| Object: To evaluate the feasibility and safety of percutaneous vertebroplasty using 131 I labeled PMMA cement in rabbits.Materials and methods:1. 131 I labeled PMMA: PMMA was labeled with 131 I using Chloramine-T method at room temperature and the labeling yield was measured.2. The physical characteristics of 131I-PMMA: Make 6 pieces of bone cement samples with the method above and the mix proportion is the same as the clinical use of bone cement, powder liquid ratio 3:2.The control group are ordinary bone cement samples, the mix proportion is also 3:2.The volume of each sample is about 3.2m L.Observe the liquid time, paste time, and curing time of the two groups at room temperature condition.3. Experimental grouping and treatment method: 30 experimental animals were randomly divided into two groups. All 6 rabbits in Group 1 were performed PVP using 131I-PMMA bone cement and were taken to be checked by SPECT at 1stday, 4thday, 8thday and 16 thday after operation respectively in order to evaluate the distributing rule of 131 I.24 rabbits in Group 2 were performed PVP as well as Group 1 and were randomly divided into four subgroups according to the postoperative four time points(1stday, 4thday, 8thday and 16 thday after operation).Each subgroup included 6 rabbits. The biodistribution of 131I-PMMA in rabbits was investigated at these four times.4. Observation index: ①the labeling yield of 131I-PMMA; ②the polymerization time of liquid phase, paste phase and harden phase; ③the distributing rule of 131 I in rabbits of Group 1; ④the radioactivity uptake rate of various organs in rabbits of Group 2 at different times.5. Statistic analysis: The chi-square test was used to compare the labeling yields of 131I-PMMA. The polymerization time were analyzed by independent-samples t test. The radioactivity ratio of vertebral to liver was compared with single factor analysis of variance and so did the radioactivity ratio of vertebral to kidney. The results were considered significant when p-values were less than 0.05.Result: The average labeling yield of 131I-PMMA is about 64.9±1.45%;The average liquid time, paste time, and curing time were 235.3±23.3 s、244.8±18.6 s、121.5±10.6s respectively for group 1; 246.5±10.8 s、251.0±12.3 s、123.7±6.7s respectively for group 2.There was no statistically significant difference(P > 0.05); SPECT shown 131 I accumulated within PVP-treated vertebrae. Its distribution is larger than the scope of bone cement deposition and became weak as time gone; The radioactivity uptake rate was the highest in the PVP-treated vertebral and followed by liver and kidney, and was low in the thyroid gland, heart, lung, spleen, stomach and intestinal, and the lowest in the brain, pancreatic, bone and muscle. The radioactivity uptake rate in all organs decreased with the extension of time. The radioactivity ratio of vertebral to liver and vertebral to kidney increased with the extension of time.Conclusion: It is feasible that PMMA is labeled with 131 I using Chloramine-T method, the average labeling yield of 131I-PMMA is 64.9±1.45%; It will not affect the polymerization time of PMMA if labeled with 131 I. PVP using 131 I labeled PMMA cement is safe and won’t cause acute radiation injury to normal tissue. After treatment 131 I can storage in bone cement inside and around for a long time, but its security and specific anti-tumor effect still needs further experimental observation. |
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