Meeting Upcoming Clinical and Diagnostic Needs in Oncologic Imaging: A Structured Reporting System for...

Fibroblast activation protein (FAP)-targeted imaging has emerged as a promising diagnostic tool for various oncologic and nononcologic conditions. However, the increasing employment of FAP-targeted imaging with small-molecule radiotracers mandates a standardized reporting system to ensure consistent interpretation across various clinical scenarios, especially in oncologic imaging. This study proposes an FAP reporting and data system (RADS) framework (FAP-RADS version 1.0) to address those needs, aiming to standardize FAP-targeted imaging reports, improve clinical communication, and support multicenter research. Methods: We conducted a comprehensive literature review and combined the findings with expert consensus in nuclear medicine to design a new scoring system based on the principles of the molecular imaging RADS framework. FAP-RADS version 1.0 is intended for use across multiple tumor types with variable radiotracer uptake patterns and is nonspecific to imaging modality (FAP PET and FAP SPECT) and radiotracer compound structure. We aimed to ensure that the system would be user-friendly and applicable to routine clinical practice. Results: FAP-RADS version 1.0 introduces a 5-point scale to assess the likelihood of malignancy in lesions based on the imaging characteristics of the lesions. The scoring system can be applied to different FAP ligands with varying pharmacokinetics. The framework does not rely on SUV thresholds, making it flexible and robust for clinical use. The implementation of this system aims to improve interdisciplinary communication, support longitudinal follow-up, and facilitate future multicenter trials. Conclusion: The proposed FAP-RADS version 1.0 is a comprehensive and flexible framework that has the potential to enhance the quality and consistency of FAP-targeted imaging interpretation in clinical practice. Its application may lead to better research outcomes, broader acceptance within the oncologic community, and streamlined regulatory processes related to FAP-based radiotracer approval.