IC‐P‐053: Voxel‐based analysis of multislice quantitative T1‐rho MRI in MCI, at‐risk and control subjects

Abstract

The aim of this study is to evaluate the application of T1ρ MRI as a non-invasive method for detection of early Alzheimer disease (AD) pathology. Previous studies using single-slice/regional imaging at 1.5T have identified significant differences in macromolecular content by capturing elevated T1ρ in subjects with AD and mild cognitive impairment (MCI) (Haris et al., 2009, 2011). We aim to detect T1ρ differences on a multi-slice, voxel-wise basis at 3T in subjects with MCI, normal cognitiion (CTL) and normal cognition at risk of AD due to family history (AR) with the hypothesis that MCI/AR subjects would show longer T1ρ times in AD relevant regions. The study included 15 consented subjects (4 MCI, 5 AR and 6 CTL) group-matched on age and sex. Subjects were scanned (Philips 3T) with TE/TR = 10/2700 ms; TSL (duration of spin-lock pulse) = 20, 50 and 80 ms; locking field, B1 = ∼13 μT; slice thickness = 5 mm; slices = 12; and voxel size = 1.83 x 1.83mm. T1ρ was quantified by plotting the log of each voxel's intensity versus TSL and fitting these data to a linear function, with the slope of this function, R1ρ = 1/T1ρ. All images were spatially normalized to a standard 2mm T 2 -weighted MNI template. Random-effects one-way ANOVA and post-hoc contrasts were applied to test between-group differences in T1ρ on a voxel-wise basis. Results showed T1ρ relaxation times trending in the expected direction (MCI > AR > CTL) in several relevant brain regions. In MCI compared to CTL, T1ρ was increased in bilateral parahippocampal, hippocampal and superior temporal gyri and, in the right hemisphere, in the anterior cingulate, caudate, thalamus and middle temporal gyrus. AR subjects also showed increased T1ρ versus CTL but in a less widespread network of regions including the right middle temporal gyrus, precentral gyrus, lentiform nucleus and inferior parietal lobe. Preliminary results are reported at an uncorrected P <0.01 and a cluster size of 20 voxels. This study extended the application of T1ρ MRI to multi-slice acquisition at 3T to detect early AD-related pathology. Preliminary results support its utility as a novel biomarker for AD.