Wednesday, 14 April 2010

Bone Scans

Bone Scans or Skeletal Scintigraphy

We start with a bone-loving agent - Tc99, a radioactive tracer which is followed by 007, our special gamma camera that can trace our tracer, no matter where it hides.

Indications
Spread of cancer
Unexplained bone pain/musculoskeletal pain

How to Read a Bone Scan
"This is a bone scan of [NAME], date of birth [DOB], taken on [DATE]. It shows increased uptake in [HOT AREAS], while osteopenic, or reduced uptake in [COLD AREAS]. This is suggestive of [DIAGNOSIS]."

Dark or "cold" spots
- areas that absorb little or no amount of tracer
Lack of blood supply to the bone/bone infarction
Certain types of cancer eg multiple myeloma

Bright or "hot" spots
- areas that absorb increased amounts of tracer
Rapid bone growth or repair/abnormal bone metabolism eg Paget's disease
Arthritis
Tumour
Fracture eg hip fractures, stress fractures - poorly seen on X-Ray
Infection eg osteomyelitis
Malignancy

Contra-indications
Pregnancy, due to possible radiation exposure to foetus

Contamination/Artefacts
Urinary contamination - the kidneys clear the radioisotope. If patient wets themselves, or urine spots leak onto clothing or the body, these can be recorded as false positives. Can be confirmed as contamination on removal of hospital gowns and a second scan
Injection sites, where the radioisotope can 'leak'
Barium - bone scans should be performed before the use of any barium
Patient motion
Full bladder, which blocks the view of the pelvic bones
Jewellery/Metal accessories

Other Ix necessary for Dx
- as bone scans cannot distinguish between different pathology
X-ray tests
CTs
MRIs
Blood tests
Biopsy

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