Two-pulse phase-modulated (TPPM) 1H decoupling for detection of the C1-glycogen peak in 13C MRS using a 3T clinical scanner.

Motivation: To develop a safe MR method to non-invasively measure skeletal muscle glycogen levels in humans. Goal(s): To reduce SAR without degrading the spectral quality of the 1H-decoupled C1-glycogen peak in 13C MRS. Approach: To introduce the two-pulse phase-modulated (TPPM) 1H decoupling scheme, which is widely used for 13C NMR of organic solids, into the 13C MRS pulse sequence for a clinical scanner. Results: The 1H-decoupled C1-glycogen peak could be obtained from a solution phantom using a clinical 3T scanner while reducing SAR with shortening the duration of the TPPM 1H decoupling during 13C FID acquisition. Impact: 13C MRS with the TPPM 1H decoupling for measuring human skeletal muscle glycogen levels may be more advantageous at high magnetic fields due to the lower SAR, leading to higher SNR or shorter scan times.