1. A method of assessing a spatial frequency distribution within a sample of a structure comprising: a) subjecting the sample to a magnetic field; b) subjecting the sample to magnetic resonance excitation; c) receiving an echo signal from the sample while the sample is subjected to a magnetic field gradient; d) projecting the echo signal into a corresponding transform domain , using an invertible linear transform; e) identifying a region of interest within that transform domain, and deriving the corresponding windowing function; f) applying a linear windowing function to the echo signal to remove echo signal coming from regions of the sample outside of the region of interest; g) analyzing the one dimensional spatial frequency content in the windowed echo signal obtained in f) in order to access a one dimensional spatial frequency distribution within the region of interest within the sample of the structure without creating an image.