A new method for proton detection of H2(17)O with potential applications for functional MRI.

A method is presented for the sensitive detection of minute amounts of H2(17)O. The method is based on the increase of the T2 of the water protons following an irradiation of the 17O resonance frequency, due to the partial or full decoupling of the 1H-17O spin-spin interaction. It is demonstrated that when 17O concentrations are low, full decoupling is achieved, and at short echo times the increase in the amplitude of the proton echo signal is proportional to the 17O content of the sample. The potential of the method for indirect 17O imaging is substantiated by a simple one dimensional projection of cylindrical phantoms containing various 17O concentrations. Using interleaved sequences with and without 17O decoupling, errors due to time dependent effects are minimized.