Background In assessment of mSASSS, the spinal squaring is an important factor of scoring. However, it is difficult to evaluate the sacral squaring in mSASSS
Objectives This study aimed to suggest the new concept of squaring score with loss of concavity in the anterior border of 1st sacrum and to evaluate the reproducibility of the new squaring score of 1st sacrum in the modified Stoke AS Spinal Score (mSASSS) with correlation of MR
Methods The study group comprised 26 healthy subjects and 80 patients with AS. Two experienced radiologists assessed the scoring of 1st sacrum in mSASSS using old and new concepts independently and assessed the MR score in consensus. And, the new concept of squaring score was evaluated whether to correlate with MR scoring of 1st sacrum.
The frequencies of squaring, sclerosis or erosion of 1st sacrum were respectively obtained with old and new concepts, and the differences between the control and AS groups were statistically analyzed.
Results The frequency of squaring for 1st sacrum in the control group was 15.4% and in the patients group was 36.3%. There were statistically significant difference in the squaring score in the 1st sacrum between two groups. Kappa interobserver reliability coefficients with old and new concepts were 0.79 and 0.64, respectively. The concept of loss of concavity showed good agreement with MRI (kappa value, 0.66).
Conclusions Loss of concavity in the anterior border of 1st sacrum is useful for scoring of squaring in the 1st sacrum in mSASSS and shows good reproducibility
Disclosure of Interest None Declared