高阶扩散加权成像技术在肝结节良恶性鉴别诊断中应用的研究进展

The investigation of clinical value for high-order diffusion weighted imaging in differentiating benign and malignant liver nodules

传统的扩散加权成像(diffusion weighted imaging,DWI)方法能够通过探测水分子在生物组织中的扩散运动状态,间接获取组织细胞的异常增殖信息,在肿瘤的良恶性鉴别中被广泛应用。但DWI忽视了单位体素内水分子在毛细血管内的伪扩散运动和肿瘤细胞的异质性,因此,其检测结果不能准确反映肿瘤组织的病理改变。鉴于此,一些高阶DWI方法,包括体素内不相干运动(intravoxel incoherent motion,IVIM)成像、扩散峰度成像(diffusion kurtosis imaging,DKI)和延展指数成像等被提出。这些高阶成像方法在原DWI的基础上,通过进一步挖掘水分子在单位体素内的运动特征,分别从血流灌注和肿瘤异质性等方面扩展了原DWI方法的探测范围,为肿瘤的良恶性鉴别提供了更加丰富的参考依据。肝结节作为一种高发肿瘤,常伴有复杂的血供和异质性特征,并严重威胁人类的健康与生命。对肝结节的准确鉴别不仅有助于临床医生采取恰当的治疗手段,而且能显著改善患者预后。鉴于高阶DWI方法的诊断优势,其在肝结节的临床诊断中发挥了重要作用。本文系统地探讨了三种高阶DWI方法IVIM、DKI和延展指数成像方法对肝结节良恶性鉴别的诊断价值。

The conventional diffusion weighted imaging(DWI)method can indirectly obtain the abnormal proliferation information of tissue cells by detecting the diffusion movement of water molecules in biological tissues.Thereby,this technique has been widely used in the differentiation of benign and malignant tumors.However,since DWI method ignores the pseudo-diffusion movement of water molecules in capillaries and the heterogeneity of tumor cells in a voxel,its detection results cannot accurately reflect the pathological changes of tumor tissues.In view of this,several high-order DWI methods are proposed,such as intravoxel incoherent motion(IVIM)imaging,diffusion kurtosis imaging(DKI)and stretched exponential imaging methods,to further reveal the movement characteristics of water molecules in tissues.In contrast to conventional DWI method,these high-order imaging methods can not only probe the diffusion movement of water molecules,but also reflect the blood perfusion and tumor heterogeneity,which could provide more valuable references for differentiation of benign and malignant tumors.The liver nodules seriously threaten human health and life due to its high incidence.Also,the hepatic tumors are often accompanied by complex blood supply and heterogeneous characteristics.Therefore,the accurate identification for liver nodules can not only help clinicians to adopt appropriate treatment strategies,but also significantly improve patient outcomes.Given above advantages of high-order DWI methods,they play important roles in the clinical diagnosis of hepatic nodules.This paper systematically discussed the clinical value of three high-order DWI methods,IVIM imaging,DKI and stretched exponential imaging,in the diagnosis and differentiation of benign and malignant liver nodules.