Fig. 8.

The effect of reversing the direction of the imaging gradients on the phase changes observed in the volume-current phantom. The upper row shows the spatial pattern of phase changes over time for the central slice through the phantom when the PE direction was along −y and the RO direction was along −z. The lower row shows the corresponding phase changes observed in the same phantom when the PE direction was along +y and the RO direction was along +z, as was the case for all previous results. Note that the direction of the ionic currents is the same for the two conditions, and for both conditions the large region of phase change migrates in the −y direction. However, the sign of the main phase changes reverses with the gradients, suggesting that these phase changes are predominantly due to flow effects.