Imaging of sacroiliac joints.

The early diagnosis of inflammatory and degenerative disease of sacroiliac joints is markedly difficult because the clinical pattern is not dissimilar from that of diseases involving the lumbar spine and sciatic nerve. Furthermore as in inflammations in general, when only structural changes in the synovial membrane and cartilage are involved, the findings of conventional radiology are often nondiagnostic. CT is now considered the gold standard procedure because in spite of its nonnegligible limitations, single lesions in the synovial and ligamentous compartments can be distinctively evidenced. MRI, unlike other procedures, affords the early nonspecific documentation of intrinsic and/or reactive alterations in the subchondral bone, therefore it appears to fill the gap between the onset of symptoms and the imaging visualization of sacroiliitis.