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Abstract #1857

Robust Estimation of Changes in Transverse Relaxation from Magnitude MRI Data: Application to Vessel Size Imaging

Simon Walker-Samuel1, Matthew Orton1, Lesley D. McPhail1, Simon P. Robinson1

1Cancer Research UK Clinical Magnetic Resonance Research Group, Institute of Cancer Research, Sutton, Surrey, UK

Vessel size imaging using USPIO contrast agents has recently been utilised in a range of contexts, but has been reported to suffer from over-estimation of vessel size index (VSI). In this study, a novel Bayesian maximum a posteriori (MAP) approach is presented for estimating R2 and R2* and ADC. This is compared with a conventional approach (least-squares, LS). By conditioning data with the removal of parameter estimates with high uncertainties or non-significant enhancement, VSI was estimated at 8329m by LS and 6325m by MAP (difference significant, p<0.01), compared with 676m from histological measurements.