A NEW METHOD FOR PROTON DETECTION OF (H2O)-O-17 WITH POTENTIAL APPLICATIONS FOR FUNCTIONAL MRI

A method is presented for the sensitive detection of minute amounts of (H2O)-O-17. The method is based on the increase of the T-2 of the wat er protons following an irradiation of the O-17 resonance frequency, d ue to the partial or full decoupling of the H-1-O-17 spin-spin interac tion. It is demonstrated that when O-17 concentrations are low, full d ecoupling is achieved, and at short echo times the increase in the amp litude of the proton echo signal is proportional to the O-17 content o f the sample. The potential of the method for indirect O-17 imaging is substantiated by a simple one dimensional projection of cylindrical p hantoms containing various O-17 concentrations. Using interleaved sequ ences with and without O-17 decoupling, errors due to time dependent e ffects are minimized.