1. Department of Ultrasonography, Baoji Central Hospital, Baoji, Shaanxi 721008, China.
2. Department of Ultrasonography, The First Affiliated Hospital of Medical College, Xi'an Jiaotong University, Xi'an, Shaanxi 710061, China.
3. Department of Infectious Disease, Baoji Central Hospital, Baoji, Shaanxi 721008, China.