ESTIMATING TEST-RETEST RELIABILITY IN FUNCTIONAL MR-IMAGING .2. APPLICATION TO MOTOR AND COGNITIVE ACTIVATION STUDIES

Functional magnetic resonance imaging (fMRI) using blood oxygenation c ontrast has rapidly spread into many application areas. In this paper, a new statistical model is used to evaluate the reliability of fMRI a ctivation in a finger opposition motor paradigm for both within-sessio n and between-session data and in a working memory paradigm for betwee n-session data. A slice prescription procedure for between-session rep roducibility is introduced. Estimates are made for the probabilities o f correctly and falsely classifying voxels as active or inactive and r eceiver operator characteristic curves are generated. In the motor par adigm, estimated between-session reliability was found to be somewhat reduced relative to within-session reliability; however, this includes additional sources of variation and may not reflect intrinsically low er reliability. After matching false-positive classification probabili ties, between-session reliability was found to be nearly identical for both motor and cognitive activation paradigms.