Bone scans

Bone scintigraphy (a.k.a. bone scans) are a nuclear medicine (scintigraphic) study that makes use of technetium-99m (commonly Tc-99m-methylene diphosphonate (MDP)) as the active agent.

The study has three phases which follow intravenous injection of the tracer. Sometimes a fourth (delayed/delayed) phase is performed.

Clinical indications

• malignancy: detection and follow-up of skeletal metastases
• detection of radiographically occult fractures, e.g. stress or insufficiency fractures
• osteomyelitis
• reflex sympathetic dystrophy
• hip joint prosthesis: evaluation for infection or loosening
• Paget disease

Patient preparation

• optimal hydration
• remove metal objects
• void immediately before study

Tracer dose and route of administration

Tc-99m diphosphonate is administered intravenously, at a dose of 740 Mbq (20 mCi) in adults.

Phases (kinetic modelling)

Flow phase

• 2-to-5 second images are obtained for 60 seconds after injection
• demonstrates perfusion
• characterizes blood flow to a particular area

Blood pool phase

• obtained 5 minutes after injection
• demonstrates the blood pool (balance between plasma and interstitium), not the blood flow
• inflammation causes capillary dilatation and increased blood flow

If the study is going to be a triphasic bone scan, a third phase is added.

Delayed phase

• obtained 2-4 hours later
• urinary excretion has decreased the amount of the radionuclide in soft tissue
• mechanism of uptake is not known with certainty, although it has been proposed that the radiotracer attaches to hydroxyapatite crystals (chemisorption)
• degree of uptake depends on blood flow and rate of new bone formation

Delayed/delayed

• obtained 24 hours after injection as a static image

See also

• superscan
• contiguous bone activity

Siehe auch:

• Osteomyelitis
• Morbus Sudeck
• Superscan Szintigraphie
• contiguous bone activity
• Mehrphasenszintigraphie

und weiter:

• Chondrosarkom
• double density sign of osteoid osteoma
• hotter spot within hot area sign
• Skelettszintigraphie 3 Phasen
• Szintigrafie
• Rippenfrakturen in der Szintigraphie
• Enchondrom in der Skelettszintigraphie