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Cardiovascular fluid dynamics: methods for flow and pressure field analysis from magnetic resonance imaging
Linköpings universitet, Institutionen för medicinsk teknik. Linköpings universitet, Institutionen för medicin och vård. Linköpings universitet, Hälsouniversitetet.ORCID-id: 0000-0003-1395-8296
2001 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

Cardiovascular blood flow is highly complex and incompletely understood. Blood flow patterns are expected to influence the opening and closing of normal and prosthetic heart valves, the efficiency of cardiac filling and ejection, and the resistance to thrombus formation within the heart. Conventional diagnostic techniques are poorly suited to the study of the three-dimensional (3D) blood flow patterns in the heart chambers and large vessels. Noninvasive methods have also been inadequate in studying intracardiac pressure differences, which are the driving force of flow and are critical in the evaluation of many cardiovascular abnormalities.

This thesis focuses on the development of non-invasive methods for analysis of 3D cardiovascular blood flow. Simultaneous study of cardiovascular fluid dynamics allowed knowledge exchange across the two disciplines, facilitating the development process and broadening the applicability of the methods.

A time-resolved 3D phase-contrast Magnetic Resonance lrnaging (MRI) technique was used to acquire the velocity vector field in a 3D volume encompassing the entire heart or a large vessel. Cardiovascular blood flow patterns were visualized by use of particle traces, which revealed, for instance, vortical flow patterns in the left atrium.

By applying the Navier-Stokes equation along a user-defined line in the 3D velocity vector field, the relative pressure could be obtained as an excellent supplement to the flow pattern visualization. Using a delineation of the blood pool, the time-varying 3D relative pressure field in the human left ventricle was obtained from the velocity field by use of the pressure Poisson equation.

A delineation of the heart muscle, a task that is almost impossible to perform on 3D MRI either automatically or manually, was also achieved by usage of particle traces. This segmentation allows automatic calculation of the 3D relative pressure field, as well as calculation of well-established parameters such as ventricle volume and mass.

Simultaneous 3D assessment of cardiovascular pressure and flow phenomena throughout the cardiac cycle offers an opportunity to expand our understanding of the basic determinants of time-varying flow in healthy and sick hearts, with the potential for improving our methods for diagnosis, medical treatment and surgical correction of cardiovascular diseases.

sted, utgiver, år, opplag, sider
Linköping: Linköpings universitet , 2001. , s. 48
Serie
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 690
HSV kategori
Identifikatorer
URN: urn:nbn:se:liu:diva-28144Lokal ID: 12957ISBN: 91-7373-021-1 (tryckt)OAI: oai:DiVA.org:liu-28144DiVA, id: diva2:248695
Disputas
2001-05-23, Elsa Brändströmssalen, Universiterssjukhuset, Linköping, 10:15 (svensk)
Opponent
Tilgjengelig fra: 2009-10-08 Laget: 2009-10-08 Sist oppdatert: 2013-09-03
Delarbeid
1. Particle trace visualization of intracardiac flow using time-resolved 3D phase contrast MRI
Åpne denne publikasjonen i ny fane eller vindu >>Particle trace visualization of intracardiac flow using time-resolved 3D phase contrast MRI
Vise andre…
1999 (engelsk)Inngår i: Magnetic Resonance in Medicine, ISSN 0740-3194, E-ISSN 1522-2594, Vol. 41, nr 4, s. 793-799Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

The flow patterns in the human heart are complex and difficult to visualize using conventional two-dimensional (2D) modalities, whether they depict a single velocity component (Doppler echocardiography) or all three components in a few slices (2D phase contrast MRI). To avoid these shortcomings, a temporally resolved 3D phase contrast technique was used to derive data describing the intracardiac velocity fields in normal volunteers. The MRI data were corrected for phase shifts caused by eddy currents and concomitant gradient fields, with improvement in the accuracy of subsequent flow visualizations. Pathlines describing the blood pathways through the heart were generated from the temporally resolved velocity data, starting from user-specified locations and time frames. Flow trajectories were displayed as 3D particle traces, with simultaneous demonstration of morphologic 2D slices. This type of visualization is intuitive and interactive and may extend our understanding of dynamic and previously unrecognized patterns of intracardiac flow.

HSV kategori
Identifikatorer
urn:nbn:se:liu:diva-26701 (URN)10.1002/(SICI)1522-2594(199904)41:4<793::AID-MRM19>3.0.CO;2-2 (DOI)11291 (Lokal ID)11291 (Arkivnummer)11291 (OAI)
Tilgjengelig fra: 2009-10-08 Laget: 2009-10-08 Sist oppdatert: 2017-12-13
2. Three-dimensional flow in the human left atrium
Åpne denne publikasjonen i ny fane eller vindu >>Three-dimensional flow in the human left atrium
Vise andre…
2001 (engelsk)Inngår i: Heart, ISSN 1355-6037, Vol. 86, nr 4, s. 448-455Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

BACKGROUND: Abnormal flow patterns in the left atrium in atrial fibrillation or mitral stenosis are associated with an increased risk of thrombosis and systemic embolisation; the characteristics of normal atrial flow that avoid stasis have not been well defined.

OBJECTIVES: To present a three dimensional particle trace visualisation of normal left atrial flow in vivo, constructed from flow velocities in three dimensional space.

METHODS: Particle trace visualisation of time resolved three dimensional magnetic resonance imaging velocity measurements was used to provide a display of intracardiac flow without the limitations of angle sensitivity or restriction to imaging planes. Global flow patterns of the left atrium were studied in 11 healthy volunteers.

