Opportunistic CT Screening: Clinical Applications, Technical Foundations, and Best Practices

Opportunistic CT screening refers to the extraction of clinically relevant imaging biomarkers from CT examinations routinely performed for unrelated primary indications. This screening does not require additional radiation exposure, imaging time, or patient burden. Advances in automated image analysis and artificial intelligence (AI) have substantially expanded the feasibility of opportunistic CT screening across a range of conditions, including low bone mineral density, hepatic steatosis, sarcopenia, adiposity, and vascular calcifications. These biomarkers are increasingly being recognized as important contributors to fracture risk, cardiometabolic disease, and frailty; yet they often remain undiagnosed in routine clinical practice. While numerous studies have demonstrated technical feasibility and diagnostic performance, widespread clinical adoption of opportunistic CT screening remains limited. Key challenges include those related to workflow integration, standardization of measurement techniques, quality assurance, interpretability of results, and uncertainty regarding downstream clinical management and value. In particular, not all opportunistic imaging biomarkers are equally actionable, and inappropriate or indiscriminate reporting may contribute to overdiagnosis or unnecessary follow-up. The authors summarize common applications of opportunistic CT screening, highlighting typical imaging findings and biomarkers. The authors discuss the evolution of automated and AI-based approaches, with emphasis on practical considerations for deployment, including pre- and postdeployment quality assurance, algorithm monitoring, and practical considerations for clinical integration. Emerging applications also are reviewed, with attention to current limitations. With a focus on clinical integration, this review is intended to inform radiologists, informaticians, and others working in health care systems who seek to translate opportunistic CT screening from proof-of-concept studies into scalable, clinically meaningful practice.