1st Supervisor: Steven Niederer, King’s College London
2nd Supervisor: Paul Marsden, King’s College London
Additional Supervisors: Phil Blower and Rafael TM de Rosales, King’s College London

Aim of the PhD Project:

  • Demonstrate the feasibility of high-resolution tracking of individual radiolabelled particles for applications in cardiovascular disease
  • Develop methods for accurate particle tracking in the presence of cardiac motion
  • Develop methods to exploit PET time-of-flight capabilities to enhance tracking of multiple particles
  • Link data obtained from particle tracking with cardiovascular modelling approaches

Project Description / Background:

Standard radionuclide imaging involves imaging the distribution of a radiotracer in the body. In Positron Emission Particle Tracking (‘PEPT’) a single particle labelled with a large number of radioactive nuclei would be injected into the body (eg into the bloodstream) and tracked dynamically. Tracking of positron emitting particles has previously been used in numerous industrial applications in order to measure flow distributions or investigate how materials mix. These industrial applications were pioneered at Birmingham University who have demonstrated that it is possible to track (single) positron emitting particles with acceptable spatial and temporal resolution to obtain fluid velocity maps with particles travelling at speeds up to 1 ms-1  if the particle has a radioactivity of ~ 100kBq . A simple triangulation technique is used to perform the tracking. [1] Other than some limited cell tracking measurements performed at Stanford University [2], the feasibility of using PEPT in biomedical applications has not been investigated. As part of a joint programme with the Birmingham Group, we propose to try and use PEPT to measure blood flow related information in-vivo – potentially this can be done with very high resolution (~1mm for PEPT cf 5-10,m for PET). A key requirement for in-vivo PEPT is the availability of very high-specific activity radiolabelled nano-particles , such as have uniquely been developed by Rafa Torres at KCL[3]. Potential clinical applications include measuring properties of blood velocity profiles in the presence of stenoses and characterising micro-vascular disease in the heart.

The feasibility of potential clinical applications depend on the accuracy with which measurements can be made. Given the experience of the Birmingham group it is very unlikely that the technique will not work to some degree in a small animal models but whether blood flow related measurements, such as would form the basis for subsequent computational modelling of cardiac flow, can be made with an accuracy that makes them clinically useful is totally unknown. Implementing PEPT in vivo and extracting clinically useful information involves many additional technical and computational challenges to those encountered in industrial applications, notably the need for multiple particles and addressing the effects of cardiac motion – these will be addressed in this project.

The PhD-candidate should preferably have a background in physics/engineering/computer science and ideally be interested in a project that has both experimental and computational aspects which must be developed in parallel. This project provides the opportunity to have an impact on a novel imaging modality at a very early stage when many fundamental aspects of how it will work are still to be defined

References:

  1. Parker DJ. Nucl Instr Meth Phys Res Sec A. 1993; 326:592±607.
  2. Lee. IEEE Transactions On Medical Imaging, vol. 34, no. 4, april 2015
  3. Torres. Angewandte Chemie Volume 50, Issue 24, 2011

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