WORKSHOP PRESENTATION Open Access Selection of sampling points for saturation

Quantitative myocardial T1 mapping allows assessment of focal and diffuse fibrosis in the myocardium, by sam-pling the T1 relaxation curve using inversion [1] or saturation recovery (SR) preparation [2] or a combination of both [3], followed by the acquisition of multiple images with different contrasts, which are subsequently fitted to a parametric equation pixel-wise to yield the T1 maps. In myocardial T1 mapping, there is a degree of freedom in selecting which points on the relaxation curve are sampled. However, this topic has not been studied. In this study, we sought to develop an estimation theoretic framework for optimal selection of sampling points and characterized the variance of the corresponding T1 esti-mator for sampling of the SR curve. Methods Based on the signal model, yk = a (1-b exp(-xk/T1))+nk, and the least squares model, we derived the Fisher infor-mation matrix [4]. This was used to derive the Bayesian Cramer-Rao bound [4] for the variance of the T1 estima-tor for T1 values of interest between 950 and 1250 ms (~pre-contrast myocardium). The bound was evaluated for the SASHA sequence [2] which allows samplin