Visualization of the fetal thoracic skeleton with three-dimensional sonography: a preliminary report.

OBJECTIVE Evaluation of the complete anatomy of the thoracic skeleton in the developing fetus often is difficult with conventional two-dimensional (2D) sonography because of the curvature of the bones. The purpose of the present work was to assess the ability of three-dimensional (3D) sonography to provide a more complete representation of the fetal thoracic skeleton than available with 2D sonography. SUBJECTS AND METHODS We performed 3D sonographic imaging in eight healthy volunteer pregnant women after obtaining informed consent. Conventional 2D sonographic equipment was adapted to obtain 3D data and to produce volume-rendered images. The 3D sonographic images of the bony spine and thorax were evaluated for clarity with which the vertebral bodies, ribs, scapulae, clavicles, and overall thoracic anatomy were depicted. RESULTS The vertebral bodies, spine, and ribs were identifiable on 3D sonograms, which clearly showed the structural continuity of the spine and ribs in all fetuses. Zoomed images of subregions of the spine were useful for showing details of the vertebrae. Stereo glasses and rotation of the volume data proved useful in appreciating the spatial relationships of the spine and rib cage. CONCLUSION Three-dimensional sonography provides additional information about the fetal thoracic skeleton to that furnished by 2D sonography by presenting the thorax as a coherent structure rather than as a series of cross-sectional slices.