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. Author manuscript; available in PMC: 2013 Aug 15.

Published in final edited form as: Neuroimage. 2012 Jan 14;62(2):720–725. doi: 10.1016/j.neuroimage.2012.01.049

Fig. 2 — A) Twice refocused spin echo (TRSE) diffusion sequence with bipolar alternating polarity gradients was innovated for early fMRI experiments (Feinberg and Jakab, 1990). B) Initial comparison of diffusion encoding schemes revealed higher signal attenuation hence highest b-values in bipolar TRSE sequence (right) labeled Gd (+−+−) compared to the two monopolar gradient schemes (++++ and ++−−) in same time. One line from each image (horizontal axis) varying gradient amplitudes (vertical axis) incremented from maximum (−Gs to +Gs) in 128 TR repetitions, phantom 30mm diameter bottle of gadolinium doped water, acquired with inner-volume zoomed-EPI and fly-back k-space trajectory.

Fig. 2 — A) Twice refocused spin echo (TRSE) diffusion sequence with bipolar alternating polarity gradients was innovated for early fMRI experiments (Feinberg and Jakab, 1990). B) Initial comparison of diffusion encoding schemes revealed higher signal attenuation hence highest b-values in bipolar TRSE sequence (right) labeled Gd (+−+−) compared to the two monopolar gradient schemes (++++ and ++−−) in same time. One line from each image (horizontal axis) varying gradient amplitudes (vertical axis) incremented from maximum (−Gs to +Gs) in 128 TR repetitions, phantom 30mm diameter bottle of gadolinium doped water, acquired with inner-volume zoomed-EPI and fly-back k-space trajectory.