1. MSIM 842 VISUALIZATION II INSTRUCTOR: JESSICA R. CROUCH Creating and Simulating Skeletal Muscle from the Visible Human Data Set Authors: Joseph Teran Eftychios Sifakis Silvia S. Blemker Victor Ng-Thow-Hing Cynthia Lau Ronald Fedkiw Presented By: Federico Bermudez 21 Mar 20071

2. PROBLEM Create anatomically realistic simulations of the human musculoskeletal system. Create visually accurate simulations of the interactions between muscles and bones. This paper present a method for creating such simulations using the visible human data set. 21 Mar 2007 MSIM 842 VISUALIZATION II INSTRUCTOR: JESSICA R. CROUCH 2

3. MOTIVATION Anatomically and visually accurate simulations of the musculoskeletal system are critical in: biomechanics biomedical engineering surgery simulation computer graphics 21 Mar 2007 MSIM 842 VISUALIZATION II INSTRUCTOR: JESSICA R. CROUCH 3

4. APPROACH PRIOR & RELATED WORK Prior work – Simple less accurate models encompassing many muscles. – Complex models that only simulate a few number of muscles. – These models are less visually accurate. Related work – Seems to be concentrated on the use of the Finite Element Method (FEM), the Finite Volume Method (FVM), and tetrahedral meshes 21 Mar 2007 MSIM 842 VISUALIZATION II INSTRUCTOR: JESSICA R. CROUCH 4

5. APPROACH MODEL CREATION The Visible Human Data Set Run by the U.S. National Library Of Medicine Consists of MRI, CT, and anatomical Images Male data set released in Nov 1994 – Joseph Paul Jernigan (38-year-old Texas murderer executed 5 Aug 1993) – cadaver was frozen and cut (1871 axial slices at 1 millimeter intervals) – Photographed and digitized – 15 GB Female data set released in Nov 1995 – 59-year-old Maryland housewife who died from a heart attack – cadaver was frozen and cut (5189 axial slices at 0.33 millimeter intervals) – Photographed and digitized – 40 GB 21 Mar 2007 MSIM 842 VISUALIZATION II INSTRUCTOR: JESSICA R. CROUCH 5

6. APPROACH MODEL CREATION The Visible Human Data Set Problems with the data set – Male brain slightly swollen by the freezing process – Small blood vessels were collapsed by the freezing process – His inner ear ossicles were lost during preparation Site: http://www.nlm.nih.gov/research/visible/ 21 Mar 2007 MSIM 842 VISUALIZATION II INSTRUCTOR: JESSICA R. CROUCH 6

7. APPROACH MODEL CREATION The Visible Human Data Set 21 Mar 2007 MSIM 842 VISUALIZATION II INSTRUCTOR: JESSICA R. CROUCH 7 CT ScanColor Cryosections Thorax subset

8. APPROACH MODEL CREATION The Visible Human Data Set 21 Mar 2007 MSIM 842 VISUALIZATION II INSTRUCTOR: JESSICA R. CROUCH 8

9. APPROACH MODEL CREATION Repairing Errors 21 Mar 2007 MSIM 842 VISUALIZATION II INSTRUCTOR: JESSICA R. CROUCH 9

10. APPROACH MODEL CREATION Meshing Bone and Muscle 21 Mar 2007 MSIM 842 VISUALIZATION II INSTRUCTOR: JESSICA R. CROUCH 10

11. APPROACH MODEL CREATION Meshing Bone and Muscle 21 Mar 2007 MSIM 842 VISUALIZATION II INSTRUCTOR: JESSICA R. CROUCH 11

12. APPROACH MODEL CREATION Tendon and Bone Attachment Designation assign tendon, bone attachments, and muscle properties to sections of the mesh 21 Mar 2007 MSIM 842 VISUALIZATION II INSTRUCTOR: JESSICA R. CROUCH 12

13. APPROACH MODEL CREATION B-Spline Fiber Representation Use B-spline solids to assign fiber directions to individual tetrahedrons. 21 Mar 2007 MSIM 842 VISUALIZATION II INSTRUCTOR: JESSICA R. CROUCH 13

