Algorithms for pulse optimization, quantitative MRI, or model-based reconstruction require knowledge about partial derivatives of the Bloch equations.While being available for specific analytical solutions, computing them becomes challenging in the general case. Difference quotient techniques can be used, but require perturbation tuning to avoid errors.
In this work, we investigate the use of direct sensitivity analysis to estimate the partial derivatives of the Bloch equations. We validate it with an analytical sequence model and compare it to the difference quotient in an example without analytical solution. In all cases, direct sensitivity analysis provided highly accurate estimates of the partial derivatives.