Biodistribution of 3-<131I>iodo-O-mythyl-L-alpha-methyltyrosine in Tumor Bearing Rats: A Comparison Study with L-3-<131I>iodo-alpha-methyltyrosine

Choi, Chang Woon; Yang, Seung Dae; Woo, Kwang Sun; Chung, Wee Sup; Lim, Soo Jung; Suh, Yong Sup; Chun, Kwon Soo; Ahn, Soon Hyuk; Lee, Jong Doo; Hong, Sung Soon; Lim, Sang Moo

Abstract

PURPOSE: The aim of this sutdy was to evaluate the feasibility of 3-[131I]Iodo-O-methyl-L-a-methyltyrosine ([131I]OMINT) as an agent for tumor image.
MATERIALS AND METHODS
After synthesis of 4-O-methyl-L-a-methyltyrosine (OMAMT), OMAMT was labeled with 131I using Iodogen method. In viro cellular uptake study was performed using 9 L gliosarcoma cells at various time points upto 4 hr. The biodistribution (five rats implanted with the 9 L gliosarcoma cells per group) was evaluated at 30 min, 2 hr, 24 hr after iv injection of 3.7 MBq [131I]OMIMT or L-3-[131I]iodo-a-methyltyrosine ([131I]IMT). Gamma camera images were obtained at 30min, 2 hr, and 24 hr.
RESULTS
[131I]OMINT uptake was 3.3 times and 2.5 times higher than [131I]IMT uptake at 30 min and 60 min, respectively and same after 2 hr in in vitro sutdy using 9L gliosarcoma cells. Maximum accumulation in tumor occurred at 30 min for both [131IOMINT and [131I]IMT in tumor bearing rats. The tumor uptake of [131I]OMINT was significantly higher than that of [131I]IMT in tumor bearing rats. The tumor uptake of [131I]OMIMT was significantly higher than that of [131I]IMT at early time point studied (3.74 +/- 0.48 vs 0.38 +/- 0.17% ID/g at 30 min and 2.40 +/- 0.17 vs 0.24 +/- 0.03% ID/g at 2 hr, respectively, p<0.01). However, the tumor uptake of both radiolabels were not significantly different at 24 hr (0.04 +/- 0.01 vs 0.05 +/- 0.01% ID/g). Tumor was visualized as early as at 30 min in gamma camera images.
CONCLUSION
These data suggested that [131I]OMIMT might be a useful tumor imaging agent and has more advantage for the tumor imaging compared to [131I]IMT.