1. A method for generating a three-dimensional magnetic resonance (MR) image, comprising: operating an MR scanner, while a subject is situated in the MR scanner, to execute a 3D dual echo magnetic resonance data acquisition sequence; in said 3D dual echo magnetic resonance data acquisition sequence, acquiring two sets of k-space data respectively from two echoes; providing said two sets of k-space data to a computer and, in said computer, applying a 2D CAIPIRINHA undersampling to each of the two sets of k-space data, thereby extracting two sets of sampling data respectively from said two sets of k-space data; in said computer, applying an image reconstruction algorithm to each of said two sets of sampling data, thereby obtaining two initially reconstructed magnetic resonance images; and in said computer, synthesizing a final magnetic resonance image of the subject from said two initially reconstructed magnetic resonance images, and making the final magnetic resonance image available at an output of the computer in electronic form as a data file.