Bone SPET of symptomatic lumbar spondylolysis

The aim of this study was to clarify the clinical role of bone single photon emission tomography (SPET) of the lumbar spine in young persons with persistent lumbar pain which might be due to spondylolysis. Thirty-one bone SPET studies were performed on 25 patients (19 males, 6 females) aged 7-26 years (average 15.6 years) who had suffered lumbar pain associated with physical activity, and who were suspected of having spondylolysis. Planar and SPET images of the lumbar spine were obtained 2-3 h following the injection of 99Tc(m)-methylene diphosphonate using a single-head rotating gamma camera. The findings on the bone scintigram were compared with those on the radiograph. Bone scintigraphy at presentation was positive in only 7 of 15 sites of the pars interarticularis defects demonstrated on plain radiographs. On the other hand, seven sites of the pars interarticularis which were normal on the radiograph were positive on bone SPET. As clinical symptoms improved after immobilization using a lumbar corset, bone SPET tended to revert towards normal. The planar image was abnormal in only 8 (42%) of the 19 abnormal sites on the SPET image. A bone SPET study is indicated in patients who are negative on radiological tests and who are still suspected of having spondylolysis. If SPET is positive in these patients, the increased bone uptake is most likely suggestive of a state of 'stress reaction', and may be a good indicator for patient management. If negative, further radiological examinations will be required for proper assessment of the origin of lumbar pain.