Image-based method for retrospective correction of physiological motion effects in fMRI: RETROICOR

TLDR

Respiration and cardiac pulsatility induce signal modulations in fMRI that increase noise and reduce activation significance. The study presents a simple image‑based correction method that avoids the limitations of k‑space approaches for high‑frequency correction. Low‑order Fourier series are fit to the image data using cardiac and respiratory phase information obtained from a photoplethysmograph and pneumatic belt. RETROICOR effectively removes respiration‑ and cardiac‑induced noise without spatial filtering, as shown in resting‑state experiments on three subjects compared to the k‑space method. © 2000 Wiley‑Liss, Inc.

Abstract

Respiration effects and cardiac pulsatility can induce signal modulations in functional MR image time series that increase noise and degrade the statistical significance of activation signals. A simple image-based correction method is described that does not have the limitations of k-space methods that preclude high spatial frequency correction. Low-order Fourier series are fit to the image data based on time of each image acquisition relative to the phase of the cardiac and respiratory cycles, monitored using a photoplethysmograph and pneumatic belt, respectively. The RETROICOR method is demonstrated using resting-state experiments on three subjects and compared with the k-space method. The method is found to perform well for both respiration- and cardiac-induced noise without imposing spatial filtering on the correction. © 2000 Wiley-Liss, Inc.