| 1. |
- Almeida, Nuno, et al.
(författare)
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Left atrial volumetric assessment using a novel automated framework for 3D echocardiography: a multi-centre analysis
- 2017
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Ingår i: European Heart Journal Cardiovascular Imaging. - : OXFORD UNIV PRESS. - 2047-2404 .- 2047-2412. ; 18:9, s. 1008-1015
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Tidskriftsartikel (refereegranskat)abstract
- Aims This study aims at validating a software tool for automated segmentation and quantification of the left atrium (LA) from 3D echocardiography. Methods and results The LA segmentation tool uses a dual-chamber model of the left side of the heart to automatically detect and track the atrio-ventricular plane and the LA endocardium in transthoracic 3D echocardiography. The tool was tested in a dataset of 121 ultrasound images from patients with several cardiovascular pathologies (in a multi-centre setting), and the resulting volumes were compared with those assessed manually by experts in a blinded analysis using conventional contouring. Bland-Altman analysis showed good agreement between the automated method and the manual references, with differences (mean +/- 1.96 SD) of 0.5 +/- 5.7 mL for LA minimum volume and -1.6 +/- 9.7 mL for LA maximum volume (comparable to the inter-observer variability of manual tracings). The automated tool required no user interaction in 93% of the recordings, while 4% required a single click and only 2% required contour adjustments, reducing considerably the amount of time and effort required for LA volumetric analysis. Conclusion The automated tool was validated in a multi-centre setting, providing quantification of the LA volume over the cardiac cycle with minimal user interaction. The results of the automated analysis were in agreement with those estimated manually by experts. This study shows that such approach has clinical utility for the assessment of the LA morphology and function, automating and facilitating the time-consuming task of analysing 3D echocardiographic recordings.
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| 2. |
- Morais, Pedro, et al.
(författare)
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Fully automatic left ventricular myocardial strain estimation in 2D short-axis tagged magnetic resonance imaging
- 2017
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Ingår i: Physics in Medicine and Biology. - : IOP PUBLISHING LTD. - 0031-9155 .- 1361-6560. ; 62:17, s. 6899-6919
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Tidskriftsartikel (refereegranskat)abstract
- Cardiovascular diseases are among the leading causes of death and frequently result in local myocardial dysfunction. Among the numerous imaging modalities available to detect these dysfunctional regions, cardiac deformation imaging through tagged magnetic resonance imaging (t-MRI) has been an attractive approach. Nevertheless, fully automatic analysis of these data sets is still challenging. In this work, we present a fully automatic framework to estimate left ventricular myocardial deformation from t-MRI. This strategy performs automatic myocardial segmentation based on B-spline explicit active surfaces, which are initialized using an annular model. A non-rigid image-registration technique is then used to assess myocardial deformation. Three experiments were set up to validate the proposed framework using a clinical database of 75 patients. First, automatic segmentation accuracy was evaluated by comparing against manual delineations at one specific cardiac phase. The proposed solution showed an average perpendicular distance error of 2.35 +/- 1.21 mm and 2.27 +/- 1.02 mm for the endo- and epicardium, respectively. Second, starting from either manual or automatic segmentation, myocardial tracking was performed and the resulting strain curves were compared. It is shown that the automatic segmentation adds negligible differences during the strain-estimation stage, corroborating its accuracy. Finally, segmental strain was compared with scar tissue extent determined by delay-enhanced MRI. The results proved that both strain components were able to distinguish between normal and infarct regions. Overall, the proposed framework was shown to be accurate, robust, and attractive for clinical practice, as it overcomes several limitations of a manual analysis.
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| 3. |
- Myhre, Peder L., et al.
(författare)
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Cardiac troponin T and NT-proBNP for detecting myocardial ischemia in suspected chronic coronary syndrome
- 2022
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Ingår i: International Journal of Cardiology. - : Elsevier Ireland Ltd. - 0167-5273 .- 1874-1754. ; 361, s. 14-17
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Tidskriftsartikel (refereegranskat)abstract
- Background: Elevated N-terminal pro-B-type natriuretic peptides (NT-proBNP) and cardiac troponin T (cTnT) are associated with poor outcome in patients with chronic coronary syndrome (CCS). The performance of these biomarkers in diagnosing ischemia, and their association with myocardial hypoperfusion and hypokinesis is unclear. Methods: Patients with suspected CCS (history of angina, estimated cardiovascular risk >15% or a positive stress test) were included in the prospective, multi-center DOPPLER-CIP study. Patients underwent Single Positron Emission Computed Tomography for assessment of ischemia and NT-proBNP and cTnT were measured in venous blood samples. Results: We included 430 patients (25% female) aged 64 +/- 8 years. Reversible hypoperfusion and hypokinesis were present in 139 (32%) and 89 (21%), respectively. Concentrations of NT-proBNP and cTnT correlated moderately (rho = 0.50, p < 0.001). NT-proBNP and cTnT concentrations (median [IQR]) were higher in patients with versus without reversible ischemia: 150 (73-294) versus 87 (44-192) ng/L and 10 (6-13) versus 7 (4-11) ng/L, respectively (p < 0.001 for both), and the associations persisted after adjusting for possible confounders. The C-statistics to discriminate ischemia ranged from 63%-73%, were comparable for cTnT and NT-proBNP, and higher for hypokinesis than hypoperfusion, and both were superior to exercise electrocardiography and stress echocardiography. Very low concentrations (<= 5 ng/L cTnT and <= 60 ng/L NT-proBNP) ruled out reversible hypokinesis with negative predictive value >90%. Conclusion: cTnT and NT-proBNP are associated with irreversible and reversible ischemia in patients with suspected CCS, particularly hypokinesis. The diagnostic performance was comparable between the biomarkers, and very low concentrations may reliably rule out ischemia.
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| 4. |
- Myhre, Peder L., et al.
