Radionuclide procedures frequently are performed as part of the diagnostic workup of
osteomyelitis. Bone scintigraphy accurately diagnoses
osteomyelitis in bones not affected by underlying conditions. Degenerative
joint disease, fracture, and orthopedic hardware decrease the specificity of the bone scan, making it less useful in these situations.
Gallium-67 scintigraphy was often used as an adjunct to bone scintigraphy for diagnosing
osteomyelitis. However, now it is used primarily for spinal
infections when (18)F-FDG imaging cannot be performed. Except for the spine, in vitro-labeled leukocyte imaging is the nuclear medicine test of choice for diagnosing complicating
osteomyelitis. Leukocytes accumulate in bone marrow as well as in
infection. Performing complementary bone marrow imaging with (99m)Tc-sulfur
colloid facilitates the differentiation between
osteomyelitis and normal marrow and improves test overall accuracy. Antigranulocyte
antibodies and
antibody fragments, such as (99m)Tc-besilesomab and (99m)Tc-sulesomab, were developed to eliminate the disadvantages associated with in vitro-labeled leukocytes. These agents, however, have their own shortcomings and are not widely available. As
biotin is used as a
growth factor by certain bacteria, (111)In-biotin is useful to diagnose spinal
infections. Radiolabeled synthetic fragments of
ubiquicidin, a naturally occurring human
antimicrobial peptide that targets bacteria, can differentiate
infection from sterile
inflammation and may be useful to monitor response to treatment. (18)F-FDG is extremely useful in the diagnostic workup of
osteomyelitis. Sensitivity in excess of 95% and specificity ranging from 75%-99% have been reported. (18)F-FDG is the
radionuclide test of choice for spinal
infection. The test is sensitive, with a high negative predictive value, and reliably differentiates degenerative from infectious vertebral body end-plate abnormalities. Data on the accuracy of (18)F-FDG for diagnosing diabetic pedal
osteomyelitis are contradictory, and its role for this indication remains to be determined. Initial investigations suggested that (18)F-FDG accurately diagnoses prosthetic joint
infection; more recent data indicate that it cannot differentiate
infection from other causes of prosthetic failure. Preliminary data on the PET agents
gallium-68 and
iodine-124 fialuridine indicate that these agents may have a role in diagnosing
osteomyelitis.