Objective To investigate the distribution of hyaluronic acid (HA) with iohexol tracing in the knee joint cavity of rabbits using CT plain scan, three-dimensional reconstruction and X-ray and observe how different injection sites affect HA distribution. Methods Mixtures of HA and iohexol (tracer) were prepared that contained final iohexol concentrations of 2.5%, 5%, 10%, 20%, or 40%. The HA-iohexol mixtures (0.5 ml) were injected into rabbit knee joints, and the optimal iohexol concentration that allowed clear differentiation of the injected agents from the surrounding tissues was determined using dual-source CT plain scan and three-dimensional reconstruction technique. The HA-iohexol mixture (0.5 ml) containing the optimal concentration of iohexol was then injected into the knees of the rabbits either through the patella medial approach or the medial joint line approach, and HA distribution in the knee joint cavity was observed using CT scan and X-ray. Results The CT value of HA-iohexol mixture increased progressively with the tracer concentration. After injection of the mixture containing 2.5%, 5%, 10%, 20%, and 40%iohexol, the CT value ratios of the soft tissue, HA-iohexol mixture and bone cortex were 2∶7∶46, 2∶14∶44, 2∶28∶44, 2∶60∶46, and 2∶98∶45, respectively, and a iohexol concentration of 5% was determined as optimal for differntiating the injected agents from the surrounding tissues. The HA-iohexol mixutre containing 5% iohexol injected through the medial-patellar approach was distributed mainly over the patello-femoral joint, and that injected through the joint line approach was found mainly over the tibio-femoral joint. Conclusion HA-iohexol mixture containing 5% iohexol allows clear differentiation of bone cortex and soft tissues in rabit knee joint from the injected agents on CT scan and X-ray, and the injection approach can influence HA distribution in the knee joint cavity.%目的：运用双源CT扫描及X线透视技术建立玻璃酸钠（HA）在兔膝关节腔内分布的示踪模型，并观察给药位点差异对HA在兔膝关节腔内分布范围的影响。方法以碘海醇为示踪剂，分别配制碘海醇浓度为2.5%、5%、10%、20%、40%的玻璃酸钠-碘海醇（HA-I）混合制剂各0.5 ml，注入兔膝关节腔后，运用双源CT进行平扫和三维重建，筛选能够有效区分药物和周边组织的最佳示踪剂浓度。随后，分别从髌骨下和关节线两种给药位点向兔膝关节腔注射最佳碘海醇浓度的HA-I制剂0.5 ml，应用双源CT及X线透视观察药物在膝关节腔内分布特征的差异，确认该药物示踪模型的有效性。结果 HA-I混合制剂的CT值随着碘海醇浓度增加而递增，碘海醇浓度分别为2.5%、5%、10%、20%、40%时，膝关节软组织、HA-I制剂及骨组织三者的平均CT值比值分别为2∶7∶46，2∶14∶44，2∶28∶44，2∶60∶46，2∶98∶45，证实5%~10%碘海醇浓度的HA-I混合制剂可最有效区分药物和周边组织，获得最理想的药物分布范围三维重建效果。取5%碘海醇浓度的HA-I制剂进行CT扫描和X线透视示踪观察，结果提示给药位点差异与药物分布范围存在相关性，髌骨下给药的HA主要分布于髌股关节，关节线给药的HA则主要分布于胫股关节。结论5%碘海醇浓度的HA-I制剂配合CT扫描及X线透视技术，可有效区分药物和周边组织，直观显示药物在关节腔的分布范围，是一种可靠的HA药物示踪模型。
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