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Abstract #4957

A Comparison of FLASH-based Volumetric B1+ Mapping Methods in Phantom at 7 Tesla

James L. Kent1, Patrick Liebig2, Matthijs H. S. de Buck3,4,5, Ladislav Valkovič6,7, Iulius Dragonu8, and Aaron T. Hess1
1Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom, 2Siemens Healthcare AG, Erlangen, Germany, 3Spinoza Centre for Neuroimaging, Amsterdam, Netherlands, 4Department of Computational Cognitive Neuroscience and Neuroimaging, Netherlands Institute for Neuroscience, KNAW, Amsterdam, Netherlands, 5Department of Radiology and Nuclear Medicine, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, Netherlands, 6Oxford Centre for Clinical Magnetic Resonance Research, John Radcliffe Hospital, University of Oxford, Oxford, United Kingdom, 7Department of Imaging Methods, Institute of Measurement Science, Slovak Academy of Sciences, Bratislava, Slovakia, 8Research & Collaborations GB&I, Siemens Healthcare Ltd, Frimley, United Kingdom

Synopsis

Keywords: High-Field MRI, Pulse Sequence Design, B1+ Mapping, SatTFL, Sandwich, SA2RAGE, 7 Tesla

Motivation: Fast and accurate B1+ mapping is critical for parallel transmission in ultra-high field MRI, but several options exist, and which is the most optimal is unknown.

Goal(s): To evaluate three FLASH-based volumetric B1+ mapping methods; 2D SatTFL, 3D SA2RAGE and 3D Sandwich.

Approach: We acquired fully sampled absolute B1+ maps at 7T in a realistic human head phantom across multiple transmission voltages to establish a ground truth and assess the dynamic range of each method.

Results: SA2RAGE and Sandwich both enable low-power non-selective RF pulses and maintain accuracy for low B1+ regions. Sandwich has a 60% shorter acquisition time than SA2RAGE.

Impact: This study will help to inform a choice of B1+ mapping sequences when imaging at ultrahigh field.

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Abstract

Keywords