MR扩散加权成像在肝脏占位性病变中的应用

目的筛选肝脏扩散加权成像（DWI）较合适的b值,并探讨DWI对鉴别肝脏良恶性病变的价值。方法测定129例314个肝脏病变在b分别取50、500、800s/mm2时的信号强度、背景噪声,比较不同b值时同一病变信号强度、质量指数及信噪比的差异;同一b值时不同肝脏病变平均ADC的差异。结果1.肝癌DWI图像各b值时信号强度、信噪比、质量指数均不同,随b值增加而降低,各b值差异显著（F值分别为103.77、93.06、118.19,P值均〈0.01）,而噪声则与b值无关（F=2.19,P〉0.05）。2.肝脏病变分为肝癌、肝转移癌、肝囊肿、肝血管瘤,b=500s/mm2时的平均ADC值分别为（1.04±0.08）×10-3mm2/s、（1.09±0.1）×10-3mm2/s、（2.77±0.11）×10-3mm2/s、（1.84±0.12）×10-3mm2/s,各组之间两两比较,除肝癌与肝转移癌P=0.13,差别无统计学意义外,余P值均〈0.05;肝癌实质区与坏死区平均ADC值分别为（1.04±0.08）×10-3mm2/s,（1.55±0.05）×10-3mm2/s,二者比较P〈0.05。结论本研究认为b=500s/mm2为较适合的肝脏扩散加权成像b值,DWI及ADC值可以鉴别肝脏良恶性病变,鉴别肝癌的实质区和坏死区。

Application of MR diffusion weighted imaging in the diagnosis of focal space-occupying lesions in liver

Objective To discuss the value of DWI with different b-value for identification the benign and malignant hepatic lesions.Methods 314 hepatic lesions from 129 cases were investigated.Signal intensity,quality index and background noise were measured when the bvalue was 50、500、800s/mm2 respectively,comparing the differences of mean ADC-value and signal intensity with the same b-value,different hepatic lesion,or with the different b-value but the same kind of hepatic lesion.Results 1.Signal intensity and signal-to-noise rate of DWI image of hepatoma was different with different b-value,it was decreasing with the increase of b-value.The difference was significant between groups with different b-value（F=103.77、93.06、118.19,P0.01）,but background noise had no relationship with b-value（F=2.19,P0.05）.2.Hepatic lesion was classified as hepatoma,hepatic metastatic cancer,hepatic cyst and hepatic hemangioma.The mean ADC-value were（1.04±0.08）× 10-3mm2/s、（1.09±0.1）×10-3mm2/s、（2.77±0.11）×10-3mm2/s、（1.84±0.12）×10-3mm2/s respectively.Except that the difference between hepatoma and hepatic metastatic cancer had no statistical significance（P=0.13）,the pairwise comparison showed that difference had statistical significance（P0.05）;mean ADC-value of solid area and necrosis area of hepatoma were（1.04±0.08）×10-3mm2/s,（1.55± 0.05）×10-3mm2/s respectively,comparison of them showed significant different P0.05.Conclusion The DWI image with b-value of 500 s/mm2 can be used to identify benign and malignant hepatic lesions,and solid area and necrosis area of hepatoma.