磁共振表观弥散系数在脑梗死演变中的诊断价值

目的 探讨磁共振弥散加权成像（DWI）表观弥散系数（ADC）值在脑梗死诊断、分期的应用价值.方法 应用自旋回波-回波平面（SE-EPI）成像序列对98例脑梗死患者共进行117例次DWI及常规MRI检查.其中超急性12次,急性期43次,亚急性期29次,稳定期10次,慢性期23次,测量各期病灶平均ADC值及平均相对ADC（rADC）值,并分别测量梗死灶中心至病灶边缘的ADC值及rADC值.结果 超急性、急性期脑梗死灶ADC值较对侧相应区域明显下降,超急性、急性期rADC最低,随时间延长rADC由低到高,于8～14 d出现假性正常化,于慢性期高于正常水平,rADC与时间有关[（174±3.47）%vs（58±6.75）%,t=2.03,P＜0.05].超急性、急性期病灶中心rADC最低,从中心往外逐渐升高呈梯度征;亚急性期脑梗死ADC值、rADC值呈现与超急性期及急性期相反的＂梯度征＂,即病灶中心区ADC值和rADC值最高,从中心往外逐渐降低.结论 脑梗死病灶ADC值具有特征性的演变规律,有助于及时准确地对脑梗死分期诊断,为临床治疗及预后判断提供依据.

The diagnostic value of apparent diffusion coefficient in monitoring the development of cerebral infarction

Objective To study the values of apparent diffusion coefficient (ADC) changing with time and space in cerebral infarction,and to provide the evidence in defining the infarction stages.Methods 117 work-ups in 98 patients with cerebral infarction (12 hyperacute,43 acute,29 subacute,10 steady,and 23 chronic infarctions) were imaged with both conventional MRI and diffusion weighted imaging.The average ADC values,the relative ADC (rADC) values,and the ADC values or rADC values from the center to the periphery of the lesion were calculated.Results The average ADC values and the rADC values of hyperacute and acute infarction lesion depressed obviously.rADC values in hyperacute and acute stage was minimized,and progressively increased as time passed and appeared as "pseudonormal" values in approximately 8 to 14 days.Thereafter,rADC values became greater than normal in chronic stage.There was positive correlation between rADC values and time[ (174 ±3.47)% vs (58±6.75)%,t =2.03,P ＜0.05 ].The ADC values and the rADC values in hyperacute and acute lesions had gradient signs that these lesions increased from the center to the periphery.The ADC values and the rADC values in subacute lesions had adverse gradient signs that these lesions decreased from the center to the periphery.Conclusion The ADC values of infarction lesions have evolution rules with time and space.The evolution rules with time and those in space can be helpful to provide the evidence in guiding the treatment or judging the prognosis in infarction.