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Dumont DM, Byram BC. Robust Tracking of Small Displacements With a Bayesian Estimator. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2016; 63:20-34. [PMID: 26529761 PMCID: PMC4778404 DOI: 10.1109/tuffc.2015.2495111] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Radiation-force-based elasticity imaging describes a group of techniques that use acoustic radiation force (ARF) to displace tissue to obtain qualitative or quantitative measurements of tissue properties. Because ARF-induced displacements are on the order of micrometers, tracking these displacements in vivo can be challenging. Previously, it has been shown that Bayesian-based estimation can overcome some of the limitations of a traditional displacement estimator such as normalized cross-correlation (NCC). In this work, we describe a Bayesian framework that combines a generalized Gaussian-Markov random field (GGMRF) prior with an automated method for selecting the prior's width. We then evaluate its performance in the context of tracking the micrometer-order displacements encountered in an ARF-based method such as ARF impulse (ARFI) imaging. The results show that bias, variance, and mean-square error (MSE) performance vary with prior shape and width, and that an almost one order-of-magnitude reduction in MSE can be achieved by the estimator at the automatically selected prior width. Lesion simulations show that the proposed estimator has a higher contrast-to-noise ratio but lower contrast than NCC, median-filtered NCC, and the previous Bayesian estimator, with a non-Gaussian prior shape having better lesion-edge resolution than a Gaussian prior. In vivo results from a cardiac, radio-frequency ablation ARFI imaging dataset show quantitative improvements in lesion contrast-to-noise ratio over NCC as well as the previous Bayesian estimator.
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Byram B, Kim H, Van Assche L, Wolf PD, Trahey GE. The feasibility of myocardial infarct visualization using atrial kick induced strain (AKIS) contrast. ULTRASOUND IN MEDICINE & BIOLOGY 2014; 40:1104-17. [PMID: 24613554 PMCID: PMC4096930 DOI: 10.1016/j.ultrasmedbio.2013.12.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Revised: 12/13/2013] [Accepted: 12/17/2013] [Indexed: 06/03/2023]
Abstract
The most common mechanical measure of the heart integrates ventricular strain between end-diastole and end-systole in order to provide a measure of contraction. Here an approach is described for estimating a correlate to local passive mechanical properties. Passive strain is measured by estimating ventricular strain during atrial systole. During atrial systole the atria contract causing passive stretching in the ventricles from increased volume. This modification to traditional cardiac strain is here termed atrial kick induced strain (AKIS) imaging. AKIS imaging was evaluated in a canine ablation model of chronic infarct and a canine true chronic infarct model. AKIS images of ablation lesions were compared against acoustic radiation force impulse (ARFI) images and tissue blanching, and true chronic infarct AKIS images were compared against delayed enhanced-contrast magnetic resonance. AKIS images were made with 2-D and 3-D ultrasound data. In both studies, AKIS images and the comparison images show good qualitative agreement and good contrast and contrast-to-noise ratio.
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Affiliation(s)
- Brett Byram
- Department of Biomedical Engineering, Duke University, Durham, NC, USA.
| | - Han Kim
- Department of Cardiology, Duke University Medical Center, Durham, NC, USA
| | - Lowie Van Assche
- Department of Cardiology, Duke University Medical Center, Durham, NC, USA
| | - Patrick D Wolf
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
| | - Gregg E Trahey
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
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Eyerly SA, Bahnson TD, Koontz JI, Bradway DP, Dumont DM, Trahey GE, Wolf PD. Contrast in intracardiac acoustic radiation force impulse images of radiofrequency ablation lesions. ULTRASONIC IMAGING 2014; 36:133-48. [PMID: 24554293 PMCID: PMC4049337 DOI: 10.1177/0161734613519602] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
We have previously shown that intracardiac acoustic radiation force impulse (ARFI) imaging visualizes tissue stiffness changes caused by radiofrequency ablation (RFA). The objectives of this in vivo study were to (1) quantify measured ARFI-induced displacements in RFA lesion and unablated myocardium and (2) calculate the lesion contrast (C) and contrast-to-noise ratio (CNR) in two-dimensional ARFI and conventional intracardiac echo images. In eight canine subjects, an ARFI imaging-electroanatomical mapping system was used to map right atrial ablation lesion sites and guide the acquisition of ARFI images at these sites before and after ablation. Readers of the ARFI images identified lesion sites with high sensitivity (90.2%) and specificity (94.3%) and the average measured ARFI-induced displacements were higher at unablated sites (11.23 ± 1.71 µm) than at ablated sites (6.06 ± 0.94 µm). The average lesion C (0.29 ± 0.33) and CNR (1.83 ± 1.75) were significantly higher for ARFI images than for spatially registered conventional B-mode images (C = -0.03 ± 0.28, CNR = 0.74 ± 0.68).
