Evolution of T1 Relaxation, ADC, and Fractional Anisotropy during Early Brain Maturation: A Serial Imaging Study on Preterm Infants.
OBJECTIVE
The alteration of brain maturation in preterm infants contributes to neurodevelopmental disabilities during childhood. Serial imaging allows understanding of the mechanisms leading to dysmaturation in the preterm brain. The purpose of the present study was to provide reference quantitative MR imaging measures across time in preterm infants, by using ADC, fractional anisotropy, and T1 maps obtained by using the magnetization-prepared dual rapid acquisition of gradient echo technique.


METHODS
We included preterm neonates born at <30 weeks of gestational age without major brain lesions on early cranial sonography and performed 3 MRIs (3T) from birth to term-equivalent age. Multiple measurements (ADC, fractional anisotropy, and T1 relaxation) were performed on each examination in 12 defined white and gray matter ROIs.


RESULTS
We acquired 107 MRIs (35 early, 33 intermediary, and 39 at term-equivalent age) in 39 cerebral low-risk preterm infants. Measures of T1 relaxation time showed a gradual and significant decrease with time in a region- and hemispheric-specific manner. ADC values showed a similar decline with time, but with more variability than T1 relaxation. An increase of fractional anisotropy values was observed in WM regions and inversely a decrease in the cortex.


CONCLUSIONS
The gradual change with time reflects the progressive maturation of the cerebral microstructure in white and gray matter. Our study provides reference trajectories from 25 to 40 weeks of gestation of T1 relaxation, ADC, and fractional anisotropy values in low-risk preterm infants. We speculate that deviation thereof might reflect disturbed cerebral maturation; the correlation of this disturbed maturation with neurodevelopmental outcome remains to be addressed.
From the Clinic of Neonatology and Follow-up (J.S., M.B.G., A.C.T.), Department of Pediatrics.
J
http://orcid.org/0000-0001-6849-6178
J
Schneider
Department of Radiology (T.K., R.M., P.H.), University Hospital Center and University of Lausanne, Lausanne, Switzerland Advanced Clinical Imaging Technology (T.K.), Siemens Healthcare IM BM PI, Lausanne, Switzerland LTS5 (T.K.), École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
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T
Kober
From the Clinic of Neonatology and Follow-up (J.S., M.B.G., A.C.T.), Department of Pediatrics.
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M
Bickle Graz
Department of Radiology (T.K., R.M., P.H.), University Hospital Center and University of Lausanne, Lausanne, Switzerland.
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http://orcid.org/0000-0002-9573-3076
R
Meuli
Division of Development and Growth (P.S.H.), Department of Pediatrics, University Hospital of Geneva, Geneva, Switzerland.
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PS
Hüppi
Department of Radiology (T.K., R.M., P.H.), University Hospital Center and University of Lausanne, Lausanne, Switzerland.
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P
Hagmann
From the Clinic of Neonatology and Follow-up (J.S., M.B.G., A.C.T.), Department of Pediatrics Anita.Truttmann@chuv.ch.
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AC
Truttmann
D016880:Anisotropy; D001921:Brain / Q000254:growth & development*; D002658:Developmental Disabilities / Q000175:diagnosis; D005260:Female; D005865:Gestational Age; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D007223:Infant; D007231:Infant, Newborn; D007234:Infant, Premature / Q000254:growth & development*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D012016:Reference Values; D013223:Statistics as Topic