K. Mori et al. (Eds.): MICCAI 2013, Part III, LNCS 8151, pp. 291–298, 2013. © Springer-Verlag Berlin Heidelberg 2013 Patient-Specific Biomechanical Modeling of Ventricular Enlargement in Hydrocephalus from Longitudinal Magnetic Resonance Imaging Yasheng Chen 1,2 , Zheng Fan 3 , Songbai Ji 4 , Joseph Muenzer 5,6 , Hongyu An 1,2 , and Weili Lin 1,2 1 Biomedical Research Imaging Center, Dept. of 2 Radiology, 3 Neurology, 5 Pediatrics and 6 Genetics, University of North Carolina at Chapel Hill, NC, 27599 4 Thayer School of Engineering, Dartmouth College, Hanover, NH 03755 {yasheng_chen,zheng_fan,joseph_muenzer, hongyuan,weili_lin}@med.unc.edu, songbai.ji@dartmouth.edu Abstract. Ogden type of hyperelastic constitutive law has recently emerged in modeling ventricular enlargement in hydrocephalic brain with finite element method, but this material property for brain tissue has not been investigated in a patient-specific setting in hydrocephalus. Consequently, the accuracy of the si- mulated ventricular enlargement using this hyperelastic tissue property remains unknown. In this study, we evaluated this brain material model in four patients with communicating hydrocephalus under a small trans-mantle pressure differ- ence (TPMD) between brain ventricle and subarachnoid space (<1mmHg). Based upon changes in ventricular geometries obtained with sequential MRI, we found that this hyper-elastic model has a great flexibility and accuracy in modeling ventricular enlargement (with errors less than 1mm). Our study sup- ports the utility of this hyperelastic constitutive law for future hydrocephalus modeling and suggests that the observed ventricular enlargement in these pa- tients may be caused by a slight increase in TMPD. Keywords: Brain finite element modeling, Brain mechanics, Hydrocephalus, Hyper-elastic brain modeling, Finite element analysis, Ventricular enlargement. 1 Introduction Hydrocephalus is defined as an active enlargement of brain ventricles caused by the impairment of cerebrospinal fluid (CSF) homeostasis. CSF is mainly produced by the choroid plexus in the lateral and third ventricles. After flowing into the fourth ven- tricle through aqueduct of Sylvius, CSF is reabsorbed in the subarachnoid space (SAS) through arachnoid granulations in the sagittal sinus. Hydrocephalus is referred to as communicating hydrocephalus when no apparent obstruction is presented within the brain ventricular system [1]. Finite element method (FEM) based simulation of brain ventricle enlargement started with a biphasic model for brain tissue. Nagashima et al employed Biot’s consolidation