In a bone scan, how is necrosis typically indicated?

In a bone scan, necrosis is typically indicated as a cold spot. This is due to the fact that necrotic bone tissue has decreased blood flow and metabolic activity compared to surrounding healthy bone tissue. During a bone scan, a radiotracer is administered that accumulates in areas of high bone metabolism or blood flow, appearing as "hot spots." Conversely, areas of necrosis, where the bone is less active, do not uptake the radiotracer effectively, leading to a reduced appearance – hence referred to as cold spots. This clear delineation aids in diagnosing conditions such as avascular necrosis or certain cancers that may lead to bone death. Understanding this distinction is crucial for interpreting bone scan results accurately in clinical settings.