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  • Structural brain correlates of interpersonal violence: Systematic review and voxel-based meta-analysis of neuroimaging studies.

    3 July 2018

    Owing to inconsistent nomenclature and results, we have undertaken a label-based review and anatomical likelihood estimation (ALE) meta-analysis of studies measuring the quantitative association between regional grey matter (GM) volume and interpersonal violence. Following PRISMA guidelines, we identified studies by searching 3 online databases (Embase, Medline, PsycInfo) and reference lists. Thirty-five studies were included in the label-based review, providing information for 1288 participants and 86 brain regions. Per region, 0-57% of the results indicated significant reductions in GM volume, while 0-23% indicated significant increases. The only region for which more than half of all results indicated significant reductions was the parietal lobe. However, these results were dispersed across subregions. The ALE meta-analysis, which included 6 whole-brain voxel-based morphometry studies totaling 278 participants and reporting 144 foci, showed no significant clusters of reduced GM volume. No material differences were observed when excluding experiments using reactive violence as outcome or subjects diagnosed with psychopathy. Possible explanations for these findings are phenomenological and etiological heterogeneity, and insufficient power in the label-based review and ALE meta-analysis to detect small effects. We recommend that future studies distinguish between subtypes of interpersonal violence, and investigate mediation by underlying emotional and cognitive processes.

  • Distinct resting-state functional connections associated with episodic and visuospatial memory in older adults.

    3 July 2018

    Episodic and spatial memory are commonly impaired in ageing and Alzheimer's disease. Volumetric and task-based functional magnetic resonance imaging (fMRI) studies suggest a preferential involvement of the medial temporal lobe (MTL), particularly the hippocampus, in episodic and spatial memory processing. The present study examined how these two memory types were related in terms of their associated resting-state functional architecture. 3T multiband resting state fMRI scans from 497 participants (60-82 years old) of the cross-sectional Whitehall II Imaging sub-study were analysed using an unbiased, data-driven network-modelling technique (FSLNets). Factor analysis was performed on the cognitive battery; the Hopkins Verbal Learning test and Rey-Osterreith Complex Figure test factors were used to assess verbal and visuospatial memory respectively. We present a map of the macroscopic functional connectome for the Whitehall II Imaging sub-study, comprising 58 functionally distinct nodes clustered into five major resting-state networks. Within this map we identified distinct functional connections associated with verbal and visuospatial memory. Functional anticorrelation between the hippocampal formation and the frontal pole was significantly associated with better verbal memory in an age-dependent manner. In contrast, hippocampus-motor and parietal-motor functional connections were associated with visuospatial memory independently of age. These relationships were not driven by grey matter volume and were unique to the respective memory domain. Our findings provide new insights into current models of brain-behaviour interactions, and suggest that while both episodic and visuospatial memory engage MTL nodes of the default mode network, the two memory domains differ in terms of the associated functional connections between the MTL and other resting-state brain networks.

  • PEAR: PEriodic And fixed Rank separation for fast fMRI.

    2 July 2018

    PURPOSE: In functional MRI (fMRI), faster acquisition via undersampling of data can improve the spatial-temporal resolution trade-off and increase statistical robustness through increased degrees-of-freedom. High-quality reconstruction of fMRI data from undersampled measurements requires proper modeling of the data. We present an fMRI reconstruction approach based on modeling the fMRI signal as a sum of periodic and fixed rank components, for improved reconstruction from undersampled measurements. METHODS: The proposed approach decomposes the fMRI signal into a component which has a fixed rank and a component consisting of a sum of periodic signals which is sparse in the temporal Fourier domain. Data reconstruction is performed by solving a constrained problem that enforces a fixed, moderate rank on one of the components, and a limited number of temporal frequencies on the other. Our approach is coined PEAR - PEriodic And fixed Rank separation for fast fMRI. RESULTS: Experimental results include purely synthetic simulation, a simulation with real timecourses and retrospective undersampling of a real fMRI dataset. Evaluation was performed both quantitatively and visually versus ground truth, comparing PEAR to two additional recent methods for fMRI reconstruction from undersampled measurements. Results demonstrate PEAR's improvement in estimating the timecourses and activation maps versus the methods compared against at acceleration ratios of R = 8,10.66 (for simulated data) and R = 6.66,10 (for real data). CONCLUSIONS: This paper presents PEAR, an undersampled fMRI reconstruction approach based on decomposing the fMRI signal to periodic and fixed rank components. PEAR results in reconstruction with higher fidelity than when using a fixed-rank based model or a conventional Low-rank + Sparse algorithm. We have shown that splitting the functional information between the components leads to better modeling of fMRI, over state-of-the-art methods.

  • Gradient and shim pre-emphasis by inversion of a linear time-invariant system model.

    2 July 2018

    PURPOSE: The goal of this contribution is to enhance the fidelity and switching speed of gradient and shim fields by advancing pre-emphasis toward broadband and full cross-term correction. THEORY AND METHODS: The proposed approach is based on viewing gradient and shim chains as linear, time-invariant (LTI) systems. Pre-emphasis is accomplished by inversion of a broadband digital system model. In the multiple-channel case, it amounts to a matrix of broadband filters that perform concerted self- and cross-term correction. This approach is demonstrated with gradients and shims up to the third order in a 7 Tesla whole-body MR system. RESULTS: Pre-emphasis by LTI model inversion is first verified by studying settling speeds and response behavior without and with the correction. It is then demonstrated for rapid shim updating, achieving substantially enhanced fidelity of field dynamics and shim settling within approximately 1 ms. In single-shot echo-planar imaging (EPI) acquisitions in vivo, this benefit is shown to translate into enhanced geometric fidelity. CONCLUSIONS: The fidelity of gradient and shim dynamics can be greatly enhanced by pre-emphasis based on inverting a general LTI system model. Permitting shim settling on the millisecond scale, broadband multiple-channel pre-emphasis promises to render higher-order shimming fully versatile at the level of MRI sequence design. Magn Reson Med 78:1607-1622, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

  • Single-shot spiral imaging enabled by an expanded encoding model: Demonstration in diffusion MRI.

    2 July 2018

    PURPOSE: The purpose of this work was to improve the quality of single-shot spiral MRI and demonstrate its application for diffusion-weighted imaging. METHODS: Image formation is based on an expanded encoding model that accounts for dynamic magnetic fields up to third order in space, nonuniform static B0 , and coil sensitivity encoding. The encoding model is determined by B0 mapping, sensitivity mapping, and concurrent field monitoring. Reconstruction is performed by iterative inversion of the expanded signal equations. Diffusion-tensor imaging with single-shot spiral readouts is performed in a phantom and in vivo, using a clinical 3T instrument. Image quality is assessed in terms of artefact levels, image congruence, and the influence of the different encoding factors. RESULTS: Using the full encoding model, diffusion-weighted single-shot spiral imaging of high quality is accomplished both in vitro and in vivo. Accounting for actual field dynamics, including higher orders, is found to be critical to suppress blurring, aliasing, and distortion. Enhanced image congruence permitted data fusion and diffusion tensor analysis without coregistration. CONCLUSION: Use of an expanded signal model largely overcomes the traditional vulnerability of spiral imaging with long readouts. It renders single-shot spirals competitive with echo-planar readouts and thus deploys shorter echo times and superior readout efficiency for diffusion imaging and further prospective applications. Magn Reson Med 77:83-91, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

  • Spinal cord MRI at 7T.

    3 July 2018

    Magnetic resonance imaging (MRI) of the human spinal cord at 7T has been demonstrated by a handful of research sites worldwide, and the spinal cord remains one of the areas in which higher fields and resolution could have high impact. The small diameter of the cord (∼1 cm) necessitates high spatial resolution to minimize partial volume effects between gray and white matter, and so MRI of the cord can greatly benefit from increased signal-to-noise ratio and contrasts at ultra-high field (UHF). Herein we review the current state of UHF spinal cord imaging. Technical challenges to successful UHF spinal cord MRI include radiofrequency (B1) nonuniformities and a general lack of optimized radiofrequency coils, amplified physiological noise, and an absence of methods for robust B0 shimming along the cord to mitigate image distortions and signal losses. Numerous solutions to address these challenges have been and are continuing to be explored, and include novel approaches for signal excitation and acquisition, dynamic shimming and specialized shim coils, and acquisitions with increased coverage or optimal slice angulations.

  • Analysis and correction of field fluctuations in fMRI data using field monitoring.

    2 July 2018

    This work investigates the role of magnetic field fluctuations as a confound in fMRI. In standard fMRI experiments with single-shot EPI acquisition at 3 Tesla the uniform and gradient components of the magnetic field were recorded with NMR field sensors. By principal component analysis it is found that differences of field evolution between the EPI readouts are explainable by few components relating to slow and within-shot field dynamics of hardware and physiological origin. The impact of fluctuating field components is studied by selective data correction and assessment of its influence on image fluctuation and SFNR. Physiological field fluctuations, attributed to breathing, were found to be small relative to those of hardware origin. The dominant confounds were hardware-related and attributable to magnet drift and thermal changes. In raw image time series, field fluctuation caused significant SFNR loss, reflected by a 67% gain upon correction. Large part of this correction can be accomplished by traditional image realignment, which addresses slow and spatially uniform field changes. With realignment, explicit field correction increased the SFNR on the order of 6%. In conclusion, field fluctuations are a relevant confound in fMRI and can be addressed effectively by retrospective data correction. Based on the physics involved it is anticipated that the advantage of full field correction increases with field strength, with non-Cartesian readouts, and upon phase-sensitive BOLD analysis.

  • What are we injecting with our drugs?

    3 July 2018

    In preparation for a case, an anaesthetist opened a 20 ml glass vial of propofol and aspirated the propofol into a syringe via a blunt drawing-up needle. Increased resistance was felt with aspiration. On inspection, a shard of glass was found at the tip of the drawing-up needle. The shard was presumed to be from the propofol ampoule, and to have fallen into the solution upon snapping open its glass tip. This illustrative case raises the issue of contamination of drugs by particles introduced during the drawing-up process. It also highlights the possibility that during the drawing-up process, intravenous drugs may become contaminated not just with particles, but with microorganisms on the surface of the particles. In this article, we discuss relevant recent research of the implications of this type of drug contamination. We draw attention to the need for meticulous care in drawing up and administering intravenous drugs during anaesthesia, particularly propofol.

  • OxPPOPS Caesarean

    15 January 2013

  • OxPPOPS Hernia

    15 January 2013

  • OxPPOPS Breast Cancer

    15 January 2013

  • SILENCE

    13 April 2016

    The Sleep in the Intensive Care Unit: Lowering Elements of Noise in the Critical Care Environment (SILENCE) research programme is funded by a feasibility study grant awarded by the NIHR Research for Patient Benefit scheme, and is sponsored by the University of Oxford. Final results are expected late summer 2017.

  • SILENCE

    13 April 2016

  • SILENCE

    13 April 2016

    The SILENCE programme is a series of linked research projects. Updates on progress will be posted here.

  • SILENCE

    13 April 2016

  • SILENCE

    21 April 2017

    Contact details for the SILENCE research programme

  • Non-contact vital signs monitoring

    20 September 2016

    The non-contact vital signs monitoring (NVSM) study is a joint collaboration between the Department of Engineering, the Nuffield Department of Clinical Neurosciences, and Oxehealth Ltd.

  • NVSM

    25 October 2016

    Significant project milestones will be displayed here

  • Oxford Smart Specs Research Group

    13 June 2014

    DCN NLO

    We are developing a set of 'smart' electronic glasses (‘smart specs’) to enhance sight for the visually impaired.

  • Vision Group

    13 February 2014

    FMRIB NLO

    We use brain imaging techniques to investigate the human visual system, both in its normal state and in disease and disorder.

  • FMRIB P.A.I.N Group

    19 January 2015

    FMRIB NDA

    The Pain Analgesia/Anaesthesia Imaging Neuroscience group is a multidisciplinary team of scientists and clinicians. We research how the human central nervous system generates and modulates painful experiences in acute and chronic settings.

  • NeuroMetrology Lab

    13 April 2016

    DCN NDCN

    Our objective is to develop ways of accurately measuring neurological disorders such as Parkinson's disease.

  • Glioma Neurosurgery Research Group

    11 February 2016

    FMRIB NDCN

    Our research aims to understand the characteristics of individual brain tumours, combining cutting edge brain imaging, molecular neuropathology and neurosurgical techniques to develop personalized approaches for first-line cancer surgery.

  • Parkinson’s Neuropathology Group

    23 February 2016

    DCN

    We study why certain neuronal populations are vulnerable to neurodegeneration in Parkinson’s disease brain and whether pathological changes seen in the peripheral tissues mirror or precede what is ultimately seen in the brain, and how this can be used to develop biomarkers.

  • Neuro-Endocrinology Research Group

    11 February 2016

    DCN

    This cross-disciplinary research group links neuropathology, endocrinology and molecular genetics to explore how the genetics and epigenetics of pituitary tumours influences clinical characteristics and to identify targets for therapeutic intervention.

  • Large Artery Disease

    26 August 2016

    CPSD

    CPSD runs several research studies looking into the causes, investigation, and management of large artery atherosclerosis, carotid stenosis, vertebral artery disease and intracranial atherosclerosis.

  • Oxford Vascular Study

    26 August 2016

    CPSD

    The Oxford Vascular Study (OxVasc) investigates vascular diseases (e.g. strokes, heart attacks) in patients registered with eight general practices in Oxfordshire. We run a rapid-access clinic for patients with suspected Transient Ischaemic Attacks (TIAs) or minor strokes.