The optimal MR acquisition strategy for exponential decay constants estimation

Estimating the relaxation constant of an exponentially decaying signal from experimental MR data is fundamental in diffusion tensor imaging, fractional anisotropy mapping, measurements of transverse relaxation rates and contrast agent uptake. The precision of such measurements depends on the choice of acquisition parameters made at the design stage of the experiments. In this report, χ2 fitting of multipoint data is used to demonstrate that the most efficient acquisition strategy is a two-point scheme. We also conjecture that the smallest coefficient of variation of the decay constant achievable in any N-point experiment is 3.6 times larger than that in the image intensity obtained by averaging N acquisitions with minimal exponential weighting.