Emily Etchell1, Lauriane Jugé 1,2, Alice Hatt1, Ralph Sinkus3, and Lynne E. Bilston1,4
1Neuroscience Research Australia, Randwick, NSW, Australia, 2School of Medical Sciences, University of New South Wales, Kensington, NSW, Australia, 3BHF Centre of Excellence, Division of Imaging Sciences and Biomedical Engineering, King's College London, London, United Kingdom, 4Prince of Wales Clinical School, University of New South Wales, Kensington, NSW, Australia
Synopsis
Magnetic resonance (MR)
elastography provides clinical information for chronic hepatic disorders by
quantifying an increase in liver stiffness compared to heathy baseline values. Thus
far however, baseline stiffness values have only been reported for adults. We
aimed to fill this gap by quantifying healthy liver stiffness of children and
adolescents. Results showed that pediatric liver
stiffness increases with age during normal development, approaching adult
values during adolescence. This implies that comparing pediatric liver
stiffness measurements to adult baseline values when using MR elastography may
miss disease or underestimate disease severity.Introduction
Magnetic resonance (MR) elastography is capable
of non-invasively measuring mechanical properties of liver and provides
clinically useful information for chronic hepatic disorders in adults
1-5. Such a technique
could also be useful for hepatic disorders that occur in childhood, such as seen in recent studies
6-9. However, none of
these studies have reported data for healthy pediatric liver to which
pathological liver stiffness can be compared; even though differences between
adult and pediatric mechanical properties of other soft tissues have been
reported, e.g. in muscle
10 and brain
11. We aimed to measure
the mechanical properties of liver in healthy pediatric and adult participants
using MR elastography to test the hypothesis that pediatric liver stiffness
differs from adults and changes during maturation.
Methods
This study was approved by the local human
research ethics committee and adheres to the Declaration of Helsinki. MR elastography
at 28, 56 and 84Hz was performed on a 3-T scanner (Philips AchievaTX) to
measure liver shear moduli (G*) of 13 heathy children aged from 5 to 14 years (7
males, BMI 18 ± 2 kg/m
2), 11 healthy adolescents aged from 15 to 18
years (6 males, BMI 21 ± 2 kg/m
2), and 10 healthy adults aged from
22 to 36 years (5 males, BMI 24 ± 2 kg/m
2). Mean and standard deviation were calculated for G* at
28, 56 and 84 Hz, and the frequency dependence of G*. All variables were compared
between groups using ANOVA test
followed by a Tukey’s multiple comparison test.
Results
Liver G* in children and adolescents was
significantly lower than in adults at 56 Hz and 84 Hz but not at 28 Hz (ANOVA, P=0.009,
P=0.0003, P=0.40 respectively, Fig. 1 from A to C). G* varied less with
frequency in children and adolescents than adults (ANOVA, P=0.0009, Fig 1D).
Conclusions
Liver stiffness in children as measured by MR
elastography was lower than in adults, with greater differences at higher
frequencies, and stiffness increases with age during normal development,
approaching adult values during adolescence.
Clinical implications
Given that heathy pediatric liver stiffness is
lower than in adults, comparing the liver stiffness of pediatric patients with
suspected fibrotic liver disease to adult baseline values may underestimate
disease severity, or miss low grade changes, particularly in pre-adolescent
children.
Acknowledgements
This study was funded by a discovery projects grant from the
Australian Research Council. We also acknowledge financial support from the Department of
Health via the National Institute for Health Research (NIHR) comprehensive
Biomedical Research Centre award to Guy's & St Thomas' NHS Foundation Trust
in partnership with King's College London and King’s College Hospital NHS
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