New Guidance for Gold-Standard Imaging Tests Assists Clinicians in Diagnosis and Management of Alzheimer’s and Other Dementia

- Updated Appropriate Use Criteria Released by Alzheimer's Association and
Society of Nuclear Medicine and Molecular Imaging Workgroup -

Key Takeaways

• The updated guidance helps primary care physicians, neurologists and other clinicians determine the most appropriate use of amyloid and tau PET scans, the gold-standard imaging tests for Alzheimer's disease diagnosis.
• 17 real-world scenarios help clinicians determine when these tests should be ordered.
• Amyloid and tau PET should be ordered only when the results will directly impact care, including determining the cause of cognitive issues and eligibility for new treatments.
• In this rapidly evolving field, the report reflects the latest evidence and technological advances, which are the standard against which new technology is measured.

CHICAGO, Jan. 8, 2025 - New guidance for the appropriate use of amyloid and tau positron emission tomography (PET) imaging has been published by a workgroup convened by the Alzheimer's Association and the Society for Nuclear Medicine and Molecular Imaging (SNMMI), and simultaneously published in their journals: Alzheimer's & Dementia®: The Journal of the Alzheimer's Association and The Journal of Nuclear Medicine.

Driven by the availability of new treatments for early Alzheimer's disease and the latest data on gold-standard assessment tools, the updated Appropriate Use Criteria (AUC) are designed to help clinicians diagnose and manage patients who have, or are at risk for, cognitive decline.

Amyloid PET is commonly used to detect the presence of amyloid plaques in the brain, which are linked to the development of Alzheimer's disease. Tau PET is a newer imaging technique that detects the presence of tau tangles in the brain, which are also linked to the development of dementia.

The AUC recommends that dementia specialists only use amyloid or tau PET when the results will directly impact patient care, such as determining the cause(s) of cognitive issues and eligibility for treatment. Other appropriate care-related uses include reducing the need for other diagnostic tests and helping inform decisions about patient safety, such as independent living and driving.

"The field of dementia diagnosis and treatment is evolving rapidly, and this report incorporates the latest data and technological advances in recommending the best use of amyloid and tau PET. These imaging tests can also be compared to other emerging technologies, such as blood tests," said Maria C. Carrillo, Ph.D., Alzheimer's Association chief science officer and medical affairs lead, and a co-author of the paper. "Neurologists and other clinicians rely on amyloid and tau PET, and it's important they have the most up-to-date information on when they should be used."

"Amyloid and tau PET can support and enable earlier and more accurate diagnosis, which is essential to high quality care and treatment for dementia, providing appropriate support services and future planning. The clinician should also take into consideration the person's cognitive status and age, and work with the patient and family to decide whether these tests will be helpful," said Gil D. Rabinovici, M.D., lead author of the paper, and Edward and Pearl Fein Distinguished Professor in memory and aging at the University of California San Francisco. "Based on our experience, the AUC should be considered guidelines for clinicians, not a substitute for careful clinical judgment that considers the full clinical context for each patient with cognitive complaints."

The AUC include 17 real-world scenarios in which amyloid or tau PET may be considered, with the two tests considered separately and given their own rating for each scenario. Overall, the strongest evidence for their use includes:

• Assessment and prognosis of people with mild cognitive impairment.
• Assessment of people with dementia when the cause is not clearly known.
• Determining eligibility for treatment with new disease-modifying therapies, and monitoring response to these treatments.

In most cases, these tests should not be used for:

• People who do not have cognitive impairment, even if they carry the APOE4 risk-related gene for Alzheimer's.
• Nonmedical use, e.g., for legal concerns, insurance coverage or employment screening.
• In place of genetic testing in patients suspected of carrying a disease-causing genetic mutation.

"These new criteria focus on optimizing patient care," said Kevin Donohoe, M.D., chair of SNMMI's Committee on Guidance Document Oversight. "They will help providers determine the most effective use of these important PET tracers as well as describe clinical scenarios that are not likely to benefit from PET imaging. The AUC also discuss the use of PET imaging for determining eligibility for newly introduced Alzheimer's treatments and for following treated patients for response to therapy. It is expected these AUC will reduce the need for less specific diagnostic testing and provide guidance for safety considerations."

This update is the first revision since the initial AUC for amyloid PET was introduced in 2013. PET is a medical imaging test that uses a small amount of radioactive substance (called a tracer) to highlight abnormal activity in the brain or elsewhere in the body. Currently, three tracers are approved by the U.S. Food and Drug Administration (FDA) to estimate brain amyloid plaque density in adults with cognitive impairment. The first tracer to image tau pathology in the brain was approved by the FDA in 2020.

About the Alzheimer's Association

The Alzheimer's Association is a worldwide voluntary health organization dedicated to Alzheimer's care, support and research. Our mission is to lead the way to end Alzheimer's and all other dementia - by accelerating global research, driving risk reduction and early detection, and maximizing quality care and support. Our vision is a world without Alzheimer's and all other dementia®. Visit alz.org or call 800.272.3900.

About the Society for Nuclear Medicine and Molecular Imaging

The Society of Nuclear Medicine and Molecular Imaging (SNMMI) is an international scientific and medical organization dedicated to advancing nuclear medicine and molecular imaging - vital elements of precision medicine that allow diagnosis and treatment to be tailored to individual patients in order to achieve the best possible outcomes. SNMMI's members set the standard for molecular imaging and nuclear medicine practice by creating guidelines, sharing information through journals and meetings and leading advocacy on key issues that affect molecular imaging and therapy research and practice. For more information, visit www.snmmi.org.

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