title: Physiological noise in human cerebellar fMRI.
abstract: OBJECTIVE
  To compare physiological noise contributions in cerebellar and cerebral regions of interest in high-resolution functional magnetic resonance imaging (fMRI) data acquired at 7T, to estimate the need for physiological noise removal in cerebellar fMRI.
  
  
  METHODS
  Signal fluctuations in high resolution (1 mm isotropic) 7T fMRI data were attributed to one of the following categories: task-induced BOLD changes, slow drift, signal changes correlated with the cardiac and respiratory cycles, signal changes related to the cardiac rate and respiratory volume per unit of time or other. [Formula: see text] values for all categories were compared across regions of interest.
  
  
  RESULTS
  In this high-resolution data, signal fluctuations related to the phase of the cardiac cycle and cardiac rate were shown to be significant, but comparable between cerebellar and cerebral regions of interest. However, respiratory related signal fluctuations were increased in the cerebellar regions, with explained variances that were up to 80 % higher than for the primary motor cortex region.
  
  
  CONCLUSIONS
  Even at a millimetre spatial resolution, significant correlations with both cardiac and respiratory RETROICOR components were found in all healthy volunteer data. Therefore, physiological noise correction is highly likely to improve the temporal signal-to-noise ratio (SNR) for cerebellar fMRI at 7T, even at high spatial resolution.
authors.affiliation: Centre d'Imagerie Biomédicale (CIBM), Station 6, École Polytechnique Fédérale de Lausanne, 1015, Lausanne, Switzerland. Wietske.vanderzwaag@epfl.ch.
authors.forename: Wietske
authors.initials: W
authors.lastname: van der Zwaag
authors.affiliation: Centre d'Imagerie Biomédicale (CIBM), Station 6, École Polytechnique Fédérale de Lausanne, 1015, Lausanne, Switzerland.|Instituto Superior Técnico, Lisbon, Portugal.
authors.forename: João
authors.initials: J
authors.lastname: Jorge
authors.affiliation: Centre d'Imagerie Biomédicale (CIBM), Station 6, École Polytechnique Fédérale de Lausanne, 1015, Lausanne, Switzerland.
authors.forename: Denis
authors.initials: D
authors.lastname: Butticaz
authors.affiliation: Centre d'Imagerie Biomédicale (CIBM), Station 6, École Polytechnique Fédérale de Lausanne, 1015, Lausanne, Switzerland.|Department of Radiology, Université de Lausanne, Lausanne, Switzerland.
authors.forename: Rolf
authors.initials: R
authors.lastname: Gruetter
mesh_terms: D016477:Artifacts; D001931:Brain Mapping / Q000379:methods; D003198:Computer Simulation; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008959:Models, Neurological; D015233:Models, Statistical; D015203:Reproducibility of Results; D015656:Respiratory Mechanics / Q000502:physiology*; D012680:Sensitivity and Specificity; D059629:Signal-To-Noise Ratio
keywords: 3D-EPI; Cerebellum; Magnetic resonance imaging; Noise; Resolution