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Title: Quantitative cardiac SPECT
Author: Peace, Richard Aidan
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 2001
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Myocardial perfusion SPECT imaging is a sensitive and specific indicator of coronary artery disease (Fleischman et al. 1998). The clinical value of coronary scintigraphy is now established with a utilisation rate of eight procedures per 1000 population per year in the USA and two per 1000 in the EU (Pennell et al. 1998). While myocardial perfusion SPECT images are routinely interpreted by expert observers the classification is inevitably subject to inter-observer and intra-observer variability. An optimised and validated quantitative index of the presence or absence of coronary artery disease (CAD) could improve reproducibility, accuracy and diagnostic confidence. There are segmental techniques to automatically detect CAD from myocardial perfusion SPECT studies such as the CEqual quantitative analysis software (Van Train et al. 1994). However, they have not been shown to be significantly better than expert observers (Berman et al. 1998). The overall aim of this thesis was to develop, optimise and evaluate quantitative techniques for the detection of CAD in myocardial perfusion SPECT studies. This task was divided into three areas; quantification of transient ischaemic dilation (TID); quantitative detection and localisation of CAD; count normalisation of patient studies. Transient ischaemic dilation (TED) is the transient dilation of the left ventricle on immediate post stress images compared to resting technetium-99m imaging. Stolzenberg (1980) first noted TID as a specific marker for severe CAD. There are few published studies of fully quantitative evaluations of TID. The first aim of this thesis was to compare the performance of methods for quantifying TDD in myocardial perfusion SPECT. The second aim of this thesis was to investigate the use of image registration in myocardial perfusion SPECT for quantitative detection and localisation of CAD. This thesis describes two studies comparing six count normalisation techniques. These techniques were; normalise to the maximum value; to the mean voxel value; to the mean of the top 10% or 20% of counts; minimise the sum of squares between studies or the sum of absolute differences. Ten normal myocardial perfusion SPECT studies each with 300 different simulated perfusion defects were count normalised to the original studies. The fractional count normalisation error was consistently lower when the sum of absolute differences was minimised. However, a more clinically applicable measure of count normalisation performance is the effect on quantitative CAD detection. The Z-score method of automatic detection of CAD was repeated using each count normalisation technique. There was no statistically significant difference between the methods although the power of the ROC analysis was poor due to low patient numbers. The balance of evidence suggested that count normalisation by minimisation of the of absolute differences produced the best performance.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available