Prospective slice-by-slice motion correction reduces false positive activations in fMRI with task-correlated motion

- Slice-by-slice prospective motion correction was applied in an fMRI group study.
- Rate of false activations due to task-correlated motion was reduced considerably.
- Statistical power in conventional group analysis was increased.
- Prospective motion correction should be used whenever available.

ObjectiveWe aimed to test the hypothesis that slice-by-slice prospective motion correction at 7 T using an optical tracking system reduces the rate of false positive activations in an fMRI group study with a paradigm that involves task-correlated motion.Materials and methodsBrain activation during right leg movement was measured using a block design on 15 volunteers, with and without prospective motion correction. Clearly erroneous activations were compared between both cases, at the individual level. Additionally, conventional group analysis was performed.ResultsThe number of falsely activated voxels with T-values higher than 5 was reduced by 48% using prospective motion correction alone, without additional retrospective realignment. In the group analysis, the statistical power was increased - the peak T-value was 26% greater, and the number of voxels in the cluster representing the right leg was increased by a factor of 9.3.ConclusionSlice-by-slice prospective motion correction in fMRI studies with task-correlated motion can substantially reduce false positive activations and increase statistical power.