Investigation of the Imaging Capability of Magnetic Resonance Angiography Systems

Lacy, Catherine (1995) Investigation of the Imaging Capability of Magnetic Resonance Angiography Systems. Master in Management Studies thesis, University of Glasgow.

Abstract

The high incidence of heart disease, particularly on the West Coast of Scotland, makes any procedure which can enhance diagnostic performance in this area of high medical value. This study begins by comparing the known strengths and weaknesses of magnetic resonance angiography to those of conventional angiography and Duplex US. It describes in detail the theory firstly of magnetic resonance imaging, and secondly of the unique problems due to saturation and spin dephasing which arise when flowing spins are imaged. The rationale behind the design of commercially available pulse sequences specified for flow imaging is then described. The study then moves into an account of the experimental work undertaken, using a rotating drum phantom containing a paramagnetically doped blood equivalent gel to quantitatively compare the imaging performance of six angiographic sequences. First, a literature study is undertaken to critically establish the accepted normal blood flow rates in the major arteries. The rotating drum phantom and its mode of simulation of blood flow is next discussed. Acceptable relaxation times for in vivo blood are established by a thorough investigation of existing literature. Details are provided of the relaxation properties of the gel and how these were reached, and a thorough discussion of the effect on the results of the study of discrepancies between these values and those obtained for in vivo blood flow follows. The purpose of the study is to establish the effectiveness of six commercially available pulse sequences in imaging blood flow, and to define the reasons for signal loss which detracts from their clinical effectiveness. Signal voids are known to arise when imaging clinical abnormalities such as stenoses, and this study seeks to establish the imaging conditions under which it can definitively be said that signal losses are due to vessel abnormalities, and not to 'blind spots' (i.e. insensitivities to flow) resulting from the inadequency of sequence performance. Scans of the phantom using the six test sequences are used to evaluate under what imaging conditions the signal intensity will be reduced because of saturation and spin dephasing effects. giving the appearance of stenotic signal voids. Signal losses due purely to rotational phantom artefact effects are identified. The study concludes by describing other areas of blood flow imaging to which the results of this study may be applicable. It also establishes some priorities for clinical magnetic resonance angiography imaging procedure.

• Item Type: Thesis (Master in Management Studies)
• Qualification Level: Masters
• Additional Information: Adviser: B R Condon
• Keywords: Medical imaging
• Date of Award: 1995
• Depositing User: Enlighten Team
• Unique ID: glathesis:1995-75492
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 19 Nov 2019 19:39
• Last Modified: 19 Nov 2019 19:39
• URI: https://theses.gla.ac.uk/id/eprint/75492