Y-T Guo1,2, N Hou1, J-H Liang1,2, Z-K Zhang1,2, T-S Cao1,2, L-J Yuan1. 1. Department of Ultrasound Diagnosis, Tangdu Hospital, The Fourth Military Medical University, Xi'an, Shaanxi, China. 2. 3D Printing Center, The Fourth Military Medical University, Xi'an, Shaanxi, China.