Statistics Comparison between baseline and visits will be performed using conventional statistic methods as unpaired t-test or non-parametric tests such as Wilcoxon signed-rank test. In variation analyses of several groups ANOVA and ANCOVA will be used. A significant difference of p-values below 0.05 has to be determined, to determine the validity of the findings. With a significant level of 5% a power calculation estimated a needed sample size of 14 patients, with a power of 90%. The calculation is based on an expected decrease in muscle volume compared to fat (1.2 vs 0.95 with a standard deviation of 0.2). The power calculation is an estimate, but compared to a similar studyxiii the sample size includes an extra 3 subjects. Given the rare condition of PD, inclusion of patients will continue even if the required minimum is not achieved.