Patient movement during dynamic contrast enhanced breast MRI acquisition can degrade signal enhancement curves. Non-rigid image registration can improve enhancement curves, but computation time can be long, especially if all voxels are sampled for cost function estimation. This work investigates the influence of the percentage of voxels sampled (PS) on goodness-of-fit, kinetic model parameter values and uncertainties. The spatial distribution of parameter values was more strongly influenced by registration and PS compared to global tumor measures. Registration with very low PS values increased parameter uncertainties compared to unregistered. 5 PS provided similar performance to 100 PS with reduced computation time.