Real-Time Non-Rigid Registration for Image Guided Neurosurgery:
                 Current Status and Future Directions

                        Nikos Chrisochoides
                    Parallel Experimental Systems Lab
                     Computer Science Department
                   The College of William and Mary

Image   Guided  Neurosurgery   (IGNS)   is  an   important  tool   for
neurosurgical resection which is  a common therapeutic intervention in
the treatment of cerebral gliomas.   Survival rate and quality of life
for a patient greatly depend  on the precision of the resection, which
can be  significantly improved by utilizing  pre-operative brain scans
as an  aid in decision  making during the procedure.   However, during
the course of intervention the  areas of interest may dislocate due to
brain  shift/deformation,  and thus  invalidate  existing brain  image
data.  Research underway at  Brigham and Women's Hospital (Boston, MA)
and the  College of William  and Mary (Williamsburg, VA),  attempts to
use  intra-operative   MRI  to  track  brain   deformation  and  align
(register) preoperative data accordingly.

In this talk we present our experience with a parallel and distributed
FEM-based  method for  non-rigid registration.   We will  show  how we
transformed it to  real-time method and reduced its  response time for
non-rigid registration  of an average  dataset from about an  hour and
for some cases more than an hour to less than couple of minutes, which
is within the time  constraints imposed by neurosurgeons.  This helped
us,  for the first  time ever  in clinical  practice, to  complete and
present  non-rigid registration results  to neuro-surgeons  at Brigham
and Women's Hospital (BWH)  during the tumor resection procedure using
landmark tracking across the entire  brain volume.  During the last 14
months our  work is used routinely  (in average once a  month) at BWH,
for clinical studies.

We will conclude the talk with open problems and future directions.



Short Bio
----------

Nikos  Chrisochoides is  the Alumni  Memorial  Distinguished Associate
Professor of Computer Science at  the College of William and Mary. His
research  interests   are  in  parallel   and  distributed  scientific
computing  and  computational  geometry. Specifically,  parallel  mesh
generation both  theoretical and implementation  aspects. His research
is  application-driven.  Currently  he  is working  on real-time  mesh
generation for biomedical applications like non-rigid registration for
Image Guided Neurosurgery.

Chrisochoides  received  his  B.Sc.   in  Mathematics  from  Aristotle
University,  Greece and  his M.Sc.   (in Mathematics)  and  Ph.D.  (in
Computer Science)  degrees from Purdue  University.  Then he  moved to
Northeast Parallel Architectures  Center (NPAC) at Syracuse University
as the Alex Nason Postdoctoral Fellow in Computational Sciences. After
NPAC  he  worked in  the  Advanced  Computing  Research Institute,  at
Cornell University.   He joined (as an Assistant  Professor in January
1997) the  Department  of  Computer  Science and  Engineering  at  the
University of Notre Dame. In the Fall of 2000, he moved to the College
of William and Mary as  an Associate Professor. Chrisochoides has more
than 100 technical publications in parallel scientific computing.

He has held visiting positions at Harvard Medical School (Spring 2005),
MIT (Spring 2005), Brown (Fall 2004) and NASA/Langley (Summer 1994)