was produced following a recommendation by the Faculty of Intensive Care Medicine to develop a UK guideline for ancillary investigation, when one is required, to support the diagnosis of death using neurological criteria. A multidisciplinary panel reviewed the literature and UK practice in the diagnosis of death using neurological criteria and recommended cerebral CT angiography as the ancillary investigation of choice when death cannot be confirmed by clinical criteria alone. Cerebral CT angiography has been shown to have 100% specificity in supporting a diagnosis of death using neurological criteria and is an investigation available in all acute hospitals in the UK. A standardised technique for performing the investigation is described alongside a reporting template. The panel were unable to make recommendations for ancillary testing in children or patients receiving extracorporeal membrane oxygenation.

Accumulation of Brain Hypointense Foci on Susceptibility-Weighted Imaging in Childhood Ataxia Telangiectasia.

BACKGROUND AND PURPOSE: SWI hypointense cerebral lesions have been reported in adults with the inherited cerebellar neurodegenerative disorder ataxia telangiectasia. This study aims to establish the prevalence, age-dependency, and spatial distribution of these lesions in children and young people with ataxia telangiectasia. MATERIALS AND METHODS: Participants with classic ataxia telangiectasia and matched controls underwent SWI acquisition at 3T at 1 or 2 time points. SWI hypointense lesions were manually labeled according to the Microbleed Anatomical Rating Scale. Differences in prevalence of lesion number between groups with ataxia telangiectasia and without ataxia telangiectasia were tested with the Fisher exact test, and differences in age between participants with ataxia telangiectasia with and without lesions were tested using independent samples Mann-Whitney U test. The relationship between age and lesion number was modeled as an exponential function. RESULTS: Analyzable SWI datasets from 17 participants with ataxia telangiectasia (with median age at first scan of 12.4 years; range, 4.6-20.2 years; 8 [47%] were female) and 22 matched healthy controls showed prevalence of SWI hypointense lesions in 41% of participants with ataxia telangiectasia and 0% in controls (P = .001, Fisher exact test). Lesions were exclusively supratentorial and predominantly lobar. Participants with ataxia telangiectasia with SWI hypointense lesions were older than those without (median age 5.2 years versus 9.3 years, U = 10.5, P = .014). An exponential curve described the relationship between age and lesion number (R 2 = 0.67). CONCLUSIONS: SWI hypointense lesions are common in children and young people with ataxia telangiectasia, accumulating from 12 years of age onward. In contrast to cerebellar-dominant neurodegeneration in ataxia telangiectasia, SWI hypointense lesions were exclusively supratentorial. Further investigation is needed to establish the clinical relevance of these imaging-detected lesions.

Large-scale network dysfunction in vascular cognitive disorder supports connectional diaschisis in advanced arteriosclerosis.

BACKGROUND AND PURPOSE: The interrelation of cognitive performance, cerebrovascular damage and brain functional connectivity (FC) in advanced arteriosclerosis remains unclear. Our aim was to investigate the associations between FC, white matter damage and cognitive impairment in carotid artery disease. METHODS: Seventy-one participants with a recent cerebrovascular event and with written informed consent underwent resting-state functional magnetic resonance imaging and the Addenbrooke's Cognitive Examination - Revised (ACE-R). Network and inter-hemispheric FC metrics were compared between cognitively normal and impaired subjects, and interrelated with cognition. In order to explore the nature of FC changes, their associations with microstructural damage of related white matter tracts and cognitive performance were investigated, followed by mediation analysis. RESULTS: Participants with global cognitive impairment showed reduced FC compared to the cognitively intact subjects within the central executive network (CEN), and between hemispheres. Patients with executive dysfunction had decreased CEN FC whilst patients with memory loss demonstrated low FC in both the CEN and the default mode network (DMN). Global performance correlated with connectivity metrics of the CEN hub with DMN nodes, and between hemispheres. Cingulum mean diffusivity (MD) was negatively correlated with ACE-R and CEN-DMN FC. The cingulum MD-cognition association was partially mediated by CEN-DMN FC. CONCLUSIONS: Long-range functional disconnection of the CEN with DMN nodes is the main feature of cognitive impairment in elderly subjects with symptomatic carotid artery disease. Our findings provide further support for the connectional diaschisis concept of vascular cognitive disorder, and highlight a mediation role of functional disconnection to explain associations between microstructural white matter tract damage and cognitive impairment.

Measuring Cerebral and Cerebellar Glutathione in Children Using 1H MEGA-PRESS MRS.

BACKGROUND AND PURPOSE: Glutathione is an important antioxidant in the human brain and therefore of interest in neurodegenerative disorders. The purpose of this study was to investigate the feasibility of measuring glutathione in healthy nonsedated children by using the 1H Mescher-Garwood point-resolved spectroscopy (MEGA-PRESS) sequence at 3T and to compare glutathione levels between the medial parietal gray matter and the cerebellum. MATERIALS AND METHODS: Glutathione was measured using MEGA-PRESS MRS (TR = 1.8 seconds, TE = 131 ms) in the parietal gray matter (35 × 25 × 20 mm3) of 6 healthy children (10.0 ± 2.4 years of age; range, 7-14 years; 3 males) and in the cerebellum of 11 healthy children (12.0 ± 2.7 years of age; range, 7-16 years; 6 males). A postprocessing pipeline was developed to account for frequency and phase variations in the edited ON and nonedited OFF spectra. Metabolites were quantified with LCModel and reported both as ratios and water-scaled values. Glutathione was quantified in the ON-OFF spectra, whereas total NAA, total Cho, total Cr, mIns, Glx, and taurine were quantified in the OFF spectra. RESULTS: We found significantly higher glutathione, total Cho, total Cr, mIns, and taurine in the cerebellum (P < .01). Glx and total NAA were significantly higher in the parietal gray matter (P < .01). There was no significant difference in glutathione/total Cr (P = .93) between parietal gray matter and cerebellum. CONCLUSIONS: We demonstrated that glutathione measurement in nonsedated children is feasible. We found significantly higher glutathione in the cerebellum compared with the parietal gray matter. Metabolite differences between the parietal gray matter and cerebellum agree with published MRS data in adults.

Metrics and textural features of MRI diffusion to improve classification of pediatric posterior fossa tumors.

BACKGROUND AND PURPOSE: Qualitative radiologic MR imaging review affords limited differentiation among types of pediatric posterior fossa brain tumors and cannot detect histologic or molecular subtypes, which could help to stratify treatment. This study aimed to improve current posterior fossa discrimination of histologic tumor type by using support vector machine classifiers on quantitative MR imaging features. MATERIALS AND METHODS: This retrospective study included preoperative MRI in 40 children with posterior fossa tumors (17 medulloblastomas, 16 pilocytic astrocytomas, and 7 ependymomas). Shape, histogram, and textural features were computed from contrast-enhanced T2WI and T1WI and diffusivity (ADC) maps. Combinations of features were used to train tumor-type-specific classifiers for medulloblastoma, pilocytic astrocytoma, and ependymoma types in separation and as a joint posterior fossa classifier. A tumor-subtype classifier was also produced for classic medulloblastoma. The performance of different classifiers was assessed and compared by using randomly selected subsets of training and test data. RESULTS: ADC histogram features (25th and 75th percentiles and skewness) yielded the best classification of tumor type (on average >95.8% of medulloblastomas, >96.9% of pilocytic astrocytomas, and >94.3% of ependymomas by using 8 training samples). The resulting joint posterior fossa classifier correctly assigned >91.4% of the posterior fossa tumors. For subtype classification, 89.4% of classic medulloblastomas were correctly classified on the basis of ADC texture features extracted from the Gray-Level Co-Occurence Matrix. CONCLUSIONS: Support vector machine-based classifiers using ADC histogram features yielded very good discrimination among pediatric posterior fossa tumor types, and ADC textural features show promise for further subtype discrimination. These findings suggest an added diagnostic value of quantitative feature analysis of diffusion MR imaging in pediatric neuro-oncology.

