Comparative Study of X-ray Film,CT Scan in Sacroiliac Joints Lesion of Ankylosing Spondylitis

Objective To study the appearances and early fetures of sacroiliac joints(SIJ) in ankylosing spondylitis on X-ray film and CT,and to valuate the CT examination of sacroiliac joints in the same groups.Methods The plain X-ray film of 73 cases of SIJ of ankylosing spondylitis which had been proved clinicalhy were studied.All the patients had been examed with CT at the same time.The appearances presented by the two methods were concluded compared and graded,the relationship between them was analyzed with statistics.Results The erosion,cystic lesions of bone and swollen of soft tissues were the early features of sacroiliac joints in ankylosing spondylitis,but the detection rate of them by X-ray was 73%,38%,0.6%,by CT was 86%,72%,3%.They can find on CT and conventional radiography,but the detection rate of them by CT was much higher than that by X-ray plain film(Ρ0.001).CT could prove sacroilitis for those of highly suspected in clinical,but could not exclude.One or two grade higher for grade 0 to Ⅱ on plain film.The grades on CT and plain film were the same for grade Ⅲ and Ⅳ.Conclusion The early features of SIJ lesion in ankylosing spondylitis are subchordral bony erosion.Cystic lesions and swollen of soft tissue,the sensitivity of CT is much higher than that by X-ray plain film.CT could prove sacroilitis for those of highly suspected in clinical,which could not be proved by X-ray plain film.CT examinations are more valuable.