能谱CT成像在鉴别周围型肺癌和肺炎性肿块中的价值

Differentiating peripheral lung cancers from inflammatory masses using dual energy spectral CT imaging

目的 探讨能谱CT成像定量分析在鉴别诊断周围型肺癌和肺炎性肿块中的价值.方法 对60例肺内孤立性肿块（周围型肺癌35例、肺炎性肿块25例）行宝石CT能谱模式（GSI）扫描,获得动脉期和静脉期的能谱系列图像.分别测量病灶中央区、周围区的碘浓度,计算其与同层面胸主动脉碘浓度的比值即标准化碘浓度（NIC）,同时计算病灶中央区与周围区标准化碘浓度之差的绝对值（dNIC）.自动获取能谱衰减曲线并计算其斜率（λHU）.测量数据以M（Q1,Q3）表示,分别对上述参数进行2组独立样本Wilcoxon符号秩和检验,并绘制ROC曲线评估其诊断效能.结果 能谱模式双期扫描周围型肺癌中央区NIC值均明显低于炎性肿块：动脉期分别为0.03（0,0.05）和0.12（0.07,0.20）,静脉期分别为0.14（0.12,0.19）和0.30 （0.21,0.57）,差异均有统计学意义（Z值分别为-4.14、-3.70,P值均＜0.01）.而周围型肺癌dNIC值明显高于炎性肿块：动脉期分别为0.08 （0.05,0.11）和0.04（-0.02,0.08）,静脉期分别为0.23（0.17,0.34）和0.07（-0.04,0.08）,差异均有统计学意义（Z值分别为-2.56、-4.00,P值均＜0.05）.双期扫描中周围型肺癌λHU值均低于肺炎性肿块：动脉期分别为1.03（0.67,1.67）和2.75（1.61,3.19）,静脉期分别为1.58 （1.30,2.17）和3.25（2.37,4.54）,差异均有统计学意义（Z值分别为-3.90、-4.42,P值均＜0.01）.ROC曲线显示以静脉期λHU=2.11为阈值时,对2组病变鉴别诊断的敏感度可达89％,特异度可达91％.结论 运用能谱CT成像的参数进行定量分析,对周围型肺癌和肺炎性肿块的鉴别诊断有较大价值。

Objectives To investigate the clinical significance of dual energy spectral CT （DESCT） in quantitatively differentiating peripheral lung cancers from pulmonary inflammatory masses.Methods Sixty patients with 35 lung cancers and 25 inflammatory masses underwent DESCT to get arterial phase （AP） images and venous phase （VP） images.Iodine concentrations in the central and peripheral zone of the masses were measured and normalized to the aorta as normalised iodine concentration （NIC）.The difference of NIC between central and peripheral zone of the masses （dNIC） was calculated.The spectral attenuation curve was obtained automatically and the slope of curve （λHU） was also calculated in the two groups.The quantitative parameters was presented as M （Q1,Q3）,and Wilcoxon signed rank test was used to compare above two independent samples.Receiver operating characteristic （ROC） curves were generated to calculate the sensitivity and specificity.Results NICs in the central zone of peripheral lung cancers were significantly lower than that of inflammatory masses：mean NICs were 0.03 （0,0.05） versus 0.12 （0.07,0.20） in AP,and 0.14 （0.12,0.19） versus 0.30 （0.21,0.57） in VP （Z=-4.14,-3.70,respectively,P〈0.01）.While the dNIC values of lung cancers were significantly higher than that of inflammatory masses：dNIC values were 0.08 （0.05,0.11） versus 0.04 （-0.02,0.08） in AP,and 0.23 （0.17,0.34）versus 0.07 （-0.04,0.08） in VP（Z=-2.56,-4.00,respectively,P〈0.05）.Mean λHU values of lung cancers were also lower than inflammatory masses：1.03 （0.67,1.67）versus 2.75 （1.61,3.19） in AP,and 1.58 （1.30,2.17） versus 3.25 （2.37,4.54） in VP （Z=-3.90,-4.42 respectively,P〈0.01）.According to ROC curves,cutoff value of λHU =2.11 in VP had the highest sensitivity （89%） and specificity （91%） in differentiating peripheral lung cancers from inflammatory masses.Conclusions Contrast-enhanced dual energy spectral CT imaging with some quantitative parameters such as normalised iodine concentration,dNIC,and the slope of spectral attenuation curves may be a promising new method for differentiating peripheral lung cancers from inflammatory masses.