## 3 Conclusions  
The journey of NDE 4.0 is just beginning, and this Special Issue paves the way toward new horizons. How can we ensure AI earns the trust of engineers and regulators in life-or-death applications? Developing explainable models and universal validation metrics is a pressing next step. As sensor networks flood us with data, scaling NDE through cloud, edge, and fog computing beckons as an urgent challenge--and opportunity. The partnership between human inspectors and AI assistants remains uncharted; optimizing this relationship could unlock new efficiencies. With industries racing toward composites and 3D-printed parts, adapting these methods to novel materials is also worthwhile. We invite researchers, engineers, and industry pioneers to address these questions. Imagine an NDE 4.0 that does not just detect flaws but predicts and prevents them--saving time, costs, and lives. This collection is your springboard; dive in, explore, and shape the future of this vibrant field. A.O. : Writing--original draft, Writing--review and editing. V.K. : Review and editing. All authors have read and agreed to the published version of the manuscript. The authors declare no conflicts of interest. List of Contributions  
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