Ultrasound-based navigation for surgical removal of liver lesions : a feasibility study of MRI-ultrasound fusion in the operation theatre

Smit, J.N. (2017) Ultrasound-based navigation for surgical removal of liver lesions : a feasibility study of MRI-ultrasound fusion in the operation theatre.

Abstract:Surgical navigation is needed for precise localization of liver lesions and the surrounding structures, however, conventional navigation is not applicable. While preoperative surgery plans based on preoperative imaging give detailed information about the patient-specific anatomy, this is not up-to-date in the intraoperative situation due to flexibility and deformation of the liver. Therefore, navigation for liver surgery requires real-time fusion of preoperative surgery plans and MR scans with intraoperative ultrasound. In this thesis, the goal was to determine the feasibility of ultrasound-based navigation for surgical resection of liver lesions. For that purpose, the PercuNav co-registration ultrasound system was used. A deformable multimodal liver phantom was developed to test MR-US coregistration. Raw data analysis of the used co-registration software was impeded, hence alternative accuracy assessment methods have been developed. With and without deformation, this resulted in registration errors of 5-10 mm in the -2 and +2 cm areas around the registration center after point-based registration. Similar registration errors were achieved in ex vivo environments. In these experiments, three resected liver specimens with multiple lesions were used. Point-based registration showed good matching of the tumor regions between MR and US images. Deformation of the specimens due to a lack of blood flow and vessel collapse made further analysis difficult. Automatic detection of points for co-registration accuracy assessment was tested to replace manual point selection. The SIFT-based algorithm that was developed, was not sufficient between these modalities. Due to logistical limitations, intraoperative introduction of the setup was performed once. Possible benefits have been demonstrated in the case of vanishing and isoechoic lesions, as well as restrictive limitations of the current setup. A different transducer, EM field generator, co-registration method and image interface are preferred. These factors are taken into account for the development of an in-house system, for which development steps are described. It is concluded that ultrasound-based navigation by means of electromagnetic tracking is possible and shows feasibility for its intraoperative introduction during open liver surgery. Further implementation was impeded by limitations of the used system. It is expected that a satisfactory accuracy of 5-10 mm in a 4.0x4.0x4.0 cm volume is feasible in the to-be developed system, just as in the used system during this thesis.
Item Type:Essay (Master)
Faculty:TNW: Science and Technology
Subject:44 medicine, 50 technical science in general
Programme:Technical Medicine MSc (60033)
Link to this item:http://purl.utwente.nl/essays/73660
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