RESCALE: Voxel-specific task-fMRI scaling using resting state fluctuation amplitude

• Published in: NeuroImage (Orlando, Fla.) Vol. 70; pp. 80 - 88
• Main Authors: Kalcher, Klaudius, Boubela, Roland N., Huf, Wolfgang, Biswal, Bharat B., Baldinger, Pia, Sailer, Uta, Filzmoser, Peter, Kasper, Siegfried, Lamm, Claus, Lanzenberger, Rupert, Moser, Ewald, Windischberger, Christian
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Inc 15.04.2013; Elsevier; Elsevier Limited; Academic Press
• Subjects: Amplitudes; Biological and medical sciences; Cortexes; Estimates; Experiments; fALFF; Female; Fluctuation; Functional magnetic resonance imaging; Fundamental and applied biological sciences. Psychology; Humans; Magnetic Resonance Imaging; Male; Medical research; Motor Cortex - physiology; Motors; NMR; Nuclear magnetic resonance; Paradigms; Physiology; Respiration; Resting-state; Scaling; Statistics; Studies; Task Performance and Analysis; Tasks; Vertebrates: nervous system and sense organs; Visual; Visual Cortex - physiology; Young Adult; Functional magnetic resonance imaging; Resting-state; Scaling; fALFF; Nuclear magnetic resonance imaging; Functional imaging
• ISSN: 1053-8119; 1095-9572; 1095-9572
• DOI: 10.1016/j.neuroimage.2012.12.019

The BOLD signal measured in fMRI studies depends not only on neuronal activity, but also on other parameters like tissue vascularization, which may vary between subjects and between brain regions. A correction for variance from vascularization effects can thus lead to improved group statistics by reducing inter-subject variability. The fractional amplitude of low-frequency fluctuations (fALFF) as determined in a resting-state scan has been shown to be dependent on vascularization. Here we present a correction method termed RESCALE (REsting-state based SCALing of parameter Estimates) that uses local information to compute a voxel-wise scaling factor based on the correlation structure of fALFF and task activation parameter estimates from within a cube of 3×3×3 surrounding that voxel. The scaling method was used on a visuo-motor paradigm and resulted in a consistent increase in t-values in all task-activated cortical regions, with increases in peak t-values of 37.0% in the visual cortex and 12.7% in the left motor cortex. The RESCALE method as proposed herein can be easily applied to all task-based fMRI group studies provided that resting-state data for the same subject group is also acquired. ► RESCALE is a scaling method to reduce between-subject variance in task-fMRI. ► At single-subject level, local scaling factors are computed for each voxel. ► Scaling factors are based on linear relation between fALFF and parameter estimates. ► RESCALE was evaluated in a visuo-motor paradigm. ► RESCALE increased peak t-values by 37% in visual areas and 12.7% in motor areas.