title: Repeatability of functional MRI for conformal avoidance radiotherapy planning.
abstract: OBJECTIVE
  To establish the repeatability of functional magnetic resonance imaging (fMRI) examinations in order to develop an appropriate margin for functional organs at risk (fOAR) in the radiotherapy planning process.
  
  
  METHODS
  This work investigates the variability of motor cortex activation in the left and right hemispheres of 15 normal subjects. The uncertainty of the absolute position and volume of the activation was determined for each volunteer by repeating the fMRI examination three times in a single scan session.
  
  
  RESULTS
  Our study proposes the use of 2.9 mm and 2.2 mm margins for the left and right motor cortices, respectively.
  
  
  CONCLUSIONS
  From the sample of 15 volunteers we established an appropriate planning margin that is considered to represent the uncertainty in spatially measuring the fOAR for a single fMRI examination. The work will be of interest to anyone investigating the clinical robustness of fMRI.
authors.affiliation: Centre for MR Investigations, University of Hull, Hull, UK.
authors.forename: Roberto
authors.initials: R
authors.lastname: Garcia-Alvarez
authors.forename: Gary P
authors.initials: GP
authors.lastname: Liney
authors.forename: Andrew W
authors.initials: AW
authors.lastname: Beavis
mesh_terms: D000328:Adult; D001921:Brain / Q000033:anatomy & histology* / Q000528:radiation effects*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000473:pathology / Q000528:radiation effects; D011880:Radiotherapy Planning, Computer-Assisted; D020266:Radiotherapy, Conformal; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity