CPT code 78813 represents a whole-body positron emission tomography (PET) diagnostic procedure, a nuclear imaging modality that maps physiological processes and is widely used in oncology for tumor detection, staging, and treatment monitoring. Nationally, this imaging code matters because PET studies inform critical clinical decisions for cancer care, influence downstream treatment pathways, and carry significant utilization and cost implications for commercial and public payers.

Key payers examined include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find an overview of coverage and reimbursement landscapes across major payers, common billing practices, and clinical contexts in which whole-body PET is applied. The publication summarizes typical sites of service and service definitions, presents benchmark utilization and payment considerations where available, and highlights policy trends that affect prior authorization, medical necessity criteria, and site-of-service dynamics.

This report is intended for payers, providers, billing professionals, and policy analysts seeking a concise national-level briefing on CPT code 78813, its clinical role in imaging, and the administrative factors that commonly affect claim processing and coverage determinations.