Estimating T2 relaxation rates of Lactate with Hyperpolarized C13 MRI using bSSFP and Pharmacokinetic Modelling

Lactate T2 values were fit in vivo for animal and human hyperpolarized carbon-13 pyruvate MR datasets. A pharmacokinetic model was used to leverage T2 weighting of a bSSFP acquisition. For healthy rat kidneys lactate T2 values were 0.929 ± 0.111s, for TRAMP tumor 1.663 ± 0.485s, for human RCC tumor 1.119 ± 0.168s and for human RCC normal-appearing region 1.089 ± 0.375s. Lactate T2 maps showed heterogeneity across the kidney of RCC patients but median T2 values were consistent across patients. This work demonstrates a method of using bSSFP hyperpolarized data to fit T2 values.