Fast Field-Cycling (FFC) MRI allows the magnetic field to be switched during an imaging scan. FFC-MRI can be used to exploit a characteristic of contrast agents, i.e. the variation of its spin-lattice relaxation time (T1) or rate (R1= 1/T1) with magnetic field in order to increase contrast. Contrast agents play an essential role in MRI, allowing improved diagnosis and delineation of diseased tissue. However, the R1, and hence the effectiveness of contrast agents, varies significantly with magnetic field. Thus, Fast Field-Cycling (FFC) MRI can be used to take advantage of this variation to improve image contrast, allowing more sensitive detection of the agent. In this project new contrast agents, developed by a collaborating group (Invento S.r.l., Italy) were investigated for use with FFC-MRI. R1 dispersion curves of samples containing a range of contrast agents were first obtained using both a commercial relaxometer and a home-built whole-body FFC-MRI system, and the accuracy of the home-built FFC-MRI system was verified. The magnetisation behaviour of these samples during field-cycling pulse sequences was modelled in order to predict the pulse sequence parameters necessary for maximum T1 contrast. Images were obtained, using a number of novel imaging techniques developed on the home-built whole-body FFC-MRI system, and also, using standard T1 weighted imaging on a 3 T Philips clinical MRI scanner. A new FFC-MRI imaging method, ΔR1 mapping was employed to show an increase in contrast using a novel Mn2+ based liposomal contrast agent compared with T1 weighted images at 5 mT, 59 mT and 3 T. The low concentrations of Mn2+ based liposomal contrast agents used with ΔR1 mapping indicate suitability for molecular imaging
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:553785 |
| Date | January 2011 |
| Creators | Ó hÓgáin, Dara |
| Publisher | University of Aberdeen |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=185603 |
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