Long-term reproducibility analysis of fMRI using hand motor task.

This article reports test-retest reproducibility of functional MRI (fMRI) measurement on brain activation elicited by auditory-cued sequential finger tapping. Eight right-handed volunteers participated in nine fMRI sessions, approximately eight weeks apart, for the duration of more than a year. The first scan session was repeated within a day to examine the intra-session reproducibility. The frequency of activation for neural substrates relevant to the task was constructed across the subjects and sessions. The spatial reproducibility was measured as the ratio of the size of the volume as well as its overlaps with respect to the first scan session from regions-of-interest in the selected motor circuitry. Consistent activation patterns between sessions and across subjects were observed in the sensorimotor areas such as the left primary, supplementary, and premotor areas, as well as in the right cerebellar areas without evidence of session-dependent trends. Quantitative analysis showed that the reproducibility measures varied within the range obtained from studies on fMRI reproducibility covering much shorter terms. Intra-session fMRI scans yielded slightly better reproducibility measures compared to the results obtained from other scan sessions. The findings suggest that the reproducible fMRI measurement can be obtained for long-term monitoring of brain function.