TC MDP bone scan in evaluation of painful scoliosis.

A 18-year-old male presented with low back ache. The patient was investigated and was diagnosed to have painful scoliosis. X-ray and other examinations could not reveal any diagnosis. The patient was referred to undergo bone scan on clinical suspicion of osteoid osteoma and to rule out stress fracture if any. Planar bone scan was performed, which showed a lesion in L3 vertebra and was further evaluated with SPECT (Single photon emission computed tomography) study to characterize the lesion. On SPECT examination, the classical features of osteoid osteoma, the double density sign (11), was noted in the pars interarticularis region. These findings were confirmed by a CT scan, which showed a sclerotic lesion in pars interarticularis of L3 vertebra. The patient was posted for operation and was relieved of symptoms in the postoperative follow-up.