[Sacroiliitis in seronegative arthritis. The anatomicopathological aspects and imaging methods compared].

Sacroiliitis is usually the first and main feature of seronegative spondyloarthropathies. In its early stages it is difficult for diagnostic imaging techniques to demonstrate it and specificity is poor. At the same time, there may be few or even no symptoms at all. Therefore, the anatomical damage is quite often diagnosed at an advanced and irreversible stage. This study was aimed at assessing sacroiliac joint impairment during seronegative arthritis by means of diagnostic imaging techniques. The abnormal features of this condition are reported, pointing out the different findings of ankylosing spondylitis, psoriatic arthritis, Reiter's disease, reactive arthritis and sacroiliitis associated with chronic enteritis--e.g., Crohn's disease, ulcerative colitis, etc. Then, the capabilities and the features of each imaging method (conventional radiology, CT, bone scan, MRI) are reported. Modern techniques are dealt with in depth, especially relative to their capabilities in solving radiographic dilemmas. Technological progress is currently focused on MRI, whose use in early inflammatory sacroiliitis during seronegative spondyloarthropathies remains however in the experimental stage. Therefore, plain radiography is still the method of choice and its findings are used as a diagnostic criterion in unquestionable cases. To conclude, if the peculiar morphologic features of this condition are known and supported by clinical and radiographic findings, the condition can be diagnosed early, which means proper treatment and a lower incidence of highly invalidating sequelae.