Accumulation of radioiodinated L-alpha-methyltyrosine in pancreas of mice: concise communication.

L-3-iodo-alpha-methyltyrosine, labeled with either I-131 or I-123, has a high pancreatic specificity in mice. A pancreas-to-liver ratio of 8.6 +/- 2.7 is observed during the first hour after i.v. injection. Accumulation is also prominent in the kidneys, but excretion of the radioagent is rapid, 50% of the activity being eliminated during 90 min. Compared with L-[75Se]selenomethionine, the compound currently used for pancreatic imaging, L-3-[123I]or[131I]iodo-alpha-methyltyrosine has a higher pancreas-to-liver ratio, a shorter physical half-life and biological half-time, and better decay characteristics.