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Optimisation and Validation of Dynamic Susceptibility Contrast MRI Perfusion Measurements

Knutsson, Linda LU (2006)
Abstract (Swedish)
Popular Abstract in Swedish

Med magnetkamera (magnetresonans, MR) kan utmärkt morfologisk information erhållas men tekniken är även användbar för funktionella studier. En funktionell tillämpning är att mäta perfusion (kapillära blodflöden). Perfusionsrelaterad information kan åskådliggöras på flera sätt med MR, ofta via signalförändringar orsakade av spårämnen eller kontrastmedel i blodet.



Den teknik som huvudsakligen använts och utvecklats i det aktuella avhandlingsarbetet är ett exempel på en kvantitativ eller semi-kvantitativ metod för bedömning av cerebral perfusion. Metoden bygger på att man under kort tid injicerar kontrastmedel i en ven (s.k. bolusinjektion) och under snabb bildtagning (c:a 1... (More)
Popular Abstract in Swedish

Med magnetkamera (magnetresonans, MR) kan utmärkt morfologisk information erhållas men tekniken är även användbar för funktionella studier. En funktionell tillämpning är att mäta perfusion (kapillära blodflöden). Perfusionsrelaterad information kan åskådliggöras på flera sätt med MR, ofta via signalförändringar orsakade av spårämnen eller kontrastmedel i blodet.



Den teknik som huvudsakligen använts och utvecklats i det aktuella avhandlingsarbetet är ett exempel på en kvantitativ eller semi-kvantitativ metod för bedömning av cerebral perfusion. Metoden bygger på att man under kort tid injicerar kontrastmedel i en ven (s.k. bolusinjektion) och under snabb bildtagning (c:a 1 bild/sekund under 1-1,5 minut) följer dess förstapassage i vävnad och artär med dynamisk MR. Via lokal störning av magnetfältet (s.k. susceptibilitetseffekter) orsakar kontrastmedlet en temporär signalförlust i MR-bilden under passagen. Graden av signalförlust återspeglar perfusionen i vävnaden, och utifrån de erhållna signalkurvorna kan kinetiska spårämnesmodeller användas för beräkning av perfusionsparametrar som blodflöde, blodvolym och medelpassagetid i varje bildelement.



Syftet med denna doktorsavhandling var att optimera och validera den dynamiska MR-metoden för perfusionsmätning. Olika matematiska s.k. dekonvolutionsmetoder som krävs för beräkningen av blodflöde och medelpassagetid har utvärderats. Datorsimuleringar där olika bildtagningsparametrars betydelse för beräkningen av perfusionsparametrarna har analyserats, och en algoritm för automatisk identifikation av lokala arteriella signalkurvor har utvecklats. För validering och förbättring av absolutkvantifieringen genomfördes en jämförelse mellan den dynamiska MR-metoden och en etablerad nukleärmedicinsk metod, Xe-133 SPECT. Denna jämförelse visade en tillfredsställande linjär korrelation mellan metoderna, men de MR-baserade blodflödesvärdena var systematiskt högre. (Less)
Abstract
The studies presented in this thesis concern the optimisation and evaluation of the dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI) technique for the assessment of perfusion-related parameters of the brain, such as cerebral blood flow (CBF), cerebral blood volume (CBV) and mean transit time (MTT). Several methodological factors influence these measurements, for example, contrast-agent administration, arterial input function (AIF) registration, choice of deconvolution algorithm and the choice of pulse-sequence parameters.



In the first study, a comparison of two different deconvolution techniques was made, i.e., one based on the fast Fourier transform (FT) and the other on singular value decomposition... (More)
The studies presented in this thesis concern the optimisation and evaluation of the dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI) technique for the assessment of perfusion-related parameters of the brain, such as cerebral blood flow (CBF), cerebral blood volume (CBV) and mean transit time (MTT). Several methodological factors influence these measurements, for example, contrast-agent administration, arterial input function (AIF) registration, choice of deconvolution algorithm and the choice of pulse-sequence parameters.



In the first study, a comparison of two different deconvolution techniques was made, i.e., one based on the fast Fourier transform (FT) and the other on singular value decomposition (SVD). The primary result of this study was that CBF estimates obtained by FT-based deconvolution were lower than the CBF values resulting from SVD-based deconvolution. This is in agreement with the results presented in previous publications, demonstrating that the use of FT-based deconvolution underestimates high blood-flow rates (at short MTT).



In the second study, perfusion parameters were calculated from simulated data corresponding to different experimental conditions. For example, variations in signal-to-noise ratio (SNR), temporal resolution, AIF shape, signal drop and cut-off level in the truncated SVD deconvolution were investigated. The main conclusions were that the echo time requires optimisation to ensure sufficient signal drop in combination with reasonable baseline SNR, and that a broad input function can lead to underestimation of the CBF.



Regional AIFs (rAIFs) were the subject of the third investigation. By using factor analysis of dynamic studies in combination with principal component analysis, rAIFs were obtained and the CBF was calculated by using the rAIF located closest to each tissue voxel. The conclusions drawn from the study were that the use of rAIFs reduced dispersion effects which can lead to CBF underestimation.



In the fourth study, CBF was measured in absolute terms in 20 volunteers using Xe-133 SPECT and DSC-MRI. An AIF time-integral correction was introduced in order to improve the absolute CBF quantification in DSC-MRI. Average whole-brain estimates as well as regional CBF values in grey matter (GM) and white matter (WM) were obtained, and the results from the two modalities were compared. For the whole-brain average, the linear relationship was found to be CBF(MRI)=2.4?CBF(Xe)-7.9 [CBF given in units of ml/(min 100 g)], with a correlation coefficient of r=0.76. (Less)
Please use this url to cite or link to this publication:
author
opponent
  • Prof. Dr Heiland, Sabine, Heidelberg, Germany
organization
publishing date
type
Thesis
publication status
published
subject
keywords
Nukleärmedicin, radiobiologi, Nuclear medicine, radiobiology, radiologi, tomografi, medicinsk instrumentering, tomography, medical instrumentation, Clinical physics, cerebral blood volume, mean transit time, cerebral blood flow, perfusion, dynamic susceptibility contrast MRI arterial input function, Klinisk fysiologi, radiology
pages
120 pages
publisher
Lund University (Media-Tryck)
defense location
University Hospital, Main Building, Hall F3
defense date
2006-05-19 09:00
ISBN
91-628-6800-4
language
English
LU publication?
yes
id
70da8533-fdc2-43b1-810e-0a70e3c79f48 (old id 546653)
date added to LUP
2007-09-13 15:36:30
date last changed
2016-09-19 08:45:12
@phdthesis{70da8533-fdc2-43b1-810e-0a70e3c79f48,
  abstract     = {The studies presented in this thesis concern the optimisation and evaluation of the dynamic susceptibility contrast magnetic resonance imaging (DSC-MRI) technique for the assessment of perfusion-related parameters of the brain, such as cerebral blood flow (CBF), cerebral blood volume (CBV) and mean transit time (MTT). Several methodological factors influence these measurements, for example, contrast-agent administration, arterial input function (AIF) registration, choice of deconvolution algorithm and the choice of pulse-sequence parameters.<br/><br>
<br/><br>
In the first study, a comparison of two different deconvolution techniques was made, i.e., one based on the fast Fourier transform (FT) and the other on singular value decomposition (SVD). The primary result of this study was that CBF estimates obtained by FT-based deconvolution were lower than the CBF values resulting from SVD-based deconvolution. This is in agreement with the results presented in previous publications, demonstrating that the use of FT-based deconvolution underestimates high blood-flow rates (at short MTT).<br/><br>
<br/><br>
In the second study, perfusion parameters were calculated from simulated data corresponding to different experimental conditions. For example, variations in signal-to-noise ratio (SNR), temporal resolution, AIF shape, signal drop and cut-off level in the truncated SVD deconvolution were investigated. The main conclusions were that the echo time requires optimisation to ensure sufficient signal drop in combination with reasonable baseline SNR, and that a broad input function can lead to underestimation of the CBF.<br/><br>
<br/><br>
Regional AIFs (rAIFs) were the subject of the third investigation. By using factor analysis of dynamic studies in combination with principal component analysis, rAIFs were obtained and the CBF was calculated by using the rAIF located closest to each tissue voxel. The conclusions drawn from the study were that the use of rAIFs reduced dispersion effects which can lead to CBF underestimation.<br/><br>
<br/><br>
In the fourth study, CBF was measured in absolute terms in 20 volunteers using Xe-133 SPECT and DSC-MRI. An AIF time-integral correction was introduced in order to improve the absolute CBF quantification in DSC-MRI. Average whole-brain estimates as well as regional CBF values in grey matter (GM) and white matter (WM) were obtained, and the results from the two modalities were compared. For the whole-brain average, the linear relationship was found to be CBF(MRI)=2.4?CBF(Xe)-7.9 [CBF given in units of ml/(min 100 g)], with a correlation coefficient of r=0.76.},
  author       = {Knutsson, Linda},
  isbn         = {91-628-6800-4},
  keyword      = {Nukleärmedicin,radiobiologi,Nuclear medicine,radiobiology,radiologi,tomografi,medicinsk instrumentering,tomography,medical instrumentation,Clinical physics,cerebral blood volume,mean transit time,cerebral blood flow,perfusion,dynamic susceptibility contrast MRI arterial input function,Klinisk fysiologi,radiology},
  language     = {eng},
  pages        = {120},
  publisher    = {Lund University (Media-Tryck)},
  school       = {Lund University},
  title        = {Optimisation and Validation of Dynamic Susceptibility Contrast MRI Perfusion Measurements},
  year         = {2006},
}