A novel ultrasound technique to study the biomechanics of the human esophagus in vivo

Abstract

The objectives of this study were to validate a novel ultrasound technique and to use it to study the circumferential stress-strain properties of the human esophagus in vivo. A manometric catheter equipped with a high-compliance bag and a high-frequency intraluminal ultrasonography probe was used to record esophageal pressure and images. Validation studies were performed in vitro followed by in vivo studies in healthy human subjects. Esophageal distensions were performed with either an isovolumic (5-20 ml of water) or with an isobaric (10-60 mmHg) technique. Sustained distension was also performed for 3 min in each subject. The circumferential wall stress and strain were calculated. In vitro studies indicate that the ultrasound technique can make measurements of the esophageal wall with an accuracy of 0.01 mm. The in vivo studies provide the necessary data to compute the Kirchhoff's stress, Green's strain, and Young's elastic modulus during esophageal distensions. The stress-strain relationship revealed a linear shape, the slope of which corresponds to the Young's modulus. During sustained distensions, we found dynamic changes of stress and strain during the period of distension. We describe and validate a novel ultrasound technique that allows measurement of biomechanical properties of the esophagus in vivo in humans.

Resolving the three-dimensional myoarchitecture of bovine esophageal wall with diffusion spectrum imaging and tractography

“…Such differences in tissue stiffness could have teleological advantages for bolus propulsion, in that more rapid clearance would be expected in the proximal (less distensible) segment of the esophagus and slower clearance would be expected in the distal (more distensible) segment of the esophagus. Previous computational (Nicosia and Brasseur 2002;Pal and Brasseur 2002) and experimental (Yang et al 2004;Fan et al 2002;Takeda et al 2002;Nicosia et al 2001) analyses of esophageal wall mechanics have focused on the relationship between applied stress and tissue distensibility (strain) and have generally assumed an explicitly orthogonal relationship between the outer and inner musculature. The generalization of our findings throughout Mammalia may allow a broad reconsideration of the way in which intraluminal mechanical Fig.…”

Dimensions and Circumferential Stress-Strain Relation in the Porcine Esophagus in Vitro Determined by Combined Impedance Planimetry and High-Frequency Ultrasound

“…Recently, ultrasound combined with manometry or impedance planimetry was used to study the biomechanical wall properties as well as the motility of human esophagus [20][21][22][23][24][25][26]. It was demonstrated that the stress-strain relationship of esophageal wall revealed a linear shape.…”

“…It was demonstrated that the stress-strain relationship of esophageal wall revealed a linear shape. The active component (muscle contraction) was different during isovolumic and isobaric distensions, but the passive components (after atropine) were similar [24,25]. However, it seems difficult to obtain more accurate stress-strain relation data in vivo because the esophageal wall connected to the surrounding organs.…”

“…The novel potential of the system is that it allows direct measurement of wall thickness; most previous studies of cylindrical organs are based on the computation of wall thickness and assume incompressibility [8,18]. Ultrasound combined with manometry or impedance was used to study the biomechanical wall properties as well as the motility of human esophagus [20][21][22][23][24][25][26]. However, in such in vivo studies it is difficult to estimate the "true" biomechanical properties such as stress-strain owing to the contribution of surrounding organs.…”

Finite element modelling of stapled colorectal end-to-end anastomosis: Advantages of variable height stapler design

“…Morphometric and mechanical properties of gastrointestinal tissues are frequently studied in rat (Duch et al, 1996;Gao and Gregersen, 2000;Jorgensen et al, 2001a;Zhao et al, 2002;Dou et al, 2003;Smith et al, 2005) or in guinea pig (Storkholm et al, 1995;Gregersen et al, 1998;Jorgensen et al, 2001b;Liao et al, 2010). Biomechanical characteristics of human gastrointestinal tract were assessed using ultrasound Palmeri et al, 2005;Takeda et al, 2002) and magnetic resonance (Frokjaer et al, 2005;Frokjaer et al, 2007).…”