1. Department of Medical Ultrasound, Shanghai Tenth People's Hospital, School of Medicine Tongji University Shanghai 200072 P. R. China
2. Department of Nuclear Medicine The First Affiliated Hospital of Naval Medical University Shanghai 200433 P. R. China
3. Department of Materials Science and State Key Laboratory of Molecular Engineering of Polymers, Academy for Engineering and Technology Fudan University Shanghai 200433 P. R. China
4. Department of Plastic and Reconstructive Surgery, Shanghai Ninth People's Hospital Shanghai Jiao Tong University School of Medicine Shanghai 200011 P. R. China