Fetal Brain Biometric Measurements on 3D Super-Resolution Reconstructed T2-Weighted MRI: An Intra- and Inter-observer Agreement Study.

Marie Khawam,Reto Meuli,Jean-Philippe Thiran,Mériam Koob,Philippe Maeder,Meritxell Bach Cuadra,Patric Hagmann,Thomas Yu,Sébastien Tourbier,Vincent Dunet,Pierre Deman,Priscille De Dumast,Hamza Kebiri,Hélène Lajous

doi:10.3389/fped.2021.639746

Abstract

We present the comparison of two-dimensional (2D) fetal brain biometry on magnetic resonance (MR) images using orthogonal 2D T2-weighted sequences (T2WSs) vs. one 3D super-resolution (SR) reconstructed volume and evaluation of the level of confidence and concordance between an experienced pediatric radiologist (obs1) and a junior radiologist (obs2). Twenty-five normal fetal brain MRI scans (18–34 weeks of gestation) including orthogonal 3-mm-thick T2WSs were analyzed retrospectively. One 3D SR volume was reconstructed per subject based on multiple series of T2WSs. The two observers performed 11 2D biometric measurements (specifying their level of confidence) on T2WS and SR volumes. Measurements were compared using the paired Wilcoxon rank sum test between observers for each dataset (T2WS and SR) and between T2WS and SR for each observer. Bland–Altman plots were used to assess the agreement between each pair of measurements. Measurements were made with low confidence in three subjects by obs1 and in 11 subjects by obs2 (mostly concerning the length of the corpus callosum on T2WS). Inter-rater intra-dataset comparisons showed no significant difference (p > 0.05), except for brain axial biparietal diameter (BIP) on T2WS and for brain and skull coronal BIP and coronal transverse cerebellar diameter (DTC) on SR. None of them remained significant after correction for multiple comparisons. Inter-dataset intra-rater comparisons showed statistical differences in brain axial and coronal BIP for both observers, skull coronal BIP for obs1, and axial and coronal DTC for obs2. After correction for multiple comparisons, only axial brain BIP remained significantly different, but differences were small (2.95 ± 1.73 mm). SR allows similar fetal brain biometry as compared to using the conventional T2WS while improving the level of confidence in the measurements and using a single reconstructed volume.

Highlights

Biometric measurements are good markers of fetal brain maturation and growth and are a fundamental basis for the diagnosis of developmental and acquired brain abnormalities [1]
Our study showed overall good inter-observer agreement for biometric measurements performed on T2WS and on SR, without any statistically significant difference after correction for multiple comparisons
We have shown that even a radiologist without expertise in fetal brain magnetic resonance imaging (MRI) can perform accurate fetal brain biometry—thanks to SR

Summary

Introduction

Biometric measurements are good markers of fetal brain maturation and growth and are a fundamental basis for the diagnosis of developmental and acquired brain abnormalities [1]. An abnormal measurement is often the first warning of disturbed fetal growth that requires further investigation. Quantifying brain development, in comparison to reference charts, is the first routine step of prenatal diagnosis on ultrasound (US) and magnetic resonance imaging (MRI). This can detect common pathologies like microcephaly, cerebellar hypoplasia, corpus callosum dysgenesis, and ventriculomegaly [2]. The accuracy of biometric data is essential for the evaluation of prognosis and prediction of outcome as it may influence both prenatal and postnatal management. It is crucial to give appropriate parental information and counseling, as termination of pregnancy may be considered in severe cases [3]

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