Comparison between Two-Dimensional and Three-Dimensional Assessments of the Fetal Corpus Callosum: Reproducibility of Measurements and Acquisition Time

Abstract

The objective is to study the reproducibility and reliability of the fetal corpus callosum measurements between two-dimensional (2D) and three-dimensional (3D) acquisitions. This prospective study enrolled 475 fetuses, monitored between 18 and 38 weeks of gestation by two operators. Starting from a transcerebellar axial plane, 3D and 2D mid-sagittal views of the corpus callosum were obtained. Measurements of length and thickness were performed and underwent quality control by independent reviewers. The acquisition time of the two methods was measured. Means, differences, and linear correlations were analyzed using t-test, regression and Pearson's correlation coefficients, and Bland–Altman's plots. This analysis was performed for each operator to test the interobserver reproducibility. Among the 432 cases measured using both methods, 380 (88%) were validated by quality control. The mean corpus callosum length and thickness were essentially the same using 2D and 3D measurements (2D: 33.8 ± 8.7 vs. 3D: 33.7 ± 8.7 mm, 2D: 2.2 ± 0.4 vs. 3D: 2.2 ± 0.4 mm, respectively; mean ± standard deviation [SD]). Linear regression coefficients and Pearson's coefficients were similar for length (2D: 0.8283 and 0.9191 vs. 3D: 0.8271 and 0.9095), but slightly different regarding thickness (2D: 0.6775 and 0.8231 vs. 3D: 0.5831 and 0.7636). Differences between 2D and 3D measurements, considering Bland–Altman's plots and correlated with gestational age, were acceptable (2D: 0.097 ± 0.559 mm, 3D: 0.004 ± 0.111 mm). The acquisition time required was significantly lower for 3D acquisitions (3D: 25.2 ± 14.5 seconds vs. 2D: 35.1 ± 19.4 seconds, p < 0.01). Linear regression and Pearson's coefficients for the measurements of corpus callosum length and thickness using 2D or 3D acquisitions did not differ between the operators. This study confirms good reproducibility of corpus callosum assessment by transabdominal 3D acquisitions. The good feasibility in routine scans may lead to better screening for callosal dysgenesis.

Assessment of fetal corpus callosum biometry by 3D super-resolution reconstructed T2-weighted magnetic resonance imaging

“…Published biometric charts for fetal brain growth via US include CCL linear regressions ( 34 , 36 , 39 , 40 ). Prior studies also explored fetal brain morphometry using T2WS ( 37 , 41 , 42 ).…”

“…SR was assessed similarly, excluding obliquity and motion, which are irrelevant with SR. US image quality used Pomar et al’s criteria ( 34 ), including sagittal plane, CC parts visibility, sufficient zoom, CC to CSP distinction and proper caliper placement, each criteria rated as yes = 1, no = 0, with final rating of 5 points (good), 3–4 (average), 1–2 (bad) and 0 (unusable).…”

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

“…The 3D volume is then displayed as multiple orthogonal 2D images, that are isotropic (28). In the case of 2D-US, they are acquired on a mid-sagittal plane starting from the same trans-cerebellar axial view, by aligning the transducer along the anterior fontanelle and the sagittal suture which serve as an acoustic window (29).…”

“…The quality of US images was scored using the quality score proposed by Pomar et al (29) in their sonographic study of the CC. It consists of the sum of 5 criteria: strict sagittal plane with clear visibility of the cerebellar vermis, the brain stem, the fourth ventricle and the CC, the visualization of the 4 parts of the CC, a sufficient zoom, a clear differentiation of CC from the cavum septum pellucidum, and a right placement of the calipers.…”

“…Different trend is depicted by area on T2WS (blue). This is a provisional file, not the final typeset article Several biometric charts of the fetal brain growth by US, including linear regressions of LCC, have been published (29,31,34,35). Also, morphometry of the fetal brain by T2WS MRI has been previously explored (32,36,37).…”