脑梗死的MRI弥散张量成像

Diffusion tensor imaging characteristics of cerebral infarction

目的用MRI弥散张量成像（DTI）分析脑梗死的弥散张量改变，探讨脑梗死的DTI表现及其临床意义。方法采用盲法分析临床及常规MRI和（或）CT确诊的69例脑梗死患者的DTI图像，分析脑梗死的DTI信号改变，测量病变区域的各向同性（ADCiso）值和各向异性（FA）值，并与健侧相应正常解剖区域进行比较。结果根据ADCiso图和FA图上病变区的信号改变和定量测量，总结归纳出69例脑梗死病例分以下4种类型：Ⅰ型（8例）：病变区ADCiso值降低，FA值升高；ADCiso图表现为低信号，FA图表现为高信号。Ⅱ型（23例）：病变区ADCiso值和FA值均降低，但病变周围区域ADCiso值降低，FA值升高；ADCiso图为低信号，FA图呈中央低信号，周围高信号改变。Ⅲ型（7例）：病变区ADCiso值和FA值均降低；ADCiso图和FA图上均为低、等信号。Ⅳ型（31例）：病变区ADCiso值升高。FA值降低；ADCiso图表现为高信号，FA图表现为低信号。以上病变区弥散张量参数与健侧镜像区比较差异有统计学意义（P〈0．05）。结论DTI定性、定量分析有可能更好地揭示脑梗死病变的病理生理过程，有望为临床提供更精确的影像学分期，成为指导临床诊疗、监测病情进展和评定预后等的客观指标。

Objective To investigate the clinical value of diffusion tensor imaging （DTD in the evaluation of cerebral infraction. Methods Sixty-nine patients with cerebral infraction confirmed by clinical manifestation and routine MR/and/or CT were analyzed for the signal intensity changes on DTI. The isotropic apparent diffusion coefficient （ADCiso） and fractional anisotropy （FA） of the infracted area were measured and compared with those of the unaffected side. Results Four types of signal intensity changes on DTI were identified. Type Ⅰ changes were found in 8 infraction lesions, where the ADCiso decreased and FA increased, and the infraction lesions showed hypointensity on ADCiso map and hyperintensity on FA map. Type Ⅱ changes, found in 23 lesions, were characterized by decreased ADCiso and FA values, but ADCiso in the peripheral of the lesions decreased and FA increased, and the lesions were shown as isointensity or hypointensity on ADCiso and FA maps with hyperintensity on the peripheral. Type Ⅲ changes （7 lesions） were manifested by decreased ADCiso and FA values and hypointensity on ADCiso and FA maps. Type Ⅳ changes were found in 31 infraction lesions, showing increased ADCiso and decreased FA with corresponding hyperintensity on ADCiso map and hypointensity on FA map. Significant differences were found in the DTI parameters between the infraction lesions and unaffected side （P〈0.05）. Conclusion DTI for qualitative and quantitative analysis of cerebral infraction better reveals the pathophysiology of the infraction, allows more precise imaging-based staging of the lesion, and provides evidences for more objective diagnosis, treatment, monitoring and prognostic evaluation of the condition.