14. APPROACH MODEL CREATION Skeletal Motion – Contraction of the muscles drives the motion of bones. – In this model, the skeleton drives the motion and contraction of muscles, tendons, and surrounding tissue. – A realistic model involves intricate knowledge of bones and joints interaction, often requiring multiple degrees of freedom to describe their movements. – The Obstacle-set Method was used to modeled the paths of the muscles. – Cylinders and spheres were used to compute muscles and bones collisions. 21 Mar 2007 MSIM 842 VISUALIZATION II INSTRUCTOR: JESSICA R. CROUCH 14

15. APPROACH MODEL CREATION Skeletal Motion 21 Mar 2007 MSIM 842 VISUALIZATION II INSTRUCTOR: JESSICA R. CROUCH 15

16. APPROACH MODEL CREATION Skeletal Motion 21 Mar 2007 MSIM 842 VISUALIZATION II INSTRUCTOR: JESSICA R. CROUCH 16

17. APPROACH FINITE VOLUME METHOD FVM more intuitive than the finite element method (FEM) FVM reduces the stress inside a tetrahedron to a simple multidimensional force pushing on each face. The inverting FVM algorithm developed from the FVM facilitates the simulation of objects that must undergo deformation and return to their original or partial shape. Video – 01 & 02 show simulations using the inverting FVM. 21 Mar 2007 MSIM 842 VISUALIZATION II INSTRUCTOR: JESSICA R. CROUCH 17

18. APPROACH CONSTITUTIVE MODEL FOR MUSCLE An strain energy function is used to model the contracting of the muscles. Model includes only what is necessary to produce bulk length-based contraction along the muscle fiber direction. As we will see on the video, the bulk deformations of the muscles are very subtle. 21 Mar 2007 MSIM 842 VISUALIZATION II INSTRUCTOR: JESSICA R. CROUCH 18

19. APPROACH EMBEDDING FRAMEWORK The complete model of the upper limb consist of over 30 muscles constructed with over 10 million tetrahedra. A dynamic Free Form Deformation embedding scheme was used to reduce the computational cost. The BCC grid size used resulted in a tenfold reduction in the size of the simulation mesh. Time step restriction for stability was relaxed by a factor of 25. These factors enabled the full finite element simulation at rates of 4 minutes per frame on a Xeon 3.06 GHz CPU. A nonmanifold simulation mesh is obtained by collapsing equivalent vertices. 21 Mar 2007 MSIM 842 VISUALIZATION II INSTRUCTOR: JESSICA R. CROUCH 19

20. APPROACH FASCIA AND CONNECTIVE TISSUES Muscles are enclosed in a network of connective tissue that keep them in close contact during motion. Model enforces a state of frictionless contact between the muscles. In essence the intersection between different muscles is determined and recalculated each time during motion in order to maintain the muscle tissues in close contact. Video – 03 shows the simulation without fascia. 21 Mar 2007 MSIM 842 VISUALIZATION II INSTRUCTOR: JESSICA R. CROUCH 20

21. APPROACH SIMULATING SKELETAL MUSCLE 21 Mar 2007 MSIM 842 VISUALIZATION II INSTRUCTOR: JESSICA R. CROUCH 21 Run videos 1.Video – 04 - Frontal View 2.Video – 05 - Side View

22. Evaluation The construction of the muscles, tendons, and bones seems to be correct. I think the simulation shows the compression and relaxation if the muscles visually accurate. 21 Mar 2007 MSIM 842 VISUALIZATION II INSTRUCTOR: JESSICA R. CROUCH 22

23. Conclusion & Future Work The authors successfully created a visually accurate simulation of the interaction of the bones, muscle, and underlying tissue of the human right upper limb. Current hardware and algorithm technology still too complex to achieve whole body simulations. Create subject-specific models with MRI and CT data. Morph VHP data set to match specific subject or body type using anatomical landmarks. 21 Mar 2007 MSIM 842 VISUALIZATION II INSTRUCTOR: JESSICA R. CROUCH 23

24. Questions How much more complex would be to simulate the whole body. Can this technique be use to simulate the involuntary muscles such the hear heart? Can this technique be applied to the design of artificial limbs. 21 Mar 2007 MSIM 842 VISUALIZATION II INSTRUCTOR: JESSICA R. CROUCH 24