A recent study investigating the application of Positron Emission Particle Tracking (PEPT) in a living subject for the first time was published by researchers from the School of Biomedical Engineering & Imaging Sciences.
Image Credit: Kings College London
One radioactive particle can be localized and tracked in three dimensions using PEPT technology in large, dense, and/or optically opaque systems that are challenging to study with other techniques. The technology has not yet been adapted for use in biomedical applications; instead, it is currently used to study flows within complex mechanical systems, such as large engines, industrial mixers, etc.
Because there are currently no techniques for isolating and radiolabeling a single particle small enough and radioactive enough to be injected and detected in a living subject, PEPT has historically been an unexplored area in biomedical imaging.
A multidisciplinary team led by Dr. Rafael T. M. de Rosales and the lead author of this new study, Dr. Juan Pellico, were able to synthesize, radiolabel, and isolate a single submicrometer particle of silica with enough radioactivity to enable detection with both standard PET imaging and PEPT for the first time. The study was published in the journal Nature Nanotechnology.
Our ambition is to further develop these findings and developed improved PEPT tracers that will allow us to fully explore the potential of PEPT in biomedicine to provide whole-body information about blood flow dynamics in different settings, with unique applications such as the study of complex multiphase flow of blood, crucial in clinical physiology and drug delivery.
Dr. Rafael T.M. de Rosales, Reader, Imaging Chemistry, School of Biomedical Engineering & Imaging Sciences
Dr Rafael T.M. de Rosales adds, “Other potential applications include using single particles for high-precision PEPT-guided radiotherapy or surgery. Moreover, in vivo PEPT with single radiolabelled cells should allow the evaluation of the motion and migration of individual cells, and their interaction with blood vessels and tissues.”
PEPT allows you to triangulate the position of the single particle inside the body with high precision and in real time.
Dr. Rafael T.M. de Rosales, Reader, Imaging Chemistry, School of Biomedical Engineering & Imaging Sciences
Rosales continues, “In current PET imaging methods, we inject billions or even trillions of radiolabelled molecules into the patients and the resulting images represent their average distribution after a period of time, usually 10-30 minutes. This does not give you information about the velocity of these molecules or their exact location inside the body in real time, which could be useful for the study of hemodynamics, or how blood flows through your vessels.”
“PEPT, by tracking single particles in real time, should allow the study of the velocity, density, and overall dynamics of blood flow that are currently impossible to study by any other imaging modality. The study of hemodynamics at the whole-body level is particularly timely since clinical total-body PET scanners are now available, one of which will soon be installed here at King’s,” concludes Rosales.
In vivo PEPT may lead to significant advances in the assessment of aberrant events in cancer or cardiovascular illnesses where blood flow plays a significant role. In the future, clinical applications could involve a thorough examination of blood flow and pressure gradients inside abnormally flowing lesions, like tumors or vascular lesions, in order to inform patient treatment choices.
Journal Reference
Pellico, J., et al. (2024) In vivo real-time positron emission particle tracking (PEPT) and single particle PET. Nature Nanotechnology. doi.org/10.1038/s41565-023-01589-8.