PET/CT双时相显像对孤立性肺结节诊断价值的ROC曲线分析

The ROC Analysis of Dual Time Point PET/CT Imaging in Diagnosis of Solitary Pulmonary Nodule

[目的]利用ROC曲线分析评价PET/CT双时相显像对孤立性肺结节(SPN)的诊断价值。[方法]回顾性分析病理确诊或随访确诊的SPN行PET/CT双时相检查的142例患者。所有患者注射显像剂后60min行PET/CT早期显像,120min后行延迟显像。以半定量方法测定结节早期及延迟期SUVmax值,并计算代谢滞留指数(RI)。以RI≥10%为阳性判断标准对结节进行定性诊断,计算其诊断的灵敏度、特异性、准确率、阳性预测值及阴性预测值。绘制相应ROC曲线并计算曲线下面积,以分析PET/CT双时相显像诊断SPN的效能。[结果]良性结节延迟期SUVmax值与早期比较差异无统计学意义(P>0.05);而恶性结节延迟期SUVmax值较早期显著增高(P<0.05)。以RI≥10%为阳性,<10%为阴性,其诊断SPN的灵敏度、特异性、准确率、阳性预测值、阴性预测值分别为83.5%、51.3%、74.6%、81.9%、54.1%。PET/CT双时相显像诊断SPN的ROC曲线下面积为0.707±0.053,以约登指数最大值为界点,确立ROC曲线的最佳截断值为5%,对应诊断SPN的灵敏度、特异性和准确率分别为92.2%、48.7%和80.3%。[结论]PET/CT双时相显像鉴别SPN良恶性有一定的临床价值,对于早期显像诊断困难的SPN,建议双时相PET/CT检查有助于鉴别。

[Purpose] To evaluate the role of dual time point18F-FDG PET/CT imaging in diagnosis of solitary pulmonary nodule（SPN）,using receiver operating characteristic（ROC） curves analysis. [Methods] A total of 142 patients who were confirmed with SPN undergoing dual time point PET/CT were retrospectively analyzed in this study. All patients underwent early and delayed PET/CT imaging at 60 min and 120 min after intravenous injection respectively. The early and delayed maximum standardized uptake value（SUVmax） of PET/CT imaging were measured and the retention index（RI） of delayed images was calculated. The sensitivity,specificity,accuracy,positive predictive value and negative predictive value of the dual time point imaging in diagnosis of SPN were calculated,using the RI ≥10% as diagnostic positive standard. The receiver operating characteristic（ROC） curve and the area under the ROC curve（AUC） were used to evaluate the diagnostic value of dual time point imaging for SPN. [Results] The difference in average SUVmaxof early and delayed imaging among benign nodules was not statistically significant（P〉0.05）,while there was significant difference among malignant nodules in average SUVmaxof early and delayed imaging（P〈0.05）. The sensitivity,specificity,accuracy,positive predictive value and negative predictive value were 83.5%,51.3%,74.6%,81.9% and 54.1% respectively with RI ≥10% as diagnostic positive standard. The area under ROC curve was 0.707±0.053. The best cutoff value was5% according to maximum Youden index,and the corresponding sensitivity,specificity and accuracy were 92.2%,48.7% and 80.3% respectively. [Conclusions] The dual time point PET/CT imaging is useful for differentiating solitary pulmonary nodules,especially for those with diagnostic difficulty at early phase imaging.