CT相对强化比值鉴别肾嗜酸性细胞瘤与肾透明细胞癌的应用价值

Differentiation of renal oncocytoma and renal clear cell carcinoma using relative CT enhancement ratio

目的:探讨CT相对强化比值(病灶/肾皮质密度比值)鉴别肾嗜酸性细胞瘤(RO)与肾透明细胞癌(RCC)的应用价值。方法:回顾性分析经手术病理证实的14例RO和32例RCC的CT强化特征。分别测量两组病例CT增强各时相病灶强化区域及相邻肾皮质密度,比较各时相病灶CT值和病灶/肾皮质密度比值。采用独立样本t检验及卡方检验对测量结果进行统计学分析。结果:RCC于CT增强皮质期、髓质期和肾盂期测得的病灶CT绝对值均高于RO,但差异无统计学意义(P均>0.05);27例RCC(27/32,占84%)皮质期病灶/肾皮质密度比值>1,仅1例RO(1/14,占93%)病灶/肾皮质密度比值>1,两者间差异具有统计学意义(P<0.05);10例RO(10/14,占71%)髓质期病灶/肾皮质密度比值高于皮质期,呈"延迟强化"表现,仅1例RCC(1/32,占3%)髓质期病灶/肾皮质密度比值高于皮质期,呈"延迟强化"表现,两者间差异具有统计学意义(P<0.05)。以皮质期病灶/肾皮质密度比值<1为标准,诊断RO的敏感度、特异度、阳性预测值、阴性预测值、准确性分别为93%、84%、72%、84%和87%;以髓质期病灶/肾皮质密度比值高于皮质期为标准,诊断RO的敏感度、特异度、阳性预测值、阴性预测值、准确性分别71%、97%、91%、91%和89%。结论:应用CT相对强化比值(病灶/肾皮质密度比值)分析法有助于鉴别RO与RCC。

Objective：To explore the application value of relative CT enhancement ratio in differentiating renal oncocytoma（RO）and renal clear cell carcinoma（RCC）.Method：Forty-six patients with solitary renal mass included in this study underwent total or partial nephretomy,of which 14 cases were RO and 32 were RCC.The pattern and degree of enhancement were evaluated.The area was selected that demonstrated the greatest degree of enhancement of renal lesion in the corticomedullary,nephrographic,and excretory phase images.Regions of interest were also placed in adjacent normal renal cortex for comparison.The ratios of lesion/renal cortex enhancement were calculated for all three phases.The Student＇s t-test and Pearson＇s Chi-square test were used for statistical analyses.Results：All RCC masses showed more intensive enhancement than RO masses in all contrast enhanced phases of CT imaging but there was no significant defference in absolute attenuation value between these two diseases（P〉0.05）.The ratio of lesion-to-cortex attenuation in the corticomedullary phase showed significantly different values between RO and RCC.The degree of contrast enhancement in RCC was equal to or greater than that of the normal renal cortex,but it was less than that of the normal cortex in RO in the corticomedullary phase.The ratio of lesion-to-cortex attenuation in corticomedullary phase was higher than the cut off value of 1.0in most renal clear cell carcinomas（84%,27/32）,and only in one case of RO（7%,1/14）（P ﹤0.05）.In the nephrographic phase,the ratio of the lesion/cortex attenuation was higher than that of the corticomedullary phase in most RO（71%,10/14）,showing aprolonged enhancement pattern,and in RCC（3%,1/32）（P〈0.05）.In the differentiation of RO from RCC,the sensitivity,specificity,positive predictive value,negative predictive value,and accuracy for RO were 93%、84%、72%、84%and 87%,respectively,if the ratio of lesion-to-cotex attenuation in cortical phase being lower than the cut off value 1.0.The sensitivity,specificity,positive predictive value,negative predictive value,and accuracy for RO were 71%、97%、91%、91%and 89%respectively,if the ratio of lesion-to-cotex attenuation in nephrographic phase being higher than that in corticomedullary phase.Conclusion：The renal lesion-to-cortex attenuation ratios may be helpful in differentiating RO from RCC.