Application Of Dual-layer Spectral Detector CT In Patients With Solitary Pulmonary Nodules:Differentiating Benign From Malignant And Suggesting Pathological Types

Objects:The purpose of this study was to evaluate the performance of dual-layer spectral detector CT（SDCT）for the differentiation of SPN.Methods:Spectral images of 135 SPN proved by pathology findings were retrospectively analyzed both in arterial phase（AP）and venous phase（VP）.Patients were classified into two groups（malignant group,n=93;benign group,n=42）with the malignant group further grouped into small cell lung cancer（SCLC,n=30）and non-small cell lung cancer（NSCLC,n=63）.The slope of spectral Hounsfield Unit（HU）curve(λ_HU),normalized iodine concentration（NIC）,CT value of 40keV monochromatic images(CT_40keV)and normalized arterial enhancement fraction（NAEF）in contrast enhanced images were calculated and compared between the benign and malignant group,SCLC and NSCLC subgroups.ROC curve analysis was performed to assess the diagnostic performance of the above parameters.Results:All parameters values were higher in the malignant group compared to those of the benign group（all P<0.05）except for NAEF（P=0.23）.NIC,λ_HU and CT_40keV in VP(NIC_VP,λ_VPHU,CT_{VP40ke V})exhibited greater performance（P<0.001）with the area under the ROC curve（AUC）of 0.89-0.93.In the subgroup of identifying lung cancer types,the diagnostic performances of NIC_AP（AUC=0.89）were greater than other parameters.Conclusions:Quantitative measures from SDCT can help differentiate benign and malignant SPN and may help further sub-classify malignant cancer into SCLC and NSCLC.