Correlation of hyperpolarized 13 C-MRI data with tissue extract measurements.

Hyperpolarized (HP) 13C MRI provides the means to monitor lactate metabolism noninvasively in tumours. Since 13C -lactate signal levels obtained from HP 13C imaging depend on multiple factors, such as the rate of 13C substrate delivery via the vasculature, the expression level of monocarboxylate transporters (MCTs) and lactate dehydrogenase (LDH), and the local lactate pool size, the interpretation of HP 13C metabolic images remains challenging. In this study, ex vivo tissue extract measurements (i.e., NMR isotopomer analysis, western blot analysis) derived from an MDA-MB-231 xenograft model in nude rats were used to test for correlations between the in vivo 13C data and the ex vivo measures. The lactate-to-pyruvate ratio from HP 13C MRI was strongly correlated with [1- 13C ]lactate concentration measured from the extracts using NMR (R = 0.69, p < 0.05), as well as negatively correlated with tumour wet weight (R = -  0.60, p < 0.05). In this tumour model, both MCT1 and MCT4 expressions were positively correlated with wet weight ( ρ = 0.78 and 0.93, respectively, p < 0.01). Lactate pool size and the lactate-to-pyruvate ratio were not significantly correlated.

Duke Scholars

Author Casey Yesol Lee Radiation Oncology