Comparison of the two registration methods was based on differences between volumes at MRI 1 (baseline) and MRI 2 (followup) derived from each method. Because tissue volumes were predicted to decline and CSF volumes were predicted to increase, differences were tested with one-tailed paired t-tests and with family-wise Bonferroni correction; thus for 15 tissue ROIs, the critical p-value = .007, and for the 5 CSF volume ROIs, the critical p-value = .02.
