Abstract: A method for noninvasive measurement of apoptosis is described. The method includes the steps of labeling Annexin V with a positron emitter, injecting the labeled Annexin V into a target cell group, obtaining an image of the target cell group using a positron emission tomography scanner, and evaluating the image to determine an amount of cell death within the target cell group. The target cell group may be a lesion or a suspected tumor. The positron emitter may be F-18. The step of labeling Annexin V with F-18 may include the steps of selecting an F-18 labeled small molecule containing a protein conjugating group, synthesizing and purifying the selected molecule, producing a high specific activity prosthetic group as a result of the synthesizing and purifying step, and conjugating the prosthetic group to the Annexin V. The produced prosthetic group may be N-succinimidyl-4-[18F]fluorobenzoate (SFB).