[18F]F-AraG PET Imaging of Immunometabolic Activity in Individuals Without Malignancy.

Abstract

[¹⁸F]F-AraG is a clinical-stage PET tracer in immuno-oncology that accumulates in activated T cells and tissues with high mitochondrial biogenesis. Characterizing its distribution in individuals without malignancy is essential for interpreting immunometabolic states relevant to cancer biology. Methods: Twenty adults without active malignancy underwent a single [¹⁸F]F-AraG PET/CT scan, with tracer uptake assessed in relation to clinical history, medications, and demographic and physiologic factors. Results: Bilateral brown adipose tissue activation was identified in 3 participants receiving potentially brown adipose tissue-activating medications, in the absence of cold exposure or fasting. One showed elevated vertebral bone marrow uptake, previously linked to poor survival in immune checkpoint inhibitor-treated lung cancer. One of 2 participants with breast implants showed asymmetric periimplant uptake. Posterior pulmonary uptake occurred in a subset of participants, often with prior respiratory conditions and thoracic lymph node uptake. Conclusion: Whole-body [¹⁸F]F-AraG PET captures diverse immunometabolic activity in individuals without malignancy, reflecting systemic processes that may influence cancer and treatment outcomes.