Nuclear Medicine Technology: Inflammation and Infection Imaging

Nuclear Imaging of Bacterial Infection: The State of the Art and Future Directions

Increased mortality rates from infectious diseases is a growing public health concern. Successful management of acute bacterial infections requires early diagnosis and treatment, which are not always easy to achieve. Structural imaging techniques such as CT and MRI are often applied to this problem. However, these methods generally rely on secondary inflammatory changes and are frequently not specific to infection. The use of nuclear medicine techniques can add crucial complementary information, allowing visualization of infectious pathophysiology beyond morphologic imaging. This review will discuss the current structural and functional imaging techniques used for the diagnosis of bacterial infection and their roles in different clinical scenarios. We will also present several new radiotracers in development, with an emphasis on probes targeting bacteria-specific metabolism. As highlighted by the current coronavirus disease 2019 epidemic, caused by the novel severe acute respiratory syndrome coronavirus 2, similar thinking may apply in imaging viral pathogens; for this case, prominent effects on host proteins, most notably angiotensin-converting enzyme 2, might also provide worthwhile imaging targets.

99mTc-MDP as an imaging tool to evaluate the in vivo biodistribution of solid lipid nanoparticles

The aim of this study was to establish the in vivo uptake and tissue distribution of ^99mTc-MDP-encapsulated Solid Lipid Nanoparticles (SLNs) post administration. Radioactive ^99mTc-MDP encapsulated into SLNs was administered to rats to trace their biodistribution through imaging and ex vivo studies. As expected IV injected ^99mTc-MDP exhibited predominant visual bone uptake and a high localisation of particles in the kidneys (3.87%ID/g) followed by bone (2.66%ID/g). IV administered ^99mTc-MDP encapsulated by SLN showed similar uptake than ^99mTc-MDP. Orally administrated ^99mTc-MDP showed no uptake in any organs except the GI-tract while orally administered ^99mTc-MDP-SLN showed distinct transfer of ^99mTc-MDP from the GI tract with measurable levels in the kidneys and bone.