The non-invasive measurement of [1-13C]pyruvate-to-lactate conversion predicts clinically relevant disease and holds potential as: (i) a non-invasive approach to stratify high-risk PCa patients, and (ii) a tool to monitor residual/significant disease in patients given treatment (including treatments with LDHA and MCT-4 inhibitors) or on active surveillance. The gene discussed is LDHA; the disease is posterior cortical atrophy.