1. A method for localizing a high intensity focused ultrasound (HIFU) focal point in magnetic resonance guided HIFU, comprising the steps of: with a magnetic resonance data acquisition unit in which an examination subject is located, acquiring magnetic resonance from the examination subject with a first GRE magnetic resonance pulse sequence that comprises a positive monopolar gradient pulse followed by sonification of the examination subject with HIFU overlapping with activation of a motion encoding gradient, said HIFU causing an acoustic radiation force phase shift and PRFS temperature-induced phased shift of magnetic resonance signals arising in the examination subject, to produce a first imaging data set; in parallel with scanning of the examination subject with said first GRE sequence, acquiring magnetic resonance from the examination subject with a second GRE magnetic resonance pulse sequence that comprises a negative monopolar gradient pulse followed by said sonification of the examination subject with HIFU overlapping with activation of a motion encoding gradient in said second GRE sequence, said HIFU causing an acoustic radiation force-induced phase shift and PRFS temperature-induced phase shift of magnetic resonance signals arising in the examination subject in said second GRE sequence, to produce a second imaging data set; in a processor, using Fourier reconstruction or partial Fourier reconstruction, reconstructing a first GRE phase image from said first image data set and reconstructing a second GRE phase image from said second image data set; in said processor, forming a subtraction image as a difference between said first GRE phase image and said second GRE phase image; in said processor, from said subtraction image, identifying a location and/or an acoustic intensity and/or a shape of said HIFU focal point; in said processor, forming an average image of said first GRE phase image and said second GRE phase image; and from said average image, monitoring temperature at the location of said HIFU focal point.