Effects of Confounding Factors on Liver Stiffness in Two-Dimensional Shear Wave Elastography in Beagle Dogs

Abstract

BackgroundTwo-dimensional shear wave elastography (2D-SWE) is a powerful technique that can non-invasively measure liver stiffness to assess hepatic fibrosis.PurposeThis study aimed to identify the effects of confounding factors, including anesthesia, breathing, and scanning approach, on liver stiffness when performing 2D-SWE in dogs.Materials and MethodsNine healthy Beagle dogs were included in this study. Hepatic 2D-SWE was performed, and liver stiffness was compared between conscious and anesthetized states, free-breathing and breath-holding conditions, and intercostal and subcostal approaches. For the anesthetized state, the breath-holding condition was subdivided into seven phases, which included forced-expiration (5 and 10 mL/kg), end-expiration (0 cm H2O), and forced-inspiration (5, 10, 15, and 20 cm H2O), and liver stiffness was compared among these phases. Changes in liver stiffness were compared between intercostal and subcostal approaches according to breathing phases.ResultsNo significant difference was observed in liver stiffness between the conscious and anesthetized states or between the free-breathing and breath-holding conditions. No significant difference was noted in liver stiffness among the breathing phases, except for forced-inspiration with high airway pressure (15 and 20 cm H2O in the intercostal approach and 10, 15, and 20 cm H2O in the subcostal approach), which was associated with significantly higher liver stiffness (p < 0.05). Liver stiffness was significantly higher in the subcostal approach than in the intercostal approach (p < 0.05). Changes in liver stiffness were significantly higher in the subcostal approach than in the intercostal approach in all forced-inspiratory phases (p < 0.05).ConclusionIn conclusion, when performing 2D-SWE in dogs, liver stiffness is unaffected by anesthesia and free-breathing. To avoid inadvertent increases in liver stiffness, the deep inspiratory phase and subcostal approach are not recommended. Thus, liver stiffness should be interpreted considering these confounding factors.

Evaluation of liver stiffness in a population of client owned healthy dogs using two-dimensional shear wave elastography: intraobserver reliability

“…The results of the present study could not identify any statistically significant effect of sex on the SWV (P=0.39). Other canine studies (Cha et al, 2022;Jung et al, 2020;Tamura, Ohta, Nisa, et al, 2019) also failed to find an association with gender. However, the number of dogs in Holdsworth's et al study (2014) was small, and the difference could have resulted from the small sample size leading to type I error or natural variation between individuals.…”

“…The appeal to use the non-invasive 2D SWE technique in veterinary medicine is clear; but similarly to human medicine, the impact of technical and patientrelated confounders have been conflicting (Cha et al, 2022;Facin et al, 2020;Holdsworth et al, 2014;Jung et al, 2020;K. Kim et al, 2020;Tamura, Ohta, Nisa, et al, 2019;Tamura, Ohta, Shimbo, et al, 2019) regarding approach (intercostal versus subxiphoidal), depth of ROI placement, breathing phase versus sedation/anesthesia, sex and body weight.…”

“…Liver biopsy is an invasive technique associated with possible complications such as anesthetic risk, hemorrhage, air-embolism and vagotonic shock, and sampling errors can occur due to the variability in disease presence and/or severity in different parts of the liver (Bedossa et al, 2003;Cole et al, 2002;Kemp et al, 2015;Lidbury, 2017). In recent years, liver elastography has been researched in veterinary medicine (Cha et al, 2022;Holdsworth et al, 2014;Jung et al, 2020;K. Kim et al, 2020;Park et al, 2021;Tamura et al, 2021;Tamura, Ohta, Nisa, et al, 2019;Tamura, Ohta, Shimbo, et al, 2019), as studies in human medicine have shown promise of this non-invasive elastography method in both the diagnosis and monitoring of liver pathologies (Dietrich et al, 2017;Feng et al, 2016;Sigrist et al, 2017).…”

“…Therefore, specific guidelines and recommendations by EFSUMB (European Federation of Societies for Ultrasound in Medicine and Biology) have been implemented for performing elastography studies in human patients (Dietrich et al, 2017). In recent years, several veterinary studies have been published pertaining to liver elastography of both normal dogs (Cha et al, 2022;Holdsworth et al, 2014;Jeon et al, 2015;Jung et al, 2020;Kim et al, 2020;Tamura, Ohta, Nisa, et al, 2019;White et al, 2014) and dogs with various pathological hepatobiliary diseases (Facin et al, 2020;Feng et al, 2016;Huaijantug et al, 2020;Tamura et al, 2021;Tamura, Ohta, Shimbo, et al, 2019). However, many of these above-mentioned studies have been performed on a small number of purpose-bred research colony dogs, specific population groups (e.g.…”

Shear wave elastography measurements in dogs treated surgically for congenital extrahepatic portosystemic shunts

“…In human medicine, the intercostal approach is recommended as the highest intra–and interobserver agreement was obtained through that approach ( 20 ). One veterinary study in healthy Beagle dogs also showed a difference in liver elastography measurements according to approach ( 46 ), whereas another study with healthy Beagles did not find any correlation ( 25 ). Comparison of the outcomes between different studies is hindered as explained before; furthermore, while our method of recording velocities differentiates average, median, and maximum results, it is often not specified how the mean elastographic velocities in other studies are derived.…”