Preoperative Ki-67 proliferation index prediction with a radiomics nomogram in stage T1a-b lung adenocarcinoma

•Prediction of proliferation index of Ki-67 in stage T1a-b lung adenocarcinoma based on radiomics analysis.•Construction of radiomics signatures to predict Ki-67 proliferation index in stage T1a-b lung adenocarcinoma.•Establishment of radiomics nomogram to predict Ki-67 proliferation index in stage T1a-b lung adenocarcinoma. To establish a radiomics nomogram for preoperative prediction of Ki-67 proliferation index in stage T1a-b lung adenocarcinoma. A total of 206 patients with pathologically confirmed lung adenocarcinoma who underwent CT scans within 2 weeks preoperatively from January 2016 to June 2020 were retrospectively included. Ki-67 index ≤ 10% was considered low expression, and Ki-67 index > 10% was considered high expression. The primary cohort was randomized with a 7:3 ratio into a training cohort (n = 145) and a validation cohort (n = 61). The minimum redundancy maximum relevance (mRMR) and the least absolute shrinkage and selection operator (LASSO) were used for feature selection, and radiomics signature was constructed. Univariate and multivariate logistic regression analyses were used to identify clinically important risk factors and radiomics signature associated with Ki-67 proliferation index, which were then combined into radiomics nomogram. Tumor maximum diameter (P = 0.005), lobulation (P = 0.002), absent of vacuole (P