Inherent Geometry Correction for Diffusion EPI Using the Reference Echoes as Navigators
Figure 4
3T diffusion EPI abdominal images at the level of the kidneys to demonstrate the effect of the polarity of the phase encoding gradients, and the effect of geometry correction using the phase of the navigator echoes: (a) phase shift direction A, product reconstruction, and zoomed view (b); (c) and (d) product reconstruction for phase shift direction P; (e) and (f) phase-corrected reconstruction for phase shift direction P. For reference, (g) and (h) show the (zoomed) T2W TSE image at the same location. Lines in the zoomed images indicate the edge of the kidney for the phase encoding directions A (dotted) and P (dashed) and for the T2W TSE scan (solid). Note that the phase-corrected reconstruction moves the edge position towards the middle of the A and the P EPI images, closely resembling the reference T2W TSE image data.