[Nuclear magnetic resonance tomography of the sacroiliac joint. A new examination technic in the differential diagnosis of rheumatic diseases of the lumbosacral transition].

25 patients with the clinical diagnoses of possible sacroiliitis were investigated by Magnetic Resonance Tomography (MR). Using axial or coronal tomography in a T1-weighted sequence (7 slices, 1 echo, NEX: 2, slice thickness 8 mm, TR: 600 ms, TE: 33 ms) and in a T2-weighted sequence (7 slices, 4 echos, NEX: 2, slice thickness 8 mm, TR: 1800 ms, TE: 33, 66, 99, 132 ms) we found normal sacroiliac joints in 10 patients, in 12 patients we diagnosed a sacroiliitis, in 3 patients a sacroiliac sclerosis. Descriptive evaluation and T2-calculation we showed, that MR is specific in differentiation of inflammation from sclerosis. The mean T2-relaxation time is 126 ms in healthy subjects, 320 ms in sacroiliitis and 87 ms in sclerotic areas. The results are significant in the Student-T-test (5% level). In addition the method allows the distinction of sclerosis from inflammation with a resolution of 2 mm. In evaluating sacroiliac rheumatic diseases MR may be helpful as a new imaging technique to complete the information of conventional radiography, computer assisted tomography and scintigraphy.