Conventional methods to assay hepatic ATP require large tissue samples, making repeat measurements on the same animal or human impossible, and are unable to monitor the minimal changes in metabolism consistent with early or reversible cellular injury.~(31)P MRS is a modality available for the in vivo measurement of high energy phosphates. Ratio of inorganic phosphate (Pi) and phosphomonoester (PME) (markers of cellular metabolism and viability) as well as fractionated ATP may be repeatedly quantitated. ~(31...