(författare)
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Cardiac Troponin T Concentrations, Reversible Myocardial Ischemia, and Indices of Left Ventricular Remodeling in Patients with Suspected Stable Angina Pectoris: a DOPPLER-CIP Substudy
- 2018
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Ingår i: Clinical Chemistry. - : AMER ASSOC CLINICAL CHEMISTRY. - 0009-9147 .- 1530-8561. ; 64:9, s. 1370-1379
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Cardiac troponin T concentrations measured with high-sensitivity assays (hs-cTnT) provide important prognostic information for patients with stable coronary artery disease (CAD). However, whether hsc-TnT concentrations mainly reflect left ventricular (LV) remodeling or recurrent myocardial ischemia in this population is not known. METHODS: We measured hs-cTnT concentrations in 619 subjects with suspected stable CAD in a prospectively designed multicenter study. We identified associations with indices of LV remodeling, as assessed by cardiac MRI and echocardiography, and evidence of myocardial ischemia diagnosed by single positron emission computed tomography. RESULTS: Median hs-cTnT concentration was 7.8 ng/L (interquartile range, 4.8 -11.6 ng/L), and 111 patients (18%) had hs-cTnT concentrations above the upper reference limit (amp;gt; 14 ng/L). Patients with hs-cTnT amp;gt; 14 ng/L had increased LV mass (144 +/- 40 g vs 116 +/- 34 g; P amp;lt; 0.001) and volume (179 +/- 80 mL vs 158 +/- 44 mL; P = 0.006), lower LV ejection fraction (LVEF) (59 +/- 14 vs 62 +/- 11; P = 0.006) and global longitudinal strain (14.1 +/- 3.4% vs 16.9 +/- 3.2%; P amp;lt; 0.001), and more reversible perfusion defects (P amp;lt; 0.001) and reversible wall motion abnormalities (P = 0.008). Age (P = 0.009), estimated glomerular filtration rate (P = 0.01), LV mass (P = 0.003), LVEF (P = 0.03), and evidence of reversible myocardial ischemia (P = 0.004 for perfusion defects and P = 0.02 for LV wall motion) were all associated with increasing hs-cTnT concentrations in multivariate analysis. We found analogous results when using the revised US upper reference limit of 19 ng/L. CONCLUSIONS: hs-cTnT concentrations reflect both LV mass and reversible myocardial ischemia in patients with suspected stable CAD. (c) 2018 American Association for Clinical Chemistry
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| 5. |
- Pedrosa, Joao, et al.
(författare)
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Automatic Short Axis Orientation of the Left Ventricle in 3D Ultrasound Recordings
- 2016
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Ingår i: MEDICAL IMAGING 2016: ULTRASONIC IMAGING AND TOMOGRAPHY. - : SPIE-INT SOC OPTICAL ENGINEERING. - 9781510600256
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Konferensbidrag (refereegranskat)abstract
- The recent advent of three-dimensional echocardiography has led to an increased interest from the scientific community in left ventricle segmentation frameworks for cardiac volume and function assessment. An automatic orientation of the segmented left ventricular mesh is an important step to obtain a point-to-point correspondence between the mesh and the cardiac anatomy. Furthermore, this would allow for an automatic division of the left ventricle into the standard 17 segments and, thus, fully automatic per-segment analysis, e.g. regional strain assessment. In this work, a method for fully automatic short axis orientation of the segmented left ventricle is presented. The proposed framework aims at detecting the inferior right ventricular insertion point. 211 three-dimensional echocardiographic images were used to validate this framework by comparison to manual annotation of the inferior right ventricular insertion point. A mean unsigned error of 8, 05 degrees +/- 18, 50 degrees was found, whereas the mean signed error was 1, 09 degrees. Large deviations between the manual and automatic annotations (amp;gt; 30 degrees) only occurred in 3, 79% of cases. The average computation time was 666ms in a non-optimized MATLAB environment, which potentiates real-time application. In conclusion, a successful automatic real-time method for orientation of the segmented left ventricle is proposed.
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| 6. |
- Pedrosa, Joao, et al.
(författare)
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Fast and Fully Automatic Left Ventricular Segmentation and Tracking in Echocardiography Using Shape-Based B-Spline Explicit Active Surfaces
- 2017
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Ingår i: IEEE Transactions on Medical Imaging. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 0278-0062 .- 1558-254X. ; 36:11, s. 2287-2296
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Tidskriftsartikel (refereegranskat)abstract
- Cardiac volume/function assessment remains a critical step in daily cardiology, and 3-D ultrasound plays an increasingly important role. Fully automatic left ventricular segmentation is, however, a challenging task due to the artifacts and low contrast-to-noise ratio of ultrasound imaging. In this paper, a fast and fully automatic framework for the full-cycle endocardial left ventricle segmentation is proposed. This approach couples the advantages of the B-spline explicit active surfaces framework, a purely image information approach, to those of statistical shape models to give prior information about the expected shape for an accurate segmentation. The segmentation is propagated throughout the heart cycle using a localized anatomical affine optical flow. It is shown that this approach not only outperforms other state-of-the-art methods in terms of distance metrics with a mean average distances of 1.81 +/- 0.59 and 1.98 +/- 0.66 mm at end-diastole and end-systole, respectively, but is computationally efficient (in average 11 s per 4-D image) and fully automatic.
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| 7. |
- Queiros, Sandro, et al.
(författare)
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Multi-centre validation of an automatic algorithm for fast 4D myocardial segmentation in cine CMR datasets
- 2016
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Ingår i: European Heart Journal Cardiovascular Imaging. - : OXFORD UNIV PRESS. - 2047-2404 .- 2047-2412. ; 17:10, s. 1118-1127
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Tidskriftsartikel (refereegranskat)abstract
- Aims Quantitative analysis of cine cardiac magnetic resonance (CMR) images for the assessment of global left ventricular morphology and function remains a routine task in clinical cardiology practice. To date, this process requires user interaction and therefore prolongs the examination (i.e. cost) and introduces observer variability. In this study, we sought to validate the feasibility, accuracy, and time efficiency of a novel framework for automatic quantification of left ventricular global function in a clinical setting. Methods and results Analyses of 318 CMR studies, acquired at the enrolment of patients in a multi-centre imaging trial (DOPPLER-CIP), were performed automatically, as well as manually. For comparative purposes, intra-and inter-observer variability was also assessed in a subset of patients. The extracted morphological and functional parameters were compared between both analyses, and time efficiency was evaluated. The automatic analysis was feasible in 95% of the cases (302/318) and showed a good agreement with manually derived reference measurements, with small biases and narrow limits of agreement particularly for end-diastolic volume (-4.08 +/- 8.98 mL), end-systolic volume (1.18 +/- 9.74 mL), and ejection fraction (-1.53 +/- 4.93%). These results were comparable with the agreement between two independent observers. A complete automatic analysis took 5.61 +/- 1.22 s, which is nearly 150 times faster than manual contouring (14 +/- 2 min, P amp;lt; 0.05). Conclusion The proposed automatic framework provides a fast, robust, and accurate quantification of relevant left ventricular clinical indices in real-world cine CMR images.
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| 8. |
- Rademakers, Frank, et al.
