低场磁共振弥散加权成像诊断急性脑梗死的可行性

目的探讨低场磁共振弥散加权成像（DWI）在急性期脑梗死诊断中的可行性。方法对临床疑诊或确诊为脑梗死的116例患者包括11例超急性期（发病后6h内），35例急性期（发病后6-24h）及70例亚急性期（发病后2～7d）进行DWI和常规MRI检查，对超急性、急性、亚急性期的MRI表现进行分析，总结病变演变规律。结果DWI较常规MRI序列显示梗死灶更有明显优势，对超急性期脑梗死灶的敏感度为100％。急性期脑梗死灶在DWI序列上为异常高信号，且信号强度随b值升高而增强，各期脑梗死灶在DWI中异常信号强度由低逐渐增高。弥散全方向比单方向DWI成像显示病变效果好。结论低场磁共振弥散加权成像技术，通过精心调整扫描技术参数，对急性期脑梗死能作出诊断，尤其对超急性期脑梗死的诊断及治疗可提供可靠依据。

Feasibility of low field MR DWI for diagnosing acute cerebral infarction

Objective To discuss the feasibility of low field magnetic resonance（MR） diffusion weighted imaging（DWI） for diagnosing acute cerebral infarction.Methods A hundred and sixteen patients with clinically suspected or definitely diagnosed acute cerebral infarction which comprised 11 superacute（within 6 hours after onset）,35 acute（within 6 to 24 hours after onset）and 70 subacute（within 2 to 7 days after onset）underwent DWI and conventional MRI at 0.2 T low field. All patients whose MRI findings acquired from the both medalities were retrospectively analyzed together with changed regularity of the lesions. Results In showing the lesions of cerebral infarction, DWI was significantly superior to conventional MRI. The sensitivity of DWI for superacute phasic lesions was 100%. The lesions of acute cerebral infarction were abnormal hyperintense on DWI sequence and were enhanced with b value increase. The abnornmal signal intensity of varied phasic lesions on DWI was gradually enhanced. The omnidirectional DWI in showing varied phasic lesions was more clear than monedirectional DWI. Conclusion Through carefully adjusting scanning technique parameters, low field MRI can correctly diagnose acute cerebral infarction, especially can provide the reliable evidence for diagnosis and management of superacute cerebral infarction.