Tracking of liver metastases during surgery

Image-guided navigation surgery allows for full utilization of pre-operative imaging during surgery, and has the potential of reducing both irradical resections and morbidity. This is in liver surgery the first pilot study towards clinical implementation.

Image-guided navigation surgery allows the optimal use and full integration of pre-operative images during surgical procedure, and has the potential of reducing both irradical resections and morbidity. This pilot study investigates the potential of this new technique in liver surgery.

The objective of this feasibility study is to evaluate the accuracy of an in‐house developed electromagnetic navigation system to determine the distance from the resection margin to tumor tissue during liver surgery.

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On the day of surgery, three reusable electromagnetic (EM) patient trackers are placed on the back of the patient. Additionally, a single 6 degrees of freedom EM reference-marker and three surgical clips are attached to the liver with medical glue in close proximity to the tumor, but within the area that is planned to be removed by a surgery. This reference‐marker, which is placed at the start of the surgical procedure, will be used as a beacon for the EM navigation procedure, while surgical clips will be utilized for system’s accuracy verification. To subsequently correlate the precise position of the beacon to the pre-operative diagnostic CT or MR images, an intra‐operative contrast enhanced breath hold XperCT scan will be acquired once the beacon is in place. The images from this XperCT will be fused with the pre-operative diagnostic CT/MR which allows us to exactly visualize the position of the beacon on the diagnostic pre-operative CT scan.

During the following surgical procedure, anatomical structures and metastatic lesions can be identified using a blunt EM guidance probe of the electromagnetic navigation system. The accuracy of the EM system will be determined by measuring at several spots on the resection plane the distance from the resection plane to tumor tissue. These measurements will afterwards be correlated to corresponding distances in intraoperative XperCT image, which will be considered as a “gold” standard. Total time of the proposed intra-operative scan, including the planned accuracy measurements of the EM system, will take no longer than 30 minutes. Subsequent resection of the liver tumor will be performed according to standard surgical techniques. This is a feasibility study to evaluate the overall performance and accuracy of the surgical navigation system during surgery, without any impact on the surgical procedure itself.