Liver metabolite concentrations measured with 1H MR spectroscopy.
OBJECTIVE
To determine the feasibility of measuring choline and glycogen concentrations in normal human liver in vivo with proton (hydrogen 1 [1H]) magnetic resonance (MR) spectroscopy.


METHODS
Signed consent to participate in an institutional review board-approved and HIPAA-compliant study was obtained from 46 subjects (mean age, 46 years±17 [standard deviation]; 24 women) consecutively recruited during 285 days. Navigator-gated MR images were used to select 8-mL volumes for point-resolved spectroscopy (PRESS) with a 35-msec echo time. Line widths were minimized with fast breath-hold B0 field mapping and further manual shimming. Navigator-gated spectra were recorded with and without water suppression to determine metabolite concentrations with water signals as an internal reference. In three subjects, echo time was varied to determine the glycogen and choline T2. Linear regression analysis was used to examine relations between choline, hepatic lipid content, body mass index, glycogen content, and age.


RESULTS
Choline concentrations could be determined in 46 of 48 studies and was found to be 8.6 mmol per kilogram of wet weight±3.1 (range, 3.8-17.6; n=44). Twenty-seven spectra in 25 individuals with narrow line widths and low lipid content were adequate for quantitation of glycogen. The glycogen (glucosyl unit) concentration was 38.1 mmol/kg wet weight±14.4. The T2 of combined glycogen peaks in the liver of three subjects was 36 msec±8. Choline levels showed a weak but significant correlation with glycogen (r2=0.15; P<.05) but not with lipid content.


CONCLUSIONS
Navigator-gated and gradient-echo shimmed PRESS 1H MR spectroscopy may allow quantification of liver metabolites that are important for understanding and identifying disorders of glucose and lipid metabolism.
Biomedical and Metabolic Imaging Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, 10 Center Dr, CRC Building 10, Room 3-5340, MSC 1263, Bethesda, MD 20892-1263, USA. ouwerkerkr@niddk.nih.gov
Ronald
R
Ouwerkerk
Roderic I
RI
Pettigrew
Ahmed M
AM
Gharib
D002794:Choline / Q000032:analysis*; D005240:Feasibility Studies; D005260:Female; D006003:Glycogen / Q000032:analysis*; D006801:Humans; D008099:Liver / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D011522:Protons; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014018:Tissue Distribution
D011522:Protons; D006003:Glycogen; D002794:Choline