Volumetric Ultrasound and Related Dental Applications

Ultrasound is a natural 2D imaging methodology. While this is partially due to the substantially increased complexity of 3D (or 4D) ultrasound versus 2D, it is also due to the real-time display standard. For such, it is largely impossible to display 3D image volumes in real-time, unless they are segmented in a way to essentially create 2D counterparts that can be processed by the technologist or radiologist. Examples include cardiology, where the blood filled heart lends itself to real-time, i.e. 4D, segmentation due to the stark difference in echogenicity between soft tissue and blood. Obstetrics is similar as the amniotic fluid is hypoechoic compared to soft and hard tissue, which therefore allows for segmentation of the fetus from its surroundings. On the other hand, segmentation of soft tissue from other soft tissue is currently not viable. Dental applications of 3D/4D ultrasound are developing and this chapter provides geometry and imaging considerations. The chapter closes with specific examples of tissue and bone recession.