Feasibility and reproducibility of transvaginal, transabdominal, and 3D volume reconstruction sonography for measurement of the corpus callosum at different gestational ages.

Objective: To compare the feasibility and reproducibility of transvaginal and transabdominal approaches, and 3D volume reconstruction sonography for measurement of corpus callosum (CC) length at different gestational ages.

Methods: Forty-six normal fetuses were examined by 2D and 3D ultrasound at 23-25, 27-28 and 31-32 weeks of gestation. Direct mid-sagittal views were obtained by either a transabdominal and/or transvaginal approach. 3D reconstructed mid-sagittal views were obtained by 3D multiplanar manipulations and Volume Contrast Imaging in the C-plane technique (VCI-C) from volumes acquired in axial planes.

Results: The CC could be measured in 91% of transvaginal acquisitions, in 52% of transabdominal acquisitions, in 92% of multiplanar reconstructions, and in 86% of VCI-C reconstructions. The success rate was independent of gestational age for transvaginal acquisition and slightly dependent on gestational age for 3D reconstruction techniques. Transabdominal acquisition was dependent on gestational age and fetal presentation. Inter- and intra-observer agreement was slightly better for measurements obtained from direct mid-sagittal views with either transvaginal or transabdominal acquisition than in views obtained by volume reconstruction. The reproducibility of measurements taken in reconstructed mid-sagittal views decreased with gestational age.

Conclusion: 3D volume reconstruction techniques allow visualization and measurement of the CC in a high percentage of cases, with good reproducibility.