The lumbar spine: imaging in rheumatic disease.

Seronegative inflammatory spondyloarthropathies include ankylosing spondylitis, psoriatic arthritis, Reiter syndrome, juvenile chronic arthritis and colitic arthritis. These diseases share some characteristics among which the most important is the presence of the histocompatibility antigen HLA B27; moreover the frequent overlapping of the various inflammation patterns have accounted for their classification in a single group. Diagnostic imaging can differentiate among the different forms only if the diagnostic algorithm, based on clinical history and laboratory findings is followed, considering the advantages and limitations of each method. In this respect, it should be kept in mind that the findings relative to the spine and sacroiliac joints allow to establish a definitive diagnosis.