FACBC, IVACBC, and TECACBC are amino acid compounds labeled by radioisotopes. The Emory inventions provide novel, radio-labeled amino acid compounds useful in detecting and evaluating the recurrence of tumors. These compounds combine the advantageous properties of amino acids, namely, their rapid uptake, high specificity for target sites, prolonged retention in tumors, with the properties of gamma emitting radioisotopes and provide superior imaging agents to existing ones for Positron Emission Tomography (PET) or Single Photon Emission Computer Tomography (SPECT). In 2003 Emory licensed its technology portfolio to Nihon, the leading radiopharmaceutical Japanese company. The technology subsequently was sublicensed to Blue Earth Diagnostics, who obtained regulatory approval for FACBC, the first line of these compounds, in May 2016.