目的 探讨1.5 T磁共振不同b值DWI诊断肝脏转移瘤,分析优选最佳b值.方法 回顾分析30例经病理或随访综合诊断确诊的肝转移瘤患者及32例肝良性肿瘤患者70个病灶的不同b值(分别为200、400、600、800、1 000s/mm2)的DWI扫描数据,分别测量各b值下病变的DWI信号强度、表观扩散系数,观察病变DWI、ADC图影像表现,计算并比较不同b值组间病变淋巴结信号噪声比、对比噪声比和ADC值,分析不同b值下ADC值对肝转移瘤和肝良性肿瘤的鉴别诊断效能,优化出最佳b值.结果 所有病灶的DWI图像随着b值由200s/mm2升高至1 000s/mm2,图像信噪比逐渐降低,图像对比噪声比在b值为400s/mm2时最高,图像为200s/mm2、400s/mm2、600s/mm2、800s/mm2的对比噪声比无统计学差异,b值为800s/mm2时,诊断肝转移瘤敏感度、特异度较高,分别为87.63%、78.82%.结论 1.5T磁共振诊断肝转移瘤b值为800s/mm2时获得的ADC值效能最高.%Objective To determine reasonable b values in diffusion weighed imaging of liver metastases with 1.5 T MR.Methods We retrospectively analysed 30 patients with pathologically confirmed diagnosis or follow-up comprehensive liver metastases patients and 32 patients of benign liver tumors.70 lesions were analyzed, all the 70 lesions in different b values (200, 400, 600, 800, 100 s/mm2) of DWI scan data were measured, including: signal intensity values, apparent diffusion coefficient values, signal to noise ratio, and contrast to noise ratio.The image quality of each group of DWI was analyzed and compared.We analysed the diagnostic value of ADC values at different b values to the diagnosis of liver metastases.Results As b values increasing from 200 s/mm2 to 1 000 s/mm2, SNR of liver decreased gradually, the CNR in b value 400 s/mm2 was maximum.We used ROC curve for diagnosis of liver metastases in different b value.b value of 800 s/mm2 had maximum value when the diagnostic sensitivity specificity values were 87.63%, 78.82%.Conclusion The optimal b value is 800 s/mm2.
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