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Proceedings Paper

Automatic alignment of pre- and post-interventional liver CT images for assessment of radiofrequency ablation
Author(s): Christian Rieder; Stefan Wirtz; Jan Strehlow; Stephan Zidowitz; Philipp Bruners; Peter Isfort; Andreas H. Mahnken; Heinz-Otto Peitgen
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Paper Abstract

Image-guided radiofrequency ablation (RFA) is becoming a standard procedure for minimally invasive tumor treatment in clinical practice. To verify the treatment success of the therapy, reliable post-interventional assessment of the ablation zone (coagulation) is essential. Typically, pre- and post-interventional CT images have to be aligned to compare the shape, size, and position of tumor and coagulation zone. In this work, we present an automatic workflow for masking liver tissue, enabling a rigid registration algorithm to perform at least as accurate as experienced medical experts. To minimize the effect of global liver deformations, the registration is computed in a local region of interest around the pre-interventional lesion and post-interventional coagulation necrosis. A registration mask excluding lesions and neighboring organs is calculated to prevent the registration algorithm from matching both lesion shapes instead of the surrounding liver anatomy. As an initial registration step, the centers of gravity from both lesions are aligned automatically. The subsequent rigid registration method is based on the Local Cross Correlation (LCC) similarity measure and Newton-type optimization. To assess the accuracy of our method, 41 RFA cases are registered and compared with the manually aligned cases from four medical experts. Furthermore, the registration results are compared with ground truth transformations based on averaged anatomical landmark pairs. In the evaluation, we show that our method allows to automatic alignment of the data sets with equal accuracy as medical experts, but requiring significancy less time consumption and variability.

Paper Details

Date Published: 17 February 2012
PDF: 8 pages
Proc. SPIE 8316, Medical Imaging 2012: Image-Guided Procedures, Robotic Interventions, and Modeling, 83163E (17 February 2012); doi: 10.1117/12.911188
Show Author Affiliations
Christian Rieder, Fraunhofer MEVIS (Germany)
Stefan Wirtz, Fraunhofer MEVIS (Germany)
Jan Strehlow, Fraunhofer MEVIS (Germany)
Stephan Zidowitz, Fraunhofer MEVIS (Germany)
Philipp Bruners, RWTH Aachen Univ. Hospital (Germany)
Peter Isfort, RWTH Aachen Univ. Hospital (Germany)
Andreas H. Mahnken, RWTH Aachen Univ. Hospital (Germany)
Heinz-Otto Peitgen, Fraunhofer MEVIS (Germany)

Published in SPIE Proceedings Vol. 8316:
Medical Imaging 2012: Image-Guided Procedures, Robotic Interventions, and Modeling
David R. Holmes III; Kenneth H. Wong, Editor(s)

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