title: Head-repositioning does not reduce the reproducibility of fMRI activation in a block-design motor task.
abstract: It is hypothesized that, based upon partial volume effects and spatial non-uniformities of the scanning environment, repositioning a subject's head inside the head coil between separate functional MRI scans will reduce the reproducibility of fMRI activation compared to a series of functional runs where the subject's head remains in the same position. Nine subjects underwent fMRI scanning where they performed a sequential, oppositional finger-tapping task. The first five runs were conducted with the subject's head remaining stable inside the head coil. Following this, four more runs were collected after the subject removed and replaced his/her head inside the head coil before each run. The coefficient of variation was calculated for four metrics: the distance from the anterior commisure to the center of mass of sensorimotor activation, maximum t-statistic, activation volume, and average percent signal change. These values were compared for five head-stabilization runs and five head-repositioning runs. Voxelwise intraclass correlation coefficients were also calculated to assess the spatial distribution of sources of variance. Interestingly, head repositioning was not seen to significantly affect the reproducibility of fMRI activation (p<0.05). In addition, the threshold level affected the reproducibility of activation volume and percent signal change.
authors.affiliation: Division of Physics, Office of Science and Engineering Laboratories, Center for Devices and Radiological Health, US Food and Drug Administration, Silver Spring, MD 20993, USA. david.soltysik@fda.hhs.gov
authors.forename: David A
authors.initials: DA
authors.lastname: Soltysik
authors.forename: David
authors.initials: D
authors.lastname: Thomasson
authors.forename: Sunder
authors.initials: S
authors.lastname: Rajan
authors.forename: Javier
authors.initials: J
authors.lastname: Gonzalez-Castillo
authors.forename: Paul
authors.initials: P
authors.lastname: DiCamillo
authors.forename: Nadia
authors.initials: N
authors.lastname: Biassou
mesh_terms: D000328:Adult; D003627:Data Interpretation, Statistical; D005260:Female; D005385:Fingers / Q000294:innervation / Q000502:physiology; D007839:Functional Laterality / Q000502:physiology; D006257:Head / Q000502:physiology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D016014:Linear Models; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000502:physiology; D009068:Movement / Q000502:physiology*; D010100:Oxygen / Q000097:blood; D011187:Posture / Q000502:physiology; D011597:Psychomotor Performance / Q000502:physiology*; D015203:Reproducibility of Results; D013003:Somatosensory Cortex / Q000502:physiology
chemical_list: D010100:Oxygen