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Affiliation(s)
| | - Tristram D. Bahnson
- Duke Center for Atrial Fibrillation, Duke Heart Center, and Clinical Cardiac Electrophysiology Section of the Division of Cardiovascular Medicine, Duke University, Durham, NC, USA
| | - Jason I. Koontz
- Duke Center for Atrial Fibrillation, Duke Heart Center, and Clinical Cardiac Electrophysiology Section of the Division of Cardiovascular Medicine, Duke University, Durham, NC, USA
| | - David P. Bradway
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
| | - Douglas M. Dumont
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
| | - Gregg E. Trahey
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
- Department of Radiology, Duke University Medical Center, Durham, NC, USA
| | - Patrick D. Wolf
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
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Eyerly SA, Bahnson TD, Koontz JI, Bradway DP, Dumont DM, Trahey GE, Wolf PD. Intracardiac acoustic radiation force impulse imaging: a novel imaging method for intraprocedural evaluation of radiofrequency ablation lesions. Heart Rhythm 2012; 9:1855-62. [PMID: 22772134 PMCID: PMC3483372 DOI: 10.1016/j.hrthm.2012.07.003] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2012] [Indexed: 11/19/2022]
Abstract
BACKGROUND Arrhythmia recurrence after cardiac radiofrequency ablation (RFA) for atrial fibrillation has been linked to conduction through discontinuous lesion lines. Intraprocedural visualization and corrective ablation of lesion line discontinuities could decrease postprocedure atrial fibrillation recurrence. Intracardiac acoustic radiation force impulse (ARFI) imaging is a new imaging technique that visualizes RFA lesions by mapping the relative elasticity contrast between compliant-unablated and stiff RFA-treated myocardium. OBJECTIVE To determine whether intraprocedure ARFI images can identify RFA-treated myocardium in vivo. METHODS In 8 canines, an electroanatomical mapping-guided intracardiac echo catheter was used to acquire 2-dimensional ARFI images along right atrial ablation lines before and after RFA. ARFI images were acquired during diastole with the myocardium positioned at the ARFI focus (1.5 cm) and parallel to the intracardiac echo transducer for maximal and uniform energy delivery to the tissue. Three reviewers categorized each ARFI image as depicting no lesion, noncontiguous lesion, or contiguous lesion. For comparison, 3 separate reviewers confirmed RFA lesion presence and contiguity on the basis of functional conduction block at the imaging plane location on electroanatomical activation maps. RESULTS Ten percent of ARFI images were discarded because of motion artifacts. Reviewers of the ARFI images detected RFA-treated sites with high sensitivity (95.7%) and specificity (91.5%). Reviewer identification of contiguous lesions had 75.3% specificity and 47.1% sensitivity. CONCLUSIONS Intracardiac ARFI imaging was successful in identifying endocardial RFA treatment when specific imaging conditions were maintained. Further advances in ARFI imaging technology would facilitate a wider range of imaging opportunities for clinical lesion evaluation.
