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A novel single-scan selective homonuclear multiple-quantum coherence-transfer technique, Sel-MQC, is presented that achieves lactate editing with complete lipid and water suppression. The method is suitable for studying tissues with high fat content and those subject to substantial motion. Frequency-selective excitation is employed to selectively prepare lactate into its multiple-quantum states; lipid and water are left in the single-quantum modes and eliminated by the multiple-quantum selection gradients. The efficiency of lipid suppression is monitored by a 2D Sel-MQC experiment which separates lipid and lactate along the multiple-quantum-evolution dimension. The spatial distribution of lactate can be imaged by the spectroscopic imaging version of Sel-MQC. Sel-MQC sequences were demonstrated both in phantoms and in vivo, using subcutaneously implanted murine EMT6 tumors.

The two-dimensional gradient-enhanced heteronuclear multiple-quantum experiment, ge-HMQC, can be modified to produce spectra that are unaffected by magnetic field inhomogeneity broadening along the evolution dimension. Two sequences are proposed. In the first one, ge-SHARP1-HMQC, refocusing is accomplished by asymmetric partitioning of the evolution time. In the second, ge-SHARP-HMQC, an additional heteronuclear 180° pulse is applied during the evolution time. The two sequences differ in their response to the evolution of heteronuclear scalar couplings and chemical shifts. Results on model solutions demonstrate the expected immunity of the 13 C spectral resolution to poor shimming and the concomitant higher detection sensitivity of the narrowed signals.