FIG 3. Signal intensity time curves of gradient-echo (GRE) and spin-echo (SE) echo-planar imaging sequences. Region of interest measurements were obtained from three representative locations: globus pallidus, caudate head, and thalamus. The y axes for both gradient-echo and spin-echo sequences are scaled to the same range of signal intensity (400–1600 A.U.). Note that the signal change is more prominent on the gradient-echo sequence than on the spin-echo sequence. The signal intensity difference between the thalamus and globus pallidus is also more prominent for the gradient-echo sequence.