扩散加权成像在肾脏T2加权成像低信号病变定性诊断中的应用价值

Application value of diffusion-weighted imaging signal pattern in the qualitative diagnosis of renal lesions with T2WI hypointensity

目的分析在肾脏T2加权成像(T2WI)低信号病变中磁共振扩散加权成像(DWI)信号特征对于肾脏良恶性病变的诊断价值。方法回顾性分析解放军总医院第一医学中心放射诊断科2016年2月至2017年2月经手术、活检或随访证实具有最终诊断的病例135例肾脏T2WI低信号病变患者(病变内≥75%区域表现为低信号)的DWI影像学资料。135例患者中良性43例,男18例、女25例,年龄28~70岁,平均43.5岁;恶性92例,男62例、女30例,年龄17~86岁,平均54.1岁。DWI信号特征分为6类,包括:均匀高信号、均匀低信号、不均匀高信号、晕环状高信号、晕环结节状高信号、结节状高信号。采用kappa分析对2名观察者的阅片结果进行一致性检验,用χ^2检验方法分析DWI信号特征在良恶性病变中差异有无统计学意义,并分别计算出差异有统计学意义DWI信号特征在肾脏良恶性病变的敏感度、特异度、阳性预测值、阴性预测值。结果肾脏T2WI低信号疾病135例,共计135个病灶,良性43个病灶,恶性92个病灶。2名观察者读片结果的一致性极好(kappa值为0.878 6)。肾脏T2WI低信号病变中DWI均匀高信号、均匀低信号、不均匀高信号、晕环状高信号、晕环结节状高信号、结节状高信号在良性病灶中所占比例分别为4.7%(2/43)、25.6%(11/43)、30.2%(13/43)、18.6%(8/43)、11.6%(5/43)、9.3%(4/43),在恶性病灶中所占比例分别为10.9%(10/92)、0(0/92)、17.4%(16/92)、13.0%(12/92)、56.5%(52/92)、2.2%(2/92)。DWI晕环结节状高信号及均匀低信号在肾脏T2WI低信号良恶性疾病之间差异均有统计学意义(均P<0.01)。DWI晕环结节状高信号在T2WI低信号恶性病变中诊断效能高,敏感度、特异度、阳性预测值、阴性预测值分别为56.5%(52/92)、88.4%(38/43)、91.2%(52/57)、48.7%(38/78)。DWI均匀低信号在肾脏T2WI低信号良性病变中诊断效能高,敏感度、特异度、阳性预测值、阴性预测值分别为25.6%(11/43)、100.0%(92/92)、100.0%(11/11)、74.2%(92/124)。结论DWI信号特征有助于肾脏T2WI低信号病变的准确定性诊断,DWI晕环结节状高信号倾向于恶性病变,DWI均匀低信号倾向于良性病变。

Objective To analyze the diagnostic value of diffusion-weighted imaging(DWI)signal pattern in renal lesions with T2WI hypointensity.Methods Retrospective analysis was performed on DWI imaging datasets of 135 renal lesions with hypointentsity on T2WI confirmed by surgery,biopsy,or follow-up in the First Medical Center of Chinese PLA General Hospital from February 2016 to February 2017.One hundred and thirty-five renal lesions,43 benign lesions(age from 28 to 70 years,mean age was 43.5 years,male 18 lesions and female 25 lesions)and 92 malignant lesions(age from 17 to 86 years,mean age was 54.1 years,male 62 lesions and female 30 lesions).DWI signal pattern was classified into six categories:homogeneously high signal,homogeneously low signal,heterogeneously high signal,high halo signal,high halo and nodular signal,and high nodular signal.The agreement between two observers were tested using kappa statistic.The statistical difference between DWI signal characteristics in benign and malignant lesions was analyzed with Chi-Square test.Diagnostic efficacy in differentiation of benign and malignant renal lesions using DWI signal pattern were calculated.Results One hundred and thirty-five lesions were detected in 135 cases with T2WI hypointensity.There were 43 benign lesions and 92 malignant lesions.The agreement between two observers was very good(kappa value=0.878 6).In renal T2WI hypointensity lesions,the proportion of DWI homogeneous high signal,homogeneous low signal,heterogeneous high signal,high halo signal,high halo and nodular signal,high nodular signal was 4.7%(2/43),25.6%(11/43),30.2%(13/43),18.6%(8/43),11.6%(5/43),9.3%(4/43),respectively.The proportion of malignant lesions was 10.9%(10/92),0(0/92),17.4%(16/92),13.0%(12/92),56.5%(52/92)and 2.2%(2/92),respectively.The difference of high halo and nodules signal and homogeneous low signal was statistically significant(all P<0.01).The sensitivity,specificity,positive prediction value(PPV)and negative prediction value(NPV)of high halo and nodular signal for malignancy were 56.5%(52/92),88.4%(38/43),91.2%(52/57)and 48.7%(38/78),respectively and homogeneous low signal for benign lesions were 25.6%(11/43),100.0%(92/92),100.0%(11/11)and 74.2%(92/124),respectively.Conclusions DWI signal features may facilitated the accurate diagnosis of renal lesions with T2WI hypointensity.Malignant lesions exhibit a higher propensity with high halo and nodular signal on DWI while benign lesions with homogeneous low signal.