This thesis describes the development of MRI techniques for identifying disease within cardiac muscle of the rodent heart at 4.7 T. The new methods allow measurement of myocardial T1 and T2* relaxation times and ventricular volumes from cine images. Before in-vivo application, each MRI pulse sequence and imaging protocol was tested using tissue representative phantoms on a cardiac motion simulator. A multi-slice cardiac cine pulse sequence was developed for measuring cardiac volumes that used a modified slice acquisition order compared to standard cine MRI to extend TR and thereby increase the signal without extending the total scan time. This acquisition method was compared to a slower conventional cine pulse sequence by measuring the signal to noise ratio and the left ventricular mass and volumes of the mouse heart. T1 values are known to increase in hearts affected by dilated and hypertrophic cardiomyopathy, so pulse sequences were developed for measuring myocardial relaxation values. In-vivo T1 measurements were made using saturation and inversion recovery pulse sequences. Comparison of the results showed that the inversion recovery pulse sequence gave results that were more consistent with published values from similar studies so it was concluded that this should be used for future cardiomyopathy investigations. A study was carried out on an in-vivo control group to test the effectiveness of the superparamagnetic contrast agent Ferumoxytol in enhancing T2* differences between healthy and pathological tissues. It was found that Ferumoxytol did not affect the T2* of the healthy myocardium and this result was confirmed by histology which revealed very little Ferumoxytol uptake in the heart but plentiful uptake in the liver. The results of this study indicate that future investigations in rats with induced cardiomyopathy can assume that changes in myocardial relaxation times are due to the effects of cardiac disease rather than the contrast agent.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:698859 |
| Date | January 2016 |
| Creators | Firth, Matthew Steven |
| 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=230984 |
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