Patterns of accidental craniocerebral injury occurring in early childhood.

OBJECTIVE: To describe the range of intracranial injuries encountered in 0-2-year-olds in cases of accidental head injury where the mechanism of trauma was well characterised and to assess the clinical consequences. DESIGN: A retrospective review of imaging and clinical data. SETTING: Two tertiary paediatric referral centres. PATIENTS: All children aged 0-2 undergoing cranial CT as indicated by National Institute for Health and Clinical Excellence guidance for head injury from 2006 to 2011. After exclusion criteria, 149 patients were included. MAIN OUTCOME MEASURES: Rates of skull fracture, intracranial haemorrhage, parenchymal injuries and ischaemic change per type of mechanism of injury. Rates of neurological sequelae on follow-up. RESULTS: Skull fractures were demonstrated in 54 (36%) patients of whom 17 (11%) had thin underlying subdural haemorrhage (SDH). Extradural haemorrhage complicated one fracture and two cases of isolated subdural haematomas were seen without skull fracture. Radiologically evident brain parenchymal injuries were present in three patients, all with mechanisms of injury involving high levels of force; severe neurological sequelae were only seen in one patient, who had diffuse hypoxic-ischaemic damage at presentation and whose (accidental) mechanism of injury involved extensive acceleration/deceleration/translational forces. CONCLUSIONS: Skull fractures and focal SDH are relatively common following minor trauma in this age group but in the vast majority of cases there are no long-term neurological sequelae. Conversely, diffuse brain injury with severe subsequent neurological impairment was only seen in patients with a correspondingly severe mechanism of injury.

Don't neglect 'neglect'- an update on post stroke neglect.

OBJECTIVES: Post-stroke neglect is common and an independent predictor of functional outcome. Assessment of neglect is very demanding, the treatment extremely difficult and the literature vast; we performed a literature search for all aspects of this difficult subject. METHODS: We searched the PubMed, EMBASE databases and historical manuals for authoritative studies on post stroke neglect between 1951 and 2011. FINDINGS: There is a great dearth of randomised controlled data on neglect because standardised assessment does not occur frequently. Eighty-eight manuscripts were identified in the literature, which were quite heterogeneous in their content and addressing diverse aspects of this clinical entity. INTERPRETATION AND IMPLICATIONS: The most important historical papers were selected along with the most widely accepted and proven strategies for assessment and treatment. Standardised assessment of neglect does not always occur, but several useful strategies are available and are described in the following sections.

Cancer presenting during pregnancy: radiological perspectives.

Malignancy presenting during pregnancy is rare. When it does, there are important considerations and challenges for the radiologist. The physiological changes of pregnancy may mask signs and symptoms of malignancy leading to delayed presentation. Endocrine and physiological changes during pregnancy can interact with tumour biology to alter the behaviour and patterns of growth of certain tumours. The timing and choice of imaging technique pose potential risks to the foetus, but this must be weighed against the risks to both mother and foetus of inadequate investigation or misdiagnosis. This review outlines the general principles and approach to imaging the pregnant patient with suspected malignancy, following which there is a more detailed discussion of the effects of pregnancy on tumour biology and presentation of specific tumours. Imaging strategies are discussed for the different entities, and where possible, evidence-based imaging recommendations are made.

Disconnection as a mechanism for cognitive dysfunction in multiple sclerosis.

Disconnection of cognitively important processing regions by injury to the interconnecting white matter provides a potential mechanism for cognitive dysfunction in multiple sclerosis. The contribution of tract-specific white matter injury to dysfunction in different cognitive domains in patients with multiple sclerosis has not previously been studied. We apply tract-based spatial statistics (TBSS) to diffusion tensor imaging (DTI) in a cohort of multiple sclerosis patients to identify loci where reduced white matter tract fractional anisotropy (FA) predicts impaired performance in cognitive testing. Thirty-seven multiple sclerosis patients in remission (median age 43.5 years; Expanded Disability Status Scale range 1.5-6.5; 35 relapsing remitting, two secondary-progressive) underwent 3 T MRI including high-resolution DTI. Multiple sclerosis patients underwent formal testing of performance in multiple cognitive domains. Normalized cognitive scores were used for voxel-wise statistical analysis using TBSS, while treating age as a covariate of no interest. Permutation-based inference on cluster size (t > 2, P <0.05 corrected) was used to correct for multiple comparisons. Statistical mapping revealed differential patterns of FA reduction for tests of sustained attention, working memory and processing speed, visual working memory and verbal learning and recall. FA was not associated with frontal lobe function or visuospatial perception. Cognitively relevant tract localizations only partially overlapped with areas of high FLAIR lesion probability, confirming the contribution of normal-appearing white matter abnormality to cognitive dysfunction. Of note, tract localizations showing significant associations with cognitive impairment were found to interconnect cortical regions thought to be involved in processing in these cognitive domains, or involve possible compensatory processing pathways. This suggests that TBSS reveals functionally relevant tract injury underlying cognitive dysfunction in patients with multiple sclerosis.

Cerebral manifestations in liver disease and transplantation.

Patients with liver disease frequently develop cerebral complications. The brain may be affected directly by the pathological process or agent responsible for the liver disease, as a consequence of the metabolic and haemodynamic derangement caused by hepatic dysfunction, or as a complication of the treatment of liver disease. Computed tomography (CT) and magnetic resonance imaging (MRI) can be helpful in the diagnosis and management of these complications, and advanced techniques such as diffusion weighted imaging (DWI) and magnetic resonance spectroscopy (MRS) are providing new insights into the underlying pathophysiological processes. We present a radiological overview of the cerebral manifestations of liver disease, categorized as acute presentations, chronic presentations, and conditions occurring in the context of liver transplantation.

Intraplaque haemorrhage mimicking carotid pseudoaneurysm on magnetic resonance angiography.

Contrast-enhanced magnetic resonance angiography (CE-MRA) is a commonly used technique to assess the extracranial carotid arteries. We describe two patients (investigated for carotid artery atherosclerotic disease) who underwent CE-MRA. Results suggested pseudoaneurysms of the extracranial carotid arteries. Magnetic resonance direct thrombus imaging (MRDTI) showed that the appearances were due to intraplaque haemorrhage adjacent to the vessel, with the T1-shortening effect of methaemoglobin within the intraplaque haemorrhage mimicking blood flow on the CE-MRA sequence. The cases presented demonstrate this diagnostic pitfall and illustrate the contribution of simple magnetic resonance plaque imaging to establishing the correct diagnosis.

Imaging in the investigation of paraneoplastic syndromes.

Paraneoplastic syndromes are a heterogeneous group of disease presentations caused by underlying tumours. As they are non-metastatic in nature an intensive diagnostic evaluation is warranted to identify potentially curable lesions. The selection of the appropriate method of imaging is important in these cases, especially when history and physical examination are unrevealing. In this review the important paraneoplastic syndromes and underlying malignancies are discussed along with relevant imaging strategies.

Aneurysmal sub-arachnoid haemorrhage in patients with Noonan syndrome: a report of two cases and review of neurovascular presentations in this syndrome.

To date, intracranial aneurysms have been reported in two patients with Noonan syndrome. We report two unrelated patients with Noonan syndrome who presented with sub-arachnoid haemorrhage secondary to intracranial aneurysms. These cases are discussed and other cerebrovascular abnormalities that have been described in association with Noonan syndrome are reviewed. Ultrastructural and genetic factors contributing to these associations are considered.