[Diagnostic significance of magnetic resonance in low back pain].

OBJECTIVE This study was aimed at assessing the diagnostic value of magnetic resonance (MR) in spinal diseases amongst observers having several levels of experience. METHODS A selection was made of 20 MR exams which were classified as being normal [10] or altered [10]; such classification was called "standard" and then compared to a second classification made by 15 observers having varying levels of experience, called "test". RESULTS The Kappa index was 0,56 (96,7 % sensitivity and 59,3 % specificity) for identifying alterations. A 0,19 Kappa index was obtained for disk hernia when diagnostic correctness was considered, 0,15 for degenerative disk disease, 0,03 for infectious diskitis and 0,24 for spondylarthrosis. CONCLUSIONS The authors concluded that MR is an image exam having high sensitivity and moderate specificity for identifying anatomical alterations of the spinal column; however, it does not allow assessors having little experience to satisfactorily explain an aetiological diagnosis. It is thus believed that routine requests for this exam by non-specialists leads to an unnecessary increase in costs and frequent diagnostic and therapeutic errors.