A Study Of Differential Diagnostic Value Of Dual Energy Imaging By Dual Source CT In Solitary Pulmonary Nodules

Objective:To study the correlation between dual source CT dual energy imaging iodine map parameters and microvessel density?MVD?in solitary pulmonary nodules?SPN?,and to explore the differential diagnostic value of dual source CT dual energy imaging for SPN.Methods:61 patients with SPN who underwent dual energy scanning with dual source CT and confirmed by pathology from March 2017 to October 2018 were enrolled in the Affiliated Hospital of Zunyi Medical University.There were 30 males and 31 females,aged from 27 to 74 years old,with an average age of 52.43±11.68 years.According to the pathological results,all cases were divided into two groups,including 29 cases of benignancy and 32 cases of malignancy.All cases undewent single energy conventional non-contrast?CNC?scanning and dual energy contrast-enhanced scanning with German Siemens second-generation dual source CT?SOMATOM Definition Flash?.The radiation dose table is automatically generated after scanning.The CNC images and the contrast-enhanced images were reconstructed?slice thickness 1mm?and imported the post-processing workstation,using the"Liver VNC"program in Dual Energy software to obtain the virtual non-contrast?A-VNC,V-VNC?images and the iodine maps at artery phase and vein phase.Record the mean CT value,noise and signal to noise ratio?SNR?of CNC and VNC images,evaluate the image quality of A-VNC and V-VNC.Record the overlay value?AOL,VOL?,iodine concentration?AIC,VIC?and normalized iodine concentration?ANIC,VNIC?at artery phase and vein phase respectively.The microvessel density?MVD?of 61 cases of SPN were obtained by PV-9000 two-step immunohistochemical detection system.All data were statistically analysed.Comparing the image quality indexes of CNC and VNC images,radiation dose of single energy and dual energy scanning mode,iodine map parameters and the MVD of benign and malignant SPNs.The correlation between SPN iodine map parameters and microvessel density?MVD?was analyzed.The diagnostic efficiency of the best diagnostic index for judging malignant SPNs in the dual source CT iodine parameters was analyzed by ROC curve.Results:?1?There was no significant difference in image quality parameters?CT value,SD,SNR?of CNC,A-VNC and V-VNC?p>0.05?.A significant difference was observed between VNCs and CNC,the image quality score of A-VNC and V-VNC were lower than CNC?p>0.05?,no significantly difference was observed between A-VNC and V-VNC.?2?The CTDI_vol?17.14±2.06?,DLP?467.70±65.85?and ED?6.54±0.92?of dual energy scanning mode were lower than single energy scanning mode and the difference was significant?p<0.05?.The effective radiation dose received by patients can be reduced by40%if conventional non-contrast scan was cancelled.?3?The AOL,AIC,ANIC,VNIC and MVD were lower in the benign group than in the malignant group?p<0.05?.?4?All iodine parameters were positively correlated with MVD?p<0.05?,among which ANIC had the best correlation?r=0.828,p<0.05?.The correlation between the iodine parameters and MVD in arterial phase was better than that in venous phase,and the correlation between VNIC and MVD was the best among the iodine parameters in venous phase?r=0.673,p<0.05?.?5?When ANIC>0.05 or VNIC>0.3 as the threshold for the diagnosis of malignant SPN,the sensitivity was 84.4%and 81.2%,the specificity was 51.7%and72.4%,the diagnostic coincidence rate was 68.9%and 77.0%respectively.When ANIC>0.12 and VNIC>0.44 for the diagnosis of malignant SPN,the sensitivity,specificity and diagnosis coincidence rate were 50.0%,96.6%and 72.1%respectively.Conclusions:?1?Iodine map parameters can be used as a non-invasive index for evaluating angiogenesis of tumors and are conducive to the differential diagnosis of SPNs.?2?The VNC images by dual energy imaging can meet the clinical diagnosis requirements and reduce the radiation dose received by patients,which has potential clinical application value.