Abstract
Global and regional cortical thicknesses based on T1-weighted magnetic resonance images acquired at 1.5 T and 3 T were measured on a relatively large cohort of 295 subjects using FreeSurfer software. Multivariate regression analysis was performed using Pillai's trace test to determine significant differences in cortical thicknesses measured at these two field strengths. Our results indicate that global cortical thickness is not affected by the field strength or gender. In contrast, the regional cortical thickness was observed to be field dependent. Specifically, the cortical thickness in regions such as parahippocampal, superior temporal, precentral and posterior cingulate is thicker at 3 T than at 1.5 T. In contrast regions such as cuneus and pericalcarine showed higher cortical thickness at 1.5 T than at 3 T. These differences appear to be age-dependent. The differences in regional cortical thickness between field strengths were similar in both genders. Further, male vs. female differences in regional cortical thickness were observed only at 1.5 T and not at 3 T. Our results indicate that magnetic field strength has a significant effect on the estimation of regional, but not global, cortical thickness. In addition, the pulse sequence, scanner type, and spatial resolution do not appear to have significant effect on the measured cortical thickness.
Highlights
Global and regional cortical thicknesses provide valuable insight into normal brain development and the effect of various neurological and neuropsychiatric disorders
In an earlier study that mainly focused on comparing cortical thickness between relapsing-remitting multiple sclerosis (MS) and normal controls, we investigated cortical thickness, its age-dependence and the effect of gender and field strength in a sample of 125 normal controls [13]
Our results indicate that field strength has a significant effect on the measured regional cortical thickness and that these differences seem to be influenced by gender
Summary
Global and regional cortical thicknesses provide valuable insight into normal brain development and the effect of various neurological and neuropsychiatric disorders. Cortical thickness is an intrinsic biological parameter and should be independent of external factors such as the MRI scanner type, imaging sequence, spatial resolution and/or field strength. Published studies evaluated the effect of such external factors on the measured cortical thickness. Study by Han et al [11], based on a small population of 15 subjects, reported that the mean or global cortical thickness was up to 0.17 mm higher at 3 T compared to 1.5 T. Wonderlick et al [12], again based on a small sample of 11 subjects, evaluated the effect of MR pulse sequence, resolution and parallel imaging techniques on the estimation of cortical thickness and concluded that cortical thickness and volumetric measurements were reliably reproduced across differences in acquisition
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