A diagnostic system is disclosed, and comprises a diagnostic device and a fluid heat transfer system. The diagnostic device has an associated bed for supporting a portion of a subject during a diagnostic procedure. The fluid heat transfer system comprises a fluid circulation component, a heater component, and a fluid line. The heater component includes a heater element and a mixing valve, and the fluid circulation component is fluidly coupled to the heater component so that a fluid can be pumped from the fluid circulation component to the heater component. The fluid line extends from the heater to the fluid circulation component, and the mixing valve is positioned near the bed so that heat can be rapidly transferred through the fluid line to alter a body temperature of the subject.