title: The quest for the best: The impact of different EPI sequences on the sensitivity of random effect fMRI group analyses.
abstract: We compared the sensitivity of standard single-shot 2D echo planar imaging (EPI) to three advanced EPI sequences, i.e., 2D multi-echo EPI, 3D high resolution EPI and 3D dual-echo fast EPI in fixed effect and random effects group level fMRI analyses at 3T. The study focused on how well the variance reduction in fixed effect analyses achieved by advanced EPI sequences translates into increased sensitivity in the random effects group level analysis. The sensitivity was estimated in a functional MRI experiment of an emotional learning and a reward based learning tasks in a group of 24 volunteers. Each experiment was acquired with the four different sequences. The task-related response amplitude, contrast level and respective t-value were proxies for the functional sensitivity across the brain. All three advanced EPI methods increased the sensitivity in the fixed effects analyses, but standard single-shot 2D EPI provided a comparable performance in random effects group analysis when whole brain coverage and moderate resolution are required. In this experiment inter-subject variability determined the sensitivity of the random effects analysis for most brain regions, making the impact of EPI pulse sequence improvements less relevant or even negligible for random effects analyses. An exception concerns the optimization of EPI reducing susceptibility-related signal loss that translates into an enhanced sensitivity e.g. in the orbitofrontal cortex for multi-echo EPI. Thus, future optimization strategies may best aim at reducing inter-subject variability for higher sensitivity in standard fMRI group studies at moderate spatial resolution.
authors.affiliation: Neurocomputation and Neuroimaging Unit, Department of Psychology and Educational Science, Free University Berlin, Habelschwerdter Allee 45, 14195 Berlin, Germany; Department of Neurophysics, Max Planck Institute for Human Cognitive and Brain Sciences, Stephanstrasse 1a, 04103 Leipzig, Germany. Electronic address: Evgeniya.Kirilina@fu-berlin.de.
authors.forename: Evgeniya
authors.initials: E
authors.lastname: Kirilina
authors.affiliation: Laboratoire de Recherche en Neuroimagerie, Département des Neurosciences Cliniques, Centre Hospitalier Universitaire Vaudois, Chemin de Mont Paisible 16, 1011 Lausanne, Switzerland; Wellcome Trust Centre for Neuroimaging, UCL Institute of Neurology, University College London, 12 Queen Square, London WC1N 3BG, UK.
authors.forename: Antoine
authors.initials: A
authors.lastname: Lutti
authors.affiliation: Department of Cognitive Neuroscience, Maastricht Brain Imaging Centre, Faculty of Psychology & Neuroscience, Maastricht University, PO Box 616, 6200MD Maastricht, The Netherlands.
authors.forename: Benedikt A
authors.initials: BA
authors.lastname: Poser
authors.affiliation: Neurocomputation and Neuroimaging Unit, Department of Psychology and Educational Science, Free University Berlin, Habelschwerdter Allee 45, 14195 Berlin, Germany.
authors.forename: Felix
authors.initials: F
authors.lastname: Blankenburg
authors.affiliation: Department of Neurophysics, Max Planck Institute for Human Cognitive and Brain Sciences, Stephanstrasse 1a, 04103 Leipzig, Germany; Wellcome Trust Centre for Neuroimaging, UCL Institute of Neurology, University College London, 12 Queen Square, London WC1N 3BG, UK.
authors.forename: Nikolaus
authors.initials: N
authors.lastname: Weiskopf
mesh_terms: D000328:Adult; D054022:Cerebrum / Q000502:physiology*; D017352:Echo-Planar Imaging / Q000379:methods*; D004644:Emotions / Q000502:physiology*; D005149:Facial Expression; D005260:Female; D059907:Functional Neuroimaging / Q000379:methods*; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D007858:Learning / Q000502:physiology*; D008297:Male; D012201:Reward; D012680:Sensitivity and Specificity; D055815:Young Adult
keywords: 3D EPI; Echo planar imaging (EPI); Inter-subject variability; Multi-echo EPI; Random effects analysis; fMRI sensitivity