(författare)
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Determining optimal noninvasive parameters for the prediction of left ventricular remodeling in chronic ischemic patients
- 2013
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Ingår i: Scandinavian Cardiovascular Journal. - : Informa Healthcare. - 1401-7431 .- 1651-2006. ; 47:6, s. 329-334
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Tidskriftsartikel (refereegranskat)abstract
- Objectives. DOPPLER-CIP aims to determine the optimal noninvasive parameters (myocardial function, perfusion, ventricular blood flow, cell integrity) and methodology (ergometry, echocardiography, scintigraphy, MRI) in a given ischemic substrate that best predicts the impact of an intervention (or the lack thereof) on adverse morphological ventricular remodeling and functional recovery. Moreover, the relative predictive value of each of these parameters, in respect to the cost of extracting this information in order to enable optimization of cost-effectiveness for improved health care, will be determined by this project. Design. DOPPLER-CIP is a multi-center registry study. All patients with ischemic heart disease included in this study undergo at least two noninvasive stress imaging examinations at baseline. The presence/or absence of left ventricular (LV) remodeling will be assessed after a follow-up of 2 years, during which all cardiac events will be registered. Results. 676 patients were included. Currently, baseline data analysis is almost finished and the follow-up is ongoing. Conclusions. After completion, DOPPLER-CIP will provide evidence-based guidelines toward the most effective use of cardiac imaging in the chronically ischemic heart disease patient. The study will generate information, knowledge, and insight into the new imaging methodologies and into the pathophysiology of chronic ischemic heart disease.
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| 9. |
- Tabassian, Mahdi, et al.
(författare)
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Machine learning of the spatio-temporal characteristics of echocardiographic deformation curves for infarct classification
- 2017
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Ingår i: The International Journal of Cardiovascular Imaging. - : SPRINGER. - 1569-5794 .- 1875-8312 .- 1573-0743. ; 33:8, s. 1159-1167
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to analyze the whole temporal profiles of the segmental deformation curves of the left ventricle (LV) and describe their interrelations to obtain more detailed information concerning global LV function in order to be able to identify abnormal changes in LV mechanics. The temporal characteristics of the segmental LV deformation curves were compactly described using an efficient decomposition into major patterns of variation through a statistical method, called Principal Component Analysis (PCA). In order to describe the spatial relations between the segmental traces, the PCA-derived temporal features of all LV segments were concatenated. The obtained set of features was then used to build an automatic classification system. The proposed methodology was applied to a group of 60 MRI-delayed enhancement confirmed infarct patients and 60 controls in order to detect myocardial infarction. An average classification accuracy of 87% with corresponding sensitivity and specificity rates of 89% and 85%, respectively was obtained by the proposed methodology applied on the strain rate curves. This classification performance was better than that obtained with the same methodology applied on the strain curves, reading of two expert cardiologists as well as comparative classification systems using only the spatial distribution of the end-systolic strain and peak-systolic strain rate values. This study shows the potential of machine learning in the field of cardiac deformation imaging where an efficient representation of the spatio-temporal characteristics of the segmental deformation curves allowed automatic classification of infarcted from control hearts with high accuracy.
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| 10. |
- Bernard, Olivier, et al.
(författare)
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Standardized evaluation system for left ventricular segmentation algorithms in 3D echocardiography.
- 2016
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Ingår i: IEEE Transactions on Medical Imaging. - : Institute of Electrical and Electronics Engineers (IEEE). - 0278-0062 .- 1558-254X. ; 35:4, s. 967-977
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Tidskriftsartikel (refereegranskat)abstract
- Real-time 3D Echocardiography (RT3DE) has been proven to be an accurate tool for left ventricular (LV) volume assessment. However, identification of the LV endocardium remains a challenging task, mainly because of the low tissue/blood contrast of the images combined with typical artifacts. Several semi and fully automatic algorithms have been proposed for segmenting the endocardium in RT3DE data in order to extract relevant clinical indices, but a systematic and fair comparison between such methods has so far been impossible due to the lack of a publicly available common database. Here, we introduce a standardized evaluation framework to reliably evaluate and compare the performance of the algorithms developed to segment the LV border in RT3DE. A database consisting of 45 multivendor cardiac ultrasound recordings acquired at different centers with corresponding reference measurements from 3 experts are made available. The algorithms from nine research groups were quantitatively evaluated and compared using the proposed online platform. The results showed that the best methods produce promising results with respect to the experts' measurements for the extraction of clinical indices, and that they offer good segmentation precision in terms of mean distance error in the context of the experts' variability range. The platform remains open for new submissions.
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| 11. |
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| 12. |
- Fransen, Erik, et al.
(författare)
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Occupational Noise, Smoking, and a High Body Mass Index are Risk Factors for Age-related Hearing Impairment and Moderate Alcohol Consumption is Protective : A European Population-based Multicenter Study
- 2008
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Ingår i: Journal of the Association for Research in Otolaryngology. - : Springer. - 1525-3961 .- 1438-7573. ; 9:3, s. 264-276
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Tidskriftsartikel (refereegranskat)abstract
- A multicenter study was set up to elucidate the environmental and medical risk factors contributing to age-related hearing impairment (ARHI). Nine subsamples, collected by nine audiological centers across Europe, added up to a total of 4,083 subjects between 53 and 67 years. Audiometric data (pure-tone average [PTA]) were collected and the participants filled out a questionnaire on environmental risk factors and medical history. People with a history of disease that could affect hearing were excluded. PTAs were adjusted for age and sex and tested for association with exposure to risk factors. Noise exposure was associated with a significant loss of hearing at high sound frequencies (>1 kHz). Smoking significantly increased high-frequency hearing loss, and the effect was dose-dependent. The effect of smoking remained significant when accounting for cardiovascular disease events. Taller people had better hearing on average with a more pronounced effect at low sound frequencies (<2 kHz). A high body mass index (BMI) correlated with hearing loss across the frequency range tested. Moderate alcohol consumption was inversely correlated with hearing loss. Significant associations were found in the high
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| 13. |
- Fröberg, Asa, et al.
(författare)
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High variability in strain estimation errors when using a commercial ultrasound speckle tracking algorithm on tendon tissue
- 2016
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Ingår i: Acta Radiologica. - : Sage Publications. - 0284-1851 .- 1600-0455. ; 57:10, s. 1223-1229
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Tidskriftsartikel (refereegranskat)abstract
- Background: Ultrasound speckle tracking offers a non-invasive way of studying strain in the free Achilles tendon where no anatomical landmarks are available for tracking. This provides new possibilities for studying injury mechanisms during sport activity and the effects of shoes, orthotic devices, and rehabilitation protocols on tendon biomechanics. Purpose: To investigate the feasibility of using a commercial ultrasound speckle tracking algorithm for assessing strain in tendon tissue. Material and Methods: A polyvinyl alcohol (PVA) phantom, three porcine tendons, and a human Achilles tendon were mounted in a materials testing machine and loaded to 4% peak strain. Ultrasound long-axis cine-loops of the samples were recorded. Speckle tracking analysis of axial strain was performed using a commercial speckle tracking software. Estimated strain was then compared to reference strain known from the materials testing machine. Two frame rates and two region of interest (ROI) sizes were evaluated. Results: Best agreement between estimated strain and reference strain was found in the PVA phantom (absolute error in peak strain: 0.21 +/- 0.08%). The absolute error in peak strain varied between 0.72 +/- 0.65% and 10.64 +/- 3.40% in the different tendon samples. Strain determined with a frame rate of 39.4Hz had lower errors than 78.6Hz as was the case with a 22mm compared to an 11mm ROI. Conclusion: Errors in peak strain estimation showed high variability between tendon samples and were large in relation to strain levels previously described in the Achilles tendon.
