O-17-DECOUPLED H-1 DETECTION USING A DOUBLE-TUNED COIL

O-17-decoupled proton MR spectroscopy and imaging with a double-tuned radiofrequency (RF) coil at 2 T was used to detect and quantify H-2 O- 17 in tissue phantoms containing various concentrations of O-17-enrich ed water in 5% gelatin. The pulse sequence used in these experiments c onsisted of a conventional proton spin-echo sequence with RF irradiati on at the O-17 resonance frequency applied between the proton 90 degre es pulse and the signal acquisition window. The double-tuned coil prov ided several advantages over systems using separate RF coils for O-17 decoupling and proton excitation/detection, including ensuring that th e same (or similar) sample volumes are excited and decoupled and permi tting accurate calibration of the O-17 decoupling pulse amplitude, The efficiency of O-17 decoupling as a function of decoupling RF amplitud e, decoupling duration, and decoupling resonance offset was investigat ed, Finally, the specific absorption rate of the O-17 decoupled pulse sequence was investigated and found to lie within federal guidelines a t 1.5 T. Copyright (C) 1996 Elsevier Science inc.