Two unmet clinical needs facing the management of prostate cancer are to determine the best treatment for individual patients and to evaluate therapy response. In this study, we applied 3D dynamic imaging technique using hyperpolarized 13C nuclei to non-invasively probe prostate cancer metabolism. Pyruvate-to-lactate conversion kPL correlated well with biopsy and histological finding in pre-surgery prostate cancer patients. kPL values dramatically decreased in a patient 6 weeks into androgen-deprivation therapy with associated PSA decrease, indicating early treatment response. A non-responder patient with castration-resistant cancer exhibited high kPL one month after treatment that correlated with clinical progression.