1. Department of Medical Ultrasound; Shanghai Tenth People's Hospital; Tongji University School of Medicine; Shanghai 200072 China
2. State Key Laboratory of High Performance Ceramics and Superfine Microstructures; Shanghai Institute of Ceramics; Chinese Academy of Sciences; Shanghai 200050 China
3. Department of Pharmaceutical Science Laboratory; Åbo Akademi University; Turku 20540 Finland
4. Department of Medical Ultrasound; Shanghai General Hospital; Shanghai Jiaotong University School of Medicine; Shanghai 200080 China