Change search
ReferencesLink to record
Permanent link

Direct link
Ultrasonic Methods for Quantitative Carotid Plaque Characterization
KTH, School of Technology and Health (STH), Medical Engineering, Medical Imaging.ORCID iD: 0000-0002-2487-7400
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Cardiovascular diseases are the leading causes of death worldwide and improved diagnostic methods are needed for early intervention and to select the most suitable treatment for patients. Currently, carotid artery plaque vulnerability is typically determined by visually assessing ultrasound B-mode images, which is influenced by user-subjectivity. Since plaque vulnerability is correlated to the mechanical properties of the plaque, quantitative techniques are needed to estimate plaque stiffness as a surrogate for plaque vulnerability, which would reduce subjectivity during plaque assessment. The work in this thesis focused on three noninvasive ultrasound-based techniques to quantitatively assess plaque vulnerability and measure arterial stiffness. In Study I, a speckle tracking algorithm was validated in vitro to assess strain in common carotid artery (CCA) phantom plaques and thereafter applied in vivo to carotid atherosclerotic plaques where the strain results were compared to visual assessments by experienced physicians. In Study II, hard and soft CCA phantom plaques were characterized with shear wave elastography (SWE) by using phase and group velocity analysis while being hydrostatically pressurized followed by validating the results with mechanical tensile testing. In Study III, feasibility of assessing the stiffness of simulated plaques and the arterial wall with SWE was demonstrated in an ex vivo setup in small porcine aortas used as a human CCA model. In Study IV, SWE and pulse wave imaging (PWI) were compared when characterizing homogeneous CCA soft phantom plaques. The techniques developed in this thesis have demonstrated potential to characterize carotid artery plaques. The results show that the techniques have the ability to noninvasively evaluate the mechanical properties of carotid artery plaques, provide additional data when visually assessing B-mode images, and potentially provide improved diagnoses for patients suffering from cerebrovascular diseases.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2016. , 70 p.
Series
TRITA-STH : report, ISSN 1653-3836 ; 2016:08
Keyword [en]
Atherosclerosis, Cardiovascular Disease, Carotid Artery, Elasticity, ex vivo, in vivo, Phantom, Plaque, Polyvinyl Alcohol, Pulse Wave Imaging, Shear Wave Elastography, Speckle Tracking, Stroke, Ultrasound
National Category
Medical Image Processing
Research subject
Medical Technology
Identifiers
URN: urn:nbn:se:kth:diva-192339ISBN: 978-91-7729-085-8OAI: oai:DiVA.org:kth-192339DiVA: diva2:967794
Public defence
2016-10-13, T2, Hälsovägen 11c, Huddinge, 15:05 (English)
Opponent
Supervisors
Note

Doctoral thesis in medical technology and medical sciences

QC 20160921

Available from: 2016-09-21 Created: 2016-09-09 Last updated: 2016-09-21Bibliographically approved
List of papers
1. Ultrasound speckle tracking strain estimation of in vivo carotid artery plaque with in vitro sonomicrometry validation
Open this publication in new window or tab >>Ultrasound speckle tracking strain estimation of in vivo carotid artery plaque with in vitro sonomicrometry validation
Show others...
2015 (English)In: Ultrasound in Medicine and Biology, ISSN 0301-5629, E-ISSN 1879-291X, Vol. 41, no 1, 77-88 p.Article in journal (Refereed) Published
Abstract [en]

Our objective was to validate a previously developed speckle tracking (ST) algorithm to assess strain in common carotid artery plaques. Radial and longitudinal strain was measured in common carotid artery gel phantoms with a plaque-mimicking inclusion using an in-house ST algorithm and sonomicrometry. Moreover, plaque strain by ST for seven patients (77 ± 6 y) with carotid atherosclerosis was compared with a quantitative visual assessment by two experienced physicians. In vitro, good correlation existed between ST and sonomicrometry peak strains, both radially (r = 0.96, p < 0.001) and longitudinally (r = 0.75, p < 0.01). In vivo, greater pulse pressure-adjusted radial and longitudinal strains were found in echolucent plaques than in echogenic plaques. This illustrates the feasibility of ultrasound ST strain estimation in plaques and the possibility of characterizing plaques using ST strain in vivo.

Place, publisher, year, edition, pages
Elsevier, 2015
Keyword
Carotid artery, Invitro, Invivo, Phantom, Plaque characterization, Speckle tracking, Strain, Ultrasound, Validation
National Category
Medical Image Processing
Identifiers
urn:nbn:se:kth:diva-159741 (URN)10.1016/j.ultrasmedbio.2014.06.013 (DOI)000347898500011 ()25308946 (PubMedID)2-s2.0-84919843935 (ScopusID)
Note

QC 20150220. QC 20160226

Available from: 2015-02-09 Created: 2015-02-09 Last updated: 2016-09-21Bibliographically approved
2. Shear wave elastography plaque characterization with mechanical testing validation: a phantom study.
Open this publication in new window or tab >>Shear wave elastography plaque characterization with mechanical testing validation: a phantom study.
Show others...
2015 (English)In: Physics in medicine and biology, Vol. 60, no 8, 3151-3174 p.Article in journal (Refereed) Published
Abstract [en]

Determining plaque vulnerability is critical when selecting the most suitable treatment for patients with atherosclerotic plaque. Currently, clinical non-invasive ultrasound-based methods for plaque characterization are limited to visual assessment of plaque morphology and new quantitative methods are needed. In this study, shear wave elastography (SWE) was used to characterize hard and soft plaque mimicking inclusions in six common carotid artery phantoms by using phase velocity analysis in static and dynamic environments. The results were validated with mechanical tensile testing. In the static environment, SWE measured a mean shear modulus of 5.8±0.3kPa and 106.2±17.2kPa versus 3.3±0.5kPa and 98.3±3.4kPa measured by mechanical testing in the soft and hard plaques respectively. Furthermore, it was possible to measure the plaques' shear moduli throughout a simulated cardiac cycle. The results show good agreement between SWE and mechanical testing and indicate the possibility for in vivo arterial plaque characterization using SWE.

