Application of F-19 chemical shift imaging in studies of mice with orally administered 5-fluorouracil

In vivo quantitative metabolic mapping is an ideal tool for pharmacokinetic studies. Oral 5-fluorouracil (5-FU) and its metabolites in mice were image d simultaneously by the F-19 fast spin echo (FSE) sequence using interleave d frequency selection at 9.4T. However, 5-FU images in the small intestine have never been obtained regardless of concentration. The reason for the di screpancy between image intensity and concentration was T-2. At a pH above 6, a dramatic decrease in T-2 of a F-19 5-FU signal in an aqueous solution was found; T-2 was shorter in the small intestine (14 ms) than in the stoma ch (52 ms). The F-19 CSI sequence in FID sampling mode was employed for det ecting short T-2 signals. With a 13-min resolution time, the detection of t he 5-FU signals in the region of the small intestine (0.6 mmol/kg) was succ essful with a 5 x 5 mm(2) in-plane resolution. Furthermore, two signals sep arated by 2 ppm were clearly distinguishable, but failed to be separately d etectable with the F-19 FSE sequence. For quantitative simultaneous monitor ing of 5-FU and its metabolites of varying T-2, the F-19 CSI sequence in FI D sampling mode was found to be superior to the F-19 FSE sequence. (C) 2001 Wiley-Liss, Inc.