Postdeployment Monitoring and Surveillance Methods, Guidelines, and Possibilities for AI in Radiology.

As radiology AI systems move from predeployment validation to routine radiology practice, attention is shifting toward postdeployment monitoring and postmarket surveillance in a total product life cycle (TPLC) paradigm. In an operational sense, the human clinical oversight can be positioned along a spectrum encompassing human-in-the-loop (HITL), human-in-a-parallel loop (HIPL), human-on-the-loop (HOTL), human-over-the-loop (HOVL), and human-out-of-the-loop (HOOTL) models. Each of these models offers a trade between the verification workload and autonomy and risk. The authors provide a deeper understanding of the definitions first and then present HOTL as a pragmatic model of human-AI oversight for high-stakes imaging, demonstrating a balance between the trade-offs and benefits. The proposed monitoring system is based on two families of data points that do not require immediate determination of the ground truth, namely temporal stability of inputs and outputs and predictive divergence relative to a deployment initiation baseline. The authors also bring uncertainty quantification into the fray as a third element in helping prioritize reviews when labels are delayed or not continually feasible. The described threshold-based alerting system is paired with tiered escalation mechanisms and root cause analysis to distinguish degradation of the AI algorithm from data or integration pipeline issues. The result is an education-first proactive road map for postdeployment monitoring that allows preservation and prioritization of patient safety while enabling responsible scaling of radiology AI. ©RSNA, 2026 See the invited commentary by Rouzrokh and Rouzrokh in this issue.