Bone Scan (Nuclear Medicine) Explained: Metastases, Occult Fracture and Paget's
A whole-body bone scan detects metastases, occult fractures and Paget's. Learn how it compares to PSMA-PET and MRI.
Tc-99m MDP bone scan is a whole-body nuclear medicine test showing areas of increased bone turnover — metastases, fractures, Paget's disease, osteomyelitis, arthritis. Radiation dose is ~4–6 mSv. In prostate cancer, PSMA-PET is now more sensitive than bone scan for early metastases.
The bone scan uses technetium-99m methylene diphosphonate (Tc-99m MDP) which is taken up by osteoblasts. It shows whole-body osteoblastic activity — metastases from breast, prostate, lung, thyroid, and kidney; occult fractures (stress fractures, sacral insufficiency fractures often invisible on X-ray for 2–3 weeks); Paget's disease; infection (three-phase scan). Sensitivity for osteoblastic mets > 90% but poor for purely lytic lesions (myeloma). PSMA-PET/CT (68Ga or 18F-labelled) now outperforms bone scan for prostate cancer staging (proPSMA trial 2020) — sensitivity 85% vs 38% for detecting distant disease. MRI is superior for spine metastases and marrow disease. Bone scan interpretation follows classic patterns: solitary hot spot in a rib after trauma → fracture; symmetrical joint uptake → arthritis; solitary "eye of Christ" appearance in vertebra → osteoid osteoma; multiple randomly distributed hot spots → metastases. SPECT/CT adds anatomic localisation and improves specificity dramatically.
- Radiation dose
- ~4–6 mSv
- Best for
- Osteoblastic mets, occult fractures, Paget's
- Poor for
- Lytic lesions (myeloma)
- Prostate cancer
- PSMA-PET now preferred
- SPECT/CT
- Improves specificity
Bone scan vs alternatives
| Question | Best test |
|---|---|
| Occult stress fracture | Bone scan (or MRI) |
| Prostate cancer staging | PSMA-PET/CT |
| Multiple myeloma bone survey | Whole-body MRI or low-dose CT (not bone scan) |
| Spinal metastases with cord compression | MRI |
| Osteomyelitis (chronic) | Three-phase bone scan or WBC scan |
How the scan works
IV injection of Tc-99m MDP; wait 2–4 hours for tracer uptake.
Whole-body planar imaging; SPECT/CT for problem areas.
Hydration and voiding before imaging reduce bladder artefact.
Modern low-dose protocols keep exposure comparable to CT abdomen.
- Cancer + new back pain + neurological signs — MRI to exclude cord compression.
- Bone scan super-scan pattern + hypercalcaemia — oncology emergency.
- Solitary equivocal hot spot — SPECT/CT or targeted MRI.
When to order bone scan
- 1Cancer with bone-avid biology?Bone scan (or PSMA-PET in prostate).
- 2Occult fracture suspected?Bone scan or targeted MRI.
- 3Suspected Paget's disease?Bone scan.
- 4Myeloma?Whole-body MRI or low-dose CT — NOT bone scan.
Related questions people ask
Frequently asked questions
- Bone scan shows whole-body osteoblastic activity.
- Excellent for metastases, fractures, Paget's.
- PSMA-PET now preferred for prostate cancer.
- Myeloma needs MRI or low-dose CT — not bone scan.
- SPECT/CT improves specificity.
References
2 sources- EANM/SNMMIBone Scintigraphy Procedure Guidelines
European/US nuclear medicine.
eanm.org
- NICE NG131Prostate cancer
PSMA-PET adoption.
nice.org.uk
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