T-2 Relaxation Times Of C-13 Metabolites In A Rat Hepatocellular Carcinoma Model Measured In Vivo Using C-13-Mrs Of Hyperpolarized [1-C-13]Pyruvate

A single-voxel Carr-Purcell-Meibloom-Gill sequence was developed to measure localized T-2 relaxation times of C-13-labeled metabolites in vivo for the first time. Following hyperpolarized [1-C-13]pyruvate injections, pyruvate and its metabolic products, alanine and lactate, were observed in the liver of five rats with hepatocellular carcinoma and five healthy control rats. The T-2 relaxation times of alanine and lactate were both significantly longer in HCC tumors than in normal livers (p<0.002). The HCC tumors also showed significantly higher alanine signal relative to the total C-13 signal than normal livers (p<0.006). The intra- and inter-subject variations of the alanine T-2 relaxation time were 11% and 13%, respectively. The intra- and inter-subject variations of the lactate T-2 relaxation time were 6% and 7%, respectively. The intra-subject variability of alanine to total carbon ratio was 16% and the inter-subject variability 28%. The intra-subject variability of lactate to total carbon ratio was 14% and the inter-subject variability 20%. The study results show that the signal level and relaxivity of [1-C-13]alanine may be promising biomarkers for HCC tumors. Its diagnostic values in HCC staging and treatment monitoring are yet to be explored. Copyright (C) 2010 John Wiley & Sons, Ltd.