Abstract Background Persistent subsolid nodules requiring follow-up are often detected during lung cancer screening; however, changes in their invasiveness can be overlooked owing to slow growth. The purpose of this exploratory study was to develop a method to automatically identify invasive tumors during multiple health check-ups. Methods We retrospectively reviewed patients who underwent screening using low-dose computed tomography (CT) between 2014 and 2019. Patients with lung adenocarcinomas manifesting as subsolid nodules resected after 5 years of follow-up were enrolled. The resected tumors were categorized into invasive or less-invasive groups. The annual growth or change rate (Δ) of the nodule voxel histogram on three-dimensional CT (e.g., tumor volume [cm 3 ], solid volume percentage [%], mean CT value [HU], variance, kurtosis, skewness, and entropy) was assessed using radiomics. Multivariate regression modeling was employed to design a discriminant model. Results Forty-seven tumors (282 detectable lesions over 5 years) were included (23 and 24 in the invasive and less-invasive groups, respectively). The median tumor volumes at the initial screening were 130 and 106 mm 3 in the less-invasive and invasive groups, respectively; the difference was not significant ( P = 0.489). In the multivariate regression analysis to identify the invasive group, Δskewness was an independent predictor (adjusted odds ratio, 0.021; P = 0.043). When combined with Δvariance (odds ratio, 1.630; P = 0.037), the assessment method had high accuracy for detecting invasive lesions (true-positive rate, 88%; false-positive rate, 80%). Conclusions During check-ups, close investigation by surgery for subsolid nodules can be suggested with the application of radiomics, particularly focusing on skewness. Trial registration: Not applicable.
<i>Background/Aims:</i> For lung preservation, one of two types of solutions is commonly employed: Euro-Collins (EC) or low potassium dextran glucose (LPDG). These two solutions have been compared regarding biological, morphometrical and physiological outcomes in many experiments. However, the dynamic mechanics of perfused lung are not well understood because the dynamic characteristics cannot be assessed under static conditions; hence, the primary goal of the present study was to assess this in perfused rat lungs during the preservation period, comparing EC with LPDG at 0 or 9 h at 4°C. <i>Methods:</i> Lung impedance was measured using a forced oscillation technique. Lung resistance and elastance values were obtained by the fast Fourier transform algorithm. The instability of central airways and heterogeneity of ventilation were estimated. <i>Results:</i> In the EC group, airway resistance and instability were high after perfusion, and the lung elastance was high and more heterogeneous after cold storage. In contrast, those parameters were stable in the LPDG group during cold storage. <i>Conclusion:</i> Such dynamic stability might facilitate the handling of lung grafts and eliminate injurious cyclic ventilation stress after reperfusion. Thus, we conclude that the impedance frequency characteristic represents a novel informative parameter for investigating lung preservation techniques.
