1. Department of Pediatrics, Affiliated Hospital of Yanbian University, Yanji 133000, P. R. China
2. Department of Basic Medical Sciences, School of Medicine, Xiamen University, Xiamen 361102, P. R. China
3. Human Anatomy and Histoembryology, Medical College of Yanbian University, Yanji 133000, P. R. China
4. Department of Radiology, The Second Affiliated Hospital of Xiamen Medical College, Xiamen 361000, P. R. China