Chencai Wang1, Chaohsiung Hsu1, Stephanie Wolohan1, and Yung-Ya Lin1
A general indirect-detection and spin-amplification
scheme has been developed to enhance the sensitivity of heteronuclear MRS
and MRI based on dynamic
instability of the solvent proton magnetization under collective feedback
fields of radiation damping and the distant dipolar field. The heteronuclear solute spins are first detected by the
solvent proton spins through various magnetization transfer mechanisms and
serve as small “input” signals to perturb the solvent proton magnetization,
which is prepared in an unstable state. The weakly detected signal is then
amplified through subsequent nonlinear evolution of the solvent proton
magnetization to achieve 10x SNR improvement for 13C MRS and MRI.
