Deuterated water imaging of the rat brain following metabolism of [ 2 H 7 ]glucose

Purpose To determine whether deuterated water (HDO) generated from the metabolism of [ 2 H 7 ]glucose is a sensitive biomarker of cerebral glycolysis and oxidative flux. Methods A bolus of [ 2 H 7 ]glucose was injected through the tail vein at 1.95 g/kg into Sprague‐Dawley rats. A 2 H surface coil was placed on top of the head to record 2 H spectra of the brain every 1.3 minutes to measure glucose uptake and metabolism to HDO, lactate, and glutamate/glutamine. A two‐point Dixon method based on a gradient‐echo sequence was used to reconstruct deuterated glucose and water (HDO) images selectively. Results The background HDO signal could be detected and imaged before glucose injection. The 2 H NMR spectra showed arrival of [ 2 H 7 ]glucose and its metabolism in a time‐dependent manner. A ratio of the HDO to glutamate/glutamine resonances demonstrates a pseudo–steady state following injection, in which cerebral metabolism dominates wash‐in of HDO generated by peripheral metabolism. Brain spectroscopy reveals that HDO generation is linear with lactate and glutamate/glutamine appearance in the appropriate pseudo–steady state window. Selective imaging of HDO and glucose is easily accomplished using a gradient‐echo method. Conclusion Metabolic imaging of HDO, as a marker of glucose, lactate, and glutamate/glutamine metabolism, has been shown here for the first time. Cerebral glucose metabolism can be assessed efficiently using a standard gradient‐echo sequence that provides superior in‐plane resolution compared with CSI‐based techniques.