Infectious Foci Imaging with Targeting Radiopharmaceuticals in Nuclear Medicine

Abstract

Despite the advances in public health during the 18th and 19th centuries and the introduc‐ tion of immunization and antibiotics in the 20th century, bacterial infection is among the most frequently encountered and costly causes of diseases and one of the major causes of morbidity and mortality especially in developing countries (El-Ghany et al., 2005). Localiz‐ ing and distinguishing the “infection foci” in body sites are very important and life saving processes. The identification of an infection at early stage of disease is critical for a favorable outcome. The diagnosis of deep seated infections such as osteomyelitis, endocarditis and in‐ tra-abdominal abscesses is still a challenging problem. Although imaging techniques such as x-ray, computerized tomography (CT-scan), magnetic resonance imaging (MRI) and ultraso‐ nography (US) might be helpful, but none of these techniques are specific for infection diag‐ nosis because of their limitations due to insignificant anatomical changes in the early stages of the infection process. In addition, these techniques are not capable of differentiating be‐ tween inflammatory and infectious processes. In contrast, nuclear medicine procedures can determine the location and the degree of disease activity in infectious processes based on physiologic and/or metabolic changes that are associated with these diseases rather than gross changes in the structure (Hall et al., 1998). This method requires a reliable radiophar‐ maceutical that can selectively concentrate in sites of infection. Various 99mTc-labeled com‐ pounds have been developed for the scintigraphic detection of infection and sterile inflammation in humans. Unfortunately, these radiopharmaceuticals do not discriminate be‐ tween infection and sterile inflammatory process, which is often of clinical importance (Welling et al., 2001). In recent years, the development of radiolabeled antimicrobial agents for specific diagnosis of infection has received considerable attention, sparking a lively de‐ bate about the infection specificity of these radiopharmaceuticals (Oyen et al., 2005). Direct