A Multicenter Prospective Diagnostic Accuracy Study of Three CT-Based Artificial Intelligence Models for Predicting Malignancy Risk in Pulmonary Nodules Using Pathology as the Gold Standard

Inclusion Criteria

Inclusion Criteria: * Age ≥ 18 years, any sex. * At least one pulmonary nodule detected on chest CT, with initial nodule diameter ≤ 3 cm. * The nodule undergoes surgical resection or biopsy with a definitive benign or malignant pathological diagnosis. * Time interval between CT examination and pathological examination ≤ 6 months. * Availability of complete CT imaging data in DICOM format with adequate image quality (no severe artifacts), meeting input requirements of all three AI models. Availability of complete clinicopathologic information including histologic type and grade, with clear pathological diagnosis suitable as gold standard labels for AI validation. -The patient (or legally authorized representative) is willing and able to sign written informed consent. Exclusion Criteria: * Pathological results are unclear, inconclusive, or disputed; nodule nature or grade cannot be reliably determined. * The patient receives treatments between CT and pathology that may significantly alter nodule appearance (e.g., chemotherapy, radiotherapy, targeted therapy). * CT imaging data are incomplete (missing essential series) or have severe motion, metal, or other artifacts preventing accurate AI analysis. * Required metadata for any AI model are missing and cannot be imputed. History of other malignant tumors (malignancies other than the index non-small cell lung cancer). * Severe psychiatric illness, cognitive impairment, or other conditions that prevent cooperation with study-related procedures and follow-up. Participation in another clinical study that may interfere with the results of this research. -The patient or legal representative refuses participation. Exclusion (Post-Enrollment / Removal from Analysis) Participants already enrolled may be excluded from the analysis set if: * They are later found not to meet inclusion criteria or to meet exclusion criteria. * No usable data are available after enrollment. * Required AI model assessments are not completed (e.g., technical failure to generate outputs). * Critical data are missing, preventing contribution to primary analysis. * The interval between CT and pathology exceeds 6 months.