枕大孔前后缘深度MRI测量在颅底凹陷症诊断中的价值

Value of MRI measurement of depths of the anterior and posterior lips of the foramen magnum in the diagnosis of basilar invagination

目的用MRI测量并探讨枕大孔前缘深度(the depth of the anterior lip of the foramen magnum ,简称FMAD)和枕大孔后缘深度(the depth of the posterior lip of the foramen magnum ,简称FMPD),为诊断颅底凹陷症提供依据.方法在正中矢状面自旋回波(SE)T1WI图像上,测量320名正常人和36名颅底凹陷症患者FMAD和FMPD,并计算FMAD与FMPD之比值.将对照组性别、年龄之间及对照组与异常组之间各指标进行比较.结果 (1)对照组0～9岁FMAD差异无统计学意义,而10岁以后各年龄组FMAD男性大于女性(t值分别为5.54、6.58、5.92、7.13、6.32、5.14和4.48,P值均<0.05);对照组同性别0 ～ 9 岁FMAD小于10岁以后各年龄组(男性F值分别为3.66、4.45、6.32、4.08、5.78、7.13和5.99,P值均<0.05;女性F值分别为3.88、5.75、6.78、6.75、5.96、6.98和7.08,P值均 < 0.05),而10岁以后各年龄组间无显著年龄差异;异常组FMAD 95%可信区间为25.93～27.27 mm,对照组为34.53～35.32 mm,两者无交叉.(2)对照组FMPD性别和年龄差异均无统计学意义;异常组FMPD 95%可信区间为33.17～35.63 mm,对照组为32.83～33.64 mm,两者交叉.(3)对照组FMAD/FMPD性别和年龄差异亦均无统计学意义;异常组该比值 95%可信区间为0.72～0.80,对照组为1.05～1.08,两者无交叉.结论 (1)颅底凹陷症患者FMAD及FMAD/FMPD均明显小于正常人,FMAD < 27 mm或FMAD/FMPD < 0.8可诊断为颅底凹陷症.(2)颅底凹陷症患者FMPD与正常人无明显差异.

Objective To investigate the depth of the anterior lip of the foramen magnum (FMAD) and the depth of the posterior lip of the foramen magnum (FMPD) by MRI, and to study their clinical significances in the diagnosis of basilar invagination. Methods FMAD and FMPD on midsagittal SE T_1WI were measured in 320 normal subjects and in 36 patients with basilar invagination. The ratio between FMAD and FMPD was calculated. The sex and age differences in the normal group and the differences between the patients and normal subjects were analyzed. Results (1)There was no significant sex difference in FMAD in 0 ~ 9 year group, but FMAD of the male was bigger than that of the female in all age groups after 10 years (t=5.54, 6.58, 5.92, 7.13, 6.32, 5.14, and 4.48, respectively, all P<0.05); FMAD in 0 ~ 9 year group was less than that in all age groups after 10 years in the same sex (F=3.66, 4.45, 6.32, 4.08, 5.78, 7.13, and 5.99, respectively in the male, all P<0.05; F=3.88, 5.75, 6.78, 6.75, 5.96, 6.98, and 7.08, respectively in the female, all P<0.05), but there was no significant difference in FMAD among different age groups after 10 years. It ranged from 25.93 mm to 27.27 mm in patients and from 34.53 mm to 35.32 mm in normal subjects. There was no overlap between them.(2)There was no significant sex and age differences in FMPD in the control group. It ranged from 33.17 mm to 35.63 mm in patients and it ranged from 32.83 mm to 33.64 mm in normal subjects. There was overlap between them.(3)There was no significant sex and age differences in FMAD/FMPD in the control group; It ranged from 0.72 to 0.80 in patients and from 1.05 to 1.08 in normal subjects. There was no overlap between them. Conclusion (1)The basilar invagination can be diagnosed when FMAD is less than 27 mm or FMAD/FMPD is less than 0.8. (2)There is no significant difference in FMPD between patients and normal subjects.