Developing a method for estimating Body Segment Parameters using Dual Photon Absorptiometry, Magnetic Resonance Imaging, and Photogrammetry

Abstract

<p> An accurate estimation of Body Segment Parameters (BSPs) is needed to understand human movement. These include segment mass, centre of mass, and moment of inertia about the centre of mass. Bone density scanners, such as DPX, can measure BSPs, but are limited to only two dimensions. MRI produces images in three dimensions, but cannot directly measure mass. For this study, MRI was used in conjunction with a DPX scan of the human body. The result was the development of a method to estimate mass, and subsequently, centre of mass, and moment of inertia from MRI images. Next, ellipses were created from the dimensions of transverse plane slices (produced from MRI). Three different density profiles were applied to the ellipses, and mass, centre of mass and moment of inertia about the centre of mass of each slice was calculated. It was found that constant density transverse plane ellipses could be used to estimate BSPs for most regions of the body. Photogrammetry can also be used to generate the dimensions of ellipses that represent transverse plane slices. Therefore, the suitability of photogrammetry to estimate slice BSPs was tested. It was found that depending on the density profile used, photogrammetry is an effective method for estimating BSPs. An exception to this estimation was in the chest, where ellipses may not be representative of the body. </p>