Panel reports first global harmonized protocol to measure key brain region tied to memory
An international panel of experts has developed the first global harmonized protocol for measuring a key region of the brain tied to memory, according to research reported at the Alzheimer's Association International Conference 2012 in Vancouver.
The harmonized protocol for measuring the hippocampus, development of which was funded by the Alzheimer's Association, will be presented for review and input at the conference and then validated with data derived from healthy and diseased brain tissues and compared for accuracy and consistency against protocols currently used in Alzheimer's research.
The hippocampus is a part of the brain important for memory. Changes in the size of the hippocampus measured by MRI may prove to be a key biomarker for Alzheimer's disease. For example, measurements of hippocampal atrophy may be used to help select research subjects with greater likelihood of progression to Alzheimer's for participation in clinical trials.
"However, different methods of data gathering and analysis around the world lead to different size estimates, hampering comparison of studies and clinical use," said Maria Carrillo, Ph.D., Alzheimer's Association senior director of medical and scientific relations. "Thus, there is an urgent need to define a global harmonized protocol for measurement of the hippocampus."
To prepare the harmonized protocol, neurologist Giovanni Frisoni, M.D., of the National Alzheimer's Center in Italy and colleagues first surveyed the 12 most used protocols for the manual segmentation of the hippocampus in Alzheimer's literature. They divided the hippocampus into several blocks (segmentation units, or SUs) and measured how informative and reliable each block was in the measurement of Alzheimer's-related atrophy.
This data was given to a panel of 16 international experts in hippocampal segmentation who developed the first draft of the harmonized protocol. This draft protocol was provided to five independent international research centers who were asked to segment a sample of 40 brains using the methods and landmarks described in the harmonized protocol. These "benchmark" MRI images were used to improve the protocol— to reduce ambiguity, aid comprehension and improve compliance with the protocol, and provide reference descriptions and images to assist with future problem solving.
"The availability of a standard and shared protocol for hippocampal volumetry measured on magnetic resonance images provides researchers with an international standard of measurement that will help validate the new Alzheimer's diagnostic criteria and encourage their use in clinical settings, enable comparisons of the effect of disease modifying drugs, and represent the gold standard for automated segmentation algorithms," Frisoni said.