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| 14. |
- Galderisi, Maurizio, et al.
(författare)
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Recommendations of the European Association of Echocardiography : how to use echo-Doppler in clinical trials
- 2011
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Ingår i: European Journal of Echocardiography. - : Oxford University Press (OUP). - 1525-2167 .- 1532-2114. ; 12:5, s. 339-353
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Tidskriftsartikel (refereegranskat)abstract
- The European Association of Echocardiography (EAE) has developed the present recommendations to assist clinical researchers in the design, implementation, and conduction of echocardiographic protocols for clinical trials and to guarantee their quality. Clinical trials should be designed and conducted based on the knowledge of the pathophysiology of the clinical condition studied, the technical characteristics of the echo-Doppler modalities, and the variability of the tested parameters. These procedures are important to choose the most reliable and reproducible techniques and parameters. Quality assurance must be guaranteed by adequate training of peripheral site operators to obtain optimal echo-Doppler data and by using a core laboratory for accurate and reproducible data analysis.
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| 15. |
- Grönlund, Christer, et al.
(författare)
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Simultaneous quantification of myocardial and blood flow velocities based on duplex mode ultrasound imaging
- 2013
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Ingår i: Biomedical engineering online. - : BioMed Central (BMC). - 1475-925X. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Ultrasound imaging of the heart is a commonly used clinical tool to assess cardiac function. The basis for this analysis is the quantification of cardiac blood flow and myocardial velocities. These are typically measured using different imaging modes and on different cardiac cycles. However, due to beat-to-beat variations such as irregular heart rhythm and transient events, simultaneous acquisition is preferred. There exists specialized ultrasound systems for this purpose; however, it would be beneficial if this could be achieved using conventional ultrasound systems due to their wide availability. The conventional Duplex mode ultrasound allows simultaneous acquisition, however at a highly reduced spatial and temporal resolution.METHODS: The aim of this work was to present and evaluate the performance of a novel method to recover myocardial tissue velocity using conventional Duplex ultrasound imaging, and to demonstrate its feasibility for the assessment of simultaneous blood flow and myocardial velocity in-vivo. The essence of the method was the estimation of the axial phase shift of robust echogenic structures between subsequent image frames. The performance of the method was evaluated on synthetic tissue mimicking B-mode image sequences at different frame rates (20--60 Hz) and tissue velocities (peak velocities 5-15cm/s), using cardiac deformation and displacement characteristics. The performance was also compared to a standard 2-D speckle tracking technique.RESULTS: The method had an overall high performance at frame rates above 25 Hz, with less than 15% error of the peak diastolic velocity, and less than 10 ms peak timing error. The method showed superior performance compared to the 2-D tracking technique at frame rates below 50 Hz. The in-vivo quantification of simultaneous blood flow and myocardial tissue velocities verified the echocardiographic patterns and features of healthy subjects and the specific patient group.CONCLUSIONS: A novel myocardial velocity quantification method was presented and high performance at frame rates above 25Hz was shown. In-vivo quantification of simultaneous myocardial and blood flow velocities was feasible using the proposed method and conventional Duplex mode imaging. We propose that the methodology is suitable for retrospective as well as prospective studies on the mechanics and hemodynamics of the heart.
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| 16. |
- Hendrickx, Jan-Jaap, et al.
(författare)
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Familial aggregation of pure tone hearing thresholds in an aging European population
- 2013
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Ingår i: Otology and Neurotology. - : Lippincott Williams & Wilkins. - 1531-7129 .- 1537-4505. ; 34:5, s. 838-844
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To investigate the familial correlations and intraclass correlation of age-related hearing impairment (ARHI) in specific frequencies. In addition, heritability estimates were calculated.STUDY DESIGN: Multicenter survey in 8 European centers.SUBJECTS: One hundred ninety-eight families consisting of 952 family members, screened by otologic examination and structured interviews. Subjects with general conditions, known to affect hearing thresholds or known otologic cause were excluded from the study.RESULTS: We detected familial correlation coefficients of 0.36, 0.37, 0.36, and 0.30 for 0.25, 0.5, 1, and 2 kHz, respectively, and correlation coefficients of 0.20 and 0.18 for 4 and 8 kHz, respectively. Variance components analyses showed that the proportion of the total variance attributable to family differences was between 0.32 and 0.40 for 0.25, 0.5, 1, and 2 kHz and below 0.20 for 4 and 8 kHz. When testing for homogeneity between sib pair types, we observed a larger familial correlation between female than male subjects. Heritability estimates ranged between 0.79 and 0.36 across the frequencies.DISCUSSION: Our results indicate that there is a substantial shared familial effect in ARHI. We found that familial aggregation of ARHI is markedly higher in the low frequencies and that there is a trend toward higher familial aggregation in female compared with male subjects.
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| 17. |
- Hendrickx, Jan-Jaap, et al.
(författare)
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Familial aggregation of tinnitus : a European multicentre study
- 2007
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Ingår i: B-ENT. - Louvain, Belgium : Societe Royale Belge d'Oto - Rhino - Laryngologie et de Chirurgie Cervico - Faciale. - 0001-6497. ; 3:Suppl 7, s. 51-60
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- INTRODUCTION AND AIM:Tinnitus is a common condition affecting approximately 20% of the older population. There is increasing evidence that changes in the central auditory system following cochlear malfunctioning are responsible for tinnitus. To date, few investigators have studied the influence of genetic factors on tinnitus. The present report investigates the presence of a familial effect in tinnitus subjects.METHODS:In a European multicentre study, 198 families were recruited in seven European countries. Each family had at least 3 siblings. Subjects were screened for causes of hearing loss other than presbyacusis by clinical examination and a questionnaire. The presence of tinnitus was evaluated with the question "Nowadays, do you ever get noises in your head or ear (tinnitus) which usually last longer than five minutes". Familial aggregation was tested using three methods: a mixed model approach, calculating familial correlations, and estimating the risk of a subject having tinnitus if the disorder is present in another family member.RESULTS:All methods demonstrated a significant familial effect for tinnitus. The effect persisted after correction for the effect of other risk factors such as hearing loss, gender and age. The size of the familial effect is smaller than that for age-related hearing impairment, with a familial correlation of 0.15.CONCLUSION:The presence of a familial effect for tinnitus opens the door to specific studies that can determine whether this effect is due to a shared familial environment or the involvement of genetic factors. Subsequent association studies may result in the identification of the factors responsible. In addition, more emphasis should be placed on the effect of role models in the treatment of tinnitus.
