**1. Introduction**

72 12 Chapters on Nuclear Medicine

http://www.ornl.gov/sci/isotopes/r\_w188g.html

http://www.world-nuclear.org/info/inf55.html

http://www.telatomic.com/nuclear/isotope\_generator.html http://www.wolframalpha.com/input/?i=germanium+68

1 E.O.Lawrence:(1939) University of California:"Artificial Radiactivity" speech

Radionuclide imaging has been frequently used for detection and localization of infectious and inflammatory diseases for over five decades. Although there are many infection seeking agents available and currently being used but there is a general consensus that none of them is ideal. No clear cut guidelines exist to recommend a particular radionuclide imaging procedure for a particular clinical indication, however, in some instances the literature does provide us with ample evidence for the choice of the infection specific agent whereas one may have to depend upon the routine management protocols to decide which radionuclide imaging procedure to perform in a particular situation. In fact, presently, the clinical utility of radionuclide infection imaging varies under different circumstances and clinical scenarios; but with the incorporation of hybrid imaging systems, the fusion of functional and anatomical data in form of SPECT-CT and PET-CT has certainly improved the sensitivity and specificity of detecting and localizing an infectious process. Ga-67 citrate, bone seeking radiotracers, radiolabelled leukocytes, antibody and antibody fragments labelled white cells are used in different clinical situations such as osteomyelitis, diabetic foot, infected vascular grafts, infected hip or knee prostheses, intra-abdominal infections including acute appendicitis, cardiovascular, pulmonary infections, malignant otitis externa with variable sensitivity and specificity. Similarly, the ability of F-18 FDG PET to detect infection, inflammation and granulomatous diseases due to their increased glycolytic activity has provided us with another effective agent especially in cases of fever of unknown origin, vasculitis, chronic osteomyelitis, sarcoidosis, inflammatory bowel disease and assessing response to therapy. New advances in the form of SPECT-CT have now also incremented the diagnostic capability of conventional scintigraphic procedures to localize infection. Finally, many investigational new infection seeking agents are in the process of being developed in search of an ideal. These include Tc-99m ubiquicidin, Tc-99m labelled Interleukin-8, N-formyl products, chemotactic cytokines etc. Therefore, with on going research in development of infection specific agents and the advent of hybrid imaging the future offers definite hope for better infection detection and localization in our patients.
