Besa, Cecilia

Objective The aim of this study was to compare 2-dimensional (2D) gradient recalled echo (GRE) and 2D spin echo echoplanar imaging (SE-EPI) magnetic resonance elastography (MRE) sequences of the liver in terms of image quality and quantitative liver stiffness (LS) measurement. Materials and Methods This prospective study involved 50 consecutive subjects (male/female, 33/17; mean age, 58 years) who underwent liver magnetic resonance imaging at 3.0 T including 2 MRE sequences, 2D GRE, and 2D SE-EPI (acquisition time 56 vs 16 seconds, respectively). Image quality scores were assessed by 2 independent observers based on wave propagation and organ coverage on the confidence map (range, 0–15). A third observer measured LS on stiffness maps (in kilopascal). Mean LS values, regions of interest size (based on confidence map), and image quality scores between SE-EPI and GRE-MRE were compared using paired nonparametric Wilcoxon test. Reproducibility of LS values between the 2 sequences was assessed using intraclass coefficient correlation, coefficient of variation, and Bland-Altman limits of agreement. T2* effect on image quality was assessed using partial Spearman correlation. Results There were 4 cases of failure with GRE-MRE and none with SE-EPI-MRE. Image quality scores and region of interest size were significantly higher using SE-EPI-MRE versus GRE-MRE (P < 0.0001 for both measurements and observers). Liver stiffness measurements were not significantly different between the 2 sequences (3.75 ± 1.87 kPa vs 3.55 ± 1.51 kPa, P = 0.062), were significantly correlated (intraclass coefficient correlation, 0.909), and had excellent reproducibility (coefficient of variation, 10.2%; bias, 0.023; Bland-Altman limits of agreement, −1.19; 1.66 kPa). Image quality scores using GRE-MRE were significantly correlated with T2* while there was no correlation for SE-EPI-MRE. Conclusions Our data suggest that SE-EPI-MRE may be a better alternative to GRE-MRE. The diagnostic performance of SE-EPI-MRE for detection of liver fibrosis needs to be assessed in a future study.

PurposeTo assess interplatform reproducibility of liver stiffness (LS) and spleen stiffness (SS) measured with magnetic resonance elastography (MRE) based on a 2D gradient echo (GRE) sequence.Materials and MethodsThis prospective Health Insurance Portability and Accountability Act (HIPAA)‐compliant and Institutional Review Board (IRB)‐approved study involved 12 subjects (five healthy volunteers and seven patients with liver disease). A multislice 2D‐GRE‐based MRE sequence was performed using two systems from different vendors (3.0T GE and 1.5T Siemens) on the same day. Two independent observers measured LS and SS on confidence maps. Bland–Altman analysis (with coefficient of reproducibility, CR), coefficient of variability (CV), and intraclass correlation (ICC) were used to analyze interplatform, intra‐ and interobserver variability. Human data were validated using a gelatin‐based phantom.ResultsThere was excellent reproducibility of phantom stiffness measurement (CV 4.4%). Mean LS values were 3.44–3.48 kPa and 3.62–3.63 kPa, and mean SS values were 7.54–7.91 kPa and 8.40–8.85 kPa at 3.0T and 1.5T for observers 1 and 2, respectively. The mean CVs between platforms were 9.2%–11.5% and 13.1%–14.4% for LS and SS, respectively, for observers 1 and 2. There was excellent interplatform reproducibility (ICC >0.88 and CR <36.2%) for both LS and SS, and excellent intra‐ and interobserver reproducibility (intraobserver: ICC >0.99, CV <2.1%, CR <6.6%; interobserver: ICC >0.97, CV and CR <16%).ConclusionThis study demonstrates that 2D‐GRE MRE provides platform‐ and observer‐independent LS and SS measurements. J. Magn. Reson. Imaging 2016;43:1064–1072.