体素内不相干运动扩散加权成像在肝脏良恶性病变鉴别诊断及血流灌注评价中的初步应用

Value of intravoxel incoherent motion diffusion-weighted imaging in differential diagnosis of benign and malignant hepatic lesions and blood perfusion evaluation

目的探讨体素内不相干运动扩散加权成像（IVIM-DWI）参数在脏脏良恶性病变鉴别诊断及病变血流灌注评价中的应用价值。方法回顾性分析经穿刺手术标本病理学、临床或随访结果明确诊断的86例患者（96个病灶），其中恶性48例（53个病灶），良性38例（43个病灶）。上述患者均行磁共振成像（MRI）常规平扫、增强扫描及多b值（b=0、50、100、150、200、400、600、800、1000、1200s／mm2）DWI获得IVIM双指数模型参数：快速扩散系数D触值、慢速扩散系数Dslow值及快速扩散成分所占百分比F值。根据MRI常规平扫及增强扫描对病变的血供隋况进行判定并入组，其中富血供组47个病灶、乏血供组49个病灶。数据分析包括：肝良恶性病变组及富血供乏血供病变组的Dfast值、Dslow值比较采用独立样本t检验进行统计学分析；F值比较采用两独立样本非参数检验（Mann-Whitney U秩和检验）进行统计学分析；应用受试者工作特征（ROC）曲线评价上述参数值对肝脏良恶性病变鉴别及富血供乏血供病变评定中的价值。结果良性病变组的Dfast值、Dslow值、F值高于恶性病变组，并且两者之间耽。W值、F值的差异有统计学意义（P值均〈0．01）。富血供病变组的Dfast值、Dslow值、F值高于乏血供病变组，并且两者之间Dfast值、F值的差异有统计学意义（P值均〈0．01）。ROC曲线评价Dslow值、Dfast值、F值诊断肝脏良恶性病变及肝脏富血供乏血供病变阈值、灵敏度、特异度、准确度及曲线下面积分别为1．18×10- 3mm2／s、90．69％、92．45％、91．66%、0．938，27．20×10-3 mm2／s、46．51％、73．58％、61．45％、0．589，20．25％、74．41％、50．94％、62．51%、0．653；1．17×10-3 mm2／s、59．5％、57．14%、58．33％、0．559，20．30×10-3 mm2／s、55．32％、63．26%、59．37%、0．618，17．80%、93．61％、89．79％、90．62%、0．961。结论IVIM双指数模型参数Dslow值对肝脏良恶性病变具有鉴别诊断价值，F值无需通过增强扫描就可以提供肝脏良恶性病变的血流灌注情况，可以为肝脏肿瘤的定性诊断提供一定的依据。

Objective To investigate the value of intravoxel incoherent motion diffusion-weighted imaging （IVIM-DWI） in the differential diagnosis and blood perfusion evaluation of benign and malignant hepatic lesions. Methods A retrospective analysis was performed for 86 patients （96 lesions） with pathologically or clinically confirmed hepatic lesions or hepatic lesions diagnosed based on follow-up results, among whom 48 had malignant lesions （53 lesions） and 38 had benign lesions （43 lesions）. The patients underwent conventional magnetic resonance （MR） plain scan, contrast-enhanced scan, and diffusion-weighted imaging （DWI） with different b values （b = 0, 50, 100, 150, 200, 400, 600, 800, 1 000, and 1 200 s/mm2） to determine the parameters of the double exponential model for intravoxel incoherent motion （IVIM）： fast diffusion coefficient Dfast, slow diffusion coefficient Dslow, and percentage of fast-diffusion constituent F value. The patients were divided into groups according to the blood supply to lesions on conventional MR plain scan and contrast-enhanced scan, and there were 47 lesions in abundant blood supply group and 49 in poor blood supply group. The data for analysis were Dfast, Dslow, and F values of benign/malignant lesion groups and abundant/poor blood supply groups. The independent samples t-test was used for statistical analysis; the independent samples non-parametric test Mann-Whitney U test was used for the comparison of F value; the receiver operating characteristic （ROC） curve was used to evaluate the value of above parameters in the differentiation of benign and malignant lesions and blood supply evaluation. Results Compared with the malignant lesion group, the benign lesion group had significantly higher Dslow, and F values （P 〈 0.001 or P = 0.001） and a higher Dfast value （P = 0.053）. Compared with the poor blood supply group, the abundant blood supply group had significantly higher Dfast and F values （P 〈 0.001 or P = 0.001） and a higher Dslow value （P = 0.185）. According to the ROC curve, the cut-off values of Dslow, Dfast, and F values in the diagnosis of benign/malignant hepatic lesions and evaluation of abundant/poor blood supply were 1.18× 10.3 mm2/s, 27.20× 10.3 mm2/s, 20.25%, 1.17× 10.3 mm2/ s, 20.30 × 10.3 mm2/s, and 17.80%, respectively, with sensitivities, specificities, accuracy, and areas under the ROC curve of 90.69%/92.45%/91.66%/0.938, 46.51%/73.58%/61.45%/0.589, 74.41%/50.94%/62.50%/0.653, 59.57%/57.14%/58.33%/0.559, 55.32%/63.26%/59.37%/0.618, and 93.61%/89.79%/90.62%/0.961, respectively. Conclusion The parameter of the double exponential model for IVIM, Dslow value, has a certain value in the differential diagnosis of benign and malignant hepatic lesions, and F value can show blood perfusion in benign and malignant hepatic lesions without the need for contrast-enhanced scan, which provides a reference for the qualitative diagnosis of liver tumor.