Automated MRI technique could expedite Alzheimer’s diagnosis
An automated system to measure brain tissue volume with MRI has shown promise as a tool for the rapid and accurate diagnosis of Alzheimer’s disease at an earlier stage, according to a study conducted at the Cognitive Neuroscience and Brain Imaging Laboratory, Centre National de la Recherche Scientifique in Paris. Early diagnosis of the disease could enable earlier treatment with medication that has been shown to delay the condition’s progress.
In Alzheimer’s disease, it is known that the brain exhibits atrophy and that the hippocampus region is affected at the earliest stages. MRI has enabled scientists to visualize these anatomical changes in the brain, but the standard practice of measuring brain tissue volume, called segmentation, is complicated and time-consuming and, consequently, has not been used routinely in the clinical setting. Studies have shown manual segmentation of the hippocampus to be highly effective in distinguishing patients with Alzheimer’s disease from a control group. The manual, or visual, method of evaluating atrophy on multiplanar magnetic resonance images is, however, difficult and prone to subjectivity, and it requires extensive anatomic training.
These MR images show automated hippocampal segmentation, a technique that could be used routinely in clinical settings to diagnose Alzheimer’s disease. From left to right are coronal and sagittal reconstructions of a patient with Alzheimer’s disease, and coronal and sagittal reconstructions of a healthy control. Reprinted with permission of Radiology.
As reported in the July 2008 issue of Radiology, researchers used computer software to perform an automated segmentation process to measure the volume of the hippocampus in 25 patients with Alzheimer’s disease, in 24 patients with mild cognitive impairment, and in 25 healthy older adults. They found that Alzheimer’s patients and those with mild cognitive impairment had an average volume loss in the hippocampus of 32 and 19 percent, respectively. Similar results were reported in studies using manual segmentation methods.
The investigators concluded that automated segmentation of the hippocampus, which can be performed within minutes, versus the hour required by the manual method, could be combined with other clinical and neuropsychological evaluations for the early diagnosis of Alzheimer’s disease.
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