(a)
(b)
Figure 3: (a) The spin-echo DTI signal (indicated by the red dot) varies with the echo time according to a decay curve (indicated by the dashed curve). (b) In the presence of an echo-shifting effect, the DTI signal is reduced by an additional -weighting. = spin-echo signal intensity 1, = asymmetric spin-echo signal intensity for   4, = asymmetric spin-echo signal intensity for   5. The horizontal arrow represents and the vertical arrow represents the signal reduction from Type 3 artifacts (see text for details).