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Session: Poster session I
Session starts: Thursday 24 January, 15:00

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L.B.H. Keijzer ()
M. Strachinaru ()
D.J. Bowen ()
M.D. Verweij ()
A.F.W. van der Steen ()
J.G. Bosch ()
N. de Jong ()
H.J. Vos ()

Abstract:
Diastolic dysfunction is an important cause of heart failure with a preserved ejection fraction, where a decreased active relaxation and/or increased passive stiffness prevent the heart to completely relax [1]. Currently, there is no accurate method for non-invasive stiffness measurements of the myocardium. However, early diagnosis is important for preventing further development of heart diseases and could likely help in accommodating more personalized treatment. Shear waves (SWs) can potentially be used to perform noninvasive stiffness measurements [2], called shear wave elastography (SWE). The propagation speed of SWs is linked to the stiffness of the medium in which the SWs propagate. This study focusses on SWs naturally induced by the aortic and mitral valve closure (AVC and MVC). For clinical diagnosis, high precision of the SWE measurements is important and therefore we tested the reproducibility in 10 healthy volunteers. Inter-system variability was researched by comparing a clinical scanner in conventional TDI mode (Philips; 490-570 Hz frame rate) with a second clinical system with a high frame rate mode using a diverging-wave pulse-inversion transmission scheme (Zonare; 1000 Hz). Furthermore, test-retest, inter-scan, intra-scan and inter-observer variability was investigated. For each volunteer, multiple measurements were performed with both systems within 30 minutes. Furthermore, these measurements were repeated 21-93 days later. Moreover, the effect of stress on the SWE measurements was tested by performing handgrip tests. With the Zonare system, propagation speeds were found to be in the range of 3.2-4.3 m/s (AVC) and 2.1-4.7 m/s (MVC). During the handgrip test, heartrates increased, but the propagation speeds did not significantly differ from the rest measurements. Test-retest variabilities were found to be in the same range as the inter-scan variabilities. The scanning-view quality, the limited length of the interventricular septum (IVS) and the variations in angle between the IVS and the probe are potential causes. With the Philips system, statistically different propagation speeds were obtained (AVC: 1.8-4.8 m/s; MVC: 3.7-6.4 m/s). These differences are likely caused by differences in methods, such as different frame rates and the methods used to determine propagation speeds. [1] M. R. Zile, et al., N. Engl. J. Med., 2004; [2] O. Villemain et al., JACC Cardiovasc. Imaging, 2018.