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Quantifying Brain Myelin Water Fraction in a Guinea Pig Model of Spontaneous Intrauterine Growth Restriction
Simran Sethi1, Lanette J Friesen-Waldner1, Timothy R H Regnault2,3,4
1Department of Medical Biophysics, Western University, London, Ontario, Canada.
Background:
Intrauterine growth restriction (IUGR) is an obstetrical condition where a fetus has not achieved its genetic potential. A consequence of IUGR is a decrease in brain myelin content. Myelin water imaging (MWI) has been used to assess fetal myelin water fraction (MWF) and might potentially assess myelination changes associated with IUGR.
Purpose:
To quantify and compare the MWF of non-IUGR and IUGR fetal guinea pigs (GPs) in late gestation.
Study Type:
Prospective animal model.
Animal Model:
Dunkin-Hartley GP model of spontaneous IUGR (mean ± SD: 60 ± 1.2 days gestation; 19 IUGR, 52 control).
Field Strength/Sequence:
Eight spoiled gradient-recalled (SPGR) gradient echo volumes (flip angles [α]: 2°-16°), and two sets of eight balanced steady-state free precession (bSSFP) gradient echo volumes (α: 8° - 64°), at 0° and 180° phase increments, at 3.0 T.
Assessment:
MWF maps were generated for each fetal GP brain using multicomponent driven equilibrium single pulse observation of T1/T2 (mcDESPOT). MWF was quantified in the fetal corpus callosum (CC), fornix (FOR), parasagittal white matter (PSW), and whole fetal brain.
Statistical Tests:
Linear regression was performed between five fetal IUGR markers (body volume, body-to-pregnancy volume ratio, brain-to-liver volume ratio, brain-to-placenta volume ratio, and brain-to-body volume ratio) and MWF (coefficient of determination, R2). A t-test with a linear mixed model compared the MWF of non-IUGR and IUGR fetal GPs (significance was determined at α < 0.05).
Results:
The MWF of the control fetuses are (mean ± SD): 0.23 ± 0.02 (CC), 0.31 ± 0.02 (FOR), 0.28 ± 0.02 (PSW), and 0.20 ± 0.01 (whole brain). The MWF of the IUGR fetuses are (mean ± SD): 0.19 ± 0.02 (CC), 0.27 ± 0.01 (FOR), 0.24 ± 0.03 (PSW), and 0.16 ± 0.01 (whole brain). Significant differences in MWF were found between the non-IUGR and IUGR fetuses in every comparison.
Data Conclusion:
The mean MWF of IUGR fetal GPs is significantly lower than non-IUGR fetal GPs.
Evidence Level:
2 TECHNICAL EFFICACY: Stage 1.
