Functional-based forensic surveillance: Leveraging PET and PET/MR imaging for the strategic screening of new psychoactive substances.

The rapid diversification of new psychoactive substances (NPS), often fueled by AI-driven de novo drug design, renders traditional structure-based forensic identification increasingly obsolete. This shift necessitates a transition toward receptor-based functional characterization to evaluate biological impact rather than mere molecular form. This paper proposes that leveraging preclinical PET and PET/MR imaging can provide a high-sensitivity functional filter to quantify drug-target engagement and receptor occupancy in vivo. Within this framework, a contingent screening strategy would allow direct radiolabeling to be reserved for high-priority analogs with accessible structures, while prioritizing indirect functional classification via receptor displacement assays for substances with unknown or synthetically complex scaffolds. Such a mechanism-based workflow represents a strategic opportunity for forensic resources to bypass pharmacologically inert compounds and focus exclusively on bioactive threats. By integrating AI-assisted analysis with standardized pharmacological models, including binding potential (BPnd) and distribution volume (VT), this approach can ensure forensic admissibility and offer a cost-effective, proactive solution for international Early Warning Systems. These strategic advantages position molecular imaging as a potential pillar for safeguarding public health against the next generation of synthetic psychoactive threats.