What are the three phases of a bone scan? Which phase is this?
Dynamic (perfusion), blood pool (relative vascularity), late phase (bone turn over). The latter is shown on the image.
What is the differential for the hot spot next to the sternum?
Osteosarcoma metastasis, focal thickening of chondral part of rib, iatrogenic/posttraumatic (injection, piercing, ...), calcified soft tissue tumor (calcified lymph gland, fibroadenoma etc), contamination (e.g. central venous line with some residual activity).
Delayed phase bone scan image demonstrates intense uptake in the distal right femur. A single focus of increased attenuation projects just to the right of the sternum inline with the chondral cartilage of the third rib. No other suspicious lesions identified.