Figure 4.

Axial slices from 3T gradient echo EPI, corrected using the displacement field calculated from spin echo EPI, showing complementary in-plane signal dropout patterns. Top row L to R: forward; reverse; root mean square of forward and reverse. Bottom row L to R: forward overlain with Jacobian of displacement field; reverse overlain with Jacobian of inverse displacement field; identical slice from average corrected forward and reverse spin echo EPI. For the overlays, red and blue indicate regions from which tissue was recorded as compressed or expanded, respectively, in the uncorrected images. Red thus indicates regions of recoverable dephasing dropout due to spin bunching.