IGES and .stl file of a rat brain

<strong>Rat's brain mechanical model</strong> For building the realistic 3D model, Magnetic Resonance Imaging (MRI) data was obtained from an anaesthetised male Wistar rat (250g ) fixed onto a MRI compatible stereotactic frame. The data consisted of 240 cross-sectional slices 0,22mm thick and 320x320 voxels with 0,3mm resolution (Philips Achieva 3 Tesla (T), Neuroradiology UKSH Lübeck). The brain contour was subsequently segmented using Simpleware’s (Exeter, UK) employing the built-in region growing tool and careful manual correction. The segmentation mask was then converted to a surface mesh. The physical rat brain replica was done with various software. At this state a .stl surface mesh file existed and for standard boolean operations in ProEngineer &amp; Creo Elements Student Version 2011 (PTC, Needham, MA 02494, USA) software a solid was prerequisite. With FreeCAD, an open source, under General Public License (GPL), CAD software, was used to create a shape from a mesh and then converted to a solid with the same volume like the mesh. For moulds however, the original volume of a rat brain is difficult to use. In particular areas as the olvactorium or the abrupt transition from the Telencephalon to the Metencephalon. At those points an area smoothing was done to reduce the anatomical indentations. Otherwise the physical rat brain cannot be extracted out of the mould without damage. At this time a solid volume of the brain was generated. For boolean subtraction, a second block, 1,5 times the size of the rat brain, was needed. The rat brain and the block were nestable assembled and the brain was subtracted from the block. The hollowed block was subdivided into two halves and each one fitted with either a tongue or a groove connection. Additionally a hole of 2mm diameter through the block to the olfactory region, for liquid intake, was cut.