Intra- and inter-examination repeatability of magnetic resonance spectroscopy, magnitude-based MRI, and complex-based MRI for estimation of hepatic proton density fat fraction in overweight and obese children and adults.
OBJECTIVE
Determine intra- and inter-examination repeatability of magnitude-based magnetic resonance imaging (MRI-M), complex-based magnetic resonance imaging (MRI-C), and magnetic resonance spectroscopy (MRS) at 3T for estimating hepatic proton density fat fraction (PDFF), and using MRS as a reference, confirm MRI-M and MRI-C accuracy.


METHODS
Twenty-nine overweight and obese pediatric (n = 20) and adult (n = 9) subjects (23 male, 6 female) underwent three same-day 3T MR examinations. In each examination MRI-M, MRI-C, and single-voxel MRS were acquired three times. For each MRI acquisition, hepatic PDFF was estimated at the MRS voxel location. Intra- and inter-examination repeatability were assessed by computing standard deviations (SDs) and intra-class correlation coefficients (ICCs). Aggregate SD was computed for each method as the square root of the average of first repeat variances. MRI-M and MRI-C PDFF estimation accuracy was assessed using linear regression with MRS as a reference.


RESULTS
For MRI-M, MRI-C, and MRS acquisitions, respectively, mean intra-examination SDs were 0.25%, 0.42%, and 0.49%; mean intra-examination ICCs were 0.999, 0.997, and 0.995; mean inter-examination SDs were 0.42%, 0.45%, and 0.46%; and inter-examination ICCs were 0.995, 0.992, and 0.990. Aggregate SD for each method was <0.9%. Using MRS as a reference, regression slope, intercept, average bias, and R (2), respectively, for MRI-M were 0.99%, 1.73%, 1.61%, and 0.986, and for MRI-C were 0.96%, 0.43%, 0.40%, and 0.991.


CONCLUSIONS
MRI-M, MRI-C, and MRS showed high intra- and inter-examination hepatic PDFF estimation repeatability in overweight and obese subjects. Longitudinal hepatic PDFF change >1.8% (twice the maximum aggregate SD) may represent real change rather than measurement imprecision. Further research is needed to assess whether examinations performed on different days or with different MR technologists affect repeatability of MRS voxel placement and MRS-based PDFF measurements.
Liver Imaging Group, MR3T Bydder Laboratory, Department of Radiology, University of California at San Diego, 408 Dickinson Street MC 8226, San Diego, CA, 92103-8226, USA. avishkar.tyagi@gmail.com.
Avishkar
A
Tyagi
Liver Imaging Group, MR3T Bydder Laboratory, Department of Radiology, University of California at San Diego, 408 Dickinson Street MC 8226, San Diego, CA, 92103-8226, USA.
Omid
O
Yeganeh
Liver Imaging Group, MR3T Bydder Laboratory, Department of Radiology, University of California at San Diego, 408 Dickinson Street MC 8226, San Diego, CA, 92103-8226, USA.
Yakir
Y
Levin
Liver Imaging Group, MR3T Bydder Laboratory, Department of Radiology, University of California at San Diego, 408 Dickinson Street MC 8226, San Diego, CA, 92103-8226, USA.
Jonathan C
JC
Hooker
Liver Imaging Group, MR3T Bydder Laboratory, Department of Radiology, University of California at San Diego, 408 Dickinson Street MC 8226, San Diego, CA, 92103-8226, USA.
Gavin C
GC
Hamilton
Computational and Applied Statistics Laboratory (CASL), SDSC - University of California, San Diego, La Jolla, CA, USA.
Tanya
T
Wolfson
Computational and Applied Statistics Laboratory (CASL), SDSC - University of California, San Diego, La Jolla, CA, USA.
Anthony
A
Gamst
Liver Imaging Group, MR3T Bydder Laboratory, Department of Radiology, University of California at San Diego, 408 Dickinson Street MC 8226, San Diego, CA, 92103-8226, USA.
Amir K
AK
Zand
Liver Imaging Group, MR3T Bydder Laboratory, Department of Radiology, University of California at San Diego, 408 Dickinson Street MC 8226, San Diego, CA, 92103-8226, USA.
Elhamy
E
Heba
Division of Gastroenterology, Department of Medicine, University of California at San Diego, La Jolla, CA, USA.|Division of Epidemiology, Department of Family Medicine and Preventive Medicine, University of California at San Diego, La Jolla, CA, USA.
Rohit
R
Loomba
Liver Imaging Group, MR3T Bydder Laboratory, Department of Radiology, University of California at San Diego, 408 Dickinson Street MC 8226, San Diego, CA, 92103-8226, USA.|Division of Pediatric Gastroenterology, Department of Pediatrics, Hepatology, and Nutrition, University of California at San Diego, San Diego, CA, USA.|Department of Gastroenterology, Rady Children's Hospital, San Diego, CA, USA.
Jeffrey
J
Schwimmer
Liver Imaging Group, MR3T Bydder Laboratory, Department of Radiology, University of California at San Diego, 408 Dickinson Street MC 8226, San Diego, CA, 92103-8226, USA.
Michael S
MS
Middleton
Liver Imaging Group, MR3T Bydder Laboratory, Department of Radiology, University of California at San Diego, 408 Dickinson Street MC 8226, San Diego, CA, 92103-8226, USA. csirlin@ucsd.edu.
Claude B
CB
Sirlin
D000293:Adolescent; D000328:Adult; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008099:Liver / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D065626:Non-alcoholic Fatty Liver Disease / Q000473:pathology*; D050177:Overweight / Q000473:pathology*; D063766:Pediatric Obesity / Q000473:pathology; D011446:Prospective Studies; D011522:Protons; D015203:Reproducibility of Results
D011522:Protons
Complex-based MRI; Hepatic steatosis; Inter-examination repeatability; Intra-examination repeatability; Magnetic resonance spectroscopy; Magnitude-based MRI; Obesity; PDFF; Proton density fat fraction; Quantitative imaging biomarkers