①目的探讨ＣＴ对强直性脊柱炎骶髂关节病变的诊断价值。②方法分析了４３例正常骶髂关节ＣＴ表现，并对３０例强直性脊柱炎（ＡＳ）骶髂关节病变作了双盲Ｘ线和ＣＴ对照研究。③结果正常人滑膜部关节间隙宽度为２～５ｍｍ．４０岁后，关节前下部间隙可出现局部狭窄。骶侧皮质厚度小于３ｍｍ者占８７％，前后均匀者占９０％；髂侧中部皮质厚度小于５ｍｍ，其前部皮质厚度可大于５ｍｍ（占１６％）。部分正常人可出现关节面不清晰，但不出现明确的侵蚀改变。ＡＳ骶髂关节病变的对照研究表明，对平片可疑病变，ＣＴ可排除或肯定诊断；早期病变（Ⅱ级）ＣＴ检查可提高一个级别；Ⅲ，Ⅳ级病变ＣＴ和平片分级相同。④结论ＣＴ检查可用于临床高度怀疑而平片难以确诊者；对Ⅲ，Ⅳ级病变，如仅为诊断，则ＣＴ扫描似并非必需 Objective To investigate the diagnostic value of CT in the diagnosis of sacroiliac joint disease in ankylosing spondylitis. Methods 43 cases of normal sacroiliac joint CT performance analysis, and 30 cases of ankylosing spondylitis (AS) sacroiliac joint lesions were double-blind X-ray and CT control study. ③ Results normal synovial joint gap width of 2 ~ 5mm. After age 40, there may be localized stenosis at the anterior lower joint. Sacral cortical thickness less than 3mm accounted for 87%, before and after the uniform accounted for 90%; iliac lateral cortex thickness less than 5mm, the anterior cortical thickness greater than 5mm (16%). Some normal people may appear unclear articular surface, but no clear changes in erosion. AS sacroiliac joint disease control study showed that plain film suspicious lesions, CT can rule out or affirmative diagnosis; early lesions (grade Ⅱ) CT examination can be increased by one grade; Ⅲ, Ⅳ grade lesion CT and plain film the same classification. ④ Conclusion CT examination can be used for clinical suspicion of plain film difficult to diagnose; Ⅲ, Ⅳ grade lesions, if only for the diagnosis, the CT scan may not be necessary