Compared against autopsy results, five readers of the PET scans who were blinded to clinical data reported an overall sensitivity and specificity of 86% and 92%, respectively. In comparison against biopsy, the sensitivity and specificity of flutemetamol imaging by three separate readers who were blinded to clinical data were 93% and 100%.
The results not only confirm flutemetamol’s proclivity for beta-amyloid plaques, but also suggest the possibility that imaging could someday improve diagnostic accuracy and help pinpoint treatment decisions.
"In a prior study, we found that people with NPH and concomitant Alzheimer’s have a poor response to shunting," Dr. Wolk said. "If a patient gets a shunt and doesn’t get better, we typically do another shunt. But in someone who also has Alzheimer’s, we would be less inclined to do another procedure."
In a separate study of 11 community-dwelling older adults, Dustin Hammers, Ph.D., and his colleagues compared the relationship between flutemetamol uptake and cognitive status. All of the participants (eight women and three men with a mean age of 76 years) had a prior complaint of memory loss.
In these subjects, flutemetamol uptake was significantly related to several cognitive domains, including auditory delayed memory, processing speed, mental flexibility, and semantic fluency. Cognitive performance worsened with greater uptake of flutemetamol.
"Flutemetamol uptake was highly related to worse cognitive performance on tasks traditionally impaired in patients with Alzheimer’s disease, but not in others," said Dr. Hammers, a neuropsychologist at the University of Utah’s Center for Alzheimer’s Care, Imaging, and Research in Salt Lake City.
"What we found really interesting is that this was a population of normal, elderly adults who had no cognitive problems except for a prior complaint of some memory issue," he said in an interview. "The results clearly fall in the direction of what we would expect to see in Alzheimer’s, although clearly they were in a preclinical state."
The florbetaben study was sponsored by Bayer Pharma AG. Dr. Sabbagh said that he had no financial disclosures. Dr. Wolk’s study was sponsored by GE Healthcare. He has received personal compensation from the company for consulting activities. GE Healthcare partly sponsored Dr. Hammer’s study. Dr. Hammer had no financial disclosures.