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Abstract #4280

Optimisation of Post-processing Correction of Transmit Field Inhomogeneity in R1 Maps by Relaxometry Modelling

Martina F Callaghan1, Frederic Dick2, Patrick Grabher3, Tim Keller4, Patrick Freund1,3,5, and Nikolaus Weiskopf1,5

1Wellcome Trust Centre for Neuroimaging, UCL Institute of Neurology, London, United Kingdom, 2Birkbeck/UCL Centre for Neuroimaging, London, United Kingdom, 3Spinal Cord Injury Center Balgrist, University Hospital Zurich, Zurich, Switzerland, 4Department of Psychology, Carnegie Mellon University, Pittsburgh, PA, United States, 5Department of Neurophysics, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany

Unified segmentation based correction of R1 brain maps for RF transmit field inhomogeneities (UNICORT) has previously been shown to reduce bias in R1 maps caused by inhomogeneity in the RF transmit field (B1+). This approach simultaneously estimates the B1+ inhomogeneities and R1 values from the uncorrected R1 maps without the need for additional B1+ calibration data. It employs a probabilistic framework that incorporates a physically informed generative model of smooth transmit field inhomogeneities and their multiplicative effect on R1 estimates. However, different systems may require different priors, depending on the particular transmit coil used. Here we show that these parameters can be estimated using a linear relaxometry model framework, without the need to acquire B1+ mapping data.

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