A method removes a part representing non-brain tissue of the MR brain image. For each generated magnetic field gradient, acquiring a current signal respectively at a first time of echo TE1 after an excitation radio frequency pulse and at a second time of echo TE2 after the radio frequency pulse. The MR brain image of an internal structure of the target. The first time of echo TE1 and the second time of echo TE2 are adjusted for correlating time of echo difference ΔTE=TE2−TE1 with a fat and water mutual resonance frequency difference δ, and in that fat and water information encoded in the current signal resulting from the correlation of the second and first time of echo difference ΔTE with the fat and water mutual resonance frequency difference is used as an additional input source into a multispectral analysis method for removing the part.