Method for determining by Magnetic Resonance Imaging (hereafter MRI) one or several tissue types within a voxel in an object, the method comprising: - performing a phase-cycled acquisition consisting of acquiring for said object several steady-state non-spoiled GRE images with different radiofrequency phase increments across the acquisitions of said several steady-state non-spoiled GRE images, and deriving a complex signal profile for each voxel of the acquired images, wherein for each voxel, the complex signal profile is the steady-state transverse magnetization for each RF phase increment; - generating a dictionary of simulated signal profiles, wherein each simulated signal profile is configured for simulating the previously derived complex signal profile, with TR, TE and RF excitation angle matching the imaging parameters used for the phase-cycled acquisition, and wherein said dictionary is characterized by several dimensions, wherein each dimension is associated to a variable parameter whose values vary within a predefined range of values relevant for the determination of said one or several tissue types, and so that each simulated signal profile be obtained for a different value of said parameter; - using a weight optimization algorithm configured for expressing the complex signal profile as a weighted sum of the simulated signal profiles, wherein the weight optimization algorithm receives as input the complex signal profile for each voxel and the simulated signal profiles of the dictionary, and provides as output for each voxel a matrix M of optimized weights; - for each voxel and each dimension of the obtained matrix M, extracting from the matrix M a distribution of the obtained optimized weights; - determining said one or several tissue types composing each voxel from the obtained distributions. - performing a phase-cycled acquisition consisting of acquiring for said object several steady-state non-spoiled GRE images with different radiofrequency phase increments across the acquisitions of said several steady-state non-spoiled GRE images, and deriving a complex signal profile for each voxel of the acquired images, wherein for each voxel, the complex signal profile is the steady-state transverse magnetization for each RF phase increment; - generating a dictionary of simulated signal profiles, wherein each simulated signal profile is configured for simulating the previously derived complex signal profile, with TR, TE and RF excitation angle matching the imaging parameters used for the phase-cycled acquisition, and wherein said dictionary is characterized by several dimensions, wherein each dimension is associated to a variable parameter whose values vary within a predefined range of values relevant for the determination of said one or several tissue types, and so that each simulated signal profile be obtained for a different value of said parameter; - using a weight optimization algorithm configured for expressing the complex signal profile as a weighted sum of the simulated signal profiles, wherein the weight optimization algorithm receives as input the complex signal profile for each voxel and the simulated signal profiles of the dictionary, and provides as output for each voxel a matrix M of optimized weights; - for each voxel and each dimension of the obtained matrix M, extracting from the matrix M a distribution of the obtained optimized weights; - determining said one or several tissue types composing each voxel from the obtained distributions.