Assessment of a high-SNR chemical-shift-encoded MRI with complex reconstruction for proton density fat fraction (PDFF) estimation overall and in the low-fat range

J Magn Reson Imaging. 2019 Jan;49(1):229-238. doi: 10.1002/jmri.26168. Epub 2018 Apr 29.

Abstract

Background: Improving the signal-to-noise ratio (SNR) of chemical-shift-encoded MRI acquisition with complex reconstruction (MRI-C) may improve the accuracy and precision of noninvasive proton density fat fraction (PDFF) quantification in patients with hepatic steatosis.

Purpose: To assess the accuracy of high SNR (Hi-SNR) MRI-C versus standard MRI-C acquisition to estimate hepatic PDFF in adult and pediatric nonalcoholic fatty liver disease (NAFLD) using an MR spectroscopy (MRS) sequence as the reference standard.

Study type: Prospective.

Population/subjects: In all, 231 adult and pediatric patients with known or suspected NAFLD.

Field strength/sequence: PDFF estimated at 3T by three MR techniques: standard MRI-C; a Hi-SNR MRI-C variant with increased slice thickness, decreased matrix size, and no parallel imaging; and MRS (reference standard).

Assessment: MRI-PDFF was measured by image analysts using a region of interest coregistered with the MRS-PDFF voxel.

Statistical tests: Linear regression analyses were used to assess accuracy and precision of MRI-estimated PDFF for MRS-PDFF as a function of MRI-PDFF using the standard and Hi-SNR MRI-C for all patients and for patients with MRS-PDFF <10%.

Results: In all, 271 exams from 231 patients were included (mean MRS-PDFF: 12.6% [SD: 10.4]; range: 0.9-41.9). High agreement between MRI-PDFF and MRS-PDFF was demonstrated across the overall range of PDFF, with a regression slope of 1.035 for the standard MRI-C and 1.008 for Hi-SNR MRI-C. Hi-SNR MRI-C, compared to standard MRI-C, provided small but statistically significant improvements in the slope (respectively, 1.008 vs. 1.035, P = 0.004) and mean bias (0.412 vs. 0.673, P < 0.0001) overall. In the low-fat patients only, Hi-SNR MRI-C provided improvements in the slope (1.058 vs. 1.190, P = 0.002), mean bias (0.168 vs. 0.368, P = 0.007), intercept (-0.153 vs. -0.796, P < 0.0001), and borderline improvement in the R2 (0.888 vs. 0.813, P = 0.01).

Data conclusion: Compared to standard MRI-C, Hi-SNR MRI-C provides slightly higher MRI-PDFF estimation accuracy across the overall range of PDFF and improves both accuracy and precision in the low PDFF range.

Level of evidence: 1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;49:229-238.

Keywords: Hi-SNR; MRI-C; MRS; PDFF; accuracy; hepatic steatosis; optimization; proton density fat fraction; quantitative imaging biomarker.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adipose Tissue / diagnostic imaging*
  • Adolescent
  • Adult
  • Aged
  • Child
  • Constriction, Pathologic / diagnostic imaging*
  • Cross-Sectional Studies
  • Female
  • Humans
  • Image Processing, Computer-Assisted
  • Liver / diagnostic imaging*
  • Magnetic Resonance Imaging*
  • Magnetic Resonance Spectroscopy*
  • Male
  • Middle Aged
  • Non-alcoholic Fatty Liver Disease / diagnostic imaging*
  • Prospective Studies
  • Protons
  • Reference Standards
  • Regression Analysis
  • Reproducibility of Results
  • Signal-To-Noise Ratio*
  • Young Adult

Substances

  • Protons