Fetal and placental anatomy visualized with cinematic rendering from volumetric CT data

Abstract

Avoiding unnecessary radiation exposure in children, including fetuses or embryos, is of paramount importance. However, emergent clinical situations will arise that necessitate the use of ionizing radiation-based modalities, such as computed tomography (CT), in this patient population. In such circumstances, the use of advanced visualization methods may provide optimum diagnostic utility. We present the case of a pregnant patient with Loeys-Dietz syndrome who was evaluated with CT angiography to rule out an acute aortic syndrome. The CT data from the fetus and placenta were reconstructed using the new cinematic rendering technique that allows for photorealistic display. The potential advantages of cinematic rendering relative to traditional volume rendering are discussed.

Keywords: 3D CT; Cinematic rendering; Fetal anatomy.

Fig. 1

(A) through (C): VR images of the 36-week, 6-day fetus described in this case. Excellent detail of the bony structures is apparent, although the level of anatomic detail is less than in the CR images that are also presented. (D) through (H): CR visualizations of the same field of view. Note the fine soft-tissue detail that can be achieved with CR (such as the texture of the diastatic rectus abdominis musculature in (D)). By varying the window width and level, different amounts of soft tissue, vascularity, and bone can be emphasized and a complete photorealistic anatomic picture of the fetal skeletal structure and placental vascularity can be achieved. As one example of the more robust 3D effects produced by CR, note that the superior pubic rami cause a shadow over the top of the fetal calvarium (red arrowheads in (G) and (H)), an effect that is not possible with the simpler lighting model in the traditional VR images. This realistic shadowing effect more definitively establishes the relative positions of the structures. CR, cinematic rendering; VR, volume rendering.