Table 2.

Speed function for level set expansion.

			Facial nerve
	Speed function	Purpose	δ	γ
1	e[γMw(x)δ]	Slows the rate of propagation when the structure width is small	0.5|60%	1.0|60%
2	e[-γ(|TA(x)-MI(x)|∕2000δ]	Slows the rate of propagation when the local intensity deviates from the predicted value	0.2|50%	1.1|70%