A Prosthetic Joint Infection (PJI) Scan is a nuclear medicine imaging test specifically used to detect infections in prosthetic joints, such as hip or knee replacements. Detecting infections in prosthetic joints can be challenging because traditional imaging techniques may not always clearly distinguish between infection, inflammation, or mechanical issues. Nuclear medicine scans, like those using radiolabeled white blood cells (WBCs) or other tracers, can help identify infections more effectively.