Practical Interpretation of Bone Scintigraphy: Metastases, Fractures, and Beyond

Bone scintigraphy is one of the most heavily used imaging studies in nuclear radiology. The ability of technetium 99m-diphosphonate radiotracers to adhere to and form a complex with hydroxyapatite through the process of chemisorption highlights the sites and degree of osteoblastic activity. This mechanism results in a highly sensitive study for blastic processes of bone and serves as a valuable adjunct to cross-sectional imaging. Bone scintigraphy and its ability to capture the entire skeleton are especially useful to determine the extent of disease, most commonly for blastic metastases of breast and prostatic origin, but also for disseminated infections, Paget disease, and inflammatory arthropathies. While bone scintigraphy is typically a high-sensitivity and low-specificity modality, certain entities manifest with characteristic findings referred to as "Aunt Minnies," which may be confidently diagnosed without cross-sectional imaging. Examples include hypertrophic osteoarthropathy with the classic tram-track sign, sacral insufficiency fractures represented by the "Honda" sign, Paget disease of the spine with the "Mickey Mouse" sign, SAPHO (<i>s</i>ynovitis/<i>a</i>cne/<i>p</i>ustulosis/<i>h</i>yperostosis/<i>o</i>steitis) syndrome that demonstrates bullhead sign, and complex regional pain syndrome characterized by periarticular tracer uptake. Additionally, soft-tissue and nonosseous pathologic processes, including malignant pleural effusions, ascites, and paucity of soft-tissue uptake in renal osteodystrophy, may also be depicted. Overall, bone scintigraphy is a practical and low-cost imaging tool that can help assess the entire body, assist in the staging and monitoring of blastic malignancies, and provide valuable diagnostic information in multisystemic and multifocal diseases. ^©RSNA, 2026 Supplemental material is available for this article.