My son had a spine X-ray looking for scoliosis. They found something called spondylolisthesis instead. Now they want to do a CT scan. What more can that show us?

When a problem shows up that wasn't known about or suspected, it's called an incidental finding. Defects in the spine like spondylolisthesis are often found this way. Spondylolisthesis is the separation of the vertebral body in the spine from the back half where the spinal joints are located.

The vertebral body slips forward over the vertebra below it. Problems can occur from stretch pressure on the discs and spinal nerves in that area.

X-rays are used to look at overall spinal alignment. Scoliosis and spondylolisthesis can be seen on an X-ray. Other defects in the area may show up on X-ray. CT scans shows the bone structure more clearly in a slice-by-slice fashion.

This helps the doctor see how much of the bone is disrupted and to what extent. Any other bony changes are also seen on CT scan. This helps the physician in planning treatment. Other imaging studies such as single-photon emission computed tomography (SPECT) and MRI can be useful.

SPECT shows if there are any tumors or fractures. MRI may be done when neurologic symptoms are present.