Variability in FMRI: A Re-Examination of Intersession Differences

FMRIB Technical Report TR04SS1
(A related paper has been accepted by Human Brain Mapping)

S.M. Smith, C.F. Beckmann, N. Ramnani, M.W. Woolrich,
P.R. Bannister, M. Jenkinson, P.M. Matthews, D.J. McGonigle

Oxford Centre for Functional Magnetic Resonance Imaging of the Brain (FMRIB),
Department of Clinical Neurology, University of Oxford, John Radcliffe Hospital,
Headley Way, Headington, Oxford, UK

(DM is at Laboratoire de Neurosciences Cognitives et Imagerie
Cérébrale, Hôpital de la Salpêtrière, CNRS UPR 640 - LENA, Paris)

Abstract:

We revisit the McGonigle et al (2000) paper on intersession variability, showing that, contrary to one popular interpretation of the original paper, intersession variability is not necessarily high. We also highlight how evaluating variability on the basis of thresholded single-session images alone can be misleading. Finally, we show that the use of different first-level pre-processing, time-series statistics and registration analysis methodologies can give significantly different intersession analysis results.

Keywords: FMRI, session variability, reproducibility, longitudinal studies