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Affiliation(s)
- Stephanie A Eyerly
- Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708, USA
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Yamanaka N, Kaminuma C, Taketomi-Takahashi A, Tsushima Y. Reliable measurement by virtual touch tissue quantification with acoustic radiation force impulse imaging: phantom study. JOURNAL OF ULTRASOUND IN MEDICINE : OFFICIAL JOURNAL OF THE AMERICAN INSTITUTE OF ULTRASOUND IN MEDICINE 2012; 31:1239-1244. [PMID: 22837288 DOI: 10.7863/jum.2012.31.8.1239] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
OBJECTIVES The purpose of this study was to evaluate the factors that may affect shear wave velocity (SWV) measurements by using a phantom. METHODS The SWVs (meters per second) of 4 phantom targets and background, each of different hardness (Young modulus, 8-80 kPa), were measured in the virtual touch tissue quantification mode. Ten SWV measurements were performed on each target, and the mean SWV and its standard deviation were calculated. To assess the effect of the distance between the probe and region of interest (ROI) settings, mean SWV measurements of the background at 5 to 80 mm in depth were performed with a convex probe and at 5 to 40 mm with a high-frequency linear probe. RESULTS The linear correlation between the nominal Young modulus of the phantom and those calculated from the mean SWV was highly significant for the linear probe (y = 0.98x - 0.70; r(2) = 0.99; P = .0007). For the convex probe, the linear correlation between the nominal Young modulus of the phantom and those calculated from the mean SWV was highly significant between 8 and 40 kPa (y =1.26x + 1.01; r(2) = 0.98; P = .011). Measurement variations for the linear probe were little influenced by the distance between the probe and ROI, but those for the convex probe were dependent on the distance. CONCLUSIONS The accuracy of the mean SWV measurement was dependent on the probe used and the distance between the probe and ROI settings. The linear probe provides accurate measurements throughout its range for all but its deepest limit. Measurements of 40 mm or deeper are better performed with a convex probe. Probe selection should be based on individual lesion depth.
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Affiliation(s)
- Noriko Yamanaka
- Department of Diagnostic Radiology and Nuclear Medicine, Gunma University Hospital, 3-39-22 Showa-machi, Maebashi, Gunma 371-8511, Japan
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Hsu SJ, Byram BC, Bouchard RR, Dumont DM, Wolf PD, Trahey GE. Acoustic radiation force impulse imaging of mechanical stiffness propagation in myocardial tissue. ULTRASONIC IMAGING 2012; 34:142-58. [PMID: 22972912 PMCID: PMC3500656 DOI: 10.1177/0161734612456580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Acoustic radiation force impulse (ARFI) imaging has been shown to be capable of imaging local myocardial stiffness changes throughout the cardiac cycle. Expanding on these results, the authors present experiments using cardiac ARFI imaging to visualize and quantify the propagation of mechanical stiffness during ventricular systole. In vivo ARFI images of the left ventricular free wall of two exposed canine hearts were acquired. Images were formed while the heart was externally paced by one of two electrodes positioned on the epicardial surface and either side of the imaging plane. Two-line M-mode ARFI images were acquired at a sampling frequency of 120 Hz while the heart was paced from an external stimulating electrode. Two-dimensional ARFI images were also acquired, and an average propagation velocity across the lateral field of view was calculated. Directions and speeds of myocardial stiffness propagation were measured and compared with the propagations derived from the local electrocardiogram (ECG), strain, and tissue velocity measurements estimated during systole. In all ARFI images, the direction of myocardial stiffness propagation was seen to be away from the stimulating electrode and occurred with similar velocity magnitudes in either direction. When compared with the local epicardial ECG, the mechanical stiffness waves were observed to travel in the same direction as the propagating electrical wave and with similar propagation velocities. In a comparison between ARFI, strain, and tissue velocity imaging, the three methods also yielded similar propagation velocities.
