Assessment and prevention of head motion during imaging of patients with attention deficit hyperactivity disorder.

The present study serves to detail the specific procedures for a mock scanner protocol, report on its use in the context of a multi-site study, and make suggestions for improving such protocols based on data acquired during study scanning. Specifically, a mock scanner compliance training protocol was used in a functional imaging study with a group of adolescents and adults with Attention Deficit Hyperactivity Disorder (ADHD) and a matched sample of healthy children and adults. Head motion was measured during mock and actual scanning. Participants across groups exhibited excess motion (>2 mm) on 43% of runs during the mock scanner. During actual scanning, excessive motion was limited to 10% of runs. There was a clear task-correlated head motion during a go/no-go task that occurred even after the compliance training: participants had a tendency to respond with increased head motion immediately after committing an error. This study illustrates the need to (1) report data attrition due to head motion, (2) assess task-related motion, and (3) consider mock scanner training in functional imaging protocols.