Measuring short-term liver metabolism non-invasively: postprandial and post-exercise super(1)H and super(31)P MR spectroscopy

Object: The objective of this study was to determine the effects of a standardized fat rich meal and subsequent exercise on liver fat content by super(1)H MRS and on liver adenosine triphosphate (ATP) content by super(31)P MRS in healthy subjects. Materials and methods: Hepatic super(1)H and proton decoupled super(31)P MRS were performed on nine healthy subjects on a clinical 3.0 T MR imager three times during a day: after (1) an overnight fast, (2) a following standardized fat rich meal and (3) a subsequent exercise session. Blood parameters were followed during the day to serve as a reference to MRS. Results: Liver fat content increased gradually over the day (p = 0.0001) with an overall increase of 30 %. Also gamma -NTP changed significantly over the day (p = 0.005). gamma -NTP/tP decreased by 9 % (p = 0.019, post hoc) from the postprandial to the post-exercise state. Conclusion: Our study shows that in vivo MRS can depict short lived physiological changes; entering of fat into liver cells and consumption of ATP during exercise can be measured non-invasively in healthy subjects. The physiological state may have an impact on fat and energy metabolite levels. Hepatic super(1)H and super(31)P MRS studies should be performed under standardized conditions.