Assessing cardiac stiffness using ultrasound shear wave elastography

Abstract Shear wave elastography offers a new dimension to echocardiography: it measures myocardial stiffness. Therefore, it could provide additional insights into the pathophysiology of cardiac diseases affecting myocardial stiffness and potentially improve diagnosis or guide patient treatment. The technique detects fast mechanical waves on the heart wall with high frame rate echography, and converts their propagation velocity into a stiffness value. A proper interpretation of shear wave data is required as the shear wave interacts with the intrinsic, yet dynamically changing geometrical and material characteristics of the heart under pressure. This dramatically alters the wave physics of the propagating wave, demanding adapted processing methods compared to other shear wave elastography applications as breast tumor and liver stiffness staging. Furthermore, several advanced analysis methods have been proposed to extract supplementary material features such as viscosity and anisotropy, potentially offering additional diagnostic value. This review explains the general mechanical concepts underlying cardiac shear wave elastography and provides an overview of the preclinical and clinical studies within the field. We also identify the mechanical and technical challenges ahead to make shear wave elastography a valuable tool for clinical practice.

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Shear wave elastography by high frame rate echocardiography can detect diffuse myocardial fibrosis after heart transplantation

European Heart Journal ◽

10.1093/ehjci/ehaa946.0854 ◽

2020 ◽

Vol 41 (Supplement_2) ◽

Author(s):

A Petrescu ◽

S Bezy ◽

M Cvijic ◽

P Santos ◽

J Duchenne ◽

...

Keyword(s):

Shear Wave ◽

Myocardial Fibrosis ◽

Myocardial Injury ◽

Shear Wave Elastography ◽

Diffuse Myocardial Fibrosis ◽

Frame Rate ◽

Myocardial Stiffness ◽

High Frame Rate ◽

Native T1 ◽

Propagation Velocities

Abstract Background Myocardial fibrosis is fundamental in the development of cardiac failure, regardless of ethiology. In both animal models and humans it has been shown that diffuse myocardial fibrosis (DMF) contributes to functional impairment, especially to increased passive myocardial stiffness, which is an important pathophysiological determinant of left ventricular diastolic dysfunction. Histological examination is the gold standard for myocardial fibrosis quantification, however, it requires endomyocardial biopsies which are invasive and not without risk. Echocardiographic shear wave (SW) elastography, based on high frame rate imaging, is an emerging approach for measuring myocardial stiffness in vivo. Natural SWs occur after mechanical excitation of the myocardium, e.g. after mitral valve closure (MVC) and their propagation velocity is directly related to myocardial stiffness, thus providing an opportunity to assess myocardial stiffness at end-diastole. Purpose The aim was to investigate if propagation velocities of natural SWs can be used to detect diffuse myocardial fibrosis in a cohort of heart transplant recipients. Methods We prospectively enrolled 22 patients (10.3±6.3 years after HTx) that underwent CMR during their annual check-up. We performed SW elastography in parasternal long axis views of the left ventricle using a fully programmable experimental scanner (HD-PULSE) equipped with a clinical phased array transducer (Samsung Medison P2–5AC) at 1100±250 frames per second. The SW propagation velocities at MVC were measured in the basal LV septum. Native T1 and extracellular volume (ECV) were measured at the same segment to evaluate DMF. A cut-off value for native T1 of 1040 ms and for ECV of 29% was used to define DMF in our cohort. Results We found good correlations between SW velocities and both myocardial T1 (r=0.80, p<0.0001, Figure A) and ECV (r=0.64, p=0.003, Figure B) measured with CMR. Further, we derived reference thresholds of natural SW velocities to identify DMF in HTx patients. The optimal cut-off value of SW velocity to identify patients with nativT1>1040 ms was 4.84 m/s (AUC 0.81, sensitivity 82%, specificity 82%, Figure C). To identify patients with ECV>0.29 the cut-off value of SW velocity was 4.74 m/s (AUC 0.74, sensitivity 73%, specificity 78%, Figure D). Conclusions End-diastolic shear wave propagation velocities, as measure of myocardial stiffness, showed a good correlation with CMR defined diffuse myocardial injury. Values higher than 4.74 m/s could identify diffuse myocardial injury in HTX patients with a good sensitivity and good specificity. These findings thus suggest that shear wave elastography has the potential to become a valuable non-invasive method for the detection of diffuse myocardial fibrosis. Funding Acknowledgement Type of funding source: None

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Myocardial stiffness assessed by natural shear wave elastography is related to pressure-volume loop derived parameters

European Heart Journal ◽

10.1093/eurheartj/ehab724.034 ◽

2021 ◽

Vol 42 (Supplement_1) ◽

Author(s):

S Bezy ◽

A Caenen ◽

J Duchenne ◽

M Orlowska ◽

M Amoni ◽

...

Keyword(s):

Shear Wave ◽

Wave Speed ◽

Propagation Speed ◽

Shear Wave Elastography ◽

Frame Rate ◽

Myocardial Stiffness ◽

High Frame Rate ◽

Shear Wave Speed ◽

Non Invasive ◽

Operating Chamber

Abstract Background Several cardiovascular disorders are accompanied by a stiffening of the myocardium and may result in diastolic heart failure. The non-invasive assessment of myocardial stiffness could therefore improve the understanding of the pathophysiology and guide treatment. Shear wave elastography (SWE) is a recent technique with tremendous potential for evaluating myocardial stiffness in a non-invasive way. Using high frame rate echocardiography, the propagation speed of shear waves is evaluated, which is directly related to the stiffness of the myocardium. These waves are induced by for instance mitral valve closure (MVC) and propagate throughout the cardiac muscle. However, validation of SWE against an invasive gold standard method is lacking. Purpose The aim of this study was to compare echocardiographic shear wave elastography against invasive pressure-volume loops, a gold standard reference method for assessing chamber stiffness. Methods In 15 pigs (31.2±4.1 kg) stiffness of the myocardium was acutely changed by inducing ischemia/reperfusion (I/R) injury. For this, the proximal LAD was balloon occluded for 90 minutes with subsequent reperfusion for 40 minutes. Conventional and high frame rate echocardiographic images were acquired simultaneously with pressure-volume loops during baseline conditions and after the induction of the I/R injury. Preload was reduced in order to acquire a set of pressure-volume loops to derive the end-diastolic pressure volume relation (EDPVR). From the EDPVR, the stiffness coefficient β and the operating chamber stiffness dP/dV were obtained. High frame rate echocardiographic datasets of the parasternal long axis view were acquired with an experimental ultrasound scanner (HD-PULSE) at an average frame rate of 1304±115 Hz. Tissue acceleration maps were obtained by drawing an M-mode line along the interventricular septum in order to visualize shear waves after MVC (at end-diastole). The propagation speed was assessed by semi-automatically measuring the slope (Figure A). Results I/R injury led to an elevated chamber stiffness constant β (0.09±0.03 1/ml vs. 0.05±0.01 1/ml; p<0.001) and operating chamber stiffness dP/dV (1.09±0.38 mmHg/ml vs. 0.50±0.18 mmHg/ml; p<0.01). Likewise, shear wave speed after MVC increased after the induction of the I/R injury in comparison to baseline (6.1±1.2 m/s vs. 3.2±0.8 m/s; p<0.001). Shear wave speed had a moderate positive correlation with β (r=0.63; p<0.001) (Figure B) and a strong positive correlation with dP/dV (r=0.81; p<0.001) (Figure C). Conclusion End-diastolic shear wave speed is strongly related to chamber stiffness, assessed invasively by pressure-volume loops. These results indicate that shear wave propagation speed could be used as a novel non-invasive measurement of the mechanical properties of the ventricle. FUNDunding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): FWO - Research Foundation Flanders

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Liver Elastography in Healthy Children Using Three Different Systems – How Many Measurements Are Necessary?

Ultraschall in der Medizin - European Journal of Ultrasound ◽

10.1055/a-1283-5906 ◽

2020 ◽

Author(s):

Anders Batman Mjelle ◽

Anesa Mulabecirovic ◽

Roald Flesland Havre ◽

Edda Jonina Olafsdottir ◽

Odd Helge Gilja ◽

...

Keyword(s):

Shear Wave ◽

Transient Elastography ◽

Intraclass Correlation ◽

Age Groups ◽

Liver Stiffness ◽

Shear Wave Elastography ◽

Healthy Children ◽

Significant Difference ◽

Pediatric Liver Disease ◽

Liver Elastography

Abstract Purpose Liver elastography is increasingly being applied in screening for and follow-up of pediatric liver disease, and has been shown to correlate well with fibrosis staging through liver biopsy. Because time is of the essence when examining children, we wanted to evaluate if a reliable result can be achieved with fewer acquisitions. Materials and Methods 243 healthy children aged 4–17 years were examined after three hours of fasting. Participants were divided into four age groups: 4–7 years; 8–11 years; 12–14 years and 15–17 years. Both two-dimensional shear wave elastography (2D-SWE; GE Logiq E9) and point shear wave elastography (pSWE; Samsung RS80A with Prestige) were performed in all participants, while transient elastography (TE, Fibroscan) was performed in a subset of 87 children aged 8–17 years. Median liver stiffness measurement (LSM) values of 3, 4, 5, 6, 7, and 8 acquisitions were compared with the median value of 10 acquisitions (reference standard). Comparison was performed for all participants together as well as within every specific age group. We investigated both the intraclass correlation coefficient (ICC) with absolute agreement and all outliers more than 10 %, 20 % or ≥ 0.5 or 1.0 kPa from the median of 10 acquisitions. Results For all three systems there was no significant difference between three and ten acquisitions, with ICCs ≥ 0.97. All systems needed 4 acquisitions to achieve no LSM deviating ≥ 1.0 kPa of a median of ten. To achieve no LSM deviating ≥ 20 % of a median of ten acquisitions, pSWE and TE needed 4 acquisitions, while 2D-SWE required 6 acquisitions. Conclusion Our results contradict recommendations of 10 acquisitions for pSWE and TE and only 3 for 2D-SWE.

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Noninvasive Assessment of Liver Diseases using 2D Shear Wave Elastography

Journal of Gastrointestinal and Liver Diseases ◽

10.15403/jgld.2014.1121.254.lup ◽

2016 ◽

Vol 25 (4) ◽

pp. 525-532 ◽

Cited By ~ 8

Author(s):

Monica Lupșor-Platon ◽

Radu Badea ◽

Mirela Gersak ◽

Anca Maniu ◽

Ioana Rusu ◽

...

Keyword(s):

Shear Wave ◽

Predictive Value ◽

Liver Diseases ◽

Venous Pressure ◽

Liver Stiffness ◽

Shear Wave Elastography ◽

Acoustic Radiation Force Impulse ◽

Two Dimensional ◽

Non Invasive ◽

Examination Technique

There has been great interest in the development of non-invasive techniques for the diagnosis of liver fibrosis in chronic liver diseases, including ultrasound elastographic methods. Some of these methods have already been adequately studied for the non-invasive assessment of diffuse liver diseases. Others, however, such as two-dimensional Shear Wave Elastography (SWE), of more recent appearance, have yet to be validated and some aspects are for the moment incompletely elucidated. This review discusses some of the aspects related to two-dimensional SWE: the examination technique, the examination performance indicators, intra and interobserver agreement and clinical applications. Recommendations for a high-quality examination technique are formulated. Key words: – – – Two-dimensional Shear Wave Elastography. Abbreviations: 2D- SWE: Two-dimensional Shear Wave Elastography; 3D- SWE: Three-dimensional Shear Wave Elastography; AUROC: area under the receiver operating characteristic curves; ARFI Acoustic Radiation Force Impulse Elastography; EFSUMB: European Federation of Societies for Ultrasound in Medicine and Biology; HVPG: hepatic venous pressure gradient; LS: liver stiffness; LR: likelihood ratio; NPV: negative predictive value; PPV: positive predictive value; ROI: region of interest; RT-E: Real Time-Elastography; Se: sensitivity; Sp: specificity; TE: Transient Elastography; US: ultrasound; VM: valid measurement; E: Young’s modulus

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