Please use this identifier to cite or link to this item: http://ahro.austin.org.au/austinjspui/handle/1/23561
Title: Restricted Effect of Cerebral Microbleeds on Regional Magnetic Susceptibility.
Authors: Fazlollahi, Amir;Raniga, Parnesh;Bourgeat, Pierrick;Yates, Paul A;Bush, Ashley I;Salvado, Olivier;Ayton, Scott
Affiliation: Department of Aged Care, Austin Health, Heidelberg, Victoria, Australia
CSIRO Data61, Brisbane, Australia
Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia
University of Melbourne, Parkville, Victoria, Australia
Melbourne Dementia Research Centre, Parkville, Victoria, Australia
CSIRO Health and Biosecurity, Brisbane, Australia
Issue Date: 6-Jun-2020
EDate: 2020-06-06
Citation: Journal of Alzheimer's disease : JAD 2020; online first: 6 June
Abstract: Cortical iron accumulation has been reported as a pathological feature of Alzheimer's disease (AD). The cause of cortical iron elevation in AD is unknown but may be contributed by hemosiderin deposits in cerebral microbleeds that frequently occur in this disease. To investigate the impact of cerebral microbleeds (which are more frequent in AD) on the magnetic susceptibility of the surrounding brain tissue. 32 MRI scans from the Australian Imaging, Biomarker and Lifestyle (AIBL) study were found to have cerebral microbleeds by manual assessment of susceptibility weighted images. Quantitative susceptibility mapping (QSM; an MRI technique that is sensitive to iron) was used to estimate iron content in the tissue surrounding the microbleed in four concentric radii. Furthermore, the mirror regions on the contralateral hemisphere were also demarcated. A simulation analysis was conducted to investigate the effect of QSM imaging on cerebral microbleeds with varying sizes. 77 microbleeds were identified from the available scans. The immediate proximal region to the cerebral microbleeds had enhanced tissue susceptibility (∼0.02 PPM), but importantly, this did not extend beyond one voxel radius. This finding with in vivo data was also replicated in a simulation study. However, the presence of microbleeds could lead to over-estimation of tissue QSM in unsupervised quantification, therefore processing methods to avoid this artefact without the need for their manual identification are proposed. The local changes in susceptibility due to microbleeds outside the focal lesion are restricted to 1 voxel and may be explained by partial voluming artefacts caused by limited imaging resolution. The susceptibly change induced by the microbleed is a relatively small proportion of tissue and could not account for regional iron changes observed in AD cortex.
URI: http://ahro.austin.org.au/austinjspui/handle/1/23561
DOI: 10.3233/JAD-200076
ORCID: 0000-0001-9317-0145
PubMed URL: 32538840
Type: Journal Article
Subjects: Alzheimer’s disease
cerebral microbleeds
iron
magnetic resonance imaging
quantitative susceptibility mapping
Appears in Collections:Journal articles

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