Ultrasound-based navigation during liver resection

Image-guided navigation surgery allows for optimal use and full integration of
3D models based on patient-specific anatomy. Where image-guided techniques have
proven to be useful for localization and visualization of lesions, accurate
guidance during the process of liver resection has not been accomplished yet.
Previous image-guided techniques use preoperative 3D models which in liver
surgery are not up-to-date due to liver tissue deformation. This is the first
feasibility study where navigation is based on 3D models based on
intraoperative ultrasound imaging.

The primary objective of this study is to assess the feasibility of
ultrasound-based navigation for assistance during hepatic resection. Secondary
objectives are 1) to evaluate the ease of use and support for decisiveness
during surgery, 2) to evaluate the time of all study-related actions during the
surgery, and 3) the difference between the planned resection margin and actual
resection margin.

Single center feasibility study. The duration of the study will be one year.

The patient is operated on a surgical bed with a field generator positioned
under the bed or near the head of the patient. The surgical procedure will
start according to the standard practice. After obtaining access to the target
lesion, a sensor is attached close to the targeted tumour and a 3D ultrasound
volume is acquired. After semi-automatic segmentation of this US volume, the
tumour and surrounding vasculature are visualized on a display, together with
the navigated surgical instruments. Surgical clips are placed during the
resection and are pointed at with the navigated pointer to measure distances.
Resection of the tumour continues afterwards.

Participation in the study will not involve additional visits to the hospital
for the included patients. The patients will be recruited in the NKI-AvL.
Patients will primarily be informed about the study during the pre-operative
outpatient clinic appointment by the treating surgeon. Extensive explanation is
consequently provided by the researcher. If time between the outpatient clinic
visit and the scheduled operation date is limited, the patient will be
contacted by telephone to provide them with enough time to consider
participation in the study. After 10 working days, the researcher will contact
the patient by phone to answer questions. If patients approve to inclusion,
written informed consent will be obtained by the researcher before or at
admission to the hospital before the operation.
Surgical decision making takes place based on conventional 2D ultrasound, the
navigation system is only used for accuracy evaluation. A maximal delay of
approximately 15 minutes will be added to the total time of the surgical
procedure. The surgeons are aware of the experimental setup, and are therefore
responsible for the navigation interpretation and actions. The ultimate goal of
this project is to judge the potential use of the navigation setup for further
liver resections.