平扫CT值在梗阻性肾积液中的新用途

CT value in diagnosis of obstructive renal effusion

目的探讨平扫CT值预测梗阻性肾积液性质(肾积脓或肾积水)的价值。方法回顾性分析2014年6月1日至2019年11月30日惠州市第三人民医院经手术证实的267例梗阻性肾积液患者的一般情况、平扫CT值、肾盂尿培养、合并糖尿病、无功能肾等相关信息。根据肾造瘘手术时引流液情况分为肾积脓组与肾积水组。计算不同CT值阈值鉴别肾积水与肾积脓的灵敏度、特异度、准确度、阳性预测值及阴性预测值。利用医学影像信息系统软件对CT值进行统计。结果肾积脓组82例,男36例,女46例,年龄(58.6±15.5)岁;肾积水组185例,男74例,女111例,年龄(56.2±12.1)岁;两组比较,差异无统计学意义(均P>0.05)。合并糖尿病(肾积脓组9例比肾积水组2例,P<0.05)、无功能肾(肾积脓组5例比肾积水组1例,P<0.05)为肾积脓发生的高危因素。肾积脓组CT值明显高于肾积水组[(10.016±3.120)Hu比(5.295±1.736)Hu,P<0.05]。当肾积液CT值为9.21 Hu时,约登指数最大为0.5779。进行受试者工作特征曲线(ROC)分析发现CT值鉴别肾积脓与肾积水的诊断阈值范围(曲线下面积为0.856,95%置信区间为0.808~0.896)。当CT值≥9.17 Hu,诊断肾积脓的灵敏度为80.49%,特异度为77.30%,阳性预测值为81.25%,阴性预测值为76.42%。结论通过CT值诊断鉴别肾积脓与肾积水是一种可信度较高且无创的方法,准确诊断肾积脓可尽早避免败血症等并发症的发生。

Objective To explore the value of non-contrast CT in the differential diagnosis of obstructive pyonephrosis and hydronephrosis.Methods The age,gender,non-contrast CT values,results of renal pelvis urine culture,complications of diabetes,renal non-function,etc.of the 267 patients surgically diagnosed with obstructive renal effusion at our hospital from June 1,2014 to November 30,2019 were retrospectively analyzed.According to the drainage fluid during nephrostomy,they were divided into a pyonephrosis group and a hydronephrosis group.The sensitivities,specificities,accuracies,positive predictive values,and negative predictive values of different CT value thresholds were calculated and compared.The CT value was calculated by the picture archiving and communication system software.Results There were 82 cases in the pyonephrosis group,including 36 males and 46 females,who were(58.6±15.5)years old;there were 185 cases in the hydronephrosis group,including 74 males and 111 females,who were(56.2±12.1)years old;there were no statistical differences between these two groups(both P>0.05).Nine cases had diabetes and 5 had non-functional kidney in the pyonephrosis group,and 2 and 1 in the hydronephrosis group(both P<0.05),so diabetes and non-functional kidney were the high-risk factors of pyonephrosis.The CT value in the pyonephrosis group was significantly higher than that in the hydronephrosis group[(10.016±3.120)Hu vs.(5.295±1.736)Hu,P<0.05].The maximum Youden index was 0.5779 when the CT value was 9.21 Hu.Receiver operative characteristics curve(ROC)analysis revealed a diagnostic threshold of CT attenuation value for differentiating pyonephrosis and hydronephrosis:the area under curve was 0.856,and the 95%CI was 0.808-0.896.When the CT value≥9.17 Hu,the sensitivity,specificity,accuracy,positive predictive value,and negative predictive value were 80.49%,77.30%,81.25%,and 76.42%,respectively.Conclusion CT value in the differential diagnosis of pyonephrosis and hydronephrosis is a noninvasive method with high confidence,and can accurately diagnose pyonephrosis early and avoid septic complications.