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| 18. |
- Kremer, F., et al.
(författare)
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Spatial compounding for 2D strain estimation in the mouse heart : a pilot study
- 2010
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Konferensbidrag (refereegranskat)abstract
- Estimating cardiac strain in the mouse in the lateral direction usingspeckle tracking with adapted clinical equipment was shown to be challenging dueto the fast heart rate and the large speckle size relative to the wallthickness. Compounding axial motion estimates acquired from different insonationangles can potentially improve lateral strain estimates. Therefore, the aim ofthis study was to test the feasibility of this methodology in the murine heartbased on simulated data sets. A 3D kinematic model of a murine left ventriclewas simulated and filled randomly with scatterers. Ultrasound short-axis images(10mm 6mm) were obtained by assuming a linear array transducer. Beam steeringwas simulated at 3 different angles (22, 0, 22). Axial motion was estimated ineach data set by 1D cross-correlation. A dynamic programming approach wasintegrated in the motion estimation algorithm to avoid discontinuities. Axialcomponents were combined to reconstruct the in-plane motion vector. The 2Ddisplacement fields were subsequently accumulated over the whole cycle. Theprocedure was repeated for 10 different distributions of scatterers to acquire10 different RF data sets (5 for parameter tuning and 5 for comparing themethods). Radial and circumferential RMS strain errors calculated from theaccumulated motion fields were compared with those obtained with 2D speckletracking. Spatial compounding yielded significantly better radial (RMSE: 0.07370.0078 vs. 0.112 0.0094) as well as circumferential strain (RMSE: 0.102 0.0097vs. 0.281 0.054).
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| 19. |
- Larsson, Matilda, et al.
(författare)
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A novel measure to express tracking quality in ultrasound block matching
- 2010
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Ingår i: Proceedings - IEEE Ultrasonics Symposium. - 9781457703829 ; , s. 1636-1639
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Konferensbidrag (refereegranskat)abstract
- Speckle de-correlation is a major problem in block matching based ultrasound methodologies as it limits the accuracy of the tracking result. It would be of benefit to have a quantitative measure expressing the local tracking quality as it would allow discarding unreliable motion estimates. We hypothesized that kernels showing sufficient gray scale pattern would more reliably track than kernels with more homogenous gray scale distributions. The aim of this study was to test this hypothesis in-silico. Ultrasound B-mode sequences were simulated from a kinematic model of the carotid artery. Two-dimensional motion was estimated using block matching with the normalized cross-correlation function as similarity measure. For each kernel, two measures of tracking quality were stored: the normalized cross-correlation coefficient (Ccc) and a measure of the amount of edges inside the kernel detected using a canny filter and counted on a pixel-by-pixel basis. As such, a quality measure (Cedge) between 0 (no edges) and 1 (nothing but edges) was obtained. Axial and lateral strains were subsequently obtained by linear regression in regions of interest (ROIs) with best/worst mean tracking quality scores. The root-mean-squared-error (RMSE) was significantly lower in regions with low Ccc (worst ROI) compared to ROIs with high Ccc. However, more edges in the kernel did indeed result in better overall tracking (lower RMSE). Thus, the proposed edge-detection method showed to be a better tracking quality measure than the commonly used Ccc.
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| 20. |
- Larsson, Matilda, et al.
(författare)
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Assessment of longitudinal strain in the Carotid artery wall using ultrasound-based Speckle tracking - validation in a sheep model
- 2013
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Ingår i: Proceedings of the IEEE International Ultrasonics symposium, 2013.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Assessment of strain in the longitudinal direction of the arterial wall has been suggested to improve the evaluation of arterial stiffness and atherosclerosis. Recently, we showed the feasibility of ultrasound speckle tracking to assess carotid longitudinal strain in-silico and in-vitro. However, validation in the more challenging in-vivo setting is still lacking. The aim of this study was to validate longitudinal strain assessment in the common carotid artery (CCA) in an animal setup. The left CCAs of five sheep were exposed during Isoflurane anesthesia and sonomicrometry crystals were sutured onto the artery wall to obtain reference longitudinal strain. Ultrasound long-axis images were recorded at baseline and hypertension (Phenylephrine) and an in-house speckle tracking algorithm was applied to estimate longitudinal strain. The estimated strain curves varied cyclically throughout the cardiac cycles, showing a lengthening of the arterial segment in systole. A significant correlation between peak systolic estimated and reference strain was found (r=0.95, p < 0.001). The results indicate the feasibility of arterial longitudinal strain assessment in-vivo using ultrasound speckle tracking.
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| 21. |
- Larsson, Matilda, et al.
(författare)
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Strain assessment in the carotid artery wall using ultrasound speckle tracking : validation in a sheep model.
- 2015
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Ingår i: Physics in Medicine and Biology. - : IOP Publishing. - 0031-9155 .- 1361-6560. ; 60:3, s. 1107-
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to validate carotid artery strain assessment in-vivo using ultrasound speckle tracking. The left carotid artery of five sheep was exposed and sonomicrometry crystals were sutured onto the artery wall to obtain reference strain. Ultrasound imaging was performed at baseline and stress, followed by strain estimation using an in-house speckle tracking algorithm tuned for vascular applications. The correlation between estimated and reference strain was r = 0.95 (p < 0.001) and r = 0.87 (p < 0.01) for longitudinal and circumferential strain, respectively. Moreover, acceptable limits of agreement were found in Bland-Altman analysis (longitudinally: -0.15 to 0.42%, circumferentially: -0.54 to 0.50%), which demonstrates the feasibility of estimating carotid artery strain using ultrasound speckle tracking. However, further studies are needed to test the algorithm on human in-vivo data and to investigate its potential to detect subclinical cardiovascular disease and characterize atherosclerotic plaques.
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| 22. |
- Larsson, Matilda, et al.
