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Multi-centre, multi-vendor reproducibility of 7T QSM and R2* in the human brain: Results from the UK7T study.
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NeuroImage . Dec2020, Vol. 223, pN.PAG-N.PAG. 1p. - Publication Year :
- 2020
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Abstract
- We present the reliability of ultra-high field T 2 * MRI at 7T, as part of the UK7T Network's "Travelling Heads" study. T 2 *-weighted MRI images can be processed to produce quantitative susceptibility maps (QSM) and R 2 * maps. These reflect iron and myelin concentrations, which are altered in many pathophysiological processes. The relaxation parameters of human brain tissue are such that R 2 * mapping and QSM show particularly strong gains in contrast-to-noise ratio at ultra-high field (7T) vs clinical field strengths (1.5–3T). We aimed to determine the inter-subject and inter-site reproducibility of QSM and R 2 * mapping at 7T, in readiness for future multi-site clinical studies. Ten healthy volunteers were scanned with harmonised single- and multi-echo T 2 *-weighted gradient echo pulse sequences. Participants were scanned five times at each "home" site and once at each of four other sites. The five sites had 1× Philips, 2× Siemens Magnetom, and 2× Siemens Terra scanners. QSM and R 2 * maps were computed with the Multi-Scale Dipole Inversion (MSDI) algorithm (https://github.com/fil-physics/Publication-Code). Results were assessed in relevant subcortical and cortical regions of interest (ROIs) defined manually or by the MNI152 standard space. Mean susceptibility (χ) and R 2 * values agreed broadly with literature values in all ROIs. The inter-site within-subject standard deviation was 0.001–0.005 ppm (χ) and 0.0005–0.001 ms−1 (R 2 *). For χ this is 2.1–4.8 fold better than 3T reports, and 1.1–3.4 fold better for R 2 *. The median ICC from within- and cross-site R 2 * data was 0.98 and 0.91, respectively. Multi-echo QSM had greater variability vs single-echo QSM especially in areas with large B 0 inhomogeneity such as the inferior frontal cortex. Across sites, R 2 * values were more consistent than QSM in subcortical structures due to differences in B 0 -shimming. On a between-subject level, our measured χ and R 2 * cross-site variance is comparable to within-site variance in the literature, suggesting that it is reasonable to pool data across sites using our harmonised protocol. The harmonized UK7T protocol and pipeline delivers on average a 3-fold improvement in the coefficient of reproducibility for QSM and R 2 * at 7T compared to previous reports of multi-site reproducibility at 3T. These protocols are ready for use in multi-site clinical studies at 7T. [ABSTRACT FROM AUTHOR]
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- *STANDARD deviations
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Details
- Language :
- English
- ISSN :
- 10538119
- Volume :
- 223
- Database :
- Academic Search Index
- Journal :
- NeuroImage
- Publication Type :
- Academic Journal
- Accession number :
- 146615082
- Full Text :
- https://doi.org/10.1016/j.neuroimage.2020.117358