小脑扁桃体位置临床磁共振成像研究

A clinical quantitative study of the position of cerebellar tonsils wity MR imaging

目的：用MRI测量小脑扁桃体位置，以确定其正常值范围，探讨其发育规律。材料与方法：在颅脑分正中矢状面SETT图像上测量了317例正常人和42例Chiari畸形（n＝29）及可疑患者（n＝13）的小脑扁桃体高距和枕大孔前后径，正常人按性别、年龄分16组，每组20例（70岁以上女性组仅17例），用t检验作统计分析。结果：小脑扁桃体不低于颅基线3nun者均为正常组，且其无论男女均于30－50岁时最低；不同性别同年龄组间其位置不同，但差异无统计学意义；同性别部分年龄组间其位置有显著差异，但相邻组间差异无统计学意义。Chiari畸形及可疑组其高距分别为（－11．5】6．6）规及（－3．9±0．9）m，两组间及其与正常各组间有显著差异。枕大孔前后径男稍大于女，部分年龄组有显著性别差异。其于20岁前随年龄而扩大，之后基本稳定，50岁以后又渐行扩大，Chiari畸形及可疑织间及其与大部分正常组间的差异无统计学意义。结论：小脑扁桃体位置和枕大孔前后径一生中有一定的变化规律。Chiall畸形并非都伴枕大孔扩大。

Objective: MRI was used to determie quantitatively the position of the cerebellar tonsils in normal chinese and in patients with Chiari malformations in order to define the normal range of the parameters of chinese individuals.Materials and Methods:The distance between the tonsillar tip and foamen magnum(DT) and the diameter form the anterior to posterior rim of the foramen magnum (DFM)on midsagittal MR image were measured in 317 subjects without posterior fossa abnormalities and increased intractanial pressure,and in 42 patients with Chiari malformations,Every group of age was 20 subjects in normal population,except for female group of age more than 70 years old(only 17). Results:DT of different group was different with sex and age significant difference in partial groups.The average DT of patients with confirmed or dubious Chiari malfomations was(-11.5±6. 6) mm or(- 3. 9±O. 9) mm respectively.The difference between every normal group and patient's groups was statistically(P＜0. 005). The position of the tonsils in the normal population is the lowest at age from 30 to 50 years old or so,The male DFM was larger than female's,and there was significant difference in several grougs.The dif ference of DFM between most of the normal and patient's group was not statistically significant(P>0.005).DFM becomes large as people grows up before twenty and after fifty years old or so.Conclusion:DT and DFM have regular rule of age-related change in all life.