(författare)
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Ultrasound-Based Radial and Longitudinal Strain Estimation of the Carotid Artery : A Feasibility Study
- 2011
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Ingår i: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control. - 0885-3010 .- 1525-8955. ; 58:10, s. 2244-2251
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Tidskriftsartikel (refereegranskat)abstract
- Ultrasound-based estimation of arterial wall elasticity is commonly used to assess arterial stiffness. However, previous elastography studies have mostly addressed radial strain measurements, and the longitudinal strain has been more or less ignored. This study shows the feasibility of a speckle-tracking-based algorithm for simultaneous estimation of radial and longitudinal strain in the carotid artery in silico. Additionally, these results were preliminarily confirmed in vivo.
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| 23. |
- Larsson, Matilda, et al.
(författare)
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Ultrasound speckle tracking for radial, longitudinal and circumferential strain estimation of the carotid artery : An in vitro validation via sonomicrometry using clinical and high-frequency ultrasound
- 2014
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Ingår i: Ultrasonics. - : Elsevier BV. - 0041-624X .- 1874-9968. ; 56, s. 399-408
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Tidskriftsartikel (refereegranskat)abstract
- Ultrasound speckle tracking for carotid strain assessment has in the past decade gained interest in studies of arterial stiffness and cardiovascular diseases. The aim of this study was to validate and directly contrast carotid strain assessment by speckle tracking applied on clinical and high-frequency ultrasound images in vitro. Four polyvinyl alcohol phantoms mimicking the carotid artery were constructed with different mechanical properties and connected to a pump generating carotid flow profiles. Gray-scale ultrasound long-and short-axis images of the phantoms were obtained using a standard clinical ultrasound system, Vivid 7 (GE Healthcare, Horten, Norway) and a high-frequency ultrasound system, Vevo 2100 (FUJIFILM, VisualSonics, Toronto, Canada) with linear-array transducers (12L / MS250). Radial, longitudinal and circumferential strains were estimated using an in-house speckle tracking algorithm and compared with reference strain acquired by sonomicrometry. Overall, the estimated strain corresponded well with the reference strain. The correlation between estimated peak strain in clinical ultrasound images and reference strain was 0.91 (p < 0.001) for radial strain, 0.73 (p < 0.001) for longitudinal strain and 0.90 (p < 0.001) for circumferential strain and for high-frequency ultrasound images 0.95 (p < 0.001) for radial strain, 0.93 (p < 0.001) for longitudinal strain and 0.90 (p < 0.001) for circumferential strain. A significant larger bias and root mean square error was found for circumferential strain estimation on clinical ultrasound images compared to high frequency ultrasound images, but no significant difference in bias and root mean square error was found for radial and longitudinal strain when comparing estimation on clinical and high-frequency ultrasound images. The agreement between sonomicrometry and speckle tracking demonstrates that carotid strain assessment by ultrasound speckle tracking is feasible.
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| 24. |
- Pislaru, Cristina, et al.
(författare)
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Is there a change in myocardial nonlinearity during the cardiac cycle?
- 2001
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Ingår i: Ultrasound in Medicine and Biology. - 0301-5629 .- 1879-291X. ; 27:3, s. 389-398
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Tidskriftsartikel (refereegranskat)abstract
- The distortion of a sound wave during propagation results in progressive transfer of the energy from fundamental to higher harmonics, and is dependent on the nonlinearity of the medium. We studied if relative changes in acoustical nonlinearity occur in healthy myocardium during the cardiac cycle. Radiofrequency data were acquired from transthoracic echocardiography (2.5 and 3.5 MHz), parasternal long axis view, from five dogs and nine healthy volunteers. Integrated backscatter was calculated after filtering for fundamental (FIB) and second harmonic frequencies (SHIB), from a region in the posterior myocardial wall. The results suggest that there is little difference between the SHIB and FIB, although there were large variations between individuals. The maximal changes in nonlinearity, as estimated by SHIB/FIB ratio, mostly occurred during systole. SHIB presented similar cyclic variation with FIB (p = NS). Further studies are necessary to separate the role of myocardial nonlinearity, attenuation, propagating distance, or acoustical properties of the blood. The results are important in further tissue characterization studies employing second harmonic data.
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| 25. |
- Sutherland, George, et al.
(författare)
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Quantitation of left-ventricular asynergy by cardiac ultrasound
- 2000
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Ingår i: American Journal of Cardiology. - 0002-9149 .- 1879-1913. ; 86:4, s. 4-9
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Tidskriftsartikel (refereegranskat)abstract
- The clinical evaluation of regional delays in myocardial motion (myocardial asynchrony) has proved problematic, yet it remains an important functional parameter to evaluate. Prior attempts to quantify regional asynergy have met with limited success, often thwarted by the low temporal resolution of imaging-system data acquisition. If a delay in onset of motion of 30–40 msec is clinically important to measure, then data acquisition at frame rates of 50–100 per second is required. This is out of the current temporal resolution of angiographic, nuclear, or magnetic resonance studies. Only cardiac ultrasound can currently achieve the necessary frame rates. Furthermore, quantitative studies into the accuracy with which a trained observer can identify computed regional myocardial asynchrony in a left-ventricular 2-dimensional (2-D) image have shown that regional delays of <80 msec are not normally recognized in a moving image. This may be improved to 60 msec when either training is undertaken or comparative image review is used. However, this is still out of the temporal resolution required in clinical practice. Thus, visual interpretation of asynchrony is not sufficiently accurate. Two ultrasound data sets based on either integrated backscatter or Doppler myocardial imaging data may provide the solution. Doppler myocardial imaging is a new ultrasound technique which, in either its pulsed or color Doppler format, can achieve the required temporal resolution (with temporal resolutions of 8 msec and 16 msec, respectively). In contrast, color Doppler myocardial imaging, in its curved M-mode format, can display the timing of events during the cardiac cycle for all in-plane myocardial segments. This should allow the quantitation of regional delay for all systolic and diastolic events. Potentially, asynchrony due to regional ischemia, bundle branch block, ventricular premature beats, and ventricular preexcitation could all be identified and the degree of delay quantified. This overview will aim to establish the potential role of these new ultrasound methodologies in the recognition and quantitation of left-ventricular asynergy and how they might best be introduced into clinical practice.
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| 26. |
- Ughi, Giovanni J., et al.
