Electronic Thesis and Dissertation Repository

Degree

Doctor of Philosophy

Program

Medical Biophysics

Supervisor

Ian A. Cunningham

Abstract

Digital subtraction angiography (DSA) is a technique that is widely used to enhance the visibility of small vessels obscured by background structures by subtracting a mask and contrast image. However, DSA is generally unsuccessful for imaging the heart due to the motion that occurs between mask and contrasted images which cause motion artifacts. An alternative approach known as energy subtraction angiography (ESA) exploits the iodine k-edge by acquiring contrast images with a low and high kV in rapid succession to bring the benefits of DSA without motion artifacts. However, it was concluded that image quality for ESA could not compete with DSA, and the approach was abandoned. In our work we show that conclusions about iodine SNR for ESA were based on limitations of early technical components that are no longer relevant. The goals of this thesis were to: 1) develop a theoretical model of iodine SNR that is independent of technology for DSA and ESA; 2) optimize the iodine SNR for ESA; 3) image ESA in an anthropomorphic phantom. It is concluded that, when these conditions are satisfied, ESA iodine SNR equal to that of DSA for low iodine mass loadings (artery sizes) for the same patient entrance exposure, and therefore may provide alternatives to DSA in situations where motion artifacts are expected to render a study as non-diagnostic, such as in coronary applications. In the future this will have important applications for subtraction imaging of the coronary arteries and other vessels where stenosis is vital to patient health.


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