Inflammatory involvement of the sacroiliac joints is the hallmark of the
spondyloarthropathies (SpA), in particular
ankylosing spondylitis (AS). One leading symptom of SpA is inflammatory
back pain (
IBP), which may be indicative of
sacroiliitis. Conventional diagnostic imaging is insufficient at early stages of
sacroiliitis because of the low sensitivity of conventional radiographic scans. In contrast, magnetic resonance imaging (MRI) of the sacroiliac joints depicts both acute and chronic inflammatory changes at all stages of the disease. Disadvantages of MRI are the operator-dependency, the lack of standardization, and the relatively high costs. Therefore, in the era of cuts in health care expenditure, the Diagnostic Imaging in Rheumatology Study Group of the Berlin Regional Rheumatology Center, which consists of experienced rheumatologists, skeletal radiologists, and orthopedic surgeons, has compiled a survey of diagnostic imaging in
sacroiliitis covering the clinical background, technical details, radiation exposure, and costs. Conventional x-rays remain the standard imaging procedure for the diagnosis of AS. Early
sacroiliitis can be detected with higher sensitivity by MRI using
contrast agents or fat suppression techniques. Because of its lack of radiation exposure, MRI is the method of choice in children and young women. MRI allows for a more accurate diagnosis of inflammatory
back pain by providing objective evidence of
inflammation in the sacroiliac joints. Computed tomography can be superior to MRI when bony changes have already occurred.