%0 Journal Article
%@ 1361-6560
%A Luu Manh, Ha
%A Moelker, Adriaan
%A Klein, Stefan
%A Niessen, Wiro
%A Walsum, Theo van
%D 2018
%F SisLab:3046
%I IOP
%J Physics in Medicine & Biology
%N 17
%T Quantification of non-rigid liver deformation in radiofrequency ablation interventions using image registration
%U https://eprints.uet.vnu.edu.vn/eprints/id/eprint/3046/
%V 63
%X Multi-modal image fusion for image guidance in minimally invasive liver interventions generally requires a registration of pre-operatively acquired images to interventional images of the patient. Whereas rigid registration approaches are fast and can be used in an interventional setting, the actual liver deformation may be non-rigid. The purpose of this paper is to assess the magnitude of non-rigid deformation of the liver between pre-operative and interventional CT images in case of tumor ablations, over the full liver and over parts of the liver that match the volumes typically imaged by a 3D ultrasound transducer. We acquired 3D abdominal CT scans of 38 patients that underwent radiofrequency ablation of liver tumors, pre-operative CT images as well as intra-operative CT images. To determine the magnitude of liver deformation due to pose changes and respiration, we non-rigidly registered the pre-operative CT scan to the intra-operative CT scan. By fitting this deformation to a rigid transformation in a region of interest and computing the residual displacements, the non-rigid deformation part can be quantified. We performed quantifications over the complete liver, as well as for two volumes of interest representative for sub-xiphoidal and inter-costal 3D ultrasound acquisitions. The results showed that a substantial amount of non-rigid deformation was found, and rotation of patient's pose and deep inhalation caused significant liver deformation. Hence we concluded that non-rigid motion correction in the interventions should be taken into account.