Chair for Computer Aided Medical Procedures & Augmented Reality
Lehrstuhl für Informatikanwendungen in der Medizin & Augmented Reality

Franjo Pernuš

Topic: 3D/2D Registration for Image Guided Therapy

A brief overview of existing methods, two novel methods for registering 3D CT or MR images to 2D X-ray images, and quantitative registration results will be presented. The novel registration methods are based solely on the information present in 2D and 3D images. They don’t require fiducial markers, intra-operative X-ray image segmentation, or construction of digitally reconstructed radiographs. The originality of the first approach is in using normals to bone surfaces, preoperatively defined in 3D MR or CT images, and gradients of intra-operative X-ray images at locations defined by rays, emitted from the X-ray source and passing through 3D surface points. The registration is concerned with finding the rigid transformation of a CT or MR volume, which provides the best match between surface normals and back projected gradients. The second method requires that first a 3D image is reconstructed from a few 2D X-ray images after which the preoperative 3D image is brought into the best possible spatial correspondence with the reconstructed image by optimizing a similarity measure. Because the quality of the reconstructed image is generally low, a novel similarity measure, which is able to cope with low image quality as well as with different imaging modalities, has been designed. The methods have been tested on two publicly available lumbar spine data with known “gold standard” registrations.

short bio

Franjo Pernuš received the Diploma, M.S., and Ph.D. degrees in Electrical Engineering from the University of Ljubljana, Ljubljana, Slovenia, in 1976, 1979, and 1991, respectively. In 1981 he received the Government of Canada Award for Foreign Nationals and spent a year (1981/1982) at McGill University in Montreal, Canada. Since 1976 he is with the Department of Electrical Engineering, University of Ljubljana, where he is currently Professor, Head of the Imaging Technologies Lab. and Vice-dean for research. His research interests are in biomedical image processing and analysis, computer vision, and the applications of image processing and analysis techniques to various biomedical and industrial problems. He is (co)author of over 150 refereed scientific articles on biomedical image processing and computer vision and has supervised 5 PhD students. Franjo Pernuš is Associate Editor of the IEEE Transactions on Medical Imaging (2002-), Pattern Recognition Letters (2004-), and Electrotechnical Review (1996-). He co-organized the 1st Workshop on Biomedical Image Registration (1999) and was Guest Co-Editor of the special issue on Biomedical Image Registration of the Image Vision Computing Journal. From 2002 to 2006 he was the Chair of Technical Committee 9 (Biomedical Image Analysis) of the International Association for Pattern Recognition and since 2005 he is the member of the Bio Imaging and Signal Processing Technical Committee of the IEEE Signal Processing Society. From 1997 to 2001 he was the President of the Slovenian Pattern Recognition Society. Prof. Pernuš is co-founder of Sensum, a company, which supplies machine vision solutions for the pharmaceutical industry.

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