Introduction: The mechanical properties of liver are known to change with disease1,2,3 and other factors. For example, liver stiffness measured by transient elastography was reported to be higher at expiration than during inspiration in patients with liver cirrhosis due to increased intrahepatic blood volume4 . Magnetic Resonance Elastography (MRE) has also been used to measure liver stiffness in clinical populations but whether liver compression due to respiration in MRE causes bias in measurements is not known. In this study, we aim to understand whether the effects of respiration should be considered when measuring liver stiffness using MRE.
Methods: The effect of respiration on the elastic (G’) and viscous (G”) components of the shear modulus of the liver was assessed using MRE in seven healthy female volunteers, (27±5.2) years with no history of liver or respiratory disease. MRE parameters were: 56 Hz vibration frequency; TR/TE 75.9/6.91ms; matrix = 64 x 64, FOV 220 mm, and slice thickness 10 mm. Matching T2-weighted anatomical imaging sequences were acquired at end-inspiration (maximal liver compression), and at end-expiration (minimal liver compression).
Results: No differences were seen in either the elastic or viscous components of the liver shear modulus between measurements taken at end-inspiration and end-expiration (p >0.05, Student’s t-Test).
Conclusion: The results of this study show that the mechanical properties of liver as measured by MRE are not affected by liver compression during respiration. Our results are different to the aforementioned study in which liver stiffness was increased at end-expiration compared with inspiration among chronic liver patients4 .