Identifying invasive lung adenocarcinomas manifesting as part-solid nodules by measuring the size of multiple solid portions and maximum solid portions.

Background: Previous studies have reported that the presence of solid components in part-solid nodules (PSNs) may be closely related to the degree of tumor invasion, and have proposed that the consolidation/tumor ratio (CTR) on imaging is an important criterion for determining pathological invasiveness. However, currently, there is no common assessment standard for PSNs with multifocal solid portions. This study sought to provide valuable suggestions for identifying invasive adenocarcinomas (IACs) manifesting as PSNs based on different quantitative measurement methods, including the single largest solid portion, the solid proportion, and the sum of multiple solid portion measurements. Methods: The data of 186 patients with surgically resected PSNs at Zhengzhou University People's Hospital from December 2018 to December 2022 were retrospectively reviewed. Of the 186 cases, 134 were pathologically confirmed as IAC, and 52 cases were pre-IAC. The multiplicity of the solid portion in the PSNs was determined, and the size of each solid portion was measured. The solid portions and proportions were compared among the groups. A logistic regression analysis was then conducted to identify the risk predictors associated with IAC. A synthetic minority over-sampling technique was then used to balance the data, and a receiver operating characteristic (ROC) curve analysis was conducted to estimate the predictive efficacy of the different parameters, and the precision, accuracy, F1 scores, and Matthews correlation coefficients (MCCs) of the parameters were compared. Results: The sizes of the solid portions were greater in the IAC patients than the pre-IAC patients (P<0.05), and the solid proportions differed among the different subtypes of adenocarcinoma (P<0.05). Of the 186 PSNs, 38 (20.43%) had multiple solid portions, and the long-axis diameter [odds ratio (OR): 1.301; 95% confidence interval (CI): 1.188-1.425; P<0.001], volume (OR: 1.002; 95% CI: 1.001-1.002; P<0.001), proportion based on the single largest solid portion, and the sum of multiple solid portion measurements were found to be sensitive factors in diagnosing the pathologic invasiveness of the nodules (OR >1, P<0.05), and to have an accuracy of more than 78%. Conclusions: For PSNs with multiple solid portions, measurements based on the single largest solid portion and the sum of multiple solid portions can be used to make a pathological diagnosis. Given the amount of work involved in obtaining the measurements, it is not necessary to take additional individual measurements of each solid portion.