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Characterization of the peak at 2.06 ppm in 31 P magnetic resonance spectroscopy of human liver: phosphoenolpyruvate or phosphatidylcholine?
Author(s) -
Bierwagen Alessandra,
Begovatz Paul,
Nowotny Peter,
Markgraf Daniel,
Nowotny Bettina,
Koliaki Chrysi,
Giani Guido,
Klüppelholz Birgit,
Lundbom Jesper,
Roden Michael
Publication year - 2015
Publication title -
nmr in biomedicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.278
H-Index - 114
eISSN - 1099-1492
pISSN - 0952-3480
DOI - 10.1002/nbm.3323
Subject(s) - gallbladder , metabolite , chemistry , phosphatidylcholine , in vivo , steatosis , magnetic resonance imaging , nuclear magnetic resonance , medicine , nuclear medicine , biology , phospholipid , biochemistry , radiology , physics , microbiology and biotechnology , membrane
High field MR scanners can resolve a metabolite resonating at 2.06 ppm in the in vivo proton‐decoupled liver 31 P MR spectrum. Traditionally this peak has been assigned to phosphoenolpyruvate (PEP), the key metabolite for gluconeogenesis. However, recent evidence supported the assignment to biliary phosphatidylcholine (PtdCh), which is produced in the liver and stored in the gall bladder. To elucidate the respective contributions of PtdCh and PEP to the in vivo resonance at 2.06 ppm (PEP–PtdCh), we made phantom measurements that confirmed that both biliary PtdCh and PEP resonate approximately at 2 ppm. The absolute quantification of PEP–PtdCh yielded concentrations ranging from 0.6 to 2.0 mmol/l, with mean coefficients of variation of 4.8% for intraday and 7.2% for interday reproducibility in healthy volunteers. The T 1 relaxation time of PEP–PtdCh was 0.97 ± 0.30 s in the liver and 0.44 ± 0.11 s in the gallbladder. Ingestion of a mixed meal decreased the concentration of PtdCh‐PEP by approximately 12%. In the retrospective analysis, PEP–PtdCh was 68% higher in the liver of subjects with gallbladder infiltration of the volume of interest (VOI) compared with those without gallbladder infiltration. PEP–PtdCh was also significantly higher in the liver of cholecystectomy patients compared with volunteers without gallbladder infiltration, which suggests increased intrahepatic bile fluid as a compensation for gall bladder removal. These results show that liver PtdCh is the major component of the resonance at 2.06 ppm and that careful VOI positioning is mandatory to avoid interference from the gallbladder. Copyright © 2015 John Wiley & Sons, Ltd.