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

Abstract

The liver is the central metabolic organ. It constantly adapts its metabolic capacity to current physiological requirements. However, the relationship between tissue structure and hepatic function is incompletely understood; this results in a lack of diagnostic markers in medical imaging that can provide information about the liver’s metabolic capacity. Therefore, using normal rabbit livers, we combined magnetic resonance elastography (MRE) with proteomics-based kinetic modeling of central liver metabolism to investigate the potential role of MRE for predicting the liver’s metabolic function in vivo. Nineteen New Zealand white rabbits were investigated by multifrequency MRE and positron emission tomography (PET). This yielded maps of shear wave speed (SWS), penetration rate (PR) and standardized uptake value (SUV). Proteomic analysis was performed after the scans. Hepatic metabolic functions were assessed on the basis of the HEPATOKIN1 model in combination with a model of hepatic lipid-droplet metabolism using liquid chromatography–mass spectrometry. Our results showed marked differences between individual livers in both metabolic functions and stiffness properties, though not in SUV. When livers were divided into ‘stiff’ and ‘soft’ subgroups (cutoff SWS = 1.6 m/s), stiff livers showed a lower capacity for triacylglycerol storage, while at the same time showing an increased capacity for gluconeogenesis and cholesterol synthesis. Furthermore, SWS was correlated with gluconeogenesis and PR with urea production and glutamine exchange. In conclusion, our study indicates a close relationship between the viscoelastic properties of the liver and metabolic function. This could be used in future studies to predict non-invasively the functional reserve capacity of the liver in patients.

Rapid MR elastography of the liver for subsecond stiffness sampling

“…Beyond blood perfusion, other factors such as geometric deformation with compression stiffening 49 or changes in the metabolic state of hepatocytes might dynamically alter liver stiffness. 50 In any case, by measuring dynamic changes in tissue stiffness, the proposed rapid MRE sequence could open a window into the study of relationships between biomechanics and function/perfusion properties of abdominal tissues, similar to what has recently been reported for other tissues and organs such as the lower extremities 23 or the brain. 24 Our study has limitations.…”

“…In brief, the subjects were positioned supine on a bed with an integrated vibration generator. A multifrequency waveform of six frequencies (27,33,39,44,50,56 Hz) was used for continuous mechanical excitation. Anatomy and motion were detected by a commercial elastography system (GAMPT mbH, Merseburg, Germany) using a curved-array C5-H2 transducer at 2 MHz.…”

Therapeutic effects of lincomycin and level of drug degradation in broiler tissues after treatment

“…A study of liver metabolism showed a correlation between liver viscoelastic properties and metabolism function. Alterations in blood flow and drug interactions prompt adaptation of liver function [ 23 ].…”