Methods for imaging beta cells in pancreatic tissue using radioisotopes of manganese, which may be referred to as radiomanganese, are described. Example radioisotopes of manganese include Mn-52g, Mn-52m, and Mn-51. As one example, radiomanganese can be used to image pancreatic beta cells, in which radiomanganese shows a preferential uptake. This provides for applications such as quantifying beta cell mass (e.g., functional beta cell mass), assessing transplant viability, and monitoring the efficacy of drug treatments. A pharmacological agent can be administered to modulate the uptake of divalent metals by the pancreatic beta cells, which can be correlated to a modulated uptake of radiomanganese to estimate pancreatic beta cell mass, function, or both.
