Motion capture and visualization of the hip joint with dynamic MRI and optical systems

Abstract

We present a methodology for motion tracking and visualization of the hip joint by combining MR images and optical motion capture systems. MRI is typically used to capture the subject's anatomy while optical systems are used to capture and analyse the relative movement between adjacent bones of the joint. Reflective markers are attached to the subject's skin and their trajectories are tracked and processed. However, the skin surface deforms while in motion due to muscle contraction leading to significant errors in the estimation of trajectories. In order to reduce these errors, we use MR images to capture both the anatomy and the trajectories of the bone. Prior to the scanning, we attach skin markers to the subject in order to analyse the markers displacements relative to the bone. We reconstruct the anatomical models of the subject and we compute the markers trajectories from the images. Using these calculated trajectories, we select the best markers configuration based on the criteria of markers displacements. The optimized configuration is used for recording external movements with the optical motion capture system. The resulting animation is mapped onto the virtual body of the subject including internal bones and the joint motion is visualized.

Surface Electric Field Variations Due to Different Human Postures for Wireless Endoscopy Applications

“…Motion capture technologies find wide practical application in biomedical engineering. It is commonly used to create robust systems to track human skeletal motion for athlete performance assessment, neurological disease treatment and monitoring, physiotherapy and assisted targeted medical treatment [37][38][39][40][41]. For our purposes, however it is of interest to use a motion capture system as a tool to gain data for the analysis of the skin position and soft tissue movement, which has not been fully reported previously.…”

Computer-assisted analysis of human upper arm flexion by 4D-visualization based on MRI

“…In [30], MRI acquisition was combined with optical motion capture systems. In [31], the generic patient's model was completed by body scanning, electromyographic, and mechanical measurements, as well as statistical data.…”

Tracking by means of geodesic region models applied to multidimensional and complex medical images

“…There are several techniques and methods that can be applied to tracking organs: the Point Distribution Model (PDM) or active contours [1,3,20,21,25,43,32,50], the Kalman filter [14,52], segmentation methods based on gradient and morphological operations like erosion and dilatation [44], geometrical models [34,40,39], based on camera calibration [18], applying register [27,29,24], using a commercial specialized system such as CyberKnife [17,49] or IRIS, [4] and using external and internal markers [9,54,49]. Murphy performs a comprehensive review of the work on tracking organs in real-time [35].…”