17O-decoupled 1H detection using a double-tuned coil

¹⁷O-decoupled proton MR spectroscopy and imaging with a double-tuned radiofrequency (RF) coil at 2 T was used to detect and quantify H₂ ¹⁷O in tissue phantoms containing various concentrations of ¹⁷O-enriched water in 5% gelatin. The pulse sequence used in these experiments consisted of a conventional proton spinecho sequence with RF irradiation at the ¹⁷O resonance frequency applied between the proton 90° pulse and the signal acquisition window. The double-tuned coil provided several advantages over systems using separate RF coils for ¹⁷O decoupling and proton excitation/detection, including ensuring that the same (or similar) sample volumes are excited and decoupled and permitting accurate calibration of the ¹⁷O decoupling pulse amplitude. The efficiency of ¹⁷O decoupling as a function of decoupling RF amplitude, decoupling duration, and decoupling resonance offset was investigated. Finally, the specific absorption rate of the ¹⁷O decoupled pulse sequence was investigated and found to lie within federal guidelines at 1.5 T.