Cross-validation of MR elastography and ultrasound transient elastography in liver stiffness measurement: discrepancy in the results of cirrhotic liver.

PURPOSE: To evaluate individual differences in liver stiffness measurement using both MR elastography (MRE) and ultrasound transient elastography (UTE) in patients with chronic liver disease.
MATERIALS AND METHODS: This study included 80 patients with chronic liver disease who underwent both UTE and MRE. MRE and UTE were performed using a pneumatic driver (60 Hz) and an ultrasound probe with a vibrator (50 Hz), respectively. Liver stiffness data measured using the two techniques (μ(UTE) and μ(MRE) ) were compared with respect to shear modulus. The patients were subdivided into four quartiles on the basis of average of the μ(UTE) and μ(MRE) values for each patient.
RESULTS: The analysis of the 4 quartile groups revealed that μ(UTE) was significantly higher than μ(MRE) in the two most stiff liver groups: μ(UTE) versus μ(MRE) , 7.5 (1.2) versus 6.0 (0.72) kPa for the group with [μ(UTE) + μ(MRE) ]/2 of 5.6-8.0 kPa; 15.1(4.2) versus 6.7 (1.4) kPa for the group with >8.0 kPa. However, in the least stiff liver group (i.e., the group with [μ(UTE) + μ(MRE) ]/2 < 3.2 kPa), μ(UTE) was significantly lower than μ(MRE) .
CONCLUSION: The shear modulus measured by UTE and MRE are not equivalent, especially in patients with stiff livers.