Valsalva Maneuver Decreases Liver and Spleen Stiffness Measured by Time-Harmonic Ultrasound Elastography

Abstract

Ultrasound elastography quantitatively measures tissue stiffness and is widely used in clinical practice to diagnose various diseases including liver fibrosis and portal hypertension. The stiffness of soft organs has been shown to be sensitive to blood flow and pressure-related diseases such as portal hypertension. Because of the intricate coupling between tissue stiffness of abdominal organs and perfusion-related factors such as vascular stiffness or blood volume, simple breathing maneuvers have altered the results of liver elastography, while other organs such as the spleen are understudied. Therefore, we investigated the effect of a standardized Valsalva maneuver on liver stiffness and, for the first time, on spleen stiffness using time-harmonic elastography (THE). THE acquires full-field-of-view stiffness maps based on shear wave speed (SWS), covers deep tissues, and is potentially sensitive to SWS changes induced by altered abdominal pressure in the hepatosplenic system. SWS of the liver and the spleen was measured in 17 healthy volunteers under baseline conditions and during the Valsalva maneuver. With the Valsalva maneuver, SWS in the liver decreased by 2.2% (from a median of 1.36 m/s to 1.32 m/s; p = 0.021), while SWS in the spleen decreased by 5.2% (from a median of 1.63 m/s to 1.51 m/s; p = 0.00059). Furthermore, we observed that the decrease was more pronounced the higher the baseline SWS values were. In conclusion, the results confirm our hypothesis that the Valsalva maneuver decreases liver and spleen stiffness, showing that THE is sensitive to perfusion pressure-related changes in tissue stiffness. With its extensive organ coverage and high penetration depth, THE may facilitate translation of pressure-sensitive ultrasound elastography into clinical routine.

Rapid MR elastography of the liver for subsecond stiffness sampling

“…47,48 Furthermore, a higher intra-abdominal pressure as generated by the Valsalva maneuver can lead to a collapse of hepatic veins and overall reduction of liver perfusion, resulting in hepatic softening. 7,8 Conversely and in agreement with previous studies, 18,19 our results at end-inspiration suggest that preserved hepatic flow in the presence of elevated intra-abdominal pressure leads to higher stiffness values. Although these results provide strong evidence for hepatohemodynamic effects on tissue stiffness, they are correlative and not causal.…”

“…This notion was supported by the observation that liver stiffness was higher after ingestion of water, 12,13 whereas relief of high portal pressure by shunting was reported to cause a decrease in stiffness 47,48 . Furthermore, a higher intra‐abdominal pressure as generated by the Valsalva maneuver can lead to a collapse of hepatic veins and overall reduction of liver perfusion, resulting in hepatic softening 7,8 . Conversely and in agreement with previous studies, 18,19 our results at end‐inspiration suggest that preserved hepatic flow in the presence of elevated intra‐abdominal pressure leads to higher stiffness values.…”

“…THE of the liver was performed, as described in Ref. 8, once during an end‐inspiratory breath‐hold and once during an end‐expiratory breath‐hold. In brief, the subjects were positioned supine on a bed with an integrated vibration generator.…”

“…(ii) Studies of the effect of breathing on liver stiffness, 16 including assessment of liver physiology and hemodynamics based on stiffness changes, would be greatly facilitated without the need for resynchronizing MRE acquisition to physiological maneuvers. Published studies found liver stiffness measured by rapid ultrasound elastography to be sensitive to the increase in intra‐abdominal pressure induced by forced breathing during the Valsalva maneuver 7,8,17 . Previous MRE studies reported significant differences in liver stiffness between inspiration and expiration with higher values during inspiration 18 and increasing differences in patients with fibrosis, 19 motivating the development and use of subsecond MRE for measuring stiffness during free‐breathing stiffness measurement.…”

On the relationship between metabolic capacities and in vivo viscoelastic properties of the liver

“…Liver fibrosis increases liver stiffness through accumulation and cross-linking of matrix proteins ( Huwart et al, 2008 ; Singh et al, 2015 ; Reiter et al, 2020 ). However, beyond fibrosis, the liver’s biomechanical properties are also affected by non-fibrotic alterations such as prandial states ( Yin et al, 2011 ; Jajamovich et al, 2014 ; Petzold et al, 2019 ; Obrzut et al, 2021 ), hydration ( Ipek-Ugay et al, 2016 ; Dittmann et al, 2017 ), blood perfusion ( Ipek-Ugay et al, 2016 ; Meyer et al, 2022a ), cell hypertrophy ( Garczyńska et al, 2020 ), fat accumulation ( Hudert et al, 2019 ) or inflammation ( Qu et al, 2021 ; Selvaraj et al, 2021 ), making elastography unspecifically sensitive to a variety of pathophysiological processes that occur in the course of NAFLD. Only little is known about the correlation between liver biomechanical parameters and liver metabolism.…”