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Bouchard RR, Hsu SJ, Palmeri ML, Rouze NC, Nightingale KR, Trahey GE. Acoustic radiation force-driven assessment of myocardial elasticity using the displacement ratio rate (DRR) method. ULTRASOUND IN MEDICINE & BIOLOGY 2011; 37:1087-100. [PMID: 21645966 PMCID: PMC3118908 DOI: 10.1016/j.ultrasmedbio.2011.04.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2010] [Revised: 04/08/2011] [Accepted: 04/11/2011] [Indexed: 05/04/2023]
Abstract
A noninvasive method of characterizing myocardial stiffness could have significant implications in diagnosing cardiac disease. Acoustic radiation force (ARF)-driven techniques have demonstrated their ability to discern elastic properties of soft tissue. For the purpose of myocardial elasticity imaging, a novel ARF-based imaging technique, the displacement ratio rate (DRR) method, was developed to rank the relative stiffnesses of dynamically varying tissue. The basis and performance of this technique was demonstrated through numerical and phantom imaging results. This new method requires a relatively small temporal (<1 ms) and spatial (tenths of mm(2)) sampling window and appears to be independent of applied ARF magnitude. The DRR method was implemented in two in vivo canine studies, during which data were acquired through the full cardiac cycle by imaging directly on the exposed epicardium. These data were then compared with results obtained by acoustic radiation force impulse (ARFI) imaging and shear wave velocimetry, with the latter being used as the gold standard. Through the cardiac cycle, velocimetry results portray a range of shear wave velocities from 0.76-1.97 m/s, with the highest velocities observed during systole and the lowest observed during diastole. If a basic shear wave elasticity model is assumed, such a velocity result would suggest a period of increased stiffness during systole (when compared with diastole). Despite drawbacks of the DRR method (i.e., sensitivity to noise and limited stiffness range), its results predicted a similar cyclic stiffness variation to that offered by velocimetry while being insensitive to variations in applied radiation force.
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Dumont DM, Doherty JR, Trahey GE. Noninvasive assessment of wall-shear rate and vascular elasticity using combined ARFI/SWEI/spectral Doppler imaging system. ULTRASONIC IMAGING 2011; 33:165-88. [PMID: 21842581 PMCID: PMC3266666 DOI: 10.1177/016173461103300302] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The progression of atherosclerotic disease is a complex process believed to be a function of the localized mechanical properties and hemodynamic loading associated with the arterial wall. It is hypothesized that measurements of cardiovascular stiffness and wall-shear rate (WSR) may provide important information regarding vascular remodeling, endothelial function and the growth of soft lipid-filled plaques that could help a clinician better predict the occurrence of clinical events such as stroke. Two novel ARFI based imaging techniques, combined on-axis/off-axis ARFI/Spectral Doppler Imaging (SAD-SWEI) and Gated 2D ARFI/Spectral Doppler Imaging (SAD-Gated), were developed to form co-registered depictions of B-mode echogenicity, ARFI displacements, ARF-excited transverse wave velocity estimates and estimates ofwall-shear rate throughout the cardiac cycle. Implemented on a commercial ultrasound scanner, the developed techniques were evaluated in tissue-mimicking and steady-state flow phantoms and compared with conventional techniques, other published study results and theoretical values. Initial in vivo feasibility of the method is demonstrated with results obtained from scanning the carotid arteries of five healthy volunteers. Cyclic variations over the cardiac cycle were observed in on-axis displacements, off-axis transverse-wave velocities and wall-shear rates.
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Affiliation(s)
- Douglas M Dumont
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA.
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Kaminuma C, Tsushima Y, Matsumoto N, Kurabayashi T, Taketomi-Takahashi A, Endo K. Reliable measurement procedure of virtual touch tissue quantification with acoustic radiation force impulse imaging. JOURNAL OF ULTRASOUND IN MEDICINE : OFFICIAL JOURNAL OF THE AMERICAN INSTITUTE OF ULTRASOUND IN MEDICINE 2011; 30:745-751. [PMID: 21632988 DOI: 10.7863/jum.2011.30.6.745] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
OBJECTIVES The purpose of this study was to find a reliable procedure for performing virtual touch tissue quantification of the liver. METHODS Twenty healthy volunteers were enrolled after informed consent was obtained. The liver and spleen of each volunteer were examined on the same day by two different sonologists. The shear wave velocity values at deep and superficial locations of the right and left lobes of the liver and the spleen were obtained before and after food consumption and with and without deep inspiration. The measurements were performed 5 times in each location, and the mean shear wave velocities were recorded. RESULTS No statistically significant difference was found between the mean shear wave velocities obtained by the two operators. A difference was found between the velocities obtained in the deep portion of the right lobe (5.5 cm from the probe; mean ± SD, 1.17 ± 0.25 m/s on the intercostal scan and 1.35 ± 0.45 m/s on the subcostal scan) and the superficial portion (3.5 cm; 1.56 ± 0.43 and 1.74 ± 0.74 m/s; P < .001; P < .002, respectively), and the values obtained in the deep portion of the right lobe on the intercostal scan were lower than those obtained on the subcostal scan (P < .05). There were no differences in the mean shear wave velocities of the liver before and after food consumption or with and without deep inspiration. The velocities of the spleen did not differ before and after food consumption (2.33 ± 0.47 versus 2.39 ± 0.58 m/s). CONCLUSIONS In healthy people, mean shear wave velocities were dependent on the measurement site in the liver, and food consumption or deep inspiration did not affect velocity measurements of the liver or spleen.
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Affiliation(s)
- Chie Kaminuma
- Department of Diagnostic Radiology and Nuclear Medicine, Gunma University Hospital, 3-39-22 Showa-machi, Maebashi, Gunma 371-8511, Japan.
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Giannantonio DM, Dumont DM, Trahey GE, Byram BC. Comparison of physiological motion filters for in vivo cardiac ARFI. ULTRASONIC IMAGING 2011; 33:89-108. [PMID: 21710825 PMCID: PMC3479245 DOI: 10.1177/016173461103300201] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Acoustic radiation force impulse (ARFI) imaging is being utilized to investigate mechanical properties ofcardiac tissue. The underlying physiological motion, however, presents a major challenge. This paper aims to investigate the effectiveness of various physiological motion filters using in vivo canine data with a simulated ARFI push pulse. Ideally, the motion filter will exactly model the physiological motion and, when subtracted from the total displacement, leave only the simulated ARFI displacement profile. We investigated three temporal quadratic motion filters: (1)interpolation, (2) extrapolation and (3) a weighted technique. Additionally, the various motion filters were compared when using 1-D versus 2-D autocorrelation methods to estimate motion. It was found that 2D-autocorrelation always produced better physiological motion estimates regardless of the type of filter used. The extrapolation filter gives the most accurate estimate of the physiological motion at times immediately after the ARFI push (0.1 ms) while a close-time interpolation filter using displacement estimates at times before full tissue recovery gives the most accurate estimates at later times after the ARFI push (0.7 ms). While improvements to the motion filter during atrial systole and the onset of ventricular systole are needed, the weighted, close-time interpolation and extrapolation motion filters all offer promising results for estimating cardiac physiological motion more accurately, while allowing faster ARFI frame rates than previous motion filters. This study demonstrates the ability to eliminate physiological motion in a clinically-feasible manner, opening the door for more extensive clinical experimentation.
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Affiliation(s)
- Doug M Giannantonio
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA.
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Holtel MR. Emerging Technology in Head and Neck Ultrasonography. Otolaryngol Clin North Am 2010; 43:1267-74, vii. [DOI: 10.1016/j.otc.2010.08.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Elgeti T, Beling M, Hamm B, Braun J, Sack I. Elasticity-based determination of isovolumetric phases in the human heart. J Cardiovasc Magn Reson 2010; 12:60. [PMID: 20979648 PMCID: PMC2987769 DOI: 10.1186/1532-429x-12-60] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2010] [Accepted: 10/27/2010] [Indexed: 01/09/2023] Open
Abstract
UNLABELLED BACKGROUND/MOTIVATION: To directly determine isovolumetric cardiac time intervals by magnetic resonance elastography (MRE) using the magnitude of the complex signal for deducing morphological information combined with the phase of the complex signal for tension-relaxation measurements. METHODS Thirty-five healthy volunteers and 11 patients with relaxation abnormalities were subjected to transthoracic wave stimulation using vibrations of approximately 25 Hz. A k-space-segmented, ECG-gated gradient-recalled echo steady-state sequence with a 500-Hz bipolar motion-encoding gradient was used for acquiring a series of 360 complex images of a short-axis view of the heart at a frame rate of less than 5.2 ms. Magnitude images were employed for measuring the cross-sectional area of the left ventricle, while phase images were used for analyzing the amplitudes of the externally induced waves. The delay between the decrease in amplitude and onset of ventricular contraction was determined in all subjects and assigned to the time of isovolumetric tension. Conversely, the delay between the increase in wave amplitude and ventricular dilatation was used for measuring the time of isovolumetric elasticity relaxation. RESULTS Wave amplitudes decreased during systole and increased during diastole. The variation in wave amplitude occurred ahead of morphological changes. In healthy volunteers the time of isovolumetric elasticity relaxation was 75 ± 31 ms, which is significantly shorter than the time of isovolumetric tension of 136 ± 36 ms (P < 0.01). In patients with relaxation abnormalities (mild diastolic dysfunction, n = 11) isovolumetric elasticity relaxation was significantly prolonged, with 133 ± 57 ms (P < 0.01), whereas isovolumetric tension time was in the range of healthy controls (161 ± 45 ms; P = 0.053). CONCLUSION The complex MRE signal conveys complementary information on cardiac morphology and elasticity, which can be combined for directly measuring isovolumetric tension and elasticity relaxation in the human heart.
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Affiliation(s)
- Thomas Elgeti
- Department of Radiology, Charité - Universitätsmedizin Berlin, Campus Mitte, Charitéplatz 1, 10117 Berlin, Germany
| | - Mark Beling
- Department of Cardiology, Angiology and Pulmonology, Charité - Universitätsmedizin Berlin, Campus Mitte, Charitéplatz 1, 10117 Berlin, Germany
| | - Bernd Hamm
- Department of Radiology, Charité - Universitätsmedizin Berlin, Campus Mitte, Charitéplatz 1, 10117 Berlin, Germany
| | - Jürgen Braun
- Institute of Medical Informatics, Charité - Universitätsmedizin Berlin, Campus Benjamin Franklin, Hindenburgdamm 30, 12200 Berlin, Germany
| | - Ingolf Sack
- Department of Radiology, Charité - Universitätsmedizin Berlin, Campus Mitte, Charitéplatz 1, 10117 Berlin, Germany
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Bouchard RR, Hsu SJ, Wolf PD, Trahey GE. In vivo cardiac, acoustic-radiation-force-driven, shear wave velocimetry. ULTRASONIC IMAGING 2009; 31:201-13. [PMID: 19771962 PMCID: PMC2797484 DOI: 10.1177/016173460903100305] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Shear wave elasticity imaging (SWEI) was employed to track acoustic radiation force impulse (ARFI)-induced shear waves in the mid-myocardium of the left ventricular free wall (LVFW) of a beating canine heart. Shear waves were generated and tracked with a linear ultrasound transducer that was placed directly on the exposed epicardium. Acquisition was ECG-gated and coincided with the mid-diastolic portion of the cardiac cycle. Axial displacement profiles consistent with shear wave propagation were clearly evident in all SWEI acquisitions (i.e., those including an ARFI excitation); displacement data from control cases (i.e., sequences lacking an ARFI excitation) offered no evidence of shear wave propagation and yielded a peak absolute mean displacement below 0.31 microm after motion filtering. Shear wave velocity estimates ranged from 0.82 to 2.65 m/s and were stable across multiple heartbeats for the same interrogation region, with coefficients of variation less than 19% for all matched acquisitions. Variations in velocity estimates suggest a spatial dependence of shear wave velocity through the mid-myocardium of the LVFW, with velocity estimates changing, in limited cases, through depth and lateral position.
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