Consolidation-to-Tumor Ratio (CTR) Versus Tumor Disappearance Rate (TDR) for the Differential Diagnosis of Minimally Invasive and Invasive Pulmonary Adenocarcinoma Arising From Part-Solid Nodules

OBJECTIVE: This study aimed to compare the diagnostic performance of consolidation-to-tumor ratio (CTR) and tumor disappearance rate (TDR) for differentiating minimally invasive adenocarcinoma (MIA) from invasive adenocarcinoma (IAC) in patients with part-solid nodules (PSNs), and to identify their optimal cutoff values as well as clinical application value. METHODS: A retrospective analysis was performed on 206 patients with pathologically confirmed pulmonary adenocarcinoma from PSNs who underwent chest CT and surgical resection between January 2023 and December 2025. They were divided into the MIA group and IAC group based on postoperative pathology. Two experienced radiologists independently measured and calculated CTR and TDR on 1-mm-thick CT images. ICC evaluated interobserver consistency; independent-samples t test or Mann-Whitney U test compared group differences; ROC curve analyzed diagnostic efficacy; multivariate Logistic regression identified independent diagnostic factors. RESULTS: CTR and TDR had excellent interobserver consistency (ICC=0.912 and 0.905, both P<0.001). IAC group had significantly higher CTR [(0.60±0.13) vs. (0.32±0.11), P<0.001] and lower TDR [(0.34±0.16) vs. (0.65±0.14), P<0.001] than MIA group. ROC analysis showed AUC of CTR was 0.893 (95% CI: 0.857-0.935, cutoff=0.48, sensitivity=85.7%, specificity=83.5%) and TDR was 0.902 (95% CI: 0.862-0.938, cutoff=0.52, sensitivity=85.8%, specificity=87.6%), with no significant AUC difference (P=0.375). Both CTR (OR=18.785, P<0.001) and TDR (OR=0.126, P<0.001) were independent diagnostic factors. CONCLUSION: TDR and CTR have comparable diagnostic efficacy in differentiating minimally invasive adenocarcinoma (MIA) from invasive adenocarcinoma (IAC) in part-solid pulmonary nodules. Both TDR and CTR are independent diagnostic factors for distinguishing MIA from IAC.