Seminars/Colloquia/Invited Talks

Seminars

Gary Christensen

Contemporary Topics in Medical Image Registration

PLACE:	Clark 314
EVENT:	CIS Seminar
DATE:	April 17, 2007 (rescheduled from February 27)
TIME:	1:00 - 2:00 PM

Abstract

This talk will discuss Transitive Inverse-Consistent Manifold Registration (TICMR), Boundary-Constrained Inverse Consistent Image Registration (BICIR), and the Non-Rigid Image Registration Evaluation Project (NIREP).
The TICMR method jointly estimates correspondence maps between groups of three manifolds embedded in a higher dimensional image space while minimizing inverse consistency and transitivity errors. Registering three manifolds at once provides a means for minimizing the transitivity error which is not possible when registering only two manifolds. TICMR is an iterative method that uses the closest point projection operator to define correspondences between manifolds as they are non-rigidly registered.
The BICIR method performs boundary constrained intensity based image registration by combining surface correspondence with intensity based registration. The method registers region inside an object of interest and ignores everything outside the object. This eliminates the interference caused by surrounding regions due to the regularization constraints and the boundary conditions of the image. The boundaries of the two objects are first registered using a consistent boundary registration technique. This provides the boundary conditions, which are used to compute the displacement over the object using the Element Free Galerkin Method (EFGM). The EFGM solution is used as an initialization and is fine-tuned using the intensity information inside the object.
Many non-rigid image registration methods have been developed, but are especially difficult to evaluate since point-wise inter-image correspondence is usually unknown, i.e., there is no "Gold Standard" to evaluate performance. The Non-rigid Image Registration Evaluation Project (NIREP) has been started to develop, establish, maintain, and endorse a standardized set of relevant benchmarks and metrics for performance evaluation of nonrigid image registration algorithms.

Brief Biography:

Gary E. Christensen received his BS degrees in Electrical Engineering and Computer Science, graduating Magna Cum Laude, in 1988 and his MS and DSc degrees in Electrical engineering in 1989 and 1994, respectively, from Washington University, St. Louis. In 1997, Dr. Christensen joined the faculty of the Department of Electrical and Computer Engineering, the University of Iowa, where he is currently an Associate Professor and a faculty member in the College of Engineering Imaging Group. Previously, Dr. Christensen was an Assistant Professor with the Washington University School of Medicine from 1994 to 1996 with joint appointments in the Department of Surgery, Mallinckrodt Institute of Radiology, and Department of Electrical Engineering and directed the Craniofacial Imaging Laboratory, St. Louis Children's Hospital, Washington University Medical Center. He has published over 70 scientific papers and is the co-inventor on four patents. His primary research interests include image registration, 3-D visualization, medical imaging, and deformable shape models.