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 MR data acquisition sequence; operating said MR scanner in said 3D dual echo MR data acquisition sequence, in order to acquire two sets of raw MR data respectively from two echoes produced in said 3D dual echo MR data acquisition sequence; operating said MR scanner in said 3D dual echo magnetic resonance data acquisition sequence in order to activate a phase encoding gradient that establishes a phase encoding direction, and acquiring said two sets of raw MR data by acquiring raw MR data during each of said two echoes while said phase encoding gradient is activated, and entering said raw MR data, for each of said two sets, into k-space in an electronic memory, along a spiral trajectory in k-space starting from a center of k-space and proceeding from said center to a periphery of k-space in said phase encoding direction; 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 MR images; and in said computer, synthesizing a final MR image of the subject from said two initially reconstructed MR images, and making the final MR image available at an output of the computer in electronic form as a data file.