A triphasic bone scan is an extremely
sensitive test for the diagnosis of osteomyelitis. The coexistent of underlying
bony pathologies hinder this test's specificity and may necessitate the use of alternative test such as nuclear WBC labeled scan or MRI, however in a non-violated bone a
triphasic bone scan can give the diagnosis of osteomyelitis with a high
confidence.
The initial angiographic
phase reflects the relative amount of blood flow to the area of interest, whereas
the blood pool phase indicates the amount of activity that has extravasated
into the tissues around the area of interest. The delayed bone phase reflects
the rate of bone turnover. The classic appearance of osteomyelitis on
three-phase bone scan consists of focal hyperperfusion, focal hyperemia, and
focally increased bone uptake