Nonosseous, nonurologic uptake on bone scintigraphy: atlas and analysis

Uptake in nonosseous, nonurologic tissues is occasionally found in the performance of bone scintigraphy. Proper interpretation of these cases depends on identifying the involved organs and appreciating the significance of the uptake. Because of the rarity of these findings and a relative de-emphasis of planar imaging in radiologic imaging, current era trainees may exhibit difficulty in identifying organs on planar projections. The first section of this work consists of an image atlas depicting uptake by various nonosseous, nonurologic organs on planar scintigraphy. In the second section, we discuss the etiologies of soft-tissue uptake, organized according to mechanisms of accretion: (1) metastatic calcification, (2) dystrophic calcification, (3) metabolic uptake, and (4) compartmental sequestration. Spurious or artifactual uptake represents a fifth category of apparent soft-tissue uptake which will also be reviewed. Causes of organ uptake span the gamut of trivial and artifactual to those reflecting serious malignant and systemic disorders. Clues as to etiology may be gleaned from grouping of abnormalities.