Imaging Agents

An amino acid analog having the general formula:

• wherein R1 and R2 are each independently selected from the group consisting of H, alkyl, haloalkyl, cycloalkyl, halocycloalkyl, cycloalkenyl, halocycloalkenyl, cycloalkynyl, halocycloalkynyl, acyl, haloacyl, aryl, haloaryl, heteroaryl, haloheteroaryl, alkenyl, haloalkenyl, alkynyl, haloalkynyl, Tc-99m and Re chelates;
• R3 is selected from the group consisting of H, alkyl, haloalkyl, cycloalkyl, halocycloalkyl, cycloalkenyl, halocycloalkenyl, cycloalkynyl, halocycloalkynyl, acyl, haloacyl, aryl, haloaryl, heteroaryl, haloheteroaryl, alkenyl, haloalkenyl, alkynyl, and haloalkynyl;
• X is selected from the group consisting of halogen, haloalkyl, halocycloalkyl, halocycloalkenyl, halocycloalkynyl, haloacyl, haloaryl, haloheteroaryl, haloalkenyl, haloalkynyl, Tc-99m chelate and Re chelate, where halo or halogen in X is selected from the group consisting of F, Cl, Br, I, At, F-18, Br-76, I-123, I-124, or a pharmaceutically acceptable salt thereof.