FIG. 4.

Reconstruction Algorithm for the Spectroscopic Approach. The data acquired with concentric rings is gridded in 3D (k_x, k_y, t)-space, and then Fourier-transformed to generate a set of 2D images along frequency. Maximum-intensity projection (MIP) is performed along frequency, producing an index map that identifies the maximum frequency component in each voxel. Voxels that have their dominant peak at less than -|Δf|/2 are recorded in a “fat mask,” while voxels that have their dominant peak greater than -|Δf|/2 are recorded in a “water mask.” Using the MIP index map and the water and fat masks, the spectrum in each voxel is shifted appropriately to put the water peak at 0 Hz (water-referencing) and the fat peak at Δf (fat-referencing). After performing water and fat-referencing, the 2D images at water and fat resonances are presented as the calibrated water and fat images.