Evaluation of magnetic resonance imaging for the detection of sacroiliitis in patients with early seronegative spondylarthropathy.

A prospective study was conducted in 23 patients to evaluate magnetic resonance imaging versus computed tomography and plain film radiography for the early detection of sacroiliitis in patients with spondylarthropathy and an Amor score of less than 6. Computed tomography was significantly better than the other two techniques despite some false-positive results, particularly in patients older than 40 years. Magnetic resonance imaging lacked sensitivity for detecting elementary lesions, particularly of the cartilage, but demonstrated clearly that the earliest abnormality was edema of the subchondral bone.