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Doctors might soon be able to screen for Alzheimer's disease without the use of radiation and a contrast agent, a new study reported. A team of radiologists discovered that a brain imaging method, called arterial spin labeling, which is a type of magnetic resonance imaging (MRI) could detect biomarkers of dementia in older adults before symptoms develop.

"ASL MRI is simple to perform, doesn't require special equipment and only adds a few minutes to the exam," said study author Sven Haller, M.D., from the University of Geneva in Geneva, Switzerland, reported in the press release.

For this study, the researchers recruited two groups of older adults: 148 without any neuropsychiatric illness and 65 with mild cognitive impairment. All of the participants underwent arterial spin labeling, which examines blood flow in the posterior cingulate cortex. The researchers also used two neuropsychological tests to assess mental health. The tests were done at the beginning of the study and then at the 18-month mark.

In the first group of participants, 75 of them had stable cognitive function and the remaining 73 had "deteriorating cognitive function" by the 18-month mark. When the researchers compared the results of these two subgroups' arterial spin labeling scans during baseline, they found that the group with deteriorating health already had signs of mental decline. Their brain scans revealed significantly low blood flow. Low blood flow was also apparent in the scans of the adults from the mild cognitive decline group.

"There is a known close link between neural activity and brain perfusion in the posterior cingulate cortex," Dr. Haller said. "Less perfusion indicates decreased neural activity."

The team concluded that the ASL MRI could potentially be used as a standalone test to predict Alzheimer's risk. ASL MRI could also be used as an add-on test to positron emission tomography (PET), which assesses Alzheimer's risk through brain metabolism imaging.

"ASL might replace the classic yet unspecific fluordesoxyglucose PET that measures brain metabolism." Dr. Haller said.

The study was published in the journal, Radiology.