Amyloid-β PET scans have great clinical value in diagnosing dementia patients, according to new studies reported at the Alzheimer's Association International Conference (AAIC) 2017 in London.

The findings revealed that the scans altered the diagnosis in two thirds of the patients, which flies in the face of “the prevailing wisdom, [which] has been that PET imaging does not provide sufficient additional diagnostic accuracy to justify its cost,” according to an association statement.

The studies determined that brain PET imaging “allows for more accurate detection or exclusion of Alzheimer's in a larger proportion of individuals than standard clinical assessment supported by structural and metabolic imaging, and cerebrospinal fluid.”

"A negative brain PET scan indicating sparse to no amyloid plaques rules out Alzheimer's disease as the cause of dementia symptoms,” said Dr. James A. Hendrix, Alzheimer's Association director of Global Science Initiatives.

At the meeting it was reported that an analysis of Medicare claims data found that approximately 60 percent of dementia cases were missed in clinical practice, particularly cases of early dementia.

"A swift and accurate diagnosis has a huge impact on access to Alzheimer's treatments, eligibility for research trials, plus much-needed support and information services," added Hendrix.

In one study at Oslo University Hospital, Dr. Nenad Bogdanovic, found that amyloid PET imaging was “a key contributor to either diagnosing or excluding a diagnosis of Alzheimer's disease in all 50 (100 percent) of participants.”

This compared to CSF amyloid testing, which permitted clinicians to make a diagnosis or exclusion in 88 percent of patients with a higher detection cutoff, and in only 42 percent using traditional cutoffs.

Another small study of a 135 people by doctoral student Antoine Leuzy, MSc, of Karolinska Institute in Stockholm, showed that 68 percent of 61 individuals with mild cognitive impairment had a change in diagnosis after PET scanning.

Another study by Dr. Enrico Fantoni of GE Healthcare in Amersham, U.K., looked at data from previous clinical trials, from 2000 to 2017, of brain amyloid PET scans. It found that the PET scans led to a diagnosis change in 20 percent of the individuals.

This makes the PET scanning “a valuable tool to clarify an uncertain or difficult diagnosis," advised Hendrix, adding, that misdiagnosis is “costly” to health systems, and “expensive and distressing” to those suffering with dementia as well as their families.

“Diagnosing dementia is a complex challenge, and doctors have to gather a range of clues to create a picture of what is going on in the brain,” Dr. David Reynolds, chief scientific officer at Alzheimer’s Research UK told the Telegraph.

Noting that the new research “highlights” the value of amyloid brain scans, he advised that they can improve diagnoses, “either by indicating or ruling out Alzheimer’s as the possible cause of someone’s dementia symptoms.”

In June, German researchers reported at the SNMMI 2017 meeting in Denver that less testing was needed when using dual time-point PET imaging to diagnose Alzheimer’s disease.

“We were motivated to conduct this research by the facts that Alzheimer’s disease is a growing health care concern, that it is known that imaging-based and other biomarkers can support Alzheimer’s diagnosis, and that so far the imaging-based acquisition of both Alzheimer’s biomarker categories (amyloid pathology and neuronal injury) requires two separate imaging sessions,” Dr. Henryk Barthel, assistant medical director at the Department of Nuclear medicine at the University of Leipzig, told HCB News.

“With our research we show that it might be possible in the future to obtain this dual Alzheimer’s biomarker information out of the application of one single PET tracer by imaging the patient’s brain in dual time-windows within one session,” Barthel said. “This approach will increase patient convenience and might increase patients' and caregivers' acceptance of the diagnosis.”