Synopsis
Select and interpret radionuclide bone imaging by linking tracer physiology, clinical indication, acquisition phase, uptake pattern and hybrid anatomy to a differential diagnosis while recognising its nonspecificity, lytic-lesion limits and pregnancy or breastfeeding precautions.
- 99mTc-labelled diphosphonates localise according to regional blood flow and osteoblastic activity; uptake therefore reflects bone response, not a tumour-specific marker.
- Common indications include suspected skeletal metastases, occult or stress fracture, osteomyelitis, painful prosthesis, Paget disease, avascular necrosis and unexplained focal bone pain.
- A standard study often includes delayed whole-body planar images; multiphase studies add flow and blood-pool images, while SPECT or SPECT/CT improves localisation and structural correlation.
Key red flags
New weakness, sensory change, sphincter dysfunction or severe night pain with known or suspected malignancy requires urgent assessment for spinal or structural compression.
Fever, systemic toxicity, focal bone pain and a prosthesis or recent operation need urgent evaluation for infection even if the bone scan is delayed or equivocal.
Pregnancy possibility and breastfeeding must be identified before tracer administration, with radiopharmacy or nuclear medicine advice specific to the proposed radiopharmaceutical.
Hyperaemia, increased blood-pool activity and delayed uptake can support an active inflammatory or infective process, but prostheses, surgery and arthritis can produce overlapping patterns.
Diffuse intense skeletal uptake with relatively reduced renal and soft-tissue activity can indicate widespread osteoblastic disease or metabolic bone disease and requires biochemical and anatomic correlation.
Investigation priorities
Decide whether functional bone imaging is the right question and provide cancer type, symptoms, trauma, surgery, prosthesis, medicines and previous radiology for interpretation.
Management branches
A patient has focal mid-foot pain after increased training; radiographs are normal and the clinician asks whether a stress injury is present.
- Check trauma, training load, infection symptoms, pregnancy or breastfeeding, renal function and the precise pain site; decide whether MRI would answer a high-risk structural question more directly.
- If bone scintigraphy is selected, obtain the protocol requested by nuclear medicine, ensure hydration and voiding advice, and acquire delayed images with spot views or SPECT/CT targeted to the symptomatic foot.