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Template-based CTA X-ray Angio Rigid Registration of Coronary Arteries in Frequency Domain
Authors: Timur Aksoy, Stefanie Demirci, Muzaffer Degertekin, Nassir Navab, Gozde Unal
Published in: SPIE 2013
Publication year: 2013
Abstract: This study performs 3D to 2D rigid registration of segmented pre-operative CTA coronary arteries with a single
segmented intra-operative X-ray Angio frame in both frequency and spatial domains for real-time Angiography
interventions by C-arm fluoroscopy. Most of the work on rigid registration in literature required a close initial-
ization of poses and/or positions because of the abundance of local minima and high complexity that searching
algorithms face. This study avoids such setbacks by transforming the projections into translation-invariant
Fourier domain for estimating the 3D pose. First, template DRRs as candidate poses of 3D vessels of segmented
CTA are produced by rotating the camera (image intensifier) around the DICOM angle values with a wide range
as in C-arm setup. We have compared the 3D poses of template DRRs with the real X-ray after equalizing
the scales (due to disparities in focal length distances) in 3 domains, namely Fourier magnitude, Fourier phase
and Fourier polar. The best pose candidate was chosen by one of the highest similarity measures returned by
the methods in these domains. It has been noted in literature that these methods are robust against noise and
occlusion which was also validated by our results. Translation of the volume was then recovered by distance-map
based BFGS optimization well suited to convex structure of our objective function without local minima due to
distance maps. Final results were evaluated in 2D projection space rather than with actual values in 3D due to
lack of ground truth, ill-posedness of the problem which we intend to address in future.
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