Sven Mieog

Master thesis (2)

2 records found

CT-Based Quantification of Tissue Shrinkage in Thermal Ablation of Hepatocellular Carcinoma

Master thesis (2025) - C.J. Wang (author) , M. C. Burgmans (mentor) , Alexander Broersen (mentor) , Gonnie van Erp (mentor) , Jifke Veenland (graduation committee member) , Sven Mieog (graduation committee member)

Background: Tissue shrinkage is a poorly understood phenomenon that might occur during thermal ablation (TA) of hepatocellular carcinoma (HCC). It may lead to underestimation of the minimal ablation margin (MAM), a key determinant of technical success of TA.
Objective: The objective of this study was to explore three computed tomography (CT) based methods to quantify tissue shrinkage in TA of HCC: marker-based, vessel-based, and image-based.
Methods: This single-centre study used immediate pre- and post-ablation contrast-enhanced computed tomography (CECT) scans from the prospective PROMETHEUS database. Patients were treated in the Leiden University Medical Center (LUMC) with radiofrequency ablation (RFA) or microwave ablation (MWA) and scanned during high-frequency jet ventilation (HFJV) or during apnoea. Patients with < 5 mm of craniocaudal liver displacement were included in this study. Mean distance between landmarks on pre-ablation scans was compared to that on post-ablation scans for the marker-based quantification. Mean difference between pre- and post-ablation vessel tree to ablation surface was compared for the vessel-based quantification. The image-based method used Jacobian determinant (JD) analysis to quantify voxel-wise volume changes.
Results: 10 patients with a total of 12 tumours were included in this study. Mean (standard deviation, SD) marker-based shrinkage was -1.24 (2.45) mm. Median (interquartile range, IQR) difference in vessel-to-ablation distance between pre- and post-ablation vessels within the ablation zone and a 10-mm margin was 0.07 (-0.08–0.11) mm. The image-based quantification method yielded a median (IQR) JD value of 1.01 (0.98–1.02), indicating a 1% increase in volume in the ablation zone and a 10-mm margin.
Conclusion: Based on the study results, no conclusions can be drawn on whether tissue shrinkage occurs in vivo. Clinical use of the CT-based quantification methods described in this study is limited by validation challenges. Future work should start with establishing a ground truth for tissue shrinkage.

Robotic Microwave Ablation of Liver Tumours

From Concept to Clinical Integration

Master thesis (2025) - G.P.M. Franssen (author) , T. Horeman-Franse (mentor) , Matteo Fusaglia (graduation committee member) , Koert Kuhlmann (graduation committee member) , Sven Mieog (graduation committee member)

Microwave ablation is a technique used for treating patients with colorectal liver metastases. Patients ineligible for liver surgery can often times still be treated using microwave ablation. While liver resection is increasingly performed using a robotic surgery system, microwav ...

Microwave ablation is a technique used for treating patients with colorectal liver metastases. Patients ineligible for liver surgery can often times still be treated using microwave ablation. While liver resection is increasingly performed using a robotic surgery system, microwave ablation of liver tumours cannot yet be performed robotically, as no robotic ablation device exists. This thesis aims to develop and evaluate a functioning prototype of a robotic ablation device by testing its technical performance and investigating how it could be used in clinical settings. Several tests were performed to evaluate the technical functionality of the robotic ablation device and to compare it to existing microwave ablation techniques. Additionally, the clinical conditions in which the device would be used were studied and a realistic test environment was set up to mimic real procedures and gather surgeon feedback on possible changes of the design. Test results confirmed the technical functionality and clinical feasibility of the robotic ablation device. Feedback from surgeons experienced in robotic surgery and liver ablation further supported its clinical feasibility for treating colorectal liver metastases. This thesis successfully developed and evaluated a functional prototype of a robotic ablation device, including both its technical and clinical aspects. Future work should improve certain design elements of the device, such as the handle and the shaft, and increase the realism of the phantom test environment. Performing a cadaver study is recommended to assess the device under conditions closely resembling the real clinical setting, to gather the most relevant feedback.