The major goals of this Alzheimer’s Disease Neuroimaging Initiative (ADNI) are to:
- Develop improved methods, which will lead to uniform standards for acquiring longitudinal multisite MRI and PET data on patients with Alzheimer’s disease (AD), mild cognitive impairment (MCI), and controls.
- Acquire a generally accessible data repository, which describes longitudinal changes in brain structure and metabolism. In parallel, acquire clinical, cognitive and biomarker data for validation of imaging surrogates.
- Determine those methods, which provide maximum power to determine treatment effects in trials involving these patient populations.
The Dementia Research Group, London will perform image analysis of MR scans a) for the initial preparation phase of the study and support ongoing assurance of MR acquisition quality and stability and b) to provide atrophy rate measurements of all 0,6 and 12 month scans. Consistency of MR acquisition is essential for meaningful analyses of change. To this end each MR site will need to demonstrate that, in addition to performing scans of sufficient quality, they are also able to perform sufficiently reproducible acquisitions throughout the study. Each site will be assessed with registration of serial imaging of real subjects at the preparation/qualification phase and then again prior to every time point. Control, AD and MCI subjects will be rescanned at each site and the scan-rescan pairs will be accurately registered (positionally matched). Short interval scan pairs will be used to detect MR machine noise (same day scans), machine drift and operator consistency (1-2 week intervals). All registered scans will be analyzed to detect changes in acquisition parameters, image contrast and homogeneity or voxel dimensions and brain volume differences. Normative data will be used to define acceptable levels of variance and rates of change. In conjunction with other members of the consortium working on MR quality assurance, Dr Fox will work closely with the sites to correct problems that occur in terms of variation in acquisition. Registration-based measures of rate of brain atrophy and ventricular change (using the boundary shift integral) will be derived from all 200 AD and 400 MCI subjects and 200 controls for 0,6 and 12 month time point structural MR scans. Rates of change will be available for comparison with other MR and PET analyses and with the clinical measures. All pre-processing steps and brain regions derived as part of image processing will be made fully accessible.
For more information, you can visit the ADNI website http://www.adni-info.org