Fluorine-19 Fast Recovery Fast Spin Echo Imaging for Mapping 5-Fluorouracil

Abstract

We investigated the eŠects of fast recovery (FR) to increase the sensitivity of ‰uorine-19 ( 19 F) fast spin echo (FSE) in mapping 5-‰uorouracil (5-FU) and its metabolites. We added an additional 909pulse (which ‰ips back longitudinal magnetization at the end of the sequence) to the chemical shift selective 19 F FSE pulse sequence. In 5-FU solution, FR remarkably improved the signal-to-noise (S/N) ratio of 19 F 5-FU images, having higher eŠects with shorter repetition time and smaller echo train numbers. In animal studies, FR produced a conspicuous increase in 19 F signals in the urinary bladder. FR eŠects for 19 F signals in the liver were smaller than those in other organs but still substantial. Utilization of FR in 19 F FSE images promises more sensitive observation of 19 F metabolite maps of 5-FU and other 19 F-containing compounds that have relatively long relaxation times.

Double-tuned Radiofrequency Coil for 19F and 1H Imaging

“…1,2 Most 19 F imaging studies have been conducted using tunable singletuned radiofrequency (RF) coils developed for 19 F/ 1 H imaging because the gyromagnetic ratios of 19 F nuclei (40.05 MHz/T) and 1 H nuclei (42.58 MHz/T) are very close. [3][4][5] However, retuning the RF coil during in vivo animal experiments is time consuming, and differing distributions of the RF fields between 19 F and 1 H are inconvenient for quantifying 19 F distribution using the 1 H sensitivity map. Many double nuclei studies have been using double-tuned RF coils with shunting method and multiple poles circuits, methods developed for 2 resonant frequencies that are well separated, such as combinations of 1 H and 31 P (17.24 MHz/T) and 1 H and 13 C (10.71 MHz/T).…”