Another tool that can help diagnose Alzheimer's disease is amyloid positron emission tomography (PET) imaging. Amyloid PET imaging uses a radiolabeled tracer that sticks to amyloid plaques, biological markers of the disease that were previously only visible via autopsy.
PET tracers are extremely hard to produce. “With such a short half-life you cannot stock these agents. Eventually you have to make a sterile injectable drug that's radioactive and administered to the patient all within about an eight-hour span," said Paul Gotti, vice president of Operations for Nuclear & Precision Health Solutions at Cardinal Health. Cardinal Health produces PET tracers in 31 facilities across the United States.
In a recent study of 11,000 Medicare patients, amyloid PET imaging led clinicians to change their diagnosis for more than a third of their difficult-to-diagnose patients. The scans also changed clinicians' medical management of patients in nearly two out of three cases, primarily causing them to change whether or not they prescribed Alzheimer's drugs.
This is crucial because some drugs currently prescribed to patients diagnosed with Alzheimer's can be detrimental in other conditions. “That's why it's important right now [to do PET amyloid imaging] in those very difficult-to-diagnose patients," said Luke Augustine, vice president of New Business Development for Nuclear & Precision Health Solutions at Cardinal Health.
Amyloid PET imaging is already widely used in clinical trials for Alzheimer's disease. “Most of these clinical trials in the past were set up looking for 'The Cure,'" said Augustine. “Today the majority of the clinical trials are looking to slow progression of the disease, which makes the use of amyloid PET imaging and tau PET imaging that much more important."
While amyloid PET tracers are approved by the FDA, their use in diagnosing Alzheimer's is not currently covered by Medicare. That may change soon. The second phase of this study will determine whether amyloid PET imaging changes patient outcomes.