Marius Schwalbe

A clinically applicable laser-based image-guided system for laparoscopic liver procedures

PurposeLaser range scanners (LRS) allow performing a surface scan without physical contact with the organ, yielding higher registration accuracy for image-guided surgery (IGS) systems. However, the use of LRS-based registration in laparoscopic liver surgery is still limited because current solutions are composed of expensive and bulky equipment which can hardly be integrated in a surgical scenario