J-refocused 1H PRESS DEPT for localized 13C MR spectroscopy

Area of Science:

• Magnetic Resonance Spectroscopy
• Biophysical Chemistry
• Medical Imaging

Background:

• Proton point-resolved spectroscopy (PRESS) combined with distortionless enhanced polarization transfer (DEPT) is used in multinuclear MRS for in vivo spectroscopy.
• Homonuclear proton scalar couplings can reduce DEPT enhancement during PRESS localization, complicating lipid detection.

Purpose of the Study:

• To develop and validate a J-refocused proton PRESS-localized DEPT sequence for in vivo carbon-13 MRS.
• To overcome signal contamination and improve metabolite detection, particularly for lipids.

Main Methods:

• Theoretical demonstration using product operator formalism.
• Numerical simulations of spin density matrix for various scalar coupling conditions.
• Experimental validation with glutamate and colza oil phantoms, and in vivo studies on human subjects.

Main Results:

• The J-refocused PRESS-localized DEPT sequence effectively suppresses J modulation during PRESS.
• Substantial recovery of signal enhancement was achieved.
• High signal enhancements were obtained for both saturated and unsaturated fatty acids in human calf bone marrow and skeletal muscle.

Conclusions:

• The developed J-refocused PRESS-localized DEPT sequence enables simultaneous enhanced and localized detection of numerous metabolites in vivo.
• This technique significantly improves the sensitivity and accuracy of lipid and fatty acid detection in carbon-13 MRS.
• The method shows promise for various biomedical applications requiring detailed metabolic profiling.