Fig. 1

Schematic of the SANDI model

Table 1

Parameters of spindle neuron cells

Fig. 2

Three parts of spindle neuron 03b_spindle4aFI: soma and two axon branches

Fig. 3

SpinDoctor simulation steps

Fig. 4

dMRI signals of spindle neuron soma simulated using BTPDE and MF methods. (a) and (d) correspond to signals generated at different b values at PGSE (δ=2.5 ms, Δ=5 ms); (b) and (e) correspond to signals generated at different b values at PGSE (δ=10 ms, Δ=43 ms); (c) and (f) correspond to signals generated at different b values at PGSE (δ=10 ms, Δ=433 ms). The horizontal and vertical coordinates of the figure represent the normalized magnitude of the signals |S/S0|; the signal value in the outermost circle of the figure corresponds to a b value of 500 s/mm2, the one in the middle corresponds to a b value of 1 500 s/mm2, and the one in the innermost circle corresponds to a b value of 2 500 s/mm2.

Fig. 5

Absolute and relative errors between dMRI signals simulated using BTPDE and MF methods. (a), (b), and (c) show the absolute errors at different diffusion times for b values of 500, 1 500, and 2 500 s/mm2; (d), (e), and (f) correspondingly show the relative errors for the same b value condition. The blue line of the figure is the error at (δ=2.5 ms, Δ=5 ms), the red line is the error at (δ=10 ms, Δ=43 ms), and the yellow line is the error at (δ=10 ms, Δ=433 ms). The vertical axis of the figure represents the magnitude of the error, the horizontal axis represents the gradient directions；115 gradient directions uniformly distributed over the entire sphere

Fig. 6

Brain tissue (axial, sagittal, coronal) FA

Table 2

Mean brain tissue FA

Fig. 7

Brain tissue signaling fraction map

Table 3

Mean brain tissue signal fraction

Fig. 8

Fiber reconstruction results within brain GM by NODDI-CSD method and GM-MSCSD method

Fig. 9

Fiber reconstruction results at the transition between brain GM and brain WM by NODDI-CSD method and GM-MSCSD method