The Role of Amyloid-β and Tau PET in the New Era of Alzheimer Disease Therapies.

The advent of amyloid-β (Aβ) and tau PET imaging has revolutionized Alzheimer disease (AD) research, enabling in vivo detection of hallmark pathologies and transforming both diagnosis and therapeutic development. These imaging modalities have played a central role in the clinical trials that led to the recent approval of Aβ-targeting therapies, with Aβ PET used for participant selection and treatment monitoring and tau PET increasingly integrated to assess disease staging and prognosis. This continuing-education article reviews the current clinical validation of Aβ and tau PET imaging in AD, outlines the available evidence for the recently approved anti-Aβ therapies, and examines how PET imaging was operationalized in the trials for these novel therapeutic agents. We explore the potential for translating trial-based imaging protocols into clinical practice-particularly how PET quantification beyond binary visual reads can support nuanced decisions regarding patient eligibility, risk stratification, therapeutic monitoring, and duration of treatment. In addition, we discuss the emerging landscape of tau-targeting therapies and the anticipated central role of tau PET in their clinical evaluation. Finally, we identify key knowledge gaps and unmet needs that must be addressed to facilitate broader clinical adoption of PET imaging, including standardization efforts, accessibility and reimbursement, and evidence-based guidelines for interpretation and use.