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Approche évaluative des effets physiques de l'élastographie par ondes de cisaillement en vue de son application clinique pendant la grossesse

Abstract : Shear wave elastography (SWE) is an ultrasound technique used to measure in vivo the elastic properties of tissues. The area of application of this mode is widespread and has proved its relevance in several areas, but it does not include the obstetrical field regardless of its potential clinical interest. This thesis research is part of the evaluation of the health effects of SWE in the field of perinatal care. It is based on two published articles and one article submitted in international peer-reviewed journals. First, a review of the scientific literature described the fundamental physical principles of ultrasound, the different variants of elastographic methods, and especially, the SWE technique developed by Supersonic Imagine (SSI), the CHU Estaing in Clermont Ferrand having acquired an ultrasound scanner from this brand (AIXPLORER® model). In the second part, using the Quantitative Health Risk Assessment method (QHRA method), we reviewed the literature with a view to identifying the health effects and risks of ultrasound associates in general and more specifically those related to the use of elastography techniques on the foetus[Article 1]. Two biological effects of ultrasound were identified: a mechanical effect and a thermal effect. The energetic radiation of the push wave being identified as the potential risk factor. In a third part, we initiated the ELASTORISK-I study to evaluate the thermal effect of this elastographic technique. As this study was ethically unthinkable in human fetuses, it was carried out in two parts: a study on a porcine biological tissue [Article 2] and then on a homogeneous physical phantom (Casper-1) representative of the fetal tissues [Article 3].The first part of ELASTORISK-I (article 2, chapter 3) is a comparative measurement by infrared camera, using identical experimental conditions, of the heating related to ultrasound techniques (SWE, pulsed Doppler and B-mode) on a biological tissue of a porcine. The objective was to quantify this heating and to demonstrate the interest and relevance of infrared thermography, which is a non-invasive technique for measuring surface temperature in the full field. This study shows that infrared thermography could be an experimental approach complementary to the thermocouples that are currently the reference. The results demonstrate that the most significant warm-up is associated with SWE.The second part of ELATORISK-I (article 3, chapter 4) is in the continuation of our reflection on the quantification and evaluation, in a comparative approach, of the heating related to the different ultrasound modalities (SWE, pulsed Doppler and mode-B) by using thermocouples placed in a phantom imitating human tissue (Casper-1). These results confirm the data obtained in thermography. This study has provided us with knowledge about the biological effects of SWE use and has helped to initiate debate within the scientific community about the potential health risks of SWE use in fetal imaging. It opens the field to other experiments, in particular by heterogeneous phantom combining bone (casper-2) and encourages the investigation of mechanical effects (displacements created by the "push" wave =
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  • HAL Id : tel-03092258, version 1

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Maha Issaoui. Approche évaluative des effets physiques de l'élastographie par ondes de cisaillement en vue de son application clinique pendant la grossesse. Médecine humaine et pathologie. Université Clermont Auvergne, 2019. Français. ⟨NNT : 2019CLFAS022⟩. ⟨tel-03092258⟩

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