Searching for a clearer picture of dementia imaging

The potential for PET-based amyloid imaging to advance care of Alzheimer’s patients has excited many in the field of neuroimaging for years, yet the role of such scans has been difficult to define.

In 2013, despite FDA approval of florbetapir (Amyvid, Eli Lilly/Avid Radiopharmaceuticals) as a diagnostic PET radiopharmaceutical for Alzheimer’s, CMS was not ready to spring for full coverage. CMS’ final decision was to cover one PET scan to exclude Alzheimer’s disease only for patients participating in a clinical study under the Coverage with Evidence Development program.

While CMS was not totally convinced that PET amyloid imaging improves outcomes, these scans have changed the way physicians manage their patients, according to a study presented this week at the Alzheimer’s Association International Conference in Washington, D.C.

In the first randomized, controlled study to assess whether physicians’ decision-making is altered by images of accumulated amyloid plaques, researchers found that the management strategies for patients suspected of Alzheimer’s were more likely to change when physicians are given immediate feedback on amyloid imaging results.

More than 600 patients underwent a florbetapir PET scan and were then divided into two groups: an immediate feedback arm, in which scan results were received during a follow-up at three months, and a delayed feedback arm, in which results were not received for one year.

The study, which included subjects from the U.S., Italy and France, found that 68 percent of patients in the immediate feedback group had their management plan changed compared with 56 percent in the delayed feedback group.

After three months in the immediate feedback group, Alzheimer’s disease medication use was at 67 percent in those who were amyloid positive and 27 percent for those who were amyloid negative.

In the delayed feedback group, medication use increased regardless of amyloid status, resulting in 56 percent of amyloid positive and 43 percent of amyloid negative subject receiving treatment with cholinesterase inhibitors.

While physicians may have changed their management strategies with earlier feedback from PET scans, the study found no group differences in cognitive performance or health outcomes at one year.

There are many questions that need to be answered with regard to amyloid imaging and Alzheimer’s. One study that hopes to shed some light on the topic is the Imaging Dementia–Evidence for Amyloid Scanning Study (IDEAS).

IDEAS will enroll more than 18,000 Medicare beneficiaries to assess the clinical usefulness and impact on patient-oriented outcomes of an amyloid PET scan in patients with mild cognitive impairment or dementia of uncertain cause. A website was recently launched to help patients, providers and other get up-to-date study information and learn how to get involved.

I, like so many others, have seen firsthand what Alzheimer’s can do to a loved one, and I’ll be anxiously awaiting the results.

-Evan Godt
Editorial Director – Health Imaging