National Category
Medical Image Processing
Identifiers
urn:nbn:se:kth:diva-164418 (URN)10.1088/0031-9155/60/8/3151 (DOI)000352525200013 ()25803520 (PubMedID)2-s2.0-84927602186 (ScopusID)
Funder
Swedish Research CouncilVINNOVA, 2011-01365
Note

QC 20150518

Available from: 2015-04-27 Created: 2015-04-17 Last updated: 2016-09-21Bibliographically approved
3. SHEAR WAVE ELASTOGRAPHY QUANTIFIES STIFFNESS IN EX VIVO PORCINEARTERY WITH STIFFENED ARTERIAL REGION
Open this publication in new window or tab >>SHEAR WAVE ELASTOGRAPHY QUANTIFIES STIFFNESS IN EX VIVO PORCINEARTERY WITH STIFFENED ARTERIAL REGION
2016 (English)In: Ultrasound in Medicine and Biology, ISSN 0301-5629, E-ISSN 1879-291X, Vol. 42, no 10, 2423-2435 p.Article in journal (Refereed) Published
Abstract [en]

Five small porcine aortas were used as a human carotid artery model, and their stiffness was estimatedusing shear wave elastography (SWE) in the arterial wall and a stiffened artery region mimicking a stiff plaque. Tooptimize the SWE settings, shear wave bandwidth was measured with respect to acoustic radiation force pushlength and number of compounded angles used for motion detection with plane wave imaging. The mean arterialwall and simulated plaque shear moduli varied from 41 ± 5 to 97 ± 10 kPa and from 86 ± 13 to 174 ± 35 kPa, respectively,over the pressure range 20–120 mmHg. The results revealed that a minimum bandwidth of approximately1500 Hz is necessary for consistent shear modulus estimates, and a high pulse repetition frequency using no imagecompounding is more important than a lower pulse repetition frequency with better image quality when estimatingarterial wall and plaque stiffness using SWE.

Keyword
Artery, Arteriosclerosis, Atherosclerosis, Elasticity, Ex vivo, Plaque, Phase velocity, Shear wave elastography, Ultrasound
National Category
Medical Image Processing
Research subject
Medical Technology
Identifiers
urn:nbn:se:kth:diva-192857 (URN)
Note

QC 20160921

Available from: 2016-09-21 Created: 2016-09-21 Last updated: 2016-09-21Bibliographically approved
4. Carotid Plaque Characterization in a Phantom Setup:A Comparison of Shear Wave Elastography and Pulse Wave Imaging
Open this publication in new window or tab >>Carotid Plaque Characterization in a Phantom Setup:A Comparison of Shear Wave Elastography and Pulse Wave Imaging
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Cerebrovascular disease is the second leading cause of death worldwide and determining plaque vulnerability is critical to early intervention, selecting appropriate treatment, and reducing mortality rates. Shear wave elastography (SWE) is an ultrasound-based technique to characterize the mechanical properties of tissue and pulse wave imaging (PWI) is most commonly used to measure arterial stiffness by estimating the propagation speed of the pulse wave generated from left ventricular ejection. In this study, SWE and PWI were used to characterize three homogeneous plaque mimicking inclusions in three common carotid artery phantoms by using phase velocity (PV) and group velocity (GV) analysis as well as estimating the pulse wave velocity (PWV) using PWI. Thereafter, the estimated Young’s modulus values were compared in the phantom walls. The mean wave velocities in the plaques were 1.7 ± 0.2 m/s, 1.6 ± 0.1 m/s, and 2.5 ± 0.5 m/s calculated by PV, GV, and PWI, respectively. This was lower than the mean wave speeds measured in the vessel wall (3.8 ± 0.2 m/s, 3.5 ± 0.2 m/s, and 3.3 ± 0.1 m/s by PV, GV, and PWI, respectively) showing that both techniques can detect soft vulnerable plaques. The PWV estimate was more sensitive to plaque thickness compared to the SWE GV estimate. The results indicate the ability of SWE and PWI to characterize homogeneous plaques from the arterial wall.

Keyword
Carotid Artery Phantom; Group Velocity; Shear Wave Elastography; Phase Velocity; Plaque Characterization; Pulse Wave Imaging; Pulse Wave Velocity; Stroke; Ultrasound
National Category
Medical Image Processing
Research subject
Medical Technology
Identifiers
urn:nbn:se:kth:diva-192858 (URN)
Note

QC 20160921

Available from: 2016-09-21 Created: 2016-09-21 Last updated: 2016-09-21Bibliographically approved

Open Access in DiVA

fulltext(2980 kB)45 downloads
File information
File name FULLTEXT01.pdfFile size 2980 kBChecksum SHA-512
0f8129822584abc7c4b06bf7c917c47d2b27c115975d422d20cd7f683830a61ca38839907434dd492d20e89efce1385ad69bfd560f55c346f930dd70b830cdea
Type fulltextMimetype application/pdf

Search in DiVA

By author/editor
Widman, Erik
By organisation
Medical Imaging
Medical Image Processing

Search outside of DiVA

GoogleGoogle Scholar
Total: 45 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Total: 88 hits
ReferencesLink to record
Permanent link

Direct link