OBSERVER VARIABILITY IN THE ASSESSMENT OF DISC DEGENERATION ON MAGNETIC-RESONANCE IMAGES OF THE LUMBAR AND THORACIC SPINE

Study Design. Intraobserver and interobserver reproducibility study. O bjective. This study investigates the variability in the interpretatio n of degenerative disc findings using magnetic resonance imaging. Summ ary of Background Data. Magnetic resonance imaging has been used for y ears in clinical diagnostics, primarily to investigate disc herniation and spinal stenosis. Less attention has been paid to other disc findi ngs and their assessment reliability. Methods. Three independent reade rs evaluated magnetic resonance images of the lumbar and the lower and middle thoracic spines of 122 subjects by grading 12 aspects of the i ntervertebral discs and adjacent endplates using written definitions a nd example images. Images of 20 subjects were reevaluated for the asse ssment of intraobserver agreement. Results. Agreement was highest in t he lower lumbar and poorest in the middle thoracic spine. Intraobserve r agreement was generally fair to excellent for almost all variables i n the lumbar and lower thoracic spine (most intraclass correlation and kappa coefficients for these regions were above 0.70). Interobserver agreement was notably lower than intraobserver agreement, except for o steophytes and endplate defects in some regions. Conclusions. Intraobs erver agreement in the evaluation of disc degeneration was at an accep table level, in general, in the lumbar and lower thoracic spine. Howev er, assessments were substantially more variable between readers, whic h limits comparisons of evaluations between different readers.