What type of study is this?

This is a Quantitative Study study (also classified as: Experimental Study).

September 17, 2025

Optimisation of Flip-Angle Schedules for MR Fingerprinting with inhomogeneous Transmit Fields

Key Points

B1+ informed optimisation reduces predicted T2-error by three times, improving imaging quality.
Applying Cramer-Rao bound optimisation demonstrates reduction in errors compared to conventional schedules.
In vivo experiments confirm that B1+ corrections remove shading from T1-maps.
Improved output enhances diagnostic capabilities for neurodegenerative diseases using high-resolution parameter maps.

Abstract

Motivation: Unlocking SNR benefits of ultra-high field for high-resolution quantitative MRI is hindered by transmit-field (B1+) inhomogeneities because optimal flip-angles are not realised throughout the field-of-view. Goal(s): We investigate how flip-angle schedules for MR Fingerprinting can be adjusted to enhance robustness towards B1+ inhomogeneity. Approach: We incorporate B1+ into Cramer-Rao bound optimisation, demonstrate that predicted errors are reduced compared with a conventionally optimised flip-angle schedule, and show this in invivo experiments. Results: B1+ informed CRB optimisation reduces predicted peak T2-error by a factor of three, which removes artefacts in invivo experiments. B1+ corrections successfully removed shading in T1-maps. Impact: This work addresses one of the problems of quantitative imaging at ultra-high field to make its benefit more accessible. The larger aim is to achieve high resolution parameter maps which can be useful for diagnosis and research of neurodegenerative diseases.

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