Table 1.

The effect of longitudinal averaging, isotropic Gaussian filter, seven-peak 2D convolution, and one-peak 2D convolution on overall accuracy.

Row	Implementation	Avg_L a	Gauss b	7 Peaks c	1 Peak d	AvgError e
1	Trace_L_G_7	✔	✔	✔	✖	1.300
2	Trace_L_7	✔	✖	✔	✖	1.345
3	Trace_G_7	✖	✔	✔	✖	1.523
4	Trace_L_1	✔	✖	✖	✔	2.157
5	Trace_L_G_1	✔	✔	✖	✔	2.420
Improvement in the seven-peak convolution f						46.28%
Improvement in the longitudinal average g						14.62%

^a Longitudinal average along the direction of the bundle; ^b isotropic Gaussian filter applied to the original density map; 2D convolution using ^c seven Gaussian peaks and ^d one Gaussian peak; ^e average cross-distance (in voxels) between the manually and computationally detected 330 filaments. A check mark indicates that a technique in the column was applied. For example, 1.300 voxels was the average cross-distance when the longitudinal average, isotropic Gaussian filter and seven-peak convolution were applied. ^f Improvement = difference in error between row 5 and row 1/error in row 5; ^g improvement = difference in error between row 3 and row 1/error in row 3.