Value Of Energy Spectrum CT In Qualitative Diagnosis Of Pulmonary Ground Glass Nodule

Objective: Through the analysis of quantitative parameters of energy spectrum CT,the value of qualitative diagnosis of ground glass nodule(GGN)in lung was evaluated.Materials and Methods: Data of 70 patients with lung GGN(a total of 73 lesions)who underwent energy spectrum CT examination in the third affiliated hospital of Chongqing medical university from January 2018 to February 2019 were collected.These lesions were divided into pure GGN(38 the number)and mixed GGN(35 the number)according to their imaging findings,and into benign lesion(20the number),preinvasive lesion(PIL,15 the number),minimally invasive adenocarcinoma(MIA,21 the number)and invasive adenocarcinoma(IAC,17 the number)according to their pathological types.T test or one-way ANOVA were used to compare the differences in the quantitative parameters of energy spectrum between different imaging and pathological types of pulmonary GGN,and P<0.05 was considered statistically significant.For the energy spectrum parameters with statistical difference,the ROC curve was drawn,and the area under the curve(AUC)was used to measure the differential diagnosis efficiency of each parameter.Results: The difference in imaging findings of pulmonary GGN among various pathological types was significant(P< 0.05),87.0% of PIL were pure GGN,70.6% of IAC were mixed GGN.The content of water of benign lesions in plain scan and arterial phase(408.11 ± 187.82,312.62 ± 102.29)was lower than that of PIL(447.86 ± 124.89,432.22 ± 97.23),MIA(547.61 ± 179.96,634.82 ±127.76)and IAC(705.35 ± 205.41,820.34 ± 115.51)(P < 0.05).The plain scanning slope of energy spectrum curve(k value)of benign lesions(1.32 ± 0.15)was higher than that of PIL(0.83 ± 0.11),MIA(0.67 ± 0.06)and IAC(0.54 ± 0.12)(P < 0.05).But,in the arterial phase,the k value of benign lesions(1.59 ± 0.58)was lower than that of PIL(2.96 ± 0.80),MIA(2.47 ± 0.87)and IAC(2.43 ± 0.79)(P <0.01).There was no significant difference between iodine content and standardized iodine concentration(NIC)of lung GGNs in different pathological types in the arterial phase(P > 0.05).To differentiate benign and malignant lung GGN ROC curve analysis,the results show that the energy spectrum CT scan of water content in the diagnosis of optimal threshold is 385.98 mg/mL,AUC is0.900,the sensitivity was 80.0%,and the specificity was 88.9%,The plain scanning k value in the diagnosis of best critical value of 1.11,AUC is 0.767,the sensitivity was 80.0%,and the specificity was 88.9%,water content in the diagnosis of arterial optimal threshold is 420.32mg/mL,AUC 1.000,the sensitivity was 100.0%,and the specificity was 100.0%,The optimal critical value of k value in arterial stage was2.09,AUC was 0.778,the sensitivity was 100.0%,and the specificity was 77.8%.The water content and k value of the quantitative parameters of energy spectrum CT were used in combination to identify the benignand malignant pulmonary GGN,the diagnostic accuracy was 80.8%,sensitivity 81.1%,specificity 75.0%,positive predictive value 86.8%,and negative predictive value 65.0%.Conclusion: The quantitative parameters of energy spectrum CT have certain value for the differential diagnosis between benign and malignant pulmonary GGN and among various pathological types of pulmonary GGN.