Preliminary Study Of Spectral CT Imaging In The Differential Diagnosis Of Lung Cancer

Objective To investigate the diagnostic value of spectral CT imaging in differentiating of lung cancer and tuberculosis,inflammatory disease other than tuberculosis,and pathological types of lung cancer.Methods 129 patients with pulmonary nodules or mass confirmed by pathology.Among them,lung cancer 99(Adenocarcinoma 49,squama cancer37,small cell cancer 13),pneumonia 19,tuberculosis 11.All patients received triphasic pulmonary enhanced CT scan in GSI mode on Discovery CT750 HD and reconstruction.To transmit the single energy image of 1.25 mm thick layer to Aw4.5workstation,images were analyzed By two high qualification radiologists.Normalized iodine concentration(NIC),CT value at 40 kev and slope rate of spectral curve were measured and compared.All the parameters were analyzed among three phases.The data statistics analysis by SPSS16.0 software.First,the normal distribution test was conducted in data.To test the homogeneity of variance.Compare the difference between the data of the groups using single factor analysis of variance(LSD)or two sample t test correction.Standard for difference was statistically significant(P < 0.05).The standardization of iodine concentration,(40kev)CT value and spectrum curve slope of adenocarcinoma and squamous cell carcinomas were Measured again on arterial and venous phase,Compare the differences between the two parameters.Using two independent samples t test to compare the difference.Standard for difference was statistically significant(P<0.05).Drawing characteristic curve(ROC),Computing area under curve(AUC),evaluating the diagnostic performance and obtaining The threshold value of quantitative indicators.Results 125 cases with complete data were proved by pathology through surgery or bronchoscopy,4 cases were proved by follow-up.Divided into the lung cancer group,inflammatory,tuberculosis group,adenocarcinoma and squamous carcinoma group.NIC,CT value at 40 kev and slope rate of spectral curve were found the highest in pneumonia,and lowest in tuberculosis.The above mentioned parameters were found significant difference in the three parameters either between tuberculosis and pneumonia or between tuberlosis and lung cancer in three phases.There was significant difference in NIC and CT value at 40 kev between pneumonia and lung cancer only in delayed phase.NIC,CT value at 40 kev and slope rate of spectral curve in adenocarcinoma were higher than squamous cell carcinomas in dual phase scanning.ROC curve analysis showed that:Arterial spectrum area under curve slope is the largest,0.746;When the threshold value is 105.5,arterial(40kev)CT values of differential adenocarcinoma and squamous cell carcinomas of the specific degree is highest,78%;When the threshold value is 0.247,venous phase NIC of identify the highest sensitivity of adenocarcinoma and squamous cell carcinomas,at 76%.Conclusion The difference of Spectral CT quantitative parameters between lung cancer and inflammatory lesion,tuberculosis,and between adenocarcinoma and squamous cell carcinomas showed statistical significance.it is useful in differential diagnosis.Spectral CT quantitative analysis for the diagnosis and differential diagnosis of lung cancer has great clinical application value.