SNMMI, Alzheimer’s Association: Amyloid imaging OK for some

The Society of Nuclear Medicine and Molecular Imaging (SNMMI) and the Alzheimer’s Association published appropriate use criteria for amyloid imaging Jan. 28 in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association and The Journal of Nuclear Medicine.

“As amyloid imaging becomes more prevalent in clinical settings, medical professionals must understand how to appropriately utilize the test,” Frederic H. Fahey, DSc, SNMMI president, said in a release. “Neurology and dementia experts should order the test only when appropriately indicated, and nuclear medicine and molecular imaging professionals must ensure they have been adequately trained to interpret the results of the scan. Working together, we hope that the information garnered from amyloid PET imaging will aid in diagnosis and play a pivotal role in the development of new treatments for Alzheimer’s.”

The organizations convened an Amyloid Imaging Tasksforce (AIT) comprised of dementia and imaging experts to review the research and develop consensus recommendations for amyloid imaging. The AIT emphasized early data are limited and have been focused on validation of the exam rather than clinical practice. “Translation of research findings to clinical populations poses substantial challenges,” they wrote.

Nevertheless, the AIT determined that amyloid imaging is appropriate for individuals with the following characteristics:

• Patients with persistent or progressive unexplained mild cognitive impairment;
• Patients satisfying core clinical criteria for possible Alzheimer’s disease (AD) because of unclear clinical presentation, either an atypical clinical course or an etiologically mixed presentation; and
• Patients with progressive dementia and atypically early age of onset (usually 65 years old or younger).

Amyloid imaging is inappropriate in the following situations, according to the AIT:

• Patients with core clinical criteria for probable AD with typical age of onset;
• To determine dementia severity;
• Based solely on family history of dementia or presence of apolipoprotein E;
• Patients with a cognitive complaint that is unconfirmed on clinical exam;
• In lieu of genotyping for suspected autosomal carriers;
• In asymptomatic individuals; and
• Nonmedical use (e.g. legal, insurance coverage or employment screening).

The AIT detailed three conditions for appropriate use. A dementia expert must evaluate the patient and determine objective evidence of impairment. This expert should review all available clinical evidence and all available lab and neuroimaging data.

Finally, the expert must conclude that an amyloid-positive or amyloid-negative scan would increase the level of diagnostic certainty and alter the patient management plan. A more certain diagnosis might reduce additional testing to establish a diagnosis or inform earlier and more consistent drug treatment. The diagnosis also may help patients and their families plan for future management.

The AIT emphasized that physicians performing amyloid imaging must be trained in amyloid PET interpretation, and reports should be communicated to referring physicians according the SNMMI general imaging guideline.

Finally, the guideline authors called for additional investigation of brain FDG PET, cerebrospinal fluid measures and combined presynaptic dopaminergic imaging in relation to amyloid PET.

For more about amyloid imaging in practice, please read “Florbetapir: What It Means for Dementia Evaluation."