1H decoupling for in vivo (19)F 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 (19)F[-(1)H] decoupling. It uses commercially available radiofrequency (RF) filters, a transistor-transistor logic (TTL)-controlled attenuator, and a double-resonant RF surface coil suitable for (19)F magnetic resonance spectroscopy (MRS) studies in vivo. This decoupling scheme gives a threefold improvement in signal-to-noise ratio performance compared with the conventional WALTZ-4 decoupling scheme, when significant interaction exists between the decoupler and the receiver. It can also eliminate receiver saturation (i.e., saturation due to coupling of the strong proton decoupling pulse to the (19)F coil) without the need for a high-isolation coil system, thus allowing flexibility in coil geometry. This method has been demonstrated in vivo in patients receiving 5-fluorouracil chemotherapy. Magn Reson Med 44:5-9, 2000.