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Abstract #4093

Redesigning Parallel-transmit Pulses in Runtime to Correct for the Effect of Patient Motion on B1+-maps for Ultrahigh-field MRI.

Emre Kopanoglu1 and Katherine Anna Blanter1
1CUBRIC, School of Psychology, Cardiff University, Cardiff, United Kingdom

Synopsis

Keywords: RF Pulse Design & Fields, High-Field MRI, motion

Motivation: Low-field motion-tracking methods are insufficient at ultrahigh-field as motion also affects flip-angle .

Goal(s): Our goal was to develop a method that can redesign pulses for ultrahigh-field MRI within 1 second.

Approach: We implemented a method to rapidly recalculate the post-motion basis-functions needed for pulse design and complemented it with dictionary matching to reduce pulse computation times a of small-tip-angle multi-spoke multi-slice parallel-transmit pulse design method.

Results: With basis-functions recalculated in 0.13 seconds/slice and pulses reoptimized in 0.18 seconds/slice, multi-slice multi-spoke parallel-transmit pulses can be redesigned in runtime using the proposed method. Redesigned pulses significantly reduce motion-induced error, yielding consistent excitation with pre-motion excitation.

Impact: A pulse design method is developed that can redesign practical parallel-transmit pulses in under a second. It can correct for motion-related flip angle distortions at ultrahigh-field and will help facilitate scanning of patients who cannot remain still (e.g., paediatric, dementia).

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