Quantitative 19F MR spectroscopy at 3 T to detect heterogeneous capecitabine metabolism in human liver

Chemotherapy in non-responding cancer patients leads to unnecessary toxicity. A marker is therefore required that can predict the sensitivity of a specific tumour to chemotherapy, which would enable individualisation of therapy. 19F MR spectroscopy (19F MRS) can be used to monitor the metabolism of fluorinated drugs. The aim of this study was to develop a method for quantified localised detection of fluorinated compounds in human liver. For this purpose, sensitivity-optimised localised 19F MRS methods at 3 T were used to detect MR signals from capecitabine, 5'DFUR, 5'DFCR and FBAL after oral intake of capecitabine. As the radio-frequency (rf) coil is made tuneable to 19F and 1H, the same localisation method is applied to obtain 1H MR signals of water and of the 19F metabolites. In addition, T1 measurements have been performed to correct for measurement-induced saturation effects. Finally, absolute tissue concentrations of capecitabine metabolites were obtained in vivo, which revealed a substantial spatial heterogeneity of these metabolites in human liver after chemotherapy.