K. Kalcher, R. Boubela, W. Huf, B. Biswal, P. Baldinger, U. Sailer, P. Filzmoser, C. Kasper, C. Lamm, R. Lanzenberger, E. Moser:
"RESCALE: Voxel-specific Task-fMRI Scaling Using Resting State Fluctuation Amplitude";
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.
Functional magnetic resonance imaging; Resting-state; fALFF; Scaling
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