Targeted imaging of infection

The prompt identification, localization and characterization of focal sites of infection in the patients with fever is a critical step in clinical man agement, particularly, when localizing symptoms are not present. Although t he classic signs of inflammation are suitable to localize injury at superfi cial sites or in the extremities, inflammation of internal structures, such as in the brain, chest and abdomen, can be difficult to localize without a dditional diagnostic procedures. Tissue injury, regardless of cause or anat omical site, results in a complex series of physiologic changes that we rec ognize as the inflammatory response. The inflammatory response is character ized by a series of biochemical events in the insulted cells and surroundin g structures that results in the three major pathophysiological components: increased tissue perfusion, increased vascular permeability, and leukocyti c exudation. Exploitation of the early attributes of the inflammatory proce ss are not sufficient for the routine detection of inflammation. Currently, reagents for targeting infection represent cellular or protein components involved in the inflammatory process. Such approaches have met with some su ccess as these agents comprise integral parts of the complex phenomena know n as inflammation. This same fact also limits their utility, improved agent s for targeting infection will likely be based on small molecules whose dif fusion into the lesion is not hindered by molecular size constraints and wh ich bind to molecular targets at the site of infection/inflammation. In gen eral, the lower molecular weight should also lead to enhanced blood clearan ce, avoiding elevated blood pool activity which contributes to background. New agents should also obviate the need to handle blood, as this represents potential hazards to both patient and the medical personnel alike. (C) 199 9 Published by Elsevier Science B.V. All rights reserved.