[Differential diagnosis of pure ground glass nodules in lung with spectral CT imaging].

Objective: To evaluate the differential diagnostic performance of quantitative parameters derived from the spectral CT imagingin pure ground-glass nodules. Methods: A total of 44 patients with pure ground glass nodules underwent chest energy spectrum CT and with known subsequently pathological findings in the Imaging Department of the Second Affiliated Hospital of Soochow University from August 2017 to September 2019 were retrospectively analyzed. Among them, there are 18 males and 26 females, aged from 26 to 79 (51±12) years. They were divided into as the inflammatory group (n=12), pre-invasive adenocarcinoma group (n=17) and invasive adenocarcinoma group (n=15). The aforementioned three groups were further reclassified as non-invasive adenocarcinoma group (inflammatory lesion+pre-invasive lesion) and invasive adenocarcinoma group in order to evaluating the values of water concentration (WC) for the determination of adenocarcinoma infiltration status. The values of WC derived from the arterial and venous phase of the lesion, iodine concentration (IC), standardized iodine concentration (NIC) were measured respectively.The slope of the energy spectral curve (K40-70KeV) derived from the arterial and venous phase of the lesion was also calculated. One-way ANOVA analysis was performed to compare the differences of the three groups and the multiple comparison method was used for further comparing. Intraclass correlation efficient (ICC) was used to assess the consistency of the three times of measurements. The area under curve(AUC) of Receiver Operating Characteristic (ROC) was conducted to evaluate the diagnostic performance of water based values. Results: The values of WC in the arterial and venous phases were significantly different. As in the inflammatory group, the pre-invasive lesion group and the invasive adenocarcinoma group, the values of WC was (291.95±58.66) mg/cm3, (297.61±63.96) mg/cm3and (374.52±60.62) mg/cm3 of the arterial phase, and (277.07±33.78) mg/cm3, (291.74±50.49) mg/cm3 and (373.33±75.12) mg/cm3 of the venous phase, respectively(all P<0.05). Further comparison demonstrated that no significant difference was observed for the values of WC derived from the arterial phases and venous phases between the inflammatory lesion group and the pre-invasive lesion group (all P>0.05).There were an significant differences between the invasive adenocarcinoma group, the inflammatory lesion group and the pre-invasive lesion group (all P<0.05). The values of WC derived from the venous phase achieved the largest AUC (0.770) for differentiating invasive adenocarcinoma from non-invasive adenocarcinoma (inflammatory lesions+pre-invasive lesions) in the pure ground glass nodules. The sensitivity and specificity were 66.67% and 93.10%, respectively, when using 349.31 mg/cm³ as the optimal threshold. The slope of the spectral curve and iodine-related parameters (IC, NIC) derived from arterial or venous phases among the three groups were not significantly different (all P>0.05). Conclusion: The values of WC derived from the spectral CT can better distinguish inflammatory, pre-invasive lesions and invasive adenocarcinoma, which is helpful for the qualitative analysis for pure ground glass nodules.目的： 探讨能谱CT定量参数在肺纯磨玻璃结节病变中的鉴别诊断价值。 方法： 回顾性分析2017年8月至2019年9月苏州大学附属第二医院影像科行胸部能谱CT扫描且有病理结果的44例纯磨玻璃结节患者的临床资料，其中男18例，女26例，年龄26~79（51±12）岁。分为炎性病变组（12例）、浸润前病变组（17例）、浸润性腺癌组（15例）；为判断水基值鉴别腺癌浸润程度的效能，进一步将以上三组合并为两组，即非浸润性腺癌组（炎性病变+浸润前病变）和浸润性腺癌组。分别测量病灶动脉期、静脉期的碘基值、标准化碘基值及水基值；计算病灶动脉期、静脉期能谱曲线斜率（K40~70KeV）。运用单因素方差分析进行三组间比较及多重比较法进行两两比较。采用组内相关系数（ICC）检验评估三次测量数据的一致性。应用受试者工作特征（ROC）曲线下面积（AUC）评估水基值诊断效能。 结果： 炎性病变组、浸润前病变组、浸润性腺癌组三组动脉期及静脉期的水基值差异均具有统计学意义［动脉期：（291.95±58.66）mg/cm3、（297.61±63.96）mg/cm3、（374.52±60.62）mg/cm3；静脉期：（277.07±33.78）mg/cm3、（291.74±50.49）mg/cm3、（373.33±75.12）mg/cm3］（均P<0.05）。进一步两两比较：动脉期、静脉期水基值在炎性病变组与浸润前病变组之间差异均无统计学意义（均P>0.05）；浸润性腺癌组与炎性病变组、浸润前病变组间差异均有统计学意义（均P<0.05）。在鉴别浸润性腺癌和非浸润性腺癌组（炎性病变+浸润前病变）的纯磨玻璃结节上，静脉期水基值AUC最大（0.770），以349.31 mg/cm³为最佳阈值时，灵敏度和特异度分别为66.67%、93.10%。动脉期、静脉期的能谱曲线斜率、碘相关参数（碘基值、标准化碘基值）在三组间差异均无统计学意义（均P>0.05）。 结论： 能谱CT定量参数水基值在纯磨玻璃结节定性诊断中能较好鉴别炎性病变、浸润前病变和浸润性腺癌，有助于肺纯磨玻璃结节的定性分析。.