Adding MR imaging measurements of brain atrophy rates to the standard clinical evaluation bolsters the accuracy of disease progression assessment in patients with mild cognitive impairment and Alzheimer's disease, according to a study from the Mayo Clinic in Rochester, MN.
Mayo researchers measured atrophy rates of the hippocampus, entorhinal cortex, whole brain, and ventricle in 160 individuals using MR. They found MR's ability to rate atrophy was more consistent than the ability of specific tests to assess cognitive decline. The study was published in the Feb. 24 issue of Neurology.
Of the 160 subjects (aged 52 to 94 years), 55 were cognitively normal, 41 presented with mild cognitive impairment, and 64 presented with AD. All subjects underwent MR imaging at the time of the baseline clinical assessment and at follow-up one to five years later.
Atrophy rates were greater among normal subjects who subsequently developed mild cognitive impairment or AD than among those who remained cognitively stable. Rates were also greater among mild cognitive impairment subjects who developed AD than among those who remained stable and among AD patients who showed fast disease progression compared with those showing slow progression.
"No matter which brain structure or which technique we used, there was a significant correlation between the rates of brain change or atrophy and the clinical behavior of these people over time," said principal investigator Dr. Clifford R. Jack, a professor of diagnostic radiology at the Mayo Clinic.
While the measurements were done using different techniques -- some manually, others with computer-assisted guidance -- all correlated evenly with either clinical decline or lack of clinical decline, Jack said.
Investigators also estimated hypothetical sample sizes required to perform therapeutic trials for cognitive decline. Trials based on standard cognitive tests usually require large sample sizes. Those based on MR might require smaller ones, which could have important economic implications, Jack said.
"Those savings can be converted into testing more drugs," he said. "And the more drugs that are tested, the greater the probability that one will be discovered that really has a major benefit for society."
For more information from the Diagnostic Imaging archives:
