Table 4

Sample size and scan to scan interval required to give 80% power of detecting a significant (p < 0.05) effect of a neuroprotective agent, with predicted protection of 50% and 30% (assuming the reported relative rate of dopaminergic degeneration, in each region separately)

Time interval
One year protectionTwo years protectionFive years protection
Region of interest50%30%50%30%50%30%
Striatum, whole340949852381438
Striatum, ipsilateral346961872411439
Striatum, contralateral53414831343712260
Putamen, whole310863782161335
Putamen, ipsilateral312866792171335
Putamen, contralateral63617751604442671
Caudate, whole1395385134996356155
Caudate, ipsilateral14854112372102860165
Caudate, contralateral16414545411113766182