title: Confirmation of resting-state BOLD fluctuations in the human brainstem and spinal cord after identification and removal of physiological noise.
abstract: OBJECTIVE
  Resting-state functional MRI (rs-fMRI) has been used to investigate networks within the cortex, but its use in the brainstem (BS) and spinal cord (SC) has been limited. This region presents challenges for fMRI, partly because of sources of physiological noise. This study aims to quantify noise contributions to rs-fMRI, and to obtain evidence of resting-state blood oxygenation level-dependent (BOLD) fluctuations.
  
  
  METHODS
  Resting-state-fMRI data were obtained from the BS/SC in 16 participants, at 3 Tesla, with T2-weighted single-shot fast spin-echo imaging. The peripheral pulse, respiration, and expired CO2were recorded continuously. Physiological noise was modeled from these recordings, movement parameters, and white matter regions. Model fits were then subtracted from the data. BOLD contributions were then investigated through connectivity.
  
  
  RESULTS
  Bulk motion was the largest contributor to the signal variance (19% of the total), followed by cardiac-related motion (14%), nonspecific signal variations detected in white matter (10%), respiratory-related motion (2.6%), and end-tidal CO2variations (0.7%). After noise was removed, significant left-right connectivity was detected in the SC dorsal horns and ventral horns.
  
  
  CONCLUSIONS
  Resting-state BOLD fluctuations are demonstrated in the SC, as are the dominant noise contributions. These findings are an essential step toward establishing rs-fMRI in the BS/SC. Magn Reson Med 78:2149-2156, 2017. © 2017 International Society for Magnetic Resonance in Medicine.
authors.affiliation: Centre for Neuroscience Studies, Queen's University, Kingston, Canada.
authors.forename: Shreyas
authors.initials: S
authors.lastname: Harita
authors.affiliation: Centre for Neuroscience Studies, Queen's University, Kingston, Canada.|Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Canada.|Department of Physics, Queen's University, Kingston, Canada.
authors.forename: Patrick W
authors.initials: PW
authors.lastname: Stroman
mesh_terms: D000293:Adolescent; D000328:Adult; D016477:Artifacts; D001921:Brain / Q000000981:diagnostic imaging; D001931:Brain Mapping; D001933:Brain Stem / Q000000981:diagnostic imaging*; D002102:Cadaver; D002245:Carbon Dioxide / Q000737:chemistry; D002540:Cerebral Cortex / Q000000981:diagnostic imaging; D005260:Female; D006321:Heart / Q000502:physiology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009038:Motion; D010100:Oxygen / Q000737:chemistry*; D012119:Respiration; D013116:Spinal Cord / Q000000981:diagnostic imaging*; D055815:Young Adult
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen
keywords: fMRI; human; physiological noise; resting state; spinal cord