Fig. 2

Vector representation of respiratory motion. Displacement fields derived from ground truth (a) and focused navigation (fNAV) reconstructions of simulated data (b) demonstrate the nonrigid behavior of respiratory motion during end-inspiration, and excellent visual agreement is observed between fNAV and ground truth as shown by the difference image (c). Similarly, displacement fields derived from registering the frames of extradimensional golden-angle radial sparse parallel (XD-GRASP) reconstructions of a representative healthy subject (d) and cardiac patient (g) are comparable to those derived using fNAV (e, h) as demonstrated by their corresponding difference images (f, i). An animated version of this figure is included as Additional file 2: Video S1