Reasons for a bone scan that does not show the bones clearly
Usually, a suboptimal bone scan is related to technical factors, such as not waiting at least 2 hours between radiotracer injection and scan acquisition, poor preparation of the MDP, a significantly infiltrated radiotracer dose during injection, patient motion, or the camera being set to the incorrect energy window (e.g., for 123 I rather than for 99m Tc).
Physiologic reasons for suboptimal scans include large patient size, resulting in significant photon attenuation, or poor circulation states, such as congestive heart failure in which the radiotracer is not adequately delivered to the bones. Finally, patients with osteoporosis simply do not have enough bone for good visualization of osseous structures, and patients with iron overload may also have inhibited uptake of the radiotracer.
