Impact of Prematurity on the Tissue Properties of the Neonatal Brain Stem: A Quantitative MR Approach

V. Schmidbauer; G. Dovjak; G. Geisl; M. Weber; M.C. Diogo; M.S. Yildirim; K. Goeral; K. Klebermass-Schrehof; A. Berger; D. Prayer; G. Kasprian

doi:10.3174/ajnr.A6945

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Abstract

BACKGROUND AND PURPOSE: Preterm birth interferes with regular brain development. The aim of this study was to investigate the impact of prematurity on the physical tissue properties of the neonatal brain stem using a quantitative MR imaging approach.

MATERIALS AND METHODS: A total of 55 neonates (extremely preterm [n = 30]: <28 + 0 weeks gestational age; preterm [n = 10]: 28 + 0–36 + 6 weeks gestational age; term [n = 15]: ≥37 + 0 weeks gestational age) were included in this retrospective study. In most cases, imaging was performed at approximately term-equivalent age using a standard MR protocol. MR data postprocessing software SyMRI was used to perform multidynamic multiecho sequence (acquisition time: 5 minutes, 24 seconds)–based MR postprocessing to determine T1 relaxation time, T2 relaxation time, and proton density. Mixed-model ANCOVA (covariate: gestational age at MR imaging) and the post hoc Bonferroni test were used to compare the groups.

RESULTS: There were significant differences between premature and term infants for T1 relaxation time (midbrain: P < .001; pons: P < .001; basis pontis: P = .005; tegmentum pontis: P < .001; medulla oblongata: P < .001), T2 relaxation time (midbrain: P < .001; tegmentum pontis: P < .001), and proton density (tegmentum pontis: P = .004). The post hoc Bonferroni test revealed that T1 relaxation time/T2 relaxation time in the midbrain differed significantly between extremely preterm and preterm (T1 relaxation time: P < .001/T2 relaxation time: P = .02), extremely preterm and term (T1 relaxation time/T2 relaxation time: P < .001), and preterm and term infants (T1 relaxation time: P < .001/T2 relaxation time: P = .006).

CONCLUSIONS: Quantitative MR parameters allow preterm and term neonates to be differentiated. T1 and T2 relaxation time metrics of the midbrain allow differentiation between the different stages of prematurity. SyMRI allows for a quantitative assessment of incomplete brain maturation by providing tissue-specific properties while not exceeding a clinically acceptable imaging time.

ABBREVIATIONS:

GA: gestational age
PD: proton density
T1R: T1 relaxation time
T2R: T2 relaxation time
MDME: multidynamic multiecho
ICC: intraclass correlation coefficient

Footnotes

Disclosures: Gregor Dovjak—UNRELATED: Employment: Medical University of Vienna, Comments: The medical university, where this work originated, is my employer, so I get paid by them. Mariana Diogo—RELATED: Grant: Austrian Science Fund*; UNRELATED: Employment: Neuroradiology consultant, Comments: ITM; work as a neuroradiologist. Katrin Klebermass-Schrehof—UNRELATED: Payment for Lectures, Including Service on Speakers Bureaus: Chiesi Pharmaceuticals, Natus Medical Incorporated, Comments: Payment for lectures and workshops. Angelika Berger—UNRELATED: Grants/Grants Pending: Unrestricted and restricted research grants from Chiesi, Abbvie, Roche, Nestle, and Schülke. Payment for Lectures, Including Service on Speakers Bureaus: Lecture honoraria from Abbvie, Chiesi, and Schülke. Gregor Kasprian—UNRELATED: Consultancy: Bellaria Diagnostics, Comments: Consultant for fetal MRI at Bellaria Diagnostics; Employment: Medical University of Vienna; Grants/Grants Pending: FWF Austrian Science Fund, Comments: Grant outside submitted work. *Money paid to institution.