Abstract
Background and purpose
The superficial subplate (sSP) forms the interface between the cortical plate and the deeper subplate, as a transient sublamina prominent during mid-fetal development of the human brains when many cortical malformations originate and prenatal counseling is needed. Our aim was to assess the visibility of the sSP throughout development using in vivo 3T fetal MR images in the human brain.Materials and methods
In this retrospective observational study, 51 human fetuses (19-36 gestational weeks [GWs]) medically assessed as neurotypical were imaged on a 3T MR scanner in vivo, using single-shot, fast spin echo T2-weighted sequences, and images in 3 planes were selected. Three readers twice assessed the visibility of the sSP on the selected images in the region of the frontal, parietal, temporal, and occipital lobes. To explore the relationship between the visibility of the sSP and gestational age, we used regression analysis. A quadratic model was applied to investigate the nonlinear association between visibility scores and fetal age. The interobserver agreement on the visibility of the sSP was scrutinized both pair-wise and among all 3 raters. Weighted κ statistics determined inter- and intrarater agreement.Results
The visualization of the sSP on in vivo fetal 3T MRI was possible between 19 and 27 GWs, in 1 or more lobes, (the frontal, parietal, temporal, occipital), with optimal visibility between 20 and 27 GWs, coinciding with the peaks in glycosaminoglycan expression in the sSP. Interrater agreement ranged from moderate to excellent (weighted κ = 0.57-0.93), with a mean κ of 0.81 (SD, 0.10 on first assessment, improving to κ of 0.88 with SD, 0.03 on second assessment). Intrarater agreement was good to excellent (κ = 0.75-0.90).Conclusions
The sSP is visible on T2WI on in vivo fetal MRI at 3T. A deeper understanding of the in vivo appearance of the laminar organization of the human fetal brain, including the sSP, is required to accurately interpret altered fetal brain development, thereby improving early diagnostic accuracy, reducing false-positive assessments, and supporting prenatal counseling in cases of suspected cortical malformations.