Molecular Imaging of Inflammation/Infection: Nuclear Medicine and Optical Imaging Agents and Methods

Abstract

Nuclear medicine imaging offers the possibility to study in vivo different aspects of inflammatory process by the use of radio-labeled molecules that bind to specific receptor targets on cells and tissues. This noninvasive technique, combined with pathogens engineered to express luciferase, allows quantification in the same animal of the spatial and temporal progression of the infection and identification of animal-to-animal variations in pathogen replication and dissemination. One strategy to use optical imaging in living animals is the use of luciferase reporter genes as internal sources of light called bioluminescence imaging (BLI). This enables real-time noninvasive imaging of infections and gene expression in living organisms. Nuclear medicine imaging is characterized by the use of radio pharmaceuticals (radiolabeled probes) that, administered in pico- and nanomolar amounts. These probes can also be used for early diagnosis of diseases, in susceptible subjects, for detection of disease relapse and radio-guided surgery

Imaging for Infection: From Visualization of Inflammation to Visualization of Microbes

“…These scans are used in work-up of inflammatory bowel diseases, acute osteomyelitis [43], soft-tissue infections, and suspected infections of vascular [41,44] and orthopedic prostheses [45].…”

Molecular Imaging of CXCR4 Receptor Expression in Tumors

“…The gamma emissions from these radionuclides are lower in energy than those for PET imaging, and the use of a collimator results in sensitivity that is two to three orders of magnitude lower than PET, yielding lower resolution images (spatial resolution = 8-15 mm). SPECT isotopes are often longer-lived and the most commonly used radionuclides are 123 I ( t 1/2 = 13.1 h), 111 In ( t 1/2 = 2.8 day), 99m Tc ( t 1/2 = 6 h), and 67 Ga ( t 1/2 = 78.3 h) [ 48 ] . The long half-lives of these radionuclides allow for the observation of biological processes several hours or even days after tracer administration.…”

Besilesomab for imaging inflammation and infection in peripheral bone in adults with suspected osteomyelitis

“…29,34,47,59,[62][63][64][65][66][67][68][69][70][71][72][73] These studies have also been the subject of review 20,33,51,74,75 and retrospective data analysis, 29,76 and 80 inflammatory bowel disease, [81][82][83] and septic loosening of knee 84 or hip 85 endoprosthesis, although a detailed discussion of such uses extends beyond the scope of this report. Beyond diagnosis of infection and inflammation, bone marrow scintigraphy has been used to track bone metastases in cancer patients 86,87 and has also been considered for radiotherapeutic applications.…”

“…Such developments have been the subject of recent reviews. 9,[20][21][22][23][24][25] For example, ultrasound, 26,27 computed tomography (CT), 21,22,28 magnetic resonance imaging (MRI), [29][30][31][32] optical 20 and nuclear medicine techniques 20,23,24,[33][34][35][36][37] have all been used to improve diagnostic confidence. [38][39][40] The numerous advantages of FDG-PET imaging include a higher spatial resolution in comparison to conventional nuclear medicine modalities, fast examination time (result available within 1-2 hours after tracer administration), the ability to differentiate between hematopoietic bone marrow and activated white blood cells (WBCs), and potential application to treatment monitoring.…”