Soft tissue uptake in radionuclide bone scintigraphy

Abstract

Patients with suspected malignancy, infection, inflammation, trauma, or metabolic bone disease are referred for bone scintigraphy to establish the extent, if any, of skeletal involvement. Often, extra-osseous uptake of radiotracer is identified, which may either be an incidental finding or relevant to the underlying bone pathology. While identification of urinary tract abnormalities due to the renal excretion of 99mTc-phosphates through the kidneys and bladder is not uncommon, uptake of tracer in other body systems is more unusual and may provide clues as to the underlying diagnoses. It is therefore of important not to overlook the soft tissues when reporting bone scans. In this chapter, we describe the imaging appearances of extra-osseous 99mTc-diphosphonate uptake in the head, neck, thorax, abdomen, and muscle. The pathophysiological mechanisms that account for soft tissue deposition, technical pitfalls, and artifacts that can compromise bone scintigraphic acquisition and its subsequent analysis are discussed.