Computer tomography (CT) is more sensitive than radiography for detecting early sacroiliitis. Erosion of the joint facets, joint space alteration and increased bone density (sclerosis) are considerably better visualised, but CT cannot visualise early active inflammation unless there is concomitant structural damage.

CT can also be used to detect spinal changes and is often valuable for the detection and evaluation of spinal fractures.

Additionally, CT can give information for surgery planning, image guided therapy etc.

Today CT is easily performed using modern relatively complicated technology. However, CT is often associated with a relatively high radiation dose and therefore has to be used only for valid indications. MRI or ultrasonography should always be considered as alternatives.