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 ( 1 H) to a J‐coupled phosphorus ( 31 P) 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 γ 1 H/γ 31 P≈ 2.4 resulting from 1 H‐ 1 H homonuclear J couplings of similar magnitude competing with the 1 H → 31 P transfer. Nevertheless, compared with direct 31 P Ernst‐angle excitation, signal gains of up to × 1.8 were obtained mainly as a result of T 1 differences between 31 P and the 1 H. Spectral interpretation is simplified by editing out all non‐proton‐coupled 31 P signals. The duration, ∼50 min, and power deposition, ∼1 W · kg −1 , make the application suitable for human studies.