Global differences in gray matter density were treated as confounds and were removed to ensure that differences pertained to regional rather than global changes in gray matter. Nerve Relief and Velatol
VBM analysis is sensitive to MR scan parameters. Our analysis indicated that results from fast scans were inferior to those obtained by no-flow scans. The no-flow scans include a saturation band inferior to the volume acquisition to reduce artifacts caused by inflowing blood.
In addition, the no-flow data were acquired at a 1 mm slice thickness, whereas the fast scans were acquired at 2 mm and interpolated to 1 mm.
Therefore, we only contrasted VBM results for no-flow scans. Regional
changes in gray matter were assessed nonparametrically to allow rigorous cluster-based comparisons of significance. Statistical nonparametric maps were generated using a two-group, one-scan-per-subject permutation analysis (Nichols and Holmes, 2002), in which pseudo t statistical analysis was performed over the entire brain.
