1. Department of Pathophysiology, Jinzhou Medical University, Jinzhou, Liaoning 121001, P.R. China
2. Department of Anatomy, Jinzhou Medical University, Jinzhou, Liaoning 121001, P.R. China
3. Department of Ultrasonography, The First Affiliated Hospital of Jinzhou Medical University, Jinzhou, Liaoning 121001, P.R. China