Bone scan

A bone scan (skeletal scintigraphy) is an imaging modality in which an intravenously administered radioactive tracer with an affinity for bone (e.g., Tc99m-methylene biphosphonate) is used to visualize areas of increased metabolic activity within bone with the aid of a gamma camera. Bone scans are used to evaluate bone injuries, musculoskeletal pain, joint conditions, primary bone neoplasms, and malignancies with potential for bone metastases.

A bone scan is used for the detection, evaluation, and/or follow-up of the following conditions:

• Primary malignant bone tumors (e.g., osteosarcoma)
• Bone metastasis from primary extraosseous tumors (e.g., breast cancer, prostate cancer, lung cancer)
• Inflammatory and/or degenerative disorders; (e.g., osteomyelitis, rheumatoid arthritis, psoriatic arthritis)
• Paget disease of bone
• Fractures (e.g., stress fractures, nonaccidental injury in children, fracture healing)
• Impaired vitality of bone (e.g., infarct of bone transplants, osteonecrosis)
• Bone diseases that do not show up on primary imaging studies (e.g., x-ray, CT)

References:^[1]

• Absolute contraindication: pregnancy
• Relative contraindications
  • Breastfeeding women
  • Pathology with a predominantly osteoclastic process (e.g., multiple myeloma)
  • Trauma or surgery in the region of interest within the past 6–12 months .

References:^[2]

We list the most important contraindications. The selection is not exhaustive.

1. Intravenous administration of a radionucleotide tracer with an affinity for bone (e.g., Technetium-99m diphosphonate, Technetium-99m oxidronate)
2. Uptake of tracer in areas with high bony metabolic activity (“hot spots”)
   • Uptake of the radiotracer by a particular region of the bone is dependent on:
     • Regional blood flow
     • Osteoblastic activity
     • Amount of osteoid
3. Detection of these “hot spots” with a gamma camera
4. Renal elimination of the radiopharmaceutical agent with increased uptake in the urinary tract

References:^[2][3]

• Very high sensitivity for the detection of areas of bone with increased metabolism
  • The following conditions might not be visualized on a bone scan:
    • Tumors confined to the bone marrow
    • Rapidly growing tumors with slowly regenerating bone (e.g., plasmacytoma)
    • Osteolytic metastases
• Low specificity