Table 1.

Power calculations showing the sample size needed in a paired study to determine statsitcal significance (α = 0.05) for both 28 min and 6.5 min CSI sequences at 7T, and 31 minute CSI sequence at 3T, for a change of 0.2 in the measured PCr/ATP.

ΔPCr/ATP = 0.2	7T		3T*
	28 minutes σ=0.25, α=0.05	6½ minutes σ=0.34, α=0.05	31 minutes σ=0.56, α=0.05
Power = 95%	23	40	104
Power = 90%	19	33	85
Power = 80%	15	25	64

^*3T reproducibility values for this power calculation were taken from the study by Tyler et al., (ref ¹⁵). We made this analysis using the original raw data from that study provided by Prof Tyler. If comparing this table to ref 15, please note that the values reported in Table 1 of ref. 15 were computed using the standard deviation of the absolute difference in PCR/ATP for scan 1 and scan 2, whereas here we have used the standard deviation of the signed difference.