MRI Measures of Alzheimer's Disease and the AddNeuroMed Study

Abstract

Here we describe the AddNeuroMed multicenter magnetic resonance imaging (MRI) study for longitudinal assessment in Alzheimer's disease (AD). The study is similar to a faux clinical trial and has been established to assess longitudinal MRI changes in AD, mild cognitive impairment (MCI), and healthy control subjects using an image acquisition protocol compatible with the Alzheimer's Disease Neuroimaging Initiative (ADNI). The approach consists of a harmonized MRI acquisition protocol across centers, rigorous quality control, a central data analysis hub, and an automated image analysis pipeline. Comprehensive quality control measures have been established throughout the study. An intelligent web-accessible database holds details on both the raw images and data processed using a sophisticated image analysis pipeline. A total of 378 subjects were recruited (130 AD, 131 MCI, 117 healthy controls) of which a high percentage (97.3%) of the T1-weighted volumes passed the quality control criteria. Measurements of normalized whole brain volume, whole brain cortical thickness, and point-by-point group-based cortical thickness measurements, demonstrating the power of the automated image analysis techniques employed, are reported.

Novel whole brain segmentation and volume estimation using quantitative MRI

“…important in many neurological applications. Diseases such as multiple sclerosis [1][2][3], Alzheimer's disease [4] and dementia [5,6] are associated with global and local brain atrophy. A reliable volume estimation of whole-brain grey matter (GM), white matter (WM) and cerebro-spinal fluid (CSF) allows accurate individual follow-up as well as quantitative comparison with reference groups [7].…”

APOE ε2 Allele Is Associated with Larger Regional Cortical Thicknesses and Volumes

“…Finally, the MRI sites and data coordination center worked closely together with continuous feedback as data were acquired. All MRI centers were trained to perform quality control at their site at the time the images were acquired with particular emphasis on full brain coverage, image wrap around, subject motion artifacts, contrast between gray and white matter, and image nonuniformities [29] . All scanners remained within specification for the ADNI phantom throughout the course of the study.…”

Standardization of MRI and Amyloid Imaging

“…Most common artifacts specific to DTI acquisitions include large signal dropouts due to susceptibility effects, geometric distortions and misalignment among the diffusion-weighted images [63]. Although some of these artifacts can be attenuated by post-processing techniques, an initial quality control can detect severely corrupted images that have to be repeated (on-site quality control) or excluded from the study (central quality control) [126]. Besides direct quality control of the imaging output, phantom-based monitoring of individual scanner performance is an effective way to control for consistency of image quality over the course of the study [80].…”

“…A central component of multi-centric imaging studies should be a rigorous quality control, including visual and/or automated tests for typical MR imaging artifacts, such as partial coverage of the brain, blurring due to subject motion, severe image non-uniformities or irregularities in tissue contrast [122,126]. Most common artifacts specific to DTI acquisitions include large signal dropouts due to susceptibility effects, geometric distortions and misalignment among the diffusion-weighted images [63].…”