Measurement of liver stiffness with two imaging techniques: magnetic resonance elastography and ultrasound elastometry

Purpose: To cross-validate the magnetic resonance elastography (MRE) technique with a clinical device, based on an ultrasound elastometry system called Fibroscan.

Materials and methods: Ten healthy subjects underwent an MRE and a Fibroscan test. The MRE technique used a round pneumatic driver at 60 Hz to generate shear waves inside the liver. An elastogram representing a map of the liver stiffness was generated allowing for the measurement of the average liver stiffness inside a region of interest. The Fibroscan technique used an ultrasound probe (3.5 MHz) composed of a vibrator that sent low-frequency (50 Hz) shear waves inside the right liver lobe. The probe acts as an emitter-receptor that measures the velocity of the waves propagated inside the liver tissue.

Results: The mean shear stiffness measured with the MRE and Fibroscan techniques were 1.95+/-0.06 kPa and 1.79+/-0.30 kPa, respectively. A higher standard deviation was found for the same subject with Fibroscan.

Conclusion: This study shows why MRE should be investigated beyond the Fibroscan. The MRE technique provided elasticity of the entire liver, meanwhile the Fibroscan provided values of elasticity locally.