Reproducibility of Quantitative Structural and Physiological MRI Measurements
Journal Article - Open Access
Air Force School of Aerospace Medicine Wright-Patterson AFB United States
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Quantitative longitudinal magnetic resonance imaging and spectroscopy MRIS is used to assess progress of brain disorders and treatment effects. Understanding the significance of MRIS changes requires knowledge of the inherent technical and physiological consistency of these measurements. This longitudinal study examined the variance and reproducibility of commonly used quantitative MRIS measurements in healthy subjects while controlling physiological and technical parameters. Twenty-five subjects were imaged three times over 5 days on a Siemens 3T Verio scanner equipped with a 32-channel phase array coil. Structural T1, T2-weighted, and diffusion-weighted imaging and physiological pseudocontinuous arterial spin labeling, proton magnetic resonance spectroscopydata were collected. Consistency of repeated images was evaluated with mean relative difference, mean coefficient of variation, and intraclass correlation ICC. Finally, a reproducibility rating was calculated based on the number of subjects needed for a 3 and 10 difference. Structural measurements generally demonstrated excellent reproducibility ICCs 0.8720.998 with a few exceptions. Moderate-to-low reproducibility was observed for fractional anisotropy measurements in fornix and corticospinal tracts, for cortical gray matter thickness in the entorhinal, insula, and medial orbitofrontal regions, and for the count of the periependymal hyperintensive white matter regions. The reproducibility of physiological measurements ranged from excellent for most of the magnetic resonance spectroscopy measurements to moderate for permeability-diffusivity coefficients in cingulate gray matter to low for regional blood flow in gray and white matter. This study demonstrates a high degree of longitudinal consistency across structural and physiological measurements in healthy subjects, defining the inherent variability in these commonly used sequences.
- Medicine and Medical Research