Hyperpolarized Pyruvate (13C) MR Imaging in Monitoring Patients With Prostate Cancer on Active Surveillance

This study uses a specialized MRI technique with a metabolic tracer (hyperpolarized carbon-13 pyruvate) to detect early changes in low- to intermediate-risk prostate cancer in men on active surveillance — the watch-and-wait approach — to help identify who might benefit from treatment sooner. **You may be eligible if...** - You have biopsy-confirmed prostate cancer with low to intermediate risk - You are enrolled in or planning to join active surveillance (monitoring without immediate treatment) - You have an upcoming fusion biopsy within 12 weeks (for Part 2 of the study) - You are in good overall health (ECOG 0-1) with adequate blood and kidney function **You may NOT be eligible if...** - You have high-risk prostate cancer - You are already receiving active treatment for prostate cancer - Your blood counts or kidney function are below the required thresholds Talk to your doctor to see if this trial is right for you.