2022 Thayer Investiture

Songbai Ji headshot

Songbai Ji

Adjunct Associate Professor of Engineering

Adjunct Associate Professor of Surgery, Geisel School of Medicine
Adjunct Associate Professor of Orthopaedic Surgery, Geisel School of Medicine

Research Interests

Image-guided surgery; medical imaging; multi-modality imaging; image analysis; finite element; numerical methods; image registration; traumatic brain injury; computational modeling of the human head


  • BSc, Materials Science, Shanghai Jiaotong University 1996
  • MS, Computer Science, Washington University in St. Louis 2003
  • DSc, Mechanical Engineering, Washington University in St. Louis 2003

Research Projects

  • Image-guided neurosurgery

    Image-guided neurosurgery

    Image-guided neurosurgery gives the surgeon the ability to track instruments in reference to subsurface anatomical structures. Using clinical brain displacement data, a computational technique is being developed to model the brain deformation that typically occurs during neurosurgery. The resulting deformation predictions are then used to update the patient's preoperative magnetic resonance images seen by the surgeon during the procedure.

  • Traumatic brain injury in college athletes

    Traumatic brain injury in college athletes

    Traumatic brain injury in college athletes is being studied using finite element method to simulate brain mechanical response subject to the on-field head impact biomechanics of helmeted collegiate athletes. The predicted distributions of stress and strain are correlated with the degree of altered white matter integrity quantified using diffusion tensor imaging to investigate the mechanisms of concussion/mild traumatic brain injury.

  • Measuring material properties of the human brain in vivo

    Measuring material properties of the human brain in vivo

    Despite being critical to biomechanical models, material properties of the brain remain poorly understood and have been characterized variously in part because of limited access to the in vivo brain. We use a simple indentation technique feasible in the operating room coupled to a noninvasive stereovision system to induce and measure brain surface deformation in patients undergoing open cranial surgeries in order to estimate material properties of the human brain in vivo.

Selected Publications

Surgical Image Guidance
  • S. Ji, X. Fan, K.D. Paulsen, D.W. Roberts, S.K. Mirza, S.S. Lollis. (2015). Patient Registration Using Intraoperative Stereovision in Image-guided Open Spinal Surgery. IEEE Transactions on Biomedical Engineering, (in press).
  • S. Ji, X. Fan, D.W. Roberts, K.D. Paulsen. Efficient Stereo Image Geometrical Reconstruction at Arbitrary Camera Settings from a Single Calibration. In: Barillot, C., Golland, P., Hornegger, J., Howe R. (eds.) MICCAI 2014, (Oral presentation; at a rate of ~4.00%, 36/~900)
  • S. Ji, X. Fan, D.W. Roberts, A. Hartov, Timothy J. Schaewe, David A. Simon, and K.D. Paulsen. (2014) "Brain Shift Compensation via Intraoperative Imaging and Data Assimilation," in CRC Handbook of Imaging in Biological Mechanics, (pp. 229–240) CRC Press and Taylor & Francis, Editors: Corey Neu and Guy Genin.
  • S. Ji, X. Fan, A. Hartov, D.W. Roberts, K.D. Paulsen. Cortical Surface Shift Estimation Using Optical Flow Motion Tracking and Stereovision via Projection Image Registration, Medical Image Analysis, 18:1169–1183, 2014. DOI: 10.1016/j.media.2014.07.001
  • S. Ji, D.W. Roberts, A. Hartov, and K.D. Paulsen. Intraoperative patient registration using volumetric true 3D ultrasound without fiducials, Medical Physics. 39(12), 7540–7552, (2012).
  • S. Ji, X. Fan, A. Hartov, D.W. Roberts, and K.D. Paulsen. "Estimation of intraoperative brain deformation", in Studies in Mechanobiology, Tissue Engineering and Biomaterials, Volume 11, 97–133, Y. Payan (Ed.), Springer-Verlag Berlin Heidelberg, 2012. DOI: 10.1007/8415_2012_129
  • S. Ji, X. Fan, D.W. Roberts, K.D. Paulsen, Cortical surface strain estimation using stereovision. In: Fichtinger, G., Martel, A., Peters, T. (eds.) MICCAI 2011, Part I. LNCS, vol. 6891, pp. 412–419. Springer, Berlin (2011) (Oral presentation; at a rate of 4.15%, 34/819)
Traumatic Brain Injury
  • S. Ji, W. Zhao, J.C. Ford, J.G. Beckwith, R.P. Bolander, R.M. Greenwald, L.A. Flashman, K.D. Paulsen, T.W. McAllister. (2015) Group-wise evaluation and comparison of white matter fiber strain and maximum principal strain in sports-related concussion. Journal of Neurotrauma. 32(7), 441-454. doi/abs/10.1089/neu.2013.3268 (front cover)
  • W. Zhao, J. Ruan, S. Ji. Brain pressure responses in translational head impact: a dimensional analysis and a further computational study. Biomechanics and Modeling in Mechanobiology. DOI: 10.1007/s10237-014-0634-0
  • S. Ji, W. Zhao. A pre-computed brain response atlas for instantaneous strain estimation in contact sports. Annals of Biomedical Engineering. DOI: 10.1007/s10439-014-1193-3
  • S. Ji, W. Zhao, Z. Li, T.W. McAllister. (2014) Head impact accelerations for brain strain-related responses in contact sports: a model-based investigation. Biomechanics and Modeling in Mechanobiology. DOI: 10.1007/s10237-014-0562-z
  • S. Ji, H. Ghadyani, R.P. Bolander, J.G. Beckwith, J.C. Ford, T.W. McAllister, L.A. Flashman, K.D. Paulsen, K. Ernstrom, S. Jain, R. Raman, L. Zhang and R.M. Greenwald. Parametric Comparisons of Intracranial Mechanical Responses from Three Validated Finite Element Models of the Human Head. Annals of Biomedical Engineering, 42(1): 11–24, 2014. doi:10.1007/s10439-013-0907-2