Ultrasound and magnetic resonance techniques for the haemodynamic quantification of the peripheral vascular system

Watson, Amanda Jane (2013) Ultrasound and magnetic resonance techniques for the haemodynamic quantification of the peripheral vascular system. PhD thesis, University of Glasgow.

Abstract

The aim of this thesis was to determine whether the blood flow velocities in the peripheral vascular system measured using phase contrast magnetic resonance imaging, PC-MRI, techniques could be used in the same way that blood flow velocities measured using spectral Doppler ultrasound are used to aid in the diagnosis of peripheral vascular disease. Specifically, we aimed to investigate the measurement of maximum velocities and the use of maximum velocity ratios; an area of investigation which has been neglected in studies of PC-MRI blood flow quantification to date.
A series of optimisation and comparison studies were carried out using in-house developed test phantoms. Key to the in-vitro work was the establishment of a dual modality flow test system which would allow comparison of identical flow conditions measured using ultrasound and MRI. The work was complemented by in-vivo studies in healthy volunteers. A 4D PC-MRI commercial work-in-progress protocol and software package became available during the study and was evaluated in-vitro and in-vivo using similar methods as for the 2D PC-MRI studies.
The main findings of the thesis were that 2D PC-MRI measurement of maximum velocities significantly underestimated those measured using spectral Doppler ultrasound. However, if corrections were applied to account for the overestimation of ultrasound maximum velocity due to spectral broadening, then the two methods were in agreement. In contrast, the use of maximum velocity ratios showed no difference between spectral Doppler ultrasound and 2D PC-MRI measurements.
It was noted that one of the potential problems with the use of 2D PC-MRI in the measurement of the maximum velocity at a stenosis is the accurate positioning of the 2D velocity encoded slice in the stenotic jet. 4D PC-MRI, with a time resolved velocity encoded volume dataset, offers a potential solution to this. However, our evaluation of 4D PC-MRI showed that it can significantly underestimate both maximum velocities and maximum velocity ratios in comparison with 2D PC-MRI and spectral Doppler ultrasound and requires further development before it can be used for peripheral vascular applications.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Keywords: vascular, peripheral vascular, carotid, ultrasound, Doppler, spectral Doppler ultrasound, phase contrast, magnetic resonance imaging, PC-MRI, 2D PC-MRI, velocity, velocity measurement, velocity quantification, velocity ratio, maximum velocity, phantom, flow phantom, test object, dual modality
• Subjects: R Medicine > R Medicine (General); R Medicine > RZ Other systems of medicine
• Colleges/Schools: College of Medical Veterinary and Life Sciences > School of Medicine, Dentistry & Nursing
• Supervisor's Name: Foster, Dr. John
• Date of Award: 2013
• Depositing User: Ms Amanda Jane Watson
• Unique ID: glathesis:2013-4203
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 30 Apr 2013 14:55
• Last Modified: 01 May 2013 13:06
• URI: https://theses.gla.ac.uk/id/eprint/4203