# Feasibility and optimization of 19F MRI on a clinical 3T with a large field-of-view torso coil

## TL;DR

This paper shows how to optimize 19F MRI on a clinical 3T scanner using a large coil, improving signal quality and reducing imaging time.

## Contribution

The study introduces a phase-cycled bSSFP sequence that enhances 19F MRI sensitivity and reduces banding artifacts at clinical field strengths.

## Key findings

- bSSFP-C achieved 1.8-fold greater sensitivity than SPGR with lower detection limits.
- Optimal flip angles of 12° and 64° maximized signal for SPGR and bSSFP sequences.
- Ex vivo tissue experiments validated the feasibility of 19F MRI at clinical field strengths.

## Abstract

Objective. The objective of this work is to: (1) demonstrate fluorine-19 (19F) MRI on a 3T clinical system with a large field of view (FOV) multi-channel torso coil (2) demonstrate an example parameter selection optimization for a 19F agent to maximize the signal-to-noise ratio (SNR)-efficiency for spoiled gradient echo (SPGR), balanced steady-state free precession (bSSFP), and phase-cycled bSSFP (bSSFP-C), and (3) validate detection feasibility in ex vivo tissues. Approach. Measurements were conducted on a 3.0T Discovery MR750w MRI (GE Healthcare, USA) with an 8-channel 1H/19F torso coil (MRI Tools, Germany). Numerical simulations were conducted for perfluoropolyether to determine the theoretical parameters to maximize SNR-efficiency for the sequences. Theoretical parameters were experimentally verified, and the sensitivity of the sequences was compared with a 10 min acquisition time with a 3.125 × 3.125 × 3 mm3 in-plane resolution. Feasibility of a bSSFP-C was also demonstrated in phantom and ex vivo tissues. Main Results. Flip angles (FAs) of 12 and 64° maximized the signal for SPGR and bSSFP, and validation of optimal FA and receiver bandwidth showed close agreement with numerical simulations. Sensitivities of 2.47, 5.81, and 4.44 \documentclass[12pt]{minimal}
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${\mathrm{m}}{{\mathrm{s}}^{ - 0.5}}\,\,\,{\mathrm{m}}{{\mathrm{M}}^{ - 1}}{\text{ }}$\end{document}ms−0.5mM−1  and empirical detection limits of 20.3, 1.5, and 6.2 mM were achieved for SPGR, bSSFP, and bSSFP-C, respectively. bSSFP and bSSFP-C achieved 1.8-fold greater sensitivity over SPGR (p < 0.01). Significance. bSSFP-C was able to improve sensitivity relative to simple SPGR and reduce both bSSFP banding effects and imaging time. The sequence was used to demonstrate the feasibility of 19F MRI at clinical FOVs and field strengths within ex-vivo tissues.