Table 2.

Summary of T1W MRI-based anonymization algorithms.

Anonymization algorithm	Method of anonymization	Description of algorithm	Citation
Afni_deface	Defacing	Uses a precreated mask to modify the image by replacing the voxel values of the face and ears with zero	Cox et al.28
Afni_reface	Refacing	Modifies the image by applying a scaled replacement “generic face” mask that was created by warping and averaging several public datasets; Modifies the same regions as Afni_deface	Cox et al.28
FSL’s BET	Skull-stripping	A deformable model that makes an intensity-based estimation of the brain and nonbrain threshold, determines the center of gravity of the head and defines a sphere at that point, and expands until it reaches the brain edge	Smith et al.32
AFNI’s 3Dskullstrip	Skull-stripping	Modified version of BET; uses additional processing such as nonuniformity correction and edge detection to minimize errors	“AFNI: 3Dskullstrip,” National Institute of Mental Health29