Curve fitting for every pixel of image..avoid looping

Dear users,

I want to generate coefficient maps from serial images, talking the change of intensity values over time and fit these values to a curve. Hence the same curve fitting function is applied to every voxels values. Right now I'm looping over the whole image, which talkes a long time. So I was wondering if there is a way to vectorize the curve fitting or run it for multiple data vectors at the same time? I appreciate your help and suggestions. Cheers, Lisa