I am excited that an amyloid imaging agent will now be available
because there are instances where my patients, their families, and I
would appreciate the specific information about Alzheimer's disease
that it would provide. My hope is that ordering and interpretation of
amyloid imaging will be limited to physicians skilled in the diagnosis
of dementia. I am worried about the many possibilities for misuse of
the test. Even if a nuclear medicine physician has taken the course
provided by Lilly, any physician who has low instances of contact with
the test is likely to make mistakes in interpretation.
Risks for overdiagnosis of Alzheimer's are worrisome, especially when
the amyloid imaging is not interpreted in light of the clinical history.
For example, up to 30 percent of cognitively normal people over age 70
years are expected to have a "positive" scan. As most physicians and
most lay people do not understand the distinction between "Alzheimer's disease" and "dementia," hearing the former is likely to be misinterpreted as
View all comments by David Knopman
The approval of PET amyloid imaging for clinical use is definitely an
important step forward for the field. I think PET amyloid imaging will
prove useful in the clinic, especially for those difficult dementia cases—younger patients, unusual clinical presentations, or apparently rapid
progressing dementias. Probably the most helpful information right now
will be in those cases where the scan is negative, as the evidence
suggests that a negative amyloid scan makes the diagnosis of Alzheimer's
disease dementia much less likely and other causes of dementia should be
We need more research to understand the positive predictive
value of PET amyloid imaging, particularly as we move earlier in the
disease process into early mild cognitive impairment. I do not think we
should use amyloid imaging as a screening tool in clinically normal
individuals at this point, as we don't have enough data to quantify the
increase in risk or the timeframe for progression towards AD dementia, but
hopefully that research will continue to help us understand the
preclinical stages of AD.
View all comments by Reisa Sperling
There is a lot of excitement now that Eli Lilly announced that the U.S. Food and Drug Administration had approved Amyvid for use as a diagnostic modality for Alzheimer’s disease (AD). This certainly is a tremendous advance for the Alzheimer’s field. There is no doubt that neurologists and other specialists trained in dementia evaluation will greatly benefit from utilizing Amyvid to distinguish AD from other causes of dementia. Dementia specialists agree that good clinical practice mandates that they add this test to their routine dementia workup strategy and not substitute the standard dementia workup with Amyvid scans. (A routine dementia workup typically consists of detailed neurological and cognitive evaluation, a structural scan of the brain for evaluation of reversible causes for cognitive decline and vascular changes, and targeted laboratory workup for other potential causes for cognitive decline.)
It seems that Amyvid scans will mostly aid physicians in diagnosing or ruling out dementia of the Alzheimer’s type, especially in complex and challenging cases of dementia...