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. Author manuscript; available in PMC: 2021 Jan 1.
Published in final edited form as: Neuroimage. 2020 Sep 1;223:117329. doi: 10.1016/j.neuroimage.2020.117329

Table 1.

List of shape descriptors and their definition.

Descriptors Definition
Length (mm) 1ni=1i=nt=1t=mi1vi(t)vi(t+1)2
Span (mm) 1ni=1i=nvi(1)vi(mi)2
Diameter (mm) 2volumeπ×length
Radius (mm) 1.5Nei=1i=NeEiEi¯2
Surface Area (mm2 ) Ns×voxel spacing2
Volume (mm3) N×voxel volume
Trunk Volume (mm3) Nt×voxel volume
Curl lengthspan
Elongation lengthdiameter
Irregularity surface areaπ×diameter×length
Irregularity of the end surface π×radius2area of the end surface

Bundle: trajectory form = {vi(t)|i = 1, 2, 3, … n}, voxelized form = {Vi|i = 1, 2, 3, … N}

End surface: voxelized form = {Ei|i = 1, 2, 3, … Ne}, where Ei are voxel coordinates.

Nt is the number of “trunk bundle” voxels.

Ns is the number of tract surface voxels.