Excerpt With recent advances in instrumentation (1) and the development of new localizing materials, isotope scanning has been applied to the visualization of lesions of the thyroid, kidneys, brain, liver, spleen, and bone. The addition of the pancreas to this growing list has awaited the development of a suitably labeled pancreas-specific compound. We have previously reported (2) animal distribution studies of a new agent, Se75-selenomethionine, with sufficient pancreas specificity to be useful for scanning. The present report deals with the clinical applications of this compound. The pancreas uptake of amino acids has been recognized for some time (3). This uptake is a reflection of the rapid rate of synthesis of the digestive enzymes. From 5 to 10 per cent of most amino acids are found in the pancreas within an hour after administration. Unfortunately none of the elements in the structure of amino acids (C, H, N, O, and S) have isotopes with properties suitable for scanning. Externally labeled amino ac...