Artifactual reduction in bone density as a result of technetium-99m MDP for bone scanning: report of two cases

We present two patients in whom marked changes in dual-energy X-ray absorptiometry (DXA)-measured bone mineral density were found to be the result of prior administration of technetium-99m methylene diphosphonate (MDP) for bone scanning. In patient 1, an artifactual 50% decrease in lumbar spine and 19% decrease in left total hip bone density over a 14-mo period was the result of technetium-99m injection 3 h before the second bone density measurement. In patient 2, a dramatic increase in bone density at 6 mo was the result of artifactual reduction in bone density on the baseline study as a result of technetium-99m injection 2 h earlier. Clinicians and technologists should be aware that technetium-99m used for bone scanning could cause artifactual reduction in DXA-measured bone mineral density.