Abstract: Objective:To evaluate the diagnostic value of MR for ACM.Methods:164 patients,with obscure clinical diagnosis from Jan.1990 to Dec.1999,were examed by a 1.0T superconductive MR system.The diagnosis of ACM Type Ⅰ was established in all cases and their MR appearances were summarized and analysed. Results:In all cases,60%(99/164)patients had a variable degree of syringohydromyelia;71%(117/164)had cervicomedullary kinking;75%(123/164)were associated with other malformation;70%(115/164)were associated with craniocervical junction malformation.Conclusion:MR has been proved to be the best method in diagnosis of ACM,and it can be used to find out accurately the associated malformation,degree and range of syringohydromyelia.

Key words: Arnold-Chiari malformation, magnetic resonance, syringohydromyelia