Role of Color Doppler Ultrasonography in Evaluation of Active Sacroiliitis in Ankylosing Spondylitis Patients and Its Relation With Disease Activity

Ankylosing spondylitis (AS) is the prototype of the spondyloarthropathies as a chronic inflammatory rheumatic disease presenting mainly with inflammation of the axial skeleton, peripheral arthritis, and enthesitis.

Sacroiliitis is an important sign of AS, and it is used to describe unilateral or bilateral involvement of the sacroiliac joint (SIJ) .

Early diagnosis of AS is important, since some changes associated with the disease are irreversible, and early diagnosis can also improve the ultimate clinical outcomes.

X-ray and magnetic resonance imaging (MRI) are frequently used as image tools to investigate sacroiliitis in AS patients. X-ray could show the structural lesion of sacroiliac joints (SIJs), but could not show the lesions in the early stage of disease. MRI can quantify active in¬flammatory lesions of SIJs.

However, MRI is relatively expensive and time-consuming, and its routine use in patient visits during ther¬apy would be difficult. Another factor that limits usage of MRI is that an important proportion of AS patients have prostheses. Therefore, an easier and cheaper method is needed to detect the degree of spinal inflammation.