Assessment of fetal corpus callosum biometry by 3D super-resolution reconstructed T2-weighted MRI

Objective To assess the accuracy of corpus callosum (CC) and its sub-segments’ biometry by super-resolution (SR) 3-dimensional fetal brain MRI in comparison to measurements in 2-dimensional or 3-dimensional ultrasonography (US) and clinical low-resolution T2-weighted MRI sequences (T2WS). Method We performed fetal brain biometry of the overall length of the CC, the heights of its sub-segments and its area by two observers (one junior observer, obs1, and one senior pediatric neuroradiologist, obs2) in a cohort of 57 subjects (between 21 and 35 weeks of gestational age (GA), including 11 cases of partial agenesis of CC). Obs1 made measures on US, T2WS, and SR, and obs2 in T2WS and SR. Regression curves of CC biometry with GA were done. Statistical analysis of inter-modality (US vs. T2WS, US vs. SR, and T2WS vs SR) agreement for single observer (obs1) and inter-modality (US vs. T2WS, and US vs. SR) between observers (obs1 vs obs2) were also conducted. Results Our study shows a high concordance through GA of CC measurements performed by SR in comparison with US, with a higher agreement than biometry based on T2WS clinical acquisitions. For obs1, SR measurements are highly concordant to US (except for the genu and the CC length) and helps visualizing the splenium. For obs2, SR measurements are highly concordant to US, except for the rostrum and the CC length. Rostrum and Genu (forming the anterior callosum) are the subsegments with larger variability. Regression curves by SR overlay more accurately those from the literature (by US) for the CC length, the splenium and the body than T2WS. Conclusion Super-resolution MRI could be used in the biometrical assessment of the CC, providing measurements close to US, except for the anterior part of the CC Thanks to its 3D-visualisation capacity and improved through plane spatial resolution, it allows to perform CC biometry more frequently than on T2WS. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This work was supported by the Swiss National Science Foundation (project 205321-182602). ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: This retrospective study was part of a larger research protocol at our institution approved by the Commission cantonale d'ethique de la recherche sur l'etre humain (CER-VD 2021-00124). I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes The data analyzed in this study is subject to the following licenses/restrictions: the ethical approval for the use of these data did not include public release. Requests to access these datasets should be directed to the authors.