What are "hot spots" that are visible on bone scans. Are they growth plates?

Bone scan. In all scans a 'hot spot' is a simple description of increased tracer uptake in a particular area. Depending on the patient age, reason for scan and type of scan done this will aid in diagnosis. Growth plates tend to show up as one of these hot spots because of increased bone activity in these areas.
Exposed bone mineral. A bone scan is done by injecting a radioactive isotope made up in a complex containing mdp, a substance related to the bisphosphonate drugs like fosamax (alendronate). Mdp can attach to bone mineral, but only where the protective bone-blood barrier is breached. This can be at fractures, invasive tumors, inflamed joints, and growing points as well as at normal sites of bone self-repair.