Analysis of hyperpolarized dynamic C lactate imaging in a transgenic mouse model of prostate cancer

This study investigated the application of an acquisition that selectively excites the 1-¹³C]lactate resonance and allows dynamic tracking of the conversion of ¹³C-lactate from hyperpolarized ¹³C-pyruvate at a high spatial resolution. In order to characterize metabolic processes occurring in a mouse model of prostate cancer, 20 sequential 3D images of ¹³C-lactate were acquired 5 s apart using a pulse sequence that incorporated a spectral–spatial excitation pulse and a flyback echo-planar readout to track the time course of newly converted ¹³C-lactate after injection of prepolarized ¹³C-pyruvate. The maximum lactate signal (MLS), full-width half-maximum (FWHM), time to the peak ¹³C-lactate signal (TTP) and area under the dynamic curve were calculated from the dynamic images of 10 TRAMP mice and two wild-type controls. The regional variation in ¹³C-lactate associated with the injected pyruvate was demonstrated by the peak of the ¹³C-lactate signal occurring earlier in the kidney than in the tumor region. The intensity of the dynamic ¹³C-lactate curves also varied spatially within the tumor, illustrating the heterogeneity in metabolism that was most prominent in more advanced stages of disease development. The MLS was significantly higher in TRAMP mice that had advanced disease.