Methods and Results

TSE T2 three dimensional aquisition MRI studies reconstructed with OsiriX DICOM viewer from 32 patients were used. Patients included were a series of consecutive cases with either suspected spinal stenosis or low back pain. A total of 97 disc levels were studied and axial reconstructions were made at 0°, +10°, +20°, +30° relative to the disc space orientation. For each image, DSCA was digitally measured and a severity grade was assigned by two observers according to the recently-published 4-point (A-D) morphological grading system. Interobserver kappa score was 0.71. Statistical analysis of DSCA measurements was performed using kappa and t-tests. Comparing DCSA between 0° at each level and +10°, +20° and +30° slice orientation, a significant increase in surface area was found in each case (P<0.0001). % change in DSCA combining all disc levels comparing 0° and +10°: range -15.48% to +31.89% (SD 18.40%); 0° and +20°: range -24.00% to +143.82% (SD 20.45%); 0° and +30°: range -29.35% to +231.13% (SD 26.52%). At 13 disc levels, DSCA was <100mm² at 0°, but changed to >100mm² in three cases by a +10° increase, in five cases by a +20° increase and in 10 cases by a +30° increase. In only two out of 97 levels studied did the morphological grading change as the angle increased, one of which was not amongst those above (change in DSCA from <100mm² to >100mm²).