Neurology: ASL-MRI may be safer, cheaper method of diagnosing Alzheimers
 |
John A. Detre, MD, professor of neurology and radiology at the University of Pennsylvania in Philadelphia, and colleagues wanted to compare the two imaging methods’ ability to distinguish patients with AD from healthy, age-matched controls in hopes of finding safer and more accessible tools for diagnosing the disease.
"In brain tissue, regional blood flow is tightly coupled to regional glucose consumption, which is the fuel the brain uses to function. Increases or decreases in brain function are accompanied by changes in both blood flow and glucose metabolism," said Detre in a statement. "We designed ASL-MRI to allow cerebral blood flow to be imaged noninvasively and quantitatively using a routine MRI scanner."
ASL-MRI is also appealing since FDG-PET requires exposure to small amounts of a radioactive glucose analog and costs approximately four times more than an MRI study.
Fifteen patients with AD and 19 age-matched controls underwent structural MRI. Participants were injected with 5 mCi of FDG during a pseudo-continuous ASL scan, followed by PET scanning. The ability of the two modalities in distinguishing patients from controls was then evaluated using statistical parametric mapping, regions of interest (ROI) analysis and linear correlation maps of cerebral blood flow and metabolism to neuropsychological test scores.
ASL-MRI and FDG-PET provided mostly overlapping information and ROI results showed similar degrees of functional deficits. Both modalities were able to distinguish neural networks associated with different neuropsychological tests with good overlap between the two tests.
“Given its ease of acquisition and noninvasiveness, ASL-MRI may be an appealing alternative for AD studies,” wrote the authors in the study abstract.
ASL could greatly speed diagnosis as it can be incorporated into the routine upfront MRI given when Alzheimer’s is suspected. By adding about 10 to 20 minutes to test time, ASL can turn a routine clinical test into both a structural and functional test.
"If ASL-MRI were included in the initial diagnostic work-up routinely, it would save the time for obtaining an additional PET scan, which we often will order when there is diagnostic uncertainty, and would potentially speed up diagnosis," said David Wolk, MD, assistant director of the Penn Memory Center, and a collaborator on this research.
Additional studies will focus on larger sample sizes including patients with mild cognitive impairment and other kinds of neurodegenerative conditions.
Evan Godt, Writer
Evan joined TriMed in 2011, writing primarily for Health Imaging. Prior to diving into medical journalism, Evan worked for the Nine Network of Public Media in St. Louis. He also has worked in public relations and education. Evan studied journalism at the University of Missouri, with an emphasis on broadcast media.