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Contributions to qu...
Contributions to quantitative dynamic contrast-enhanced MRI
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- Garpebring, Anders, 1980- (author)
- Umeå universitet,Radiofysik
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- Karlsson, Mikael, Professor (thesis advisor)
- Umeå universitet,Radiofysik
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- Wirestam, Ronnie, Professor (thesis advisor)
- Lunds universitet, Medicinsk strålningsfysik
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- Östlund, Nils, Phd (thesis advisor)
- Umeå universitet,Radiofysik
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- Hauksson, Jón, Phd (thesis advisor)
- Umeå universitet,Radiofysik
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- Sourbron, Steven, Phd (opponent)
- University of Leeds, Division of Medical Physics
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(creator_code:org_t)
- ISBN 9789174593136
- Umeå : Umeå Universitet, 2011
- English 108 s.
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Series: Umeå University medical dissertations, 0346-6612 ; 1457
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Abstract
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- Background: Dynamic contrast-enhanced MRI (DCE-MRI) has the potential to produce images of physiological quantities such as blood flow, blood vessel volume fraction, and blood vessel permeability. Such information is highly valuable, e.g., in oncology. The focus of this work was to improve the quantitative aspects of DCE-MRI in terms of better understanding of error sources and their effect on estimated physiological quantities. Methods: Firstly, a novel parameter estimation algorithm was developed to overcome a problem with sensitivity to the initial guess in parameter estimation with a specific pharmacokinetic model. Secondly, the accuracy of the arterial input function (AIF), i.e., the estimated arterial blood contrast agent concentration, was evaluated in a phantom environment for a standard magnitude-based AIF method commonly used in vivo. The accuracy was also evaluated in vivo for a phase-based method that has previously shown very promising results in phantoms and in animal studies. Finally, a method was developed for estimation of uncertainties in the estimated physiological quantities. Results: The new parameter estimation algorithm enabled significantly faster parameter estimation, thus making it more feasible to obtain blood flow and permeability maps from a DCE-MRI study. The evaluation of the AIF measurements revealed that inflow effects and non-ideal radiofrequency spoiling seriously degrade magnitude-based AIFs and that proper slice placement and improved signal models can reduce this effect. It was also shown that phase-based AIFs can be a feasible alternative provided that the observed difficulties in quantifying low concentrations can be resolved. The uncertainty estimation method was able to accurately quantify how a variety of different errors propagate to uncertainty in the estimated physiological quantities. Conclusion: This work contributes to a better understanding of parameter estimation and AIF quantification in DCE-MRI. The proposed uncertainty estimation method can be used to efficiently calculate uncertainties in the parametric maps obtained in DCE-MRI.
Subject headings
- TEKNIK OCH TEKNOLOGIER -- Medicinteknik -- Medicinsk bildbehandling (hsv//swe)
- ENGINEERING AND TECHNOLOGY -- Medical Engineering -- Medical Image Processing (hsv//eng)
Keyword
- Dynamic contrast-enhanced MRI
- quantitative imaging
- parameter estimation
- uncertainty estimation
- arterial input function
- radiofysik
- radiation physics
Publication and Content Type
- vet (subject category)
- dok (subject category)
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