Diffuse myocardial fibrosis evaluation using cardiac magnetic resonance T1 mapping: sample size considerations for clinical trials

Table 4 Estimated sample size in heart failure group to detect the change of ECV and λ with a power of 80%

Clinical change	Caset 1		Case 2		Case 3
	SDD₁	N₁	SDD₂	N₂	SDD₃	N₃
λ (0.063)	0.078	26	0.117	56	0.156	98
ECV (0.038)	0.048	27	0.072	58	0.096	102

Sample size need to detect a clinical meaning change of ECV and λ with 80% of power and an alpha error of 0.05. Sample size is derived from the inter-study SDD as described by Altman [33] and Marchin [32]. Note that for studies comparing active vs. placebo, these sample size numbers need to be doubled. Case 1: the inter-study SDD₁ in HF group was estimated 2.8 fold greater than the intra-study SDD; Case 2, the inter-study SDD₂ was estimated 1.5 times more than SDD₁; Case3, the inter-study SDD₃ was estimated 2 times more than SDD₁.

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