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. Author manuscript; available in PMC: 2017 Mar 1.
Published in final edited form as: J Magn Reson Imaging. 2015 Aug 13;43(3):661–668. doi: 10.1002/jmri.25028

Figure 1.

Figure 1

Simulation results from the theoretical study. (a) All possible combinations of TR, TE, and FA values that can equate the CSF and blood signal intensities in the BOLD image. The TR and TE values are represented on the x and y axis, respectively, and the FA value is represented by color scale. Note that, the imaging parameter space is divided into 2 distinct regions. The white region indicates that such TR and TE combination will not meet the signal equivalence criterion regardless the FA value. These results are obtained from step 1 of the simulation. (b) Corresponding CNR per unit time in a hypothetical parenchyma voxel. These results are obtained from step 2 of the simulation. (c) Optimal TE value as a function of TR. The symbols represent TR/TE combinations tested in the experiment. A total of three protocols were used: two using the optimized protocols with different TRs (red symbols) and one using the standard protocol (black symbol). With this strategy, both the TE and TR dependence of the CNR are examined. (d) CNR as a function of TR. For each TR, the optimal TE (and associated FA) was used to compute the CNR.