(författare)
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Automatic three-dimensional registration of intravascular optical coherence tomography images
- 2012
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Ingår i: Journal of Biomedical Optics. - 1083-3668 .- 1560-2281. ; 17:2, s. 026005-
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Tidskriftsartikel (refereegranskat)abstract
- Intravascular optical coherence tomography (IV-OCT) is a catheter-based high-resolution imaging technique able to visualize the inner wall of the coronary arteries and implanted devices in vivo with an axial resolution below 20 mu m. IV-OCT is being used in several clinical trials aiming to quantify the vessel response to stent implantation over time. However, stent analysis is currently performed manually and corresponding images taken at different time points are matched through a very labor-intensive and subjective procedure. We present an automated method for the spatial registration of IV-OCT datasets. Stent struts are segmented through consecutive images and three-dimensional models of the stents are created for both datasets to be registered. The two models are initially roughly registered through an automatic initialization procedure and an iterative closest point algorithm is subsequently applied for a more precise registration. To correct for nonuniform rotational distortions (NURDs) and other potential acquisition artifacts, the registration is consecutively refined on a local level. The algorithm was first validated by using an in vitro experimental setup based on a polyvinyl-alcohol gel tubular phantom. Subsequently, an in vivo validation was obtained by exploiting stable vessel landmarks. The mean registration error in vitro was quantified to be 0.14 mm in the longitudinal axis and 7.3-deg mean rotation error. In vivo validation resulted in 0.23 mm in the longitudinal axis and 10.1-deg rotation error. These results indicate that the proposed methodology can be used for automatic registration of in vivo IV-OCT datasets. Such a tool will be indispensable for larger studies on vessel healing pathophysiology and reaction to stent implantation. As such, it will be valuable in testing the performance of new generations of intracoronary devices and new therapeutic drugs.
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| 27. |
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| 28. |
- Van Eyken, Els, et al.
(författare)
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Contribution of the N-acetyltransferase 2 polymorphism NAT2*6A to age-related hearing impairment
- 2007
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Ingår i: Journal of Medical Genetics. - : B M J Group. - 0022-2593 .- 1468-6244. ; 44:9, s. 570-578
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundAge‐related hearing impairment (ARHI) is the most common sensory impairment in older people, affecting 50% of those aged 80 years. The proportion of older people is increasing in the general population, and as a consequence, the number of people affected with ARHI is growing. ARHI is a complex disorder, with both environmental and genetic factors contributing to the disease. The first studies to elucidate these genetic factors were recently performed, resulting in the identification of the first two susceptibility genes for ARHI, NAT2 and KCNQ4.MethodsIn the present study, the association between ARHI and polymorphisms in genes that contribute to the defence against reactive oxygen species, including GSTT1, GSTM1 and NAT2, was tested. Samples originated from seven different countries and were combined into two test population samples, the general European population and the Finnish population. Two distinct phenotypes for ARHI were studied, Zlow and Zhigh, representing hearing in the low and high frequencies, respectively. Statistical analysis was performed for single polymorphisms (GSTM1, GSTT1, NAT2*5A, NAT2*6A, and NAT2*7A), haplotypes, and gene–environment and gene–gene interactions.ResultsWe found an association between ARHI and GSTT1 and GSTM1 in the Finnish population sample, and with NAT2*6A in the general European population sample. The latter finding replicates previously published data.ConclusionAs replication is considered the ultimate proof of true associations in the study of complex disorders, this study provides further support for the involvement of NAT2*6A in ARHI.
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| 29. |
- Van Eyken, Els, et al.
(författare)
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The Contribution of GJB2 (Connexin 26) 35delG to Age-Related Hearing Impairment and Noise-Induced Hearing Loss
- 2007
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Ingår i: Otology and Neurotology. - : Lippincott Williams & Wilkins. - 1531-7129 .- 1537-4505. ; 28:7, s. 970-975
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Tidskriftsartikel (refereegranskat)abstract
- Hypothesis: The common GJB2 (Connexin 26) 35delG mutation might contribute to the development of age-related hearing impairment (ARHI) and noise-induced hearing loss (NIHL).Background: GJB2, a gene encoding a gap junction protein expressed in the inner ear, has been suggested to be involved in the potassium recycling pathway in the cochlea. GJB2 mutations account for a large number of individuals with nonsyndromic recessive hearing loss, with 35delG being the most frequent mutation in populations of European origin. Other genes involved in potassium homeostasis have been suggested to be associated with ARHI and NIHL, and distortion product otoacoustic emission distortions indicative of hearing loss alterations have been found in 35delG carriers.Method: We genotyped 35delG in two distinct sample sets: an ARHI sample set, composed of 2,311 Caucasian samples from nine different centers originating from seven different countries with an age range between 53 and 67 years, and an NIHL sample set consisting of 702 samples from the two extremes of a noise-exposed Polish sample.Results: After statistical analysis, we were unable to detect an association between 35delG and ARHI, nor between 35delG and NIHL.Conclusion: Our findings indicate that there is no increased susceptibility in 35delG carriers for the development of ARHI or NIHL.
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| 30. |
- Van Laer, Lut, et al.
(författare)
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The grainyhead like 2 gene (GRHL2), alias TFCP2L3, is associated with age-related hearing impairment
- 2008
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Ingår i: Human Molecular Genetics. - : Oxford University Press. - 0964-6906 .- 1460-2083. ; 17:2, s. 159-169
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Tidskriftsartikel (refereegranskat)abstract
- Age-related hearing impairment (ARHI) is the most prevalent sensory impairment in the elderly. ARHI is a complex disease caused by an interaction between environmental and genetic factors. The contribution of various environmental factors has been relatively extensively studied. In contrast, investigations to identify the genetic risk factors have only recently been initiated. In this paper we describe the results of an association study performed on 2418 ARHI samples derived from nine centers from seven European countries. In 70 candidate genes, a total of 768 tag single nucleotide polymorphisms (SNPs) were selected based on HAPMAP data. These genes were chosen among the monogenic hearing loss genes identified in mice and men in addition to several strong functional candidates. After genotyping and data polishing, statistical analysis of all samples combined resulted in a P-value that survived correction for multiple testing for one SNP in the GRHL2 gene. Other SNPs in this gene were also associated, albeit to a lesser degree. Subsequently, an analysis of the most significant GRHL2 SNP was performed separately for each center. The direction of the association was identical in all nine centers. Two centers showed significant associations and a third center showed a trend towards significance. Subsequent fine mapping of this locus demonstrated that the majority of the associated SNPs reside in intron 1. We hypothesize that the causative variant may change the expression levels of a GRHL2 isoform.
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| 31. |
- Widman, Erik, 1981-, et al.
(författare)
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SHEAR WAVE ELASTOGRAPHY OF THE ARTERIAL WALL – WHERE WE ARE TODAY
- 2013
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Konferensbidrag (refereegranskat)abstract
- 1. IntroductionShear Wave Elastography (SWE) is a recently developed noninvasive method for elastography assessment using ultrasound. The technique consists of sending an acoustic radiation force (pushing sequence) into the tissue that in turn generates an orthogonal low frequency propagating shear wave. The shear wave propagation is measured real time by high speed B-mode imaging. From the B-mode images, the shear wave is tracked via normalized cross-correlation and the speed is calculated, which is used to generate an elasticity map of the tissue’s shear modulus. To date, the technique has mostly been used in large homogeneous tissues such as breast and liver where it successfully detects lesions and tumors that are easily missed with normal B-mode ultrasound [1]. SWE could potentially be applied in vascular applications to assess elasticity of the arterial wall to characterize the stiffness as an early indicator of cardiac disease. Furthermore, SWE could aid in the characterization of plaques in the carotid artery, which is critical for the prevention of ischemic stroke2. Methods and ResultsAn initial study was performed using an Aixplorer SWE system (Supersonic Imagine, France) to measure the shear modulus in a polyvinyl alcohol phantom (PVA) vessel with a plaque inclusion (Figure 1). It was possible to distinguish the softer inclusion mean shear wave speed (2.1 m/s) from the arterial wall (3.5 m/s) on the SWE colour-map, but the Young’s Modulus calculation of the arterial wall (E=19.8 kPa) did not match the measured Young’s Modulus (E=53.1 kPa) from comparative mechanical testing.We have begun implementing various pushing sequences (single unfocused push, single focused push, line push, comb push) on a programmable ultrasound machine (Verasonics, USA) using a linear transducer (Philips L7-4) in a homogeneous PVA phantom. An algorithm for one dimensional cross-correlation tracking and shear wave speed estimation has been developed and initially tested in an experimental setup3. DiscussionAccording to our initial results, it is possible that SWE could be applied in vascular applications. However, the initial mechanical testing vs. SWE comparison indicated that further development to the post processing is needed before applying it on the carotid artery, which is a heterogeneous tissue with other wave propagation properties than e.g. breast tissue. The carotid artery has a difficult geometry to study for several reasons. The intima-media complex is very thin (< 1mm), and the vessel wall is not stationary. Furthermore, the cylindrical shape of the artery produces complex wave reflections within the arterial wall, which result in a polychromatic propagation of the shear wave. A few studies have applied techniques based on SWE to the arterial wall with promising results and a pilot study demonstrating the feasibility of the technique in-vivo has been published [2]. Still, a considerable effort is needed to validate and optimize the technique for the clinical vascular setting.
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| 32. |
- Widman, Erik, 1981-, et al.
(författare)
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Speckle tracking strain estimation of a carotid artery plaque phantom - Validation via sonomicrometry
- 2013
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Ingår i: 2013 IEEE International Ultrasonics Symposium (IUS). - : IEEE conference proceedings. - 9781467356848 ; , s. 1757-1760
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Konferensbidrag (refereegranskat)abstract
- Current clinical ultrasound-based methods for plaque characterization are limited to visual assessment of plaque echogenicity creating demand for quantitative diagnostic tools. Our objective was to validate radial and longitudinal speckle tracking (ST) strain in phantom plaques via sonomicrometry (sono), and to compare the peak plaque and arterial wall strain. Four carotid artery gel-phantoms with a soft wall inclusion, mimicking a vulnerable plaque, were constructed. The phantoms were connected to a programmable pump simulating a carotid flow. Cineloops were acquired using a GE Vivid E9 where radial and longitudinal strain were calculated using a normalized cross-correlation ST algorithm. The region of interest was adjusted according to the plaque size. Sonomicrometry was used as a reference measurement. The correlation between estimated mean peak strain and the reference peak strain was r = 0.96 (p < 0.001) radially and r = 0.75 (p ≤ 0.005) longitudinally. The soft plaque exhibited 35.1% (SD 16.9%) greater radial (p < 0.001) and 88.6% (SD 72.0%) greater longitudinal (p < 0.001) peak strain than the arterial wall when measured with speckle tracking. It was possible to estimate plaque strain by ST and to distinguish a soft plaque from the vessel wall via strain measurements.
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| 33. |
- Widman, Erik, 1981-, et al.
(författare)
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ULTRASOUND SPECKLE TRACKING STRAIN ESTIMATION IN CAROTID ARTERY PLAQUE PHANTOM WITH SONOMICROMETRY VALIDATION
- 2013
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Konferensbidrag (refereegranskat)abstract
- 1. IntroductionCarotid artery plaque characterization is critical for the prevention of ischemic events. Since plaque stiffness has shown to correlate with plaque vulnerability, quantification of plaque strain throughout the heart cycle would be a useful diagnostic tool. Our previous work encompassed the development and validation of a 2D speckle tracking (ST) algorithm to evaluate arterial stiffness by measuring strain in the carotid artery wall in silico, in vitro, and in vivo. The focus of previous studies has been to quantify plaque strain in the radial direction but lack validation against a ground truth measurement. Our objective was to validate radial and longitudinal strain in plaques via sonomicrometry (sono), and compare the measured plaque and arterial wall strain. 2. MethodThree carotid artery phantoms with soft wall inclusions, mimicking a vulnerable plaque, were constructed (10% polyvinyl alcohol (PVA), 3% graphite) by exposing the vessel and plaque to three and one freeze-thaw cycles (12h freeze, 12h thaw) respectively, see Fig. 1a. The phantoms were embedded in a tissue mimicking mixture (3% Agar, 4% graphite) at approximately 1cm depth with a pump (CompuFlow 1000 MR) connected to the phantom lumen simulating the carotid blood flow. B-mode cineloops (GE Vivid E9, 9LD linear transducer, 10 MHz, 42 fps) recorded the vessel movement at 20 and 30 mL/s peak flows. The radial and longitudinal deformation of the plaque and vessel wall was estimated by an in house 2D ST (kernel size 5x2 wavelengths) algorithm throughout two consecutive cycles. The region of interest was adjusted according to the plaque size. Sono crystals were placed on the plaque and vessel wall and used as a reference of truth. 3. ResultsFig. 1b and 1c show sample radial and longitudinal strain curves of a phantom with 20mL/s lumen flow with good agreement between sono and ST. A strong correlation was found at radial (r=0.67, p=0.03) and longitudinal peak systolic strain (r=0.84, p<0.001) between sono and ST. The plaque exhibited 47,3% (SD 27,4%) greater radial and 62,3% (SD 83,5%) longitudinal peak strain than the arterial wall when measured with ST. These preliminary data show that it is possible to measure radial and longitudinal strain in plaques; however, more extensive analysis is required as is the feasibility in vivo.
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| 34. |
- Widman, Erik, et al.
(författare)
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Ultrasound speckle tracking strain estimation of in vivo carotid artery plaque with in vitro sonomicrometry validation
- 2015
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Ingår i: Ultrasound in Medicine and Biology. - : Elsevier. - 0301-5629 .- 1879-291X. ; 41:1, s. 77-88
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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