title: Population-Level Correction of Systematic Motion Artifacts in fMRI in Patients with Ischemic Stroke.
abstract: The aim of this study was to reveal potential sources of systematic motion artifacts in stroke functional magnetic resonance imaging (fMRI) focusing on those causing stimulus-correlated motion on the individual-level and separate the motion effect on the fMRI signal changing from the activation-induced alteration at population level.
  
  
  
  Eleven ischemic stroke patients were examined by fMRI. The fMRI paradigm was based on passive ankle movement on both the healthy and the paretic leg's side. Three individual-level motion correction strategies were compared and we introduced five measures to characterize each subjects' in-scanner relative head movement. After analyzing the correlation of motion parameters and the subjects' physiological scale scores, we selected a parameter to model the motion-related artifacts in the second-level analysis.
  
  
  
  At first (individual) level analysis, the noise-component correction-based CompCor method provided the highest -log10(p) value of cluster-level occurrence probability at 12.4/13.6 for healthy and paretic side stimulus, respectively, with a maximal z-value of 15/16.3. Including the motion parameter at second (group) level resulted in lower cluster occurrence values at 10.9/5.55 while retaining the maximal z-value.
  
  
  
  We proposed a postprocessing pipeline for ischemic stroke fMRI data that combine the CompCor correction at first level with the modeling of motion effect at second-level analysis by a parameter obtained from fMRI data. Our solution is applicable for any fMRI-based stroke rehabilitation study since it does not require any MRI-compatible motion capture system and is based on commonly used methods.
authors.affiliation: Department of Medical Imaging, University of Debrecen, Hungary.
authors.forename: Csaba
authors.initials: C
authors.lastname: Aranyi
authors.affiliation: Department of Medical Imaging, University of Debrecen, Hungary.
authors.forename: Gábor
authors.initials: G
authors.lastname: Opposits
authors.affiliation: Department of Medical Imaging, University of Debrecen, Hungary.
authors.forename: Marianna
authors.initials: M
authors.lastname: Nagy
authors.affiliation: Department of Medical Imaging, University of Debrecen, Hungary.
authors.forename: Ervin
authors.initials: E
authors.lastname: Berényi
authors.affiliation: Department of Neurology, University of Debrecen, Hungary.
authors.forename: Csilla
authors.initials: C
authors.lastname: Vér
authors.affiliation: Department of Neurology, University of Debrecen, Hungary.
authors.forename: László
authors.initials: L
authors.lastname: Csiba
authors.affiliation: Department of Diagnostic Radiology, Kenézy Gyula County Hospital, Debrecen, Hungary.
authors.forename: Péter
authors.initials: P
authors.lastname: Katona
authors.affiliation: Preclinical Imaging and Biomarker Center, Gedeon Richter Plc., Budapest, Hungary.
authors.forename: Tamás
authors.initials: T
authors.lastname: Spisák
authors.affiliation: Department of Medical Imaging, University of Debrecen, Hungary.
authors.forename: Miklós
authors.initials: M
authors.lastname: Emri
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016477:Artifacts; D002545:Brain Ischemia / Q000000981:diagnostic imaging*; D001931:Brain Mapping / Q000379:methods; D005260:Female; D019416:Head Movements; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D009038:Motion; D020521:Stroke / Q000000981:diagnostic imaging*
keywords: CompCor; Motion correction; fMRI; ischemic stroke