1 Copyright © 20xx by ASME ASME 2010 First Global Conference on NanoEngineering for Medicine and Biology NEMB2010 Feb. 7-10, 2010, Houston, TX, USA NEMB2010-13098 MRI BASED FE MODEL OF HEAD TRAUMA: IMAGING AND MESH GENERATION Marcus Slavenas University of Illinois Urbana-Champaign, IL, USA Martin Ostoja-Starzewski University of Illinois Urbana-Champaign, IL, USA ABSTRACT In order to perform simulations of the human head under impact loading, a finite element (FE) mesh was developed from a structural magnetic resonance image set. A T1 and a T2 weighted image were acquired from a single subject and co- registered. FSL was used to segment the image according to different tissue types: scalp, skull, cerebral spinal fluid (CSF), grey matter, white matter, or non-object. A custom C++ program concatenates the image files, removes all non-object voxels, and creates a FE mesh based upon the FSL tissue identification and the image geometry. We present a highly refined FE mesh of the human head with scalp thickness, skull thickness, and white and grey matter distribution that are consistent with anatomical norms. The mesh is exported to ABAQUS and used to simulate a frontal impact by Y. Chen and M. Ostaja-Starzewski [1]. INTRODUCTION Traumatic Brain Injury (TBI) is a serious medical problem from auto accidents, sports, and combat. A better understanding of the mechanics of an impact to the head leads to better design of protective headgear and improved diagnostic abilities of trauma physicians. Modern imaging technologies like CT (computed tomography) and structural MRI (magnetic resonance imaging) have provided clinicians the ability to look into the living brain and rapidly diagnose damage or abnormalities. Functional imaging technologies like SPECT (single photon emission computed tomography) and fMRI (functional MRI) improved understanding of brain function. But, despite the great advances in brain science, the mechanical models of traumatic brain injury (TBI) remain immature. We introduce a highly refined finite element (FE) mesh based upon structural MRI data. RESEARCH APPROACH Imaging Each subject was scanned using the 3T Siemens Alegra Magnetom Scanner at the Biomedical Imaging Center at the University of Illinois, Urbana-Champaign. Two structural imaging sequences, MPRAGE and T2-VFL, provide high- resolution images with two different contrast weightings, T1 and T2, respectively. T1 signal is produced by the relaxation of nuclei from an energized state back to equilibrium, also called spin-lattice relaxation because nuclei lose energy to the object lattice. T2 signal is produced by the dephasing of adjacent nuclear spins, also called spin-spin relaxation because nuclei exchange energy with each other. The contrast is selected by changing the timing of the applied pulse sequence. The T1 and T2 images have resolutions of 1.33×1.33×1.30mm and 0.50×0.50×1.00mm (Figure 1). a) b) c) d) Figure 1) a) A T1 weighted image, sagittal view b) A T2 image of the same subject c,d) Close-ups of the same region from the two images show quite different output