H-1 decoupling for in vivo F-19 MRS studies using the time-share modulation method on a clinical 1.5 T NMR system

Time-share modulation has been implemented successfully on a clinical 1.5 T nuclear magnetic resonance (NMR) system to perform in vivo F-19[-H-1] deco upling, It uses commercially available radiofrequency (RF) filters, a trans istor-transistor logic (TTL)-controlled attenuator, and a double-resonant R F surface coil suitable for F-19 magnetic resonance spectroscopy (MRS) stud ies in vivo. This decoupling scheme gives a threefold improvement in signal -to-noise ratio performance compared with the conventional WALTZ-4 decoupli ng scheme, when significant interaction exists between the decoupler and th e receiver. It can also eliminate receiver saturation (i.e., saturation due to coupling of the strong proton decoupling pulse to the F-19 coil) withou t the need for a high-isolation coil system, thus allowing flexibility in c oil geometry. This method has been demonstrated in vivo in patients receivi ng B-fluorouracil chemotherapy. (C) 2000 Wiley-Liss, Inc.