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Quantification of Stenotic Flow Using Spiral 3D Phase-Contrast MRI
Linköping University, Department of Medical and Health Sciences. Linköping University, Faculty of Health Sciences. Linköping University, Center for Medical Image Science and Visualization (CMIV).
Linköping University, Department of Medical and Health Sciences, Clinical Physiology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart Centre, Department of Clinical Physiology. Linköping University, Center for Medical Image Science and Visualization (CMIV).
Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Center for Medical Image Science and Visualization (CMIV). Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Center, Department of Clinical Physiology in Linköping.
Linköping University, Department of Science and Technology, Media and Information Technology. Linköping University, The Institute of Technology.ORCID iD: 0000-0003-1942-7699
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2013 (English)Manuscript (preprint) (Other academic)
Abstract [en]

Purpose: To evaluate the feasibility of spiral 3D phase contrast MRI for the assessment of velocity, volume flow rate, peak velocity and turbulent kinetic energy in stenotic flow.

Materials and Methods: A-stack-of-spirals 3D phase contrast MRI sequence was evaluated in-vitro against a conventional Cartesian sequence. Measurements were made in a flow phantom with a 75% stenosis. Both spiral and Cartesian imaging were performed using different scan orientations and flow rates. Volume flow rate, peak velocity and turbulent kinetic energy (TKE) were computed for both methods. For further validation, the estimated TKE was compared to computational fluid dynamics (CFD) data.

Results: The volume flow rate, peak velocity and TKE obtained with spiral 4D flow MRI agreed well with Cartesian data and CFD data. As expected, the short echo time of the spiral sequence resulted in less prominent displacement artifacts compared to the Cartesian sequence. However, both spiral and Cartesian flow rate estimates were sensitive to displacement when the flow was oblique to the encoding directions.

Conclusion: Spiral 3D phase contrast MRI appears favorable for the assessment of stenotic flow. The spiral sequence was more than three times faster and less sensitive to displacement artifacts when compared to a conventional Cartesian sequence.

Place, publisher, year, edition, pages
2013.
National Category
Medical and Health Sciences
Identifiers
URN: urn:nbn:se:liu:diva-101107OAI: oai:DiVA.org:liu-101107DiVA: diva2:665280
Available from: 2013-11-19 Created: 2013-11-19 Last updated: 2013-12-17Bibliographically approved
In thesis
1. Fast and Accurate 4D Flow MRI for Cardiovascular Blood Flow Assessment
Open this publication in new window or tab >>Fast and Accurate 4D Flow MRI for Cardiovascular Blood Flow Assessment
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The study of blood flow is essential in understanding the physiology and pathophysiology of the cardiovascular system. Small disturbances of the blood flow may over time evolve and contribute to cardiovascular pathology. While the blood flow in a healthy human appears to be predominately laminar, turbulent or transitional blood flow is thought to be involved in the pathogenesis of several cardiovascular diseases. Wall shear stress is the frictional force of blood on the vessel wall and has been linked to the pathogenesis of atherosclerosis and aneurysms. Despite the importance of hemodynamic factors, cardiovascular diagnostics largely relies on the indirect estimation of function based on morphological data.

Time-resolved three-dimensional (3D) phase-contrast magnetic resonance imaging (MRI), often referred to as 4D flow MRI, is a versatile and non-invasive tool for cardiovascular blood flow assessment. The use of 4D flow MRI permits estimation of flow volumes, pressure losses, wall shear stress, turbulence intensity and many other unique hemodynamic parameters. However, 4D flow MRI suffers from long scan times, sometimes over 40 minutes. Furthermore, the accuracy of the many different 4D flow MRI-based applications and estimates have not been thoroughly examined.

In this thesis, the accuracy of 4D flow MRI-based turbulence intensity mapping and wall shear stress estimation was investigated by using numerical simulations of MRI flow measurements. While the results from the turbulence intensity mapping agreed well with reference values from computational fluid dynamics data, the accuracy of the MRI-based wall shear stress estimates was found to be very sensitive to different parameters, especially to spatial resolution, and wall shear stress values over 5 N/m2 were not well resolved.

To reduce the scan time, a 4D flow MRI sequence using spiral k-space trajectories was implemented and validated in-vivo and in-vitro. The scan time of 4D flow MRI was reduced by more than two-fold compared to a conventional Cartesian acquisition already accelerated using SENSE factor 2, and the data quality was maintained. For a 4D flow scan of the human heart, the use of spiral k-space trajectories resulted in a scan time of around 13 min, compared to 30 min for the Cartesian acquisition. By combining parallel imaging and spiral trajectories, the total scan time of a 4D flow measurement of the entire heart may be further reduced. This scan time reduction may also be traded for higher spatial resolution.

Numerical simulation of 4D flow MRI may act as an important tool for future optimization and validation of the spiral 4D flow sequence. The scan-time reductions offered by the spiral k-space trajectories can help to cut costs, save time, reduce discomfort for the patient as well as to decrease the risk for motion artifacts. These benefits may facilitate an expanded clinical and investigative use of 4D flow MRI, including larger patient research studies.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2013
Series
Linköping University Medical Dissertations, ISSN 0345-0082 ; 1380
National Category
Medical Engineering
Identifiers
urn:nbn:se:liu:diva-100146 (URN)10.3384/diss.diva-100146 (DOI)978-91-7519-506-3 (ISBN)
Public defence
2013-12-13, Berzeliussalen, Campus Valla, Linköpings universitet, Linköping, 09:00 (English)
Opponent
Supervisors
Available from: 2013-11-07 Created: 2013-10-29 Last updated: 2013-11-19Bibliographically approved

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Petersson, SvenDyverfeldt, PetterSigfridsson, AndreasLantz, JonasCarlhäll, Carl-JohanEbbers, Tino

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Petersson, SvenDyverfeldt, PetterSigfridsson, AndreasLantz, JonasCarlhäll, Carl-JohanEbbers, Tino
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Department of Medical and Health SciencesFaculty of Health SciencesCenter for Medical Image Science and Visualization (CMIV)Clinical PhysiologyDepartment of Clinical PhysiologyDivision of Cardiovascular MedicineDepartment of Clinical Physiology in LinköpingMedia and Information TechnologyThe Institute of Technology
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