Conventional, breath-holding magnetic resonance imaging (MRI) assesses body composition by measuring fat volumes and proton density fat fraction (PDFF). However, breath-holding MRI is not always feasible in children. This study's objective was to use free-breathing MRI to quantify visceral and subcutaneous fat volumes and PDFFs and correlate these measurements with hepatic PDFF.
This was an observational, hypothesis-forming study that enrolled 2 groups of children (ages 6–17 years), healthy children and overweight children with presumed nonalcoholic fatty liver disease. Free-breathing MRI was used to measure visceral and subcutaneous fat volumes and PDFFs, and hepatic PDFF. Imaging biomarkers were compared between groups, and correlations coefficients (r) and coefficients of determination (R2) were calculated.
When compared with the control group (n = 10), the overweight group (n = 9) had greater mean visceral (1843 vs 329 cm3, P < 0.001) and subcutaneous fat volumes (7663 vs 893 cm3, P < 0.001), as well as greater visceral (80% vs 45%, p < 0.001) and subcutaneous fat PDFFs (89% vs 75%, P = 0.003). Visceral fat volume (r = 0.79, P < 0.001) and PDFF (r = 0.92, P < 0.001) correlated with hepatic PDFF. In overweight subjects, for each unit increase in visceral fat PDFF, hepatic PDFF increased by 2.64%; visceral fat PDFF explained 54% of hepatic PDFF variation (R2 = 0.54, P = 0.02).
In this study, we used free-breathing MRI to measure body composition in children. Future studies are needed to investigate the possible value of subcutaneous and visceral fat PDFFs, and validate free-breathing MRI body composition biomarkers.
*Division of Neonatology and Developmental Biology, Department of Pediatrics, Neonatal Research Center
†Department of Radiological Sciences
‡Physics and Biology in Medicine, Interdepartmental Program
§Division of Gastroenterology, Department of Pediatrics, David Geffen School of Medicine, University of California Los Angeles and Mattel Children's Hospital at UCLA
¶Department of Biostatistics, Fielding School of Public Health, University of California Los Angeles, Los Angeles, CA.
Address correspondence and reprint requests to Kara L. Calkins, MD, MS, 10833 Le Conte Avenue, Room B2-352 MDCC, Los Angeles, CA 90095 (e-mail: KCalkins@mednet.ucla.edu).
Received 21 December, 2017
Accepted 21 January, 2019
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Supported by the National Institutes of Health (NIH/NCATS KL2TR000122 [to K.L.C.]). Supported by University of California, Los Angeles Radiology Department Exploratory Research Grant (#16-0002 [to H.H.W. and K.L.C.]). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.
H.H.W. and T.A. receive institutional research support from Siemens Healthineers. However, Siemens did not fund or participate in this study.
The authors report no conflicts of interest