Background
•
Nuclear medicine - anatomy based physiology
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Not diagnostic, but can provide additional info in diagnosis of
a disorder
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Highly sensitive
Scintigraphy
- Principles
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Radiopharmacueticals technetium 99m, gallium 67 and indium 111 are
most commonly used
•
Are injected intravenously
•
Resemble naturally occurring ions
•
Radioactive ions replace naturally occurring ones in interstitial
fluid
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In areas of accelerated bone turnover, increased exchange of bone
crystal components with I.S fluid ions
•
Bone scan will reflect areas of increased exchange
Technetium
99m Phosphate (99mTc)
•
3-phase bone scan
1st phase: flow study. immediately after injection at 2-3 sec
intervals
2nd phase: blood pool image (immediate). 5 mins post injection
3rd phase: delayed phase (bone phase). 3-4hrs post injection
4th phase: 24 hrs after
•
Deposition in bone deepens on blood flow to bone and osteoblastic
activity
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An increased uptake in 99mTc to an area is a 'hot spot'
•
Increased uptake seen with increased bone blood flow
Uses;
osteomyelitis, charcot's, #'s, DJD, RSD, Reiter's synd, plantar
fasciitis
Gallium
67
•
Inflammatory imaging agent
•
Causes an increased focal uptake at area
•
Injected I.V and scan 24-48 hrs after
•
Uses; tumors, confirming sites of infection (osteomyelitis, cellulitis)
•
Commonly used along with 99mTc scans to differentiate reactive bone
lesions from inflammatory lesions
Indium
111
•
Cell labelling
•
White blood cells migrate to sites of infection (are labelled with
Indium)
Scans taken 4 and 24 hrs post injection
Examples
of images derived from bone scans:
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Stress
Fracture of navicular (Unclear - delete?)
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Tibia
stress fracture: medial aspect of tibia
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