1. Department of RadiologyHuashan HospitalFudan University Shanghai 200040 P. R. China
2. Shanghai Key Laboratory of Green Chemistry and Chemical ProcessesSchool of Chemistry and Molecular EngineeringEast China Normal University Shanghai 200062 P. R. China
3. Department of Radiology2nd Affiliated HospitalShantou University Shantou 515065 P. R. China
4. State Key Laboratory of High Performance Ceramics and Superfine MicrostructuresShanghai Institute of CeramicsChinese Academy of Sciences Shanghai 200050 P. R. China