Novel technique for three-dimensional visualisation and quantification of deformable, moving soft-tissue body parts

Background. Three-dimensional (3D) imaging of delicate, moving soft-tissue body parts is very difficult. Our understanding of the muscles that control lip movements is based largely on histological and cadaveric studies, which provide scant information about dynamic morphology. Our aim was to develop an innovative scanning technique for the imaging and reconstruction of dynamic orofacial morphology by use of 3D and four-dimensional (4D, ie, 3D plus time) ultrasonography. Methods. Four volunteers (including one patient) underwent ultrasonography with 3D/4D imaging systems. To avoid deformation of the delicate orofacial structures, a water bath with an acoustic window was devised. The orofacial part was immersed in the bath throughout scanning, and a timer was used to synchronise lip movements with the 4D scan. Findings. 4D views showed the functional differences in superficial and deep muscle groups of the lips, and clearly showed the changes occurring with movement of the lips and mouth. In the patient, a pathological layer and its extension corresponding to surface malformation were clearly identified. Interpretation. We have developed a prototype device that has made possible 30 and 4D examination of orofacial anatomy and function. With further refinement of the device and improvement in 4D acquisition timing. this technique may offer a new way of dynamically imaging and quantifying many soft-tissue parts in 30 without deforming structure or disturbing function.