Human hepatic carbohydrate metabolism. Dynamic observation using 13C MRS without proton decoupling

Area of Science:

• Biophysics
• Medical Imaging
• Metabolic Research

Background:

• Natural-abundance 13C MR spectroscopy (MRS) offers a non-invasive method to study metabolic pathways.
• Previous studies have faced challenges in dynamic hepatic 13C MRS due to sensitivity and equipment limitations.

Purpose of the Study:

• To assess the feasibility of dynamic natural-abundance 13C MRS for observing hepatic carbohydrate metabolism.
• To evaluate the use of commercial 1.5 T MR equipment for this application.

Main Methods:

• Utilized a custom-made 20 cm circular surface coil operating at 16.04 MHz for 13C detection.
• Administered 75g of glucose orally and conducted dynamic 13C MRS over 40-60 minutes.
• Employed localized proton shimming to ensure signal quality, achieving a water line width < 20 Hz.

Main Results:

• Successfully visualized glucose and glycogen spectra in the 80-120 ppm range after oral glucose administration.
• Demonstrated clear visibility of dynamic changes in hepatic carbohydrate metabolites.
• Observed rapid changes in the hepatic glycogen pool, reaching maximum levels within 10 minutes.

Conclusions:

• Dynamic natural-abundance 13C MRS is effective for observing hepatic carbohydrate metabolism using standard clinical MR equipment.
• This non-invasive technique holds potential for direct diagnosis of hepatic carbohydrate metabolic disorders.
• The rapid dynamics of hepatic glycogen metabolism can be captured, aiding in clinical assessment.