RESULTS: In all subjects vortical flow was observed in the atrium during systole and diastolic diastasis (mean (SD) duration of systolic vortex, 280 (77) ms; and of diastolic vortex, 256 (118) ms). The volume incorporated and recirculated within the vortices originated predominantly from the left pulmonary veins. Inflow from the right veins passed along the vortex periphery, constrained between the vortex and the atrial wall.

CONCLUSIONS: Global left atrial flow in the normal human heart comprises consistent patterns specific to the phase of the cardiac cycle. Separate paths of left and right pulmonary venous inflow and vortex formation may have beneficial effects in avoiding left atrial stasis in the normal subject in sinus rhythm.

Emneord
atrium, blood flow, magnetic resonance imaging, haemodynamics
HSV kategori
Identifikatorer
urn:nbn:se:liu:diva-14554 (URN)10.1136/heart.86.4.448 (DOI)
Tilgjengelig fra: 2007-06-04 Laget: 2007-06-04 Sist oppdatert: 2016-03-14
3. Estimation of relative cardiovascular pressures using time-resolved three-dimensional phase contrast MRI
Åpne denne publikasjonen i ny fane eller vindu >>Estimation of relative cardiovascular pressures using time-resolved three-dimensional phase contrast MRI
Vise andre…
2001 (engelsk)Inngår i: Magnetic Resonance in Medicine, ISSN 0740-3194, E-ISSN 1522-2594, Vol. 45, nr 5, s. 872-879Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Accurate, easy-to-use, noninvasive cardiovascular pressure registration would be an important addition to the diagnostic armamentarium for assessment of cardiac function. A novel noninvasive and three-dimensional (3D) technique for estimation of relative cardiovascular pressures is presented. The relative pressure is calculated using the Navier-Stokes equations along user-defined lines placed within a time-resolved 3D phase contrast MRI dataset. The lines may be either straight or curved to follow an actual streamline. The technique is validated in an in vitro model and tested on in vivo cases of normal and abnormal transmitral pressure differences and intraaortic flow. The method supplements an intuitive visualization technique for cardiovascular flow, 3D particle trace visualization, with a quantifiable diagnostic parameter estimated from the same dataset.

HSV kategori
Identifikatorer
urn:nbn:se:liu:diva-26700 (URN)10.1002/mrm.1116 (DOI)11290 (Lokal ID)11290 (Arkivnummer)11290 (OAI)
Tilgjengelig fra: 2009-10-08 Laget: 2009-10-08 Sist oppdatert: 2017-12-13
4. Noninvasive measurement of time-varying three-dimensional relative pressure fields within the human heart
Åpne denne publikasjonen i ny fane eller vindu >>Noninvasive measurement of time-varying three-dimensional relative pressure fields within the human heart
Vise andre…
2002 (engelsk)Inngår i: Journal of Biomechanical Engineering, ISSN 0148-0731, E-ISSN 1528-8951, Vol. 124, nr 3, s. 288-293Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

Understanding cardiac blood flow patterns is important in the assessment of cardiovascular function. Three-dimensional flow and relative pressure fields within the human left ventricle are demonstrated by combining velocity measurements with computational fluid mechanics methods. The velocity field throughout the left atrium and ventricle of a normal human heart is measured using time-resolved three-dimensional phase-contrast MRL. Subsequently, the time-resolved three-dimensional relative pressure is calculated from this velocity field using the pressure Poisson equation. Noninvasive simultaneous assessment of cardiac pressure and flow phenomena is an important new tool for studying cardiac fluid dynamics.

HSV kategori
Identifikatorer
urn:nbn:se:liu:diva-26710 (URN)10.1115/1.1468866 (DOI)11304 (Lokal ID)11304 (Arkivnummer)11304 (OAI)
Tilgjengelig fra: 2009-10-08 Laget: 2009-10-08 Sist oppdatert: 2017-12-13
5. Myocordial segmentation of time-resolved 3D phase-contrast MRI
Åpne denne publikasjonen i ny fane eller vindu >>Myocordial segmentation of time-resolved 3D phase-contrast MRI
(engelsk)Manuskript (preprint) (Annet vitenskapelig)
Abstract [en]

Time-resolved three-dimensional (3D) phase-contrast MRI can be used to study 3D cardiac blood flow patterns and myocardial motion. The image contrast between myocardium and blood in 3D MRl is often inadequate for clear orientation and border delineation, however. To improve the accuracy and ease of segmentation, we developed a method based on a particle trace technique for time-resolved 3D cardiac velocity vector fields. A particle trace trajectory that follows the blood flow and the myocardial motion is obtained by integration of the velocity field over time. The myocardium can be differentiated by using the magnitude image data in combination with the trajectory's velocities and the expected behavior of the myocardial particle traces, that is, that traces starting in the myocardium will return to their starting point at the end of a cardiac cycle. The myocardial probability obtained in this way can be used for visualization, which eliminates the need for acquiring additional two-dimensional images. It also serves as the basis for border delineation, allowing quantification of important clinical parameters such as ventricular volume and mass.

Emneord
MR velocity imaging, three-dimensional visualization, particle trace, trajectory, heart, border delineation, contrast enhancement
HSV kategori
Identifikatorer
urn:nbn:se:liu:diva-89144 (URN)
Tilgjengelig fra: 2013-02-22 Laget: 2013-02-22 Sist oppdatert: 2013-09-03

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