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Using evolution to improve ultra-high field MRI RF excitation pulses

11th August 2020

Boris Eberhardt, Benedikt A. Poser, N. Jon. Shah, and Jörg Felder 

Currently, the MRI systems typically seen in clinical settings operate at field strengths of up to 3 T. However, systems operating at much higher field strengths are desirable due to the associated improvements in signal-to-noise ratio, increased BOLD contrast and higher spectral resolution, making it possible to image biological structures and processes in unprecedented detail.
Despite these advantages, imaging at ultra-high field strength also presents challenges which need to be overcome if it is to become part of standard clinical practice. For example, the use of ultra-high magnetic fields leads to increased radio frequency (RF) field inhomogeneities and increased RF power deposition in the form of higher specific absorption rate (SAR), resulting in images which are more prone to artefacts.

In response to these challenges, this work examines and compares global derivative-free optimisation methods to find low excitation error, low SAR solutions to the RF pulse design problem for ultra-high fields.

The figure below shows the search space for the evolution to find the best solution. It determines image quality and energy deposition.

Application of Evolution Strategies to the Design of SAR Efficient Parallel Transmit Multi Spoke Pulses for Ultra-High Field MRI

Original publication:

Application of Evolution Strategies to the Design of SAR Efficient Parallel Transmit Multi Spoke Pulses for Ultra-High Field MRI


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