In vivo fluorine‐19 magnetic resonance spectroscopy of cerebral halothane in postoperative patients: Preliminary results

Abstract

This study reports the use of 19F MRS to study halothane in the brain of eight patients recovering from halothane anesthesia of short duration. Resonances attributable to halothane were observed up to 90 min after withdrawal of the anesthetic agent. The signal-to-noise ratio for an unlocalized spectrum acquired using a 6 cm surface coil was typically 20 with data collection times of 2 min. In seven patients a single resonance was seen with a mean (+/- SD) chemical shift of +43.3 (+/- 1.8) ppm, referenced to NaF at 0 ppm. This resonance exhibited a T1 value of between 0.5 and 1 s, and a T2* (estimated from the linewidth of the resonance) between 3.5 and 10 ms. In one patient two resonances were observed with chemical shifts of +38 and +41 ppm. Because we cannot exclude the possibility that this was due to field inhomogeneity, the significance of the last finding is uncertain. However, phantom studies show that the chemical shift of halothane in different environments (such as water, olive oil, methanol, and lecithin) can vary to an extent that accounts for the two resonances seen in our patient. These results demonstrate the feasibility of in vivo 19F MRS studies of fluorinated volatile agents in humans. The potential for clinical 19F MRS of fluorinated anesthetics is discussed.

Magnetic resonance lactate and lipid signals in rat brain after middle cerebral artery occlusion model

“…Water suppression was performed using CHESS pulses (sinc RF pulses, 8-ms duration, 500-Hz bandwidth), followed by crusher gradients (3-ms duration, 58 mT/m strength). A 4-cm diameter spherical phantom containing 100 mM lactate (Sigma-Aldrich, St. Louis, MO) and fat (olive oil, Otsuka Pharmaceutical Co., Ltd., Tokyo, Japan) (Menon et al, 1993) was used. A transverse image using a T 1 -weighted spin-echo sequence (TR=500 ms, TE=10 ms) was used for placing the volume of interest (VOI) on lactate and/or fat in the phantom.…”

Mapping the biodistribution and catabolism of 5‐fluorouracil in tumor‐bearing rats by chemical‐shift selective 19F MR imaging

“…In contrast with fluorinated inhalation anaesthetics such as halothane or enflurane, which give rise to strong "F MR signals (22)(23)(24), the anesthetic agents used in our study are free of fluorine. Consequently, there is no interference with the "F MR signal of 5-FU and its metabolites.…”

Molecular imaging in oncology

“…10) and/or drug metabolism non-invasively in man [81]. 19 F-MRS (where the recorded MR signal is from the 19 F nucleus) in particular has been applied to studies of anticancer [82, 83], antibiotic [84] and anaesthetic [85, 86] drug metabolism. Furthermore, 19 F-MRS has been used to predict the response of treatment to 5-fluorouracil (5FU) [87] and has demonstrated the biliary excretion of 5FU catabolites in man [88].…”