Monitoring Liver Stiffness Changes during Controlled Hyperthermia and Microwave Ablation Using Point Shear-Wave Elastography.

Abstract

HomeRadiology: Imaging CancerVol. 1, No. 2 Previous Research HighlightsFree AccessMonitoring Liver Stiffness Changes during Controlled Hyperthermia and Microwave Ablation Using Point Shear-Wave ElastographyLuke WilkinsLuke WilkinsLuke WilkinsPublished Online:Nov 29 2019https://doi.org/10.1148/rycan.2019194013MoreSectionsPDF ToolsImage ViewerAdd to favoritesCiteTrack CitationsPermissionsReprints ShareShare onFacebookTwitterLinked InEmail Take-Away Points■ Major focus: To investigate the changes in liver stiffness following controlled hyperthermia and microwave ablation in an ex vivo bovine model using point shear-wave elastography.■ Key result: Point shear-wave elastography can provide an elasticity threshold predictive of coagulative necrosis development during microwave ablation in an ex vivo liver model.■ Impact: While there are current limitations, there are opportunities for incorporation of more advanced, real-time imaging techniques to more accurately predict zones of coagulative necrosis in tumor ablation.Noninvasive monitoring of thermal ablation can greatly decrease the risk of complications while ensuring treatment efficacy. While some thermal ablation systems have the capacity to provide real-time temperature feedback, it is typically restricted to the temperature at the device level and does not provide information on tissue temperature within the remainder of the treatment cavity. Crocetti et al explore the use of elastography as a potential method to provide real-time temperature monitoring.There are several US elastographic techniques. In point shear-wave elastography (pSWE), an acoustic radiation force is induced within the tissue. The disturbance created within the tissue moves through the tissue as a shear wave. By monitoring the corresponding tissue displacements created by the shear wave under B-mode imaging, inferences can be made regarding the stiffness of the underlying tissue. This is important for thermal ablation as it is well-known that coagulation (protein denaturation and tissue dehydration) occurs at 60°C. However, the effect of thermal-induced changes in the mechanical properties of the liver tissue has not yet been fully investigated. This article sought to investigate the changes in liver stiffness in controlled hyperthermia and microwave ablation (MWA) in an ex vivo animal model.The authors used five samples of ex vivo bovine liver that were uniformly heated to temperatures ranging from 40 to 100°C. B-mode US imaging and pSWE were then performed simultaneously. In addition, MWA was performed in 11 liver samples at 60 W. Shear wave velocity (SWV) was then measured in the regions of interest (ROIs) at 10–40 mm from the antenna. Histopathologic examination was performed to correlate mean values of SWV to treatment associated changes (within, border, or outside necrotic area). The article reports that a steep transition in liver stiffness was observed at 63.0°C ± 2.4. Through this first phase of experiments, the authors determined that the mean SWV at 60°C was 2.5 m/sec (defined as Avg60). For the next set of experiments, the threshold was defined as Avg60 + 0.5 m/sec or 3 m/sec. Eight of nine experiments showed that following stoppage of ablation when the predetermined ROI reached threshold SWV of 3 m/sec, the ROI was within the necrotic area at histologic examination. While this is notable, there was no correlation between SWV values for outside, border, and within necrosis. This markedly limits current clinical applicability of this technology. Future research may allow more accurate methods for detecting changes in tissue stiffness that would be able to predict tissue still outside the necrotic zone.Highlighted ArticleCrocetti L, Calcagni F, Gherarducci G, et al. Monitoring of thermal-induced changes in liver stiffness during controlled hyperthermia and microwave ablation in an ex vivo bovine model using point shear wave elastography. Cardiovasc Interv Radiol 2019;42(5):744–750. doi: https://doi.org/10.1007/s00270-018-02152-yHighlighted ArticleCrocetti L, Calcagni F, Gherarducci G, et al. Monitoring of thermal-induced changes in liver stiffness during controlled hyperthermia and microwave ablation in an ex vivo bovine model using point shear wave elastography. Cardiovasc Interv Radiol 2019;42(5):744–750. doi: https://doi.org/10.1007/s00270-018-02152-y Crossref, Medline, Google ScholarArticle HistoryPublished online: Nov 29 2019 FiguresReferencesRelatedDetailsCited ByRecommended Articles Elastography in Chronic Liver Disease: Modalities, Techniques, Limitations, and Future DirectionsRadioGraphics2016Volume: 36Issue: 7pp. 1987-2006US Elastography in Hepatic Fibrosis—Radiology In TrainingRadiology2021Volume: 299Issue: 2pp. 264-271Quantitative Elastography Methods in Liver Disease: Current Evidence and Future DirectionsRadiology2018Volume: 286Issue: 3pp. 738-763US Time-Harmonic Elastography: Detection of Liver Fibrosis in Adolescents with Extreme Obesity with Nonalcoholic Fatty Liver DiseaseRadiology2018Volume: 288Issue: 1pp. 99-106Update to the Society of Radiologists in Ultrasound Liver Elastography Consensus StatementRadiology2020Volume: 296Issue: 2pp. 263-274See More RSNA Education Exhibits Ultrasound Elastography Methods: Physical Principles, Techniques, and IndicationsDigital Posters2018Spleen Elastography and Portal Hypertension: An Overview and the Nitty-GrittiesDigital Posters2018Ultrasound Elastography in Children: How We Do it and What is it Helpful For?Digital Posters2019 RSNA Case Collection Hepatic AdenomatosisRSNA Case Collection2021 Cholecystitis and CholedocholithiasisRSNA Case Collection2020Radioembolization of Liver Metastasis RSNA Case Collection2020 Vol. 1, No. 2 Metrics Downloaded 178 times Altmetric Score PDF download