Diffusion dynamics of technological innovations in health: the case of an innovative medical imaging technology in France

Objectives Reports from France’s Cour des Comptes highlight a lack of aggregate data on medical imaging use. This study aims to (1) map the diffusion of PET-CT technology in France (2013–2022) and (2) identify the multi-level contextual factors explaining its uneven diffusion and utilization. Methods We employed a phased, mixed-methods design. First, we consolidated quantitative data from national databases to create aggregate proxy indicators for supply, demand, and procedures. Second, we conducted 39 semi-structured interviews with a stratified, purposive sample of key stakeholders (regulators, clinicians) and analyzed them using inductive thematic analysis. Results The supply of PET-CT technology has expanded coherently nationwide. However, its actual use varies significantly between regions, a disparity not explained by supply or epidemiological demand. This ‘supply-use’ gap is driven by interconnected factors: institutional (decentralized/distributed governance, delayed recommendations), organizational (competing ‘research’ vs. ‘access’ models of care), and professional (individual physician beliefs, variable participation in MDTs). Conclusion The diffusion of PET-CT in France challenges a purely rational model, going beyond simple supply–demand logic. It is a complex process where local institutional, organizational, and professional contexts shape trajectories. Understanding these determinants is urgent for developing equitable health policy and addressing public health challenges in nuclear medicine.