COMPARISON OF RADIOGRAPHY, COMPUTED-TOMOGRAPHY AND MAGNETIC-RESONANCE-IMAGING IN THE DETECTION OF SACROILIITIS ACCOMPANYING ANKYLOSING-SPONDYLITIS

Objective. To compare magnetic resonance (MR) imaging, computed tomogr aphy (CT), and radiography in the detection of sacroiliitis accompanyi ng ankylosing spondylitis (AS). Design and subjects. Nine volunteers a nd 24 patients were recruited. Radiography, CT, and MR imaging were co mpleted within a 1-week period in 24 patients with AS. In precontrast MR examination, spin-echo T1, fast spin-echo T2, and gradient echo wit h rephasing T2 images were obtained without fat saturation using a 0. 3-T imager for all volunteers and patients. Postcontrast MR examinatio n was performed using the same precontrast SE TI sequence for patients with AS. Results and conclusions. MR imaging directly showed the norm al cartilage in all 16 sacroiliac joints of the 8 volunteers. In the 2 4 patients with AS, cartilage abnormalities were observed in 42 sacroi liac joints. More diagnoses of sacroiliitis were made using MR and CT imaging than using radiography (P<0.001). Therefore, low-field-strengt h MR can be useful in detecting early sacroiliitis in patients with AS . MR imaging was able to reveal early cartilage changes and bone marro w edema, which could not be found by either CT or radiography.