Quality Control of Magnetic Resonance Elastography Using Percent Measurable Liver Volume Estimation.

Abstract

Although studies have described factors associated with failed magnetic resonance elastography (MRE), little is known about what factors influence usable elastography data. To identify factors that have a negative impact on percent measurable liver volume (pMLV), defined as the proportion of usable liver elastography data relative to the volume of imaged liver in patients undergoing MRE. Retrospective. A total of 264 patients (n=132 males, n=132 females; mean age=57 years) with suspected or known chronic liver disease underwent MRE paired with a liver protocol MRI. MRE was performed on a single 1.5 T scanner using a two-dimensional gradient-recalled echo phase-contrast sequence with a passive acoustic driver overlying the right hemiliver. Stiffness maps (usable data at 95% confidence) and liver contours on magnitude images of the MRE acquisition were manually traced and used to assess mean stiffness and pMLV. Hepatic fat fraction and R2 * values were also calculated. The distance from the acoustic wave generator on the skin surface to the liver edge was measured. Two radiologists performed the MR analyses with 50 overlapping cases for inter-reader analysis. Linear regression was performed to identify factors significantly associated with pMLV. Intraclass correlation was performed for inter-reader reliability. pMLV was 31% ± 20% (range 0%-86%). Complete MRE failure (i.e. pMLV=0%) occurred in 10 patients (4%). Multivariate linear regression identified higher hepatic fat fraction, R2 *, BMI, and driver-to-liver surface distance; male sex; and lower mean liver stiffness was significantly independently associated with lower pMLV. Intraclass correlation for pMLV was 0.96, suggestive of excellent reliability. Higher fat fraction, R2 *, BMI, driver-to-liver surface distance, male sex, and lower mean liver stiffness were associated with lower pMLV. Optimization of image acquisition parameters and driver placement may improve MRE quality, and pMLV likely serves as a diagnostic utility quality control metric. 3 TECHNICAL EFFICACY STAGE: 2.