Background: To investigate the value of dual energy computed tomography (DECT) parameters (including iodine concentration and monochromatic CT numbers) for predicting pure ground-glass nodules (pGGNs) of invasive adenocarcinoma (IA).Methods: A total of 55 resected pGGNs evaluated with both unenhanced thin-section CT (TSCT) and enhanced DECT scans were included. Correlations between histopathology [adenocarcinoma in situ (AIS), minimally IA (MIA), and IA] and CT scan characteristics were examined. CT scan and clinicodemographic data were investigated by univariate and multivariate analysis to identify features that helped distinguish IA from AIS or MIA.Results: Both normalized iodine concentration (NIC) of IA and slope of spectral curve [slope(k)] were not significantly different between IA and AIS or MIA. Size, performance of pleural retraction and enhanced monochromatic CT attenuation values of 120-140 keV were significantly higher for IA. In multivariate regression analysis, size and enhanced monochromatic CT number of 140 keV were independent predictors for IA. Using the two parameters together, the diagnostic capacity of IA could be improved from 0.697 or 0.635 to 0.713.Conclusions: DECT could help demonstrate blood supply and indicate invasion extent of pGGNs, and monochromatic CT number of higher energy (especially 140 keV) would be better for diagnosing IA than lower energies. Together with size of pGGNs, the diagnostic capacity of IA could be better. Several researches have used thin-section CT (TSCT) to distinguish IA from the preinvasive adenocarcinoma or MIA in terms of CT number and morphologic characteristics such as size, margin, bubble lucency, and solid proportion, and have indicated that the solid proportion has correlation with the degree of invasion of ground-glass nodules (GGNs) (4-9).Sometimes, GGNs would have no solid component, which are named pure GGNs (pGGNs). Most pGGNs tend to be preinvasive (1), while approximately 20-40% of pGGNs are pathologically malignant (10). Because of the limited resolution (0.2-0.3 mm) of CT images, stromal or myofibroblastic invasion of 5 mm or smaller in MIA or even IA greater than 5 mm in size may manifest as pGGN on high resolution CT (5). It has been proved that CT attenuation of IA is higher than its precursors (11), but there is no consensus over the cutoff of CT attenuation to indicate pGGN of IA. One study suggests that pGGNs with mean CT attenuation >−472 Hounsfield unit (HU) are more likely to be IA, with sensitivity of 75% and specificity of 81% (12). Angiogenesis is a fundamental process in the development of tumors, but enhancement characteristics of GGNs are often very difficult to assess because of low cellularity, and there are few researches about the enhancement characteristics of GGNs. Li et al. (13) found that the solid proportion of some GGNs (mostly in MIA or IA) would increase after contrast enhancement, and it could help for diagnosis of GGNs.Gemstone spectral imaging (GSI) analysis software is a specific tool in dual energy computed...