A new method for proton detection of H₂¹⁷O with potential applications for functional MRI

A method is presented for the sensitive detection of minute amounts of H₂¹⁷O. 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.