强直性脊柱炎骶髂关节影像学分析(附24例骶髂关节平片、CT和MR影像对比观察)

Comparison of radiography, computed tomography and magnetic resonance imaging in the detection of sacroiliitis for ankylosing spondylitis

目的：旨在评估强直性脊柱炎（ＡＳ）患者骶髂关节炎的ＭＲ影像特征，并比较Ｘ线平片、ＣＴ和ＭＲ影像在诊断骶髂关节炎中的作用。材料与方法：搜集２４例ＡＳ患者，分别行Ｘ线平片、ＣＴ和ＭＲＩ检查。增强前ＭＲ扫描序列包括ＳＥＴ１ＷＩ、ＦＳＥＴ２ＷＩ和梯度回波的准Ｔ２ＷＩ（ＧＲＴ２＊ＷＩ）。增强后ＭＲ扫描序列参数与增强前ＳＥＴ１ＷＩ相同。另选９例志愿者，行ＭＲ平扫检查。结果：８例志愿者１６个骶髂关节的Ｔ１ＷＩ和Ｔ２ＷＩ可直接显示正常骶髂关节软骨，表现为线形或点样的中等信号影。９例志愿者１１个骶髂关节的骨髓内可见局灶性脂肪沉积。２４例ＡＳ患者的４２个骶髂关节可见软骨异常，表现为Ｔ１ＷＩ和Ｔ２ＷＩ上正常线形中等信号的软骨影像消失，代之以不规则增粗或扭曲样中等信号。分析表明：在骶髂关节炎的诊断方面，ＭＲ和ＣＴ明显优于Ｘ线平片（Ｐ＜０．００１）。结论：同Ｘ线片比较，虽ＣＴ和ＭＲＩ均有助于ＡＳ骶髂关节炎的诊断，但ＭＲ影像可显示ＣＴ和Ｘ线所不能显示的软骨异常和骨髓内水肿改变；骨髓内脂肪沉积可属正常变异；扭曲样中等强度信号应视为软骨的异常征象。

Purpose: To evaluate characteristics of sacroiliitis on MR imaging and to compare the MR images with findings obtained by conventional radiography and CT in patients with ankylosing spondylitis (AS). Materials and methods: Twenty four AS patients were recruited. In each patient the conventional radiography, CT and MR imaging were completed within a week interval. In pre contrast MR examination, SE T 1, FSE T 2 and GR T 2 * weighted images were chosen. Post contrast MR examination was performed using the same SE T 1 sequence as the pre contrast MR examination. Another 9 healthy volunteers underwent the same examinations as the pre contrast MR imaging. Results: MR imaging directly showed the cartilage in the synovial compartment as a thin linear or dot zone of intermediate signal intensity on both T 1 and T 2 weighted images in all 16 sacroiliac (SI) joints of the 8 volunteers. Of the 11 SI joints in 9 volunteers, focal fat signal intensities were observed as higher signal intensity on both T 1, T 2 or T 2 * weighted images in the areas of bone marrow. Of 42 SI joints in 24 AS patients were observed the cartilage abnormalities. Cartilage abnormalities were shown either to loss of the normal thin zone of intermediate signal intensity or to become thick, irregular and crooked intermediate signal intensity on T 1 or T 2 weighted images. The sacroiliitis diagnosed by MR imaging and CT were significantly more than those by radiography ( P <0.001). Conclusion: Comparing with radiographs, both CT and MR are helpful to the diagnosis of sacroiliitis in patients with AS. MR can reveal the abnormality of cartilage and bone marrow edema, which cannot shown on both CT and radiographs. Normal variant should be considered as the explanation for the fat accumulation in the bone marrow. The crooked intermediate signal should be considered as another abnormal cartilage sign.