Update on the magnetic resonance imaging core of the Alzheimer's disease neuroimaging initiative

Abstract

Functions of the Alzheimer's Disease Neuroimaging Initiative (ADNI) magnetic resonance imaging (MRI) core fall into three categories: (1) those of the central MRI core laboratory at Mayo Clinic, Rochester, Minnesota, needed to generate high quality MRI data in all subjects at each time point; (2) those of the funded ADNI MRI core imaging analysis groups responsible for analyzing the MRI data; and (3) the joint function of the entire MRI core in designing and problem solving MR image acquisition, pre-processing, and analyses methods. The primary objective of ADNI was and continues to be improving methods for clinical trials in Alzheimer's disease. Our approach to the present ("ADNI-GO") and future ("ADNI-2," if funded) MRI protocol will be to maintain MRI methodological consistency in the previously enrolled "ADNI-1" subjects who are followed up longitudinally in ADNI-GO and ADNI-2. We will modernize and expand the MRI protocol for all newly enrolled ADNI-GO and ADNI-2 subjects. All newly enrolled subjects will be scanned at 3T with a core set of three sequence types: 3D T1-weighted volume, FLAIR, and a long TE gradient echo volumetric acquisition for micro hemorrhage detection. In addition to this core ADNI-GO and ADNI-2 protocol, we will perform vendor-specific pilot sub-studies of arterial spin-labeling perfusion, resting state functional connectivity, and diffusion tensor imaging. One of these sequences will be added to the core protocol on systems from each MRI vendor. These experimental sub-studies are designed to demonstrate the feasibility of acquiring useful data in a multicenter (but single vendor) setting for these three emerging MRI applications.

Figure 1

Power estimates for different scan intervals from Hua et al .

Figure 2

Association between low baseline CSF Aβ_1-42 concentrations and cortical thickness in cognitive normal elderly. Top row: cortical maps of estimated cortical thinning per unit CSF Aβ₄₂ reduction; bottom row: Significance maps from Tosun et al .

Figure 3

Association between low baseline CSF Aβ_1-42 concentrations and increased rates of cortical atrophy in MCI. Top row: Maps of estimated cortical atrophy rates per unit CSF Aβ₄₂ reduction; bottom row: Significance maps from Tosun et al .

Figure 4

Estimated sample sizes (with approximate 95% confidence intervals) needed to detect a 25% reduction in absolute (blue bars) or relative (red bars) rate of change, at p<0.05 level, with 80% power, based on a mixed effects general linear model updated from Holland et al .

Figure 5

Genome-wide association study of temporal lobe structure from Stein et al .

Figure 6

Comparison of 3D T1-weighted image sets acquired on a healthy 35 y.o. male volunteer subject. First row: Philips MPRAGE 1.0 × 1.0 × 1.2 mm spatial resolution, acquired in 9:06. Second row: Philips accelerated MPRAGE: 1.1 × 1.1 × 1.2 mm, 5:35. Third row: GE MPRAGE (as used in ADNI-1) 1.0 × 1.0 × 1.0 mm, 9:17. Fourth row: GE IR-FSPGR 1.0 × 1.0 × 1.2 mm, 9:41. Bottom row: GE accelerated IR-FSPGR 1.1 × 1.1 ×1.2 mm, 5:34. Siemens accelerated and non-accelerated MPRAGE images, although not available on this subject, are also of high quality.