Evaluation of Lower Back Pain with Bone Scintigraphy and SPECT

Bone scintigraphy and single photon emission computed tomography (SPECT) may be performed for evaluation of lower back pain, especially when a bone abnormality is suspected. Various patterns of tracer activity based on precise identification of the anatomic location of increased uptake may be observed and used to evaluate bones and joints. Lesions centered about the disk space and vertebral body include spondylodiskitis, metastatic disease, vertebral body fracture, and degenerative disease (disk disease, spondylosis deformans). In diskitis, tracer uptake has a vertical orientation. Metastatic involvement should be suspected in solitary lesions evaluated with SPECT when the area of increased uptake extends from the vertebral body into the pedicle. Fractures are seen on planar and SPECT images as a linear, horizontally oriented area of increased uptake centered in the vertebral body. In degenerative disease, increased uptake is centered about the disk space and may be seen in and project beyond the surface of the vertebral body. Lesions of the posterior arch (comprising the pedicle, lamina, and facet joints) include spondylolysis, pedicle lesions, osteoarthritis of the facet joints, and fracture of the transverse process. Scintigraphy may help differentiate long-standing asymptomatic spondylolysis from ongoing disease. In osteoarthritis of the facet joints, SPECT may be used to select patients to be treated with therapeutic injections. Increased uptake in the transverse process most often indicates a fracture, although tumors may also occur in this location. These findings at planar bone scintigraphy and SPECT allow differentiation of common pathologic conditions and can lead to a specific diagnosis.