Comparison of functional MRI image realignment tools using a computer-generated phantom

This study discusses the development of a computer-generated phantom to com pare the effects of image realignment programs on functional MRI (fMRI) pix el activation. The phantom is a whole-head MRI volume with added random noi se, activation, and motion. It allows simulation of realistic head motions with controlled areas of activation. Without motion, the phantom shows the effects of realignment on motion-free data sets. Prior to realignment, the phantom illustrates some activation corruption due to motion. Finally, thre e widely used realignment packages are examined. The results showed that th e most accurate algorithms are able to increase specificity through accurat e realignment while maintaining sensitivity through effective resampling te chniques. In fact, accurate realignment alone is not a powerful indicator o f the most effective algorithm in terms of true activation. (C) 2001 Wiley- Liss, Inc.