Conventional radiography has for many years been used
to diagnose sacroiliitis and the findings by radiography are still part of the
accepted international diagnostic criteria for ankylosing spondylitis (radiographic
axSpA). However, radiography can only show permanent (structural) damage of the
joints and/or bones. The diagnosis can therefore be difficult to obtain and may
be delayed for many years unless radiography early in the disease is replaced
or supplemented by cross sectional imaging (CT or MRI). In later stages of the
disease detection of both sacroiliitis and spinal changes can often be obtained
by radiography.
The technology behind radiography is relatively simple and there are internationally
accepted grading system for both sacroiliac joint and spinal abnormalities.