Radionuclide bone imaging in spondylolysis of the lumbar spine in children.

Bone scintigraphy and radiography were performed in seven children with back pain. Six of the children with radiographic evidence of a pars interarticularis defect also had abnormal scintigrams. Increased uptake of the bone imaging agent occurred at six of the ten sites of radiographic pars interarticularis defects, implying increased bone metabolic activity. However, the location of scintigraphic abnormalities did not correspond to the location of radiographic abnormalities in several cases. Possible explanations for the discordant findings are: (a) normal bone metabolism at the site of an old spondylolysis and (b) radiographically inapparent stress fractures. Measurements of absorbed radiation dose indicate that plain radiography, including oblique views where appropriate, has a lower absorbed radiation dose than scintigraphy or tomography and should be performed prior to these studies.