Mjolnir: Extending HAMMER Using a Diffusion Transformation Model and Histogram Equalization for Deformable Image Registration

Table 1

Parameters used in Mjolnir in the following experiments.

	Resolution
Parameters	Low	Mid	High
𝑅𝐺 (voxels): radius of spherical neighborhood in GMI computations	3	3	7
𝐷 (voxels): defines the size of the search region for finding correspondences (see 𝑅𝑠 below)	12	10	8
maxIter: the maximum number of iterations		maxIter = 50
iter ∈(0∶maxIter): the current iteration
𝛼=iter/maxIter
𝑅𝑠 (voxels): radius of spherical search neighborhood	𝑅𝑠=0.5𝐷𝑒^𝛼2/0.32+1
𝑡vox: similarity threshold for voxel similarity	𝑡vox=0.8(1−𝛼)+0.01
𝑡vol: similarity threshold for average volume similarity	𝑡vol=0.6(1−𝛼)+0.01
𝜎: the variance of the Gaussian kernel	𝜎=𝑅𝑠/3
𝑤1: weight in displacement field	𝑤1=0.7
𝑤2: weight in displacement field	𝑤2=0.3
𝑔: smoothing control in interpolation PDE	𝑔=0.8−(0.8−0.45)𝛼