Applications of non‐destructive 3D data acquisition and processing for biomechanical computation, soft tissue visualization, and 4D real‐life animation

Abstract

3D imaging, based mostly on data from x‐ray CT and MRI, has become part of the tool box for the visual representations of morphological data sensu lato. While the basic methodology continues to be refined at the acquisition and data processing levels, the time has come to explore how specific research questions can be solved by creating 3D models that are accurate and testable, and, therefore, realistic (realitätsgetreu, i.e., faithful to reality) based on nondestructive 3D data acquisition techniques that allow a particular specimen to be used subsequently for other, possibly destructive procedures, such as dissection, histology, or electron microscopy. Three different 3D modeling approaches for answering specific questions exemplify the range of possible applications and can be adapted to analogous biological systems. (1) 3D modeling of a human skeleton based on x‐ray CT data allows the depiction of the three‐dimensional orientation of muscle and external forces and the calculation of their relative magnitude as a baseline for evaluating the effects of (A) healthy versus unhealthy postures on the body as a whole; and (B) bilateral asymmetry due to preferential use of a particular side or to congenital conditions (e.g., torticollis, scoliosis). Such a 3D model allows the resolution of forces without invoking limiting preconditions in contrast to 2D models, which require certain unrealistic assumptions for flattening a 3D specimen into a 2D plane. (2) 3D modeling of soft tissue structures and organisms that lack a mineralized skeleton (e.g., lampreys, soft‐bodied invertebrates) by using MRI data to avoid the shrinkage and deformation of soft tissues associated with contrast‐stained x‐ray CT data, and by using special acquisition and visualization procedures to deal with the inherent trade‐off between tissue contrast and image resolution in MRI. (3) 4D modeling of the movement patterns of a complex organism with a multitude of moving skeletal elements, such as the simultaneous movements of the thorax, neck, skull, jaw, tongue, and larynx of a vocalizing bird, requires a combination of several techniques. First, a segmented 3D model based on x‐ray CT data is created, in which all skeletal elements are marked as independent units. This structural 3D model is then transformed into a dynamic 3D model by matching its configuration to the configuration shown in individual frames of an x‐ray video of a singing bird, which is synchronized with an audio‐recording of the bird's vocalizations to calibrate particular skeletal positions with particular notes sung by the bird. This approach transforms a 2D x‐ray video into a 3D video that can be observed from any angle. Furthermore, it controls the exposure of live organisms to radiation and, therefore, is applicable to humans, as well as to rare and valuable live specimens, in fundamental and clinical research. The principles involved in the presented 3D data processing techniques are preparing the ground for applications to emerging 3D data acquisition modes, such as x‐ray phase‐contrast, or phase‐sensitive, imaging and neutron grating interferometry.Support or Funding InformationLSU Foundation support and National Institute of Neurological Disorders and Strokes subcontract IN‐4683010‐LSU to Dominique G. Homberger; Sigma Xi Grant‐in‐Aid to Bradley M. Wood.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.