MRI DWI序列显示健康志愿者骶髂关节成像的最佳b值

Magnetic resonance diffusion weighted imaging sequence shows the best b value of sacroiliac joint imaging of healthy volunteers

背景:MRI DWI序列是一种简单易行、特异性较强、敏感度较高且能早期诊断活动性骶髂关节炎、监测其活动性的检查方法之一,但DWI序列对骶髂关节显示的最佳b值尚无统一标准。目的:通过比较10-20岁健康志愿者骶髂关节MRI不同b值时DWI及表观弥散系数差异,寻找MRI DWI序列显示骶髂关节的最佳b值。方法:随机选择21名10-20岁无骶髂关节疾病的健康志愿者作为研究对象,行骶髂关节轴位T1WI、STIR及DWI扫描(b值为0,300,600,900s/mm2),观察不同b值对骶髂关节的显示情况,对图像进行评价;同时,分别测量双侧骶髂关节的骶侧、髂侧关节旁骨髓的表观弥散系数,对不同b值双侧骶髂关节旁骨髓表观弥散系数进行统计学分析。结果与结论:21名健康志愿者42个骶髂关节在b值为300,600s/mm2时,图像显示清晰,对比度好,能清晰显示骶髂关节关节。b值为900s/mm2时,图像伪影较大,图像质量模糊,对比度差,无法完成表观弥散系数值的测量。b值为600s/mm2时,双侧骶髂关节旁骨髓所测得的表观弥散系数值变化范围小,而b值为300s/mm2时,表观弥散系数值差异性较大。结果显示600s/mm2是MRIDWI序列显示骶髂关节的最适宜b值,不仅能清晰显示双侧骶髂关节,而且所测得关节旁骨髓的表观弥散系数值精确度较高。

BACKGROUND：Magnetic resonance diffusion weighted imaging sequence is one of the inspection methods which is simple to operation, has strong specificity and high sensitive and can early diagnose the active sacroili tis and monitoring the activities, but there is no standard of b values of sacroiliac joint displayed with diffusion weighted imaging sequence. OBJECTIVE：To find the best b value displayed with magnetic resonance diffusion weighted imaging sequence through comparing the difference of diffusion weighted imaging and apparent diffusion coefficient between the healthy volunteers aged 10-20 years old under different b values of sacroiliac joint. METHODS：Twenty-one healthy volunteers without sacroiliac joint diseases, aged 10-20 years old were col ected for research. Al the health volunteers were taken MRI scan with several sequences （T1WI, STIR, DWI：b=300 s/mm2, 600 s/mm2, 900 s/mm2）. The sacroiliac joint displayed under different b values was observed, and the images were evaluated. Meanwhile, the apparent diffusion coefficient of the sacral side and iliac side joint surrounding bone marrow of bilateral sacroiliac joint was measured, and the statistical analysis of apparent diffusion coefficient of sacroiliac joint surrounding bone marrow was performed under different b values. RESULTS AND CONCLUSION：Clear images with high contrast ratio of 21 healthy volunteers （42 sacroiliac joints） could clearly show the sacroiliac joints when the b values were 300 s/mm2 and 900 s/mm2. When the b value was 900 s/mm2, the images had larger image artifacts, fuzzy image quality and poor contrast ration that unable to complete the measurement of the apparent diffusion coefficient values. When the b value was 600 s/mm2, the change of apparent diffusion coefficient of sacroiliac joint surrounding bone marrow was smal , while the b value was 300 s/mm2, the difference of apparent diffusion coefficient of sacroiliac joint was significant. The b value of 600 s/mm2 is the best b value for magnetic resonance diffusion weighted imaging sequence to display the sacroiliac joint which can clearly show the bilateral sacroiliac joint, and the apparent diffusion coefficient of bilateral sacroiliac joint surrounding bone marrow measured with the b value has higher accuracy.