A method of estimating a longitudinal magnetic relaxation T1 time for a region of a subject. The method includes providing a computer with at least two magnetic resonance (MR) images of the region of the subject that were respectively acquired at different times after the generation of a preparation pulse during a MR pulse sequence; in said computer, analyzing said at least two MR images in order to obtain, from the same location in each of the MR images, a pixel value, wherein each of the pixel values and the time at which their respective MR image was acquired form a data point; and in said computer, fitting the data points to a model representing said longitudinal magnetic relaxation by varying a single adjustable parameter to estimate the T1 time constant for the region of interest, wherein the single adjustable parameter represents a T1 time constant within the model.