In vivo phosphorus polarization transfer and decoupling from protons in three‐dimensional localized nuclear magnetic resonance spectroscopy of human brain

Refocused insensitive nucleus enhancement by polarization transfer (RINEPT) from protons (1H) to a J‐coupled phosphorus (31P) has been incorporated into three‐dimensional (3D) chemical‐shift‐imaging (CSI) sequence on a clinical imager. The technique is demonstrated on a phantom and in in vivo human brain. The polarization‐transfer efficiency (∼1.2) is lower than the theoretical maximum of γ1H/γ31P≈ 2.4 resulting from 1H‐1H homonuclear J couplings of similar magnitude competing with the 1H →31P transfer. Nevertheless, compared with direct 31P Ernst‐angle excitation, signal gains of up to × 1.8 were obtained mainly as a result of T1 differences between 31P and the 1H. Spectral interpretation is simplified by editing out all non‐proton‐coupled 31P signals. The duration, ∼50 min, and power deposition, ∼1 W · kg−1, make the application suitable for human studies.

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