Prospective chest CT cohort with opportunistic multidimensional phenotype capture in routine care at a tertiary hospital in western China: Protocol.

INTRODUCTION: Routine chest CT contains clinically relevant multidomain information beyond the immediate examination indication, but translation into routine care requires more than identifying individual biomarkers. This protocol describes a prospective observational cohort designed to evaluate whether technical assessability, standardised multidomain research phenotyping, routine radiology reporting and documented care can be linked reproducibly within routine clinical chest CT at a tertiary hospital in western China. METHODS AND ANALYSIS: This is a single-centre, prospective, consecutive-enrolment observational imaging cohort embedded in routine outpatient and inpatient chest CT practice rather than a dedicated screening programme. The study is organised around a scan-to-phenotype-to-report-to-care framework while retaining a phase 1 feasibility- and implementation-focused primary objective. The initial cohort target is approximately 3000 prospectively consented adults. At the time of this revision, formal recruitment has not commenced and no participant-level study data have been collected or analysed; recruitment will begin after funding and operational preparations are completed and any required ethics notification or amendment has been addressed. The core clinical-reporting layer includes pulmonary nodules, emphysema, interstitial lung abnormalities, coronary artery calcification and pulmonary artery/ascending aorta metrics. The extended measurement layer includes vertebral attenuation, vertebral deformity, thoracic muscle metrics and liver attenuation-based variables when technically assessable. Research phenotyping will be completed independently before routine-report abstraction. Primary phase 1 analyses will assess screening and enrolment flow, baseline data completeness, core phenotype assessability, report-quality abstraction completion and availability of within-system 6-month follow-up data. Secondary analyses will describe phenotype frequencies and distributions, cross-domain co-occurrence, report-quality indicators and early care-pathway documentation using prespecified operational definitions and variable-specific denominators. Descriptive estimates will be reported with 95% confidence intervals where appropriate. Follow-up will occur at 6 months, 12 months and annually thereafter using routine hospital systems. No additional research imaging is planned, and repeat chest CT is not mandated by the protocol. ETHICS AND DISSEMINATION: The study was approved by the Medical Ethics Committee of Dazhou Central Hospital, Dazhou, China (approval no. 2026(084); approved 27 April 2026), and written informed consent will be obtained before cohort enrolment and research data abstraction. Potentially actionable research-identified findings will undergo senior radiologist confirmation and, when confirmed and not already adequately addressed in routine care, will be communicated through the institutional clinical pathway. Planned outputs include a cohort profile or baseline resource paper and subsequent phenotype-specific analyses. TRIAL REGISTRATION: Not applicable. This is an observational cohort protocol rather than a clinical trial.