ORCID Profile
0000-0002-5837-8861
Current Organisations
The University of Auckland
,
Institute of Psychiatry Psychology and Neuroscience
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Publisher: Springer Science and Business Media LLC
Date: 04-2022
DOI: 10.1038/S41593-022-01042-4
Abstract: Human brain structure changes throughout the lifespan. Altered brain growth or rates of decline are implicated in a vast range of psychiatric, developmental and neurodegenerative diseases. In this study, we identified common genetic variants that affect rates of brain growth or atrophy in what is, to our knowledge, the first genome-wide association meta-analysis of changes in brain morphology across the lifespan. Longitudinal magnetic resonance imaging data from 15,640 in iduals were used to compute rates of change for 15 brain structures. The most robustly identified genes GPR139, DACH1 and APOE are associated with metabolic processes. We demonstrate global genetic overlap with depression, schizophrenia, cognitive functioning, insomnia, height, body mass index and smoking. Gene set findings implicate both early brain development and neurodegenerative processes in the rates of brain changes. Identifying variants involved in structural brain changes may help to determine biological pathways underlying optimal and dysfunctional brain development and aging.
Publisher: SAGE Publications
Date: 16-06-2022
DOI: 10.1177/0271678X221107988
Abstract: Active conductive head cooling is a simple and non-invasive intervention that may slow infarct growth in ischemic stroke. We investigated the effect of active conductive head cooling on brain temperature using whole brain echo-planar spectroscopic imaging. A cooling cap (WElkins Temperature Regulation System, 2nd Gen) was used to administer cooling for 80 minutes to healthy volunteers and chronic stroke patients. Whole brain echo-planar spectroscopic imaging scans were obtained before and after cooling. Brain temperature was estimated using the Metabolite Imaging and Data Analysis System software package, which allows voxel-level temperature calculations using the chemical shift difference between metabolite (N-acetylaspartate, creatine, choline) and water resonances. Eleven participants (six healthy volunteers, five post-stroke) underwent 80 ± 5 minutes of cooling. The average temperature of the coolant was 1.3 ± 0.5°C below zero. Significant reductions in brain temperature (ΔT = –0.9 ± 0.7°C, P = 0.002), and to a lesser extent, rectal temperature (ΔT = –0.3 ± 0.1°C, P = 0.03) were observed. Exploratory analysis showed that the occipital lobes had the greatest reduction in temperature (ΔT = –1.5 ± 1.2°C, P = 0.002). Regions of infarction had similar temperature reductions to the contralateral normal brain. Future research could investigate the feasibility of head cooling as a potential neuroprotective strategy in patients being considered for acute stroke therapies.
Publisher: Elsevier BV
Date: 12-2021
Publisher: Wiley
Date: 22-10-2021
DOI: 10.1002/MRM.29048
Abstract: Quantitative susceptibility mapping (QSM) estimates the spatial distribution of tissue magnetic susceptibilities from the phase of a gradient‐echo signal. QSM algorithms require a signal mask to delineate regions with reliable phase for subsequent susceptibility estimation. Existing masking techniques used in QSM have limitations that introduce artifacts, exclude anatomical detail, and rely on parameter tuning and anatomical priors that narrow their application. Here, a robust masking and reconstruction procedure is presented to overcome these limitations and enable automated QSM processing. Moreover, this method is integrated within an open‐source software framework: QSMxT . A robust masking technique that automatically separates reliable from less reliable phase regions was developed and combined with a two‐pass reconstruction procedure that operates on the separated sources before combination, extracting more information and suppressing streaking artifacts. Compared with standard masking and reconstruction procedures, the two‐pass inversion reduces streaking artifacts caused by unreliable phase and high dynamic ranges of susceptibility sources. It is also robust across a range of acquisitions at 3 T in volunteers and phantoms, at 7 T in tumor patients, and in an in silico head phantom, with significant artifact and error reductions, greater anatomical detail, and minimal parameter tuning. The two‐pass masking and reconstruction procedure separates reliable from less reliable phase regions, enabling a more accurate QSM reconstruction that mitigates artifacts, operates without anatomical priors, and requires minimal parameter tuning. The technique and its integration within QSMxT makes QSM processing more accessible and robust to streaking artifacts.
Location: United Kingdom of Great Britain and Northern Ireland
Start Date: 2020
End Date: 2023
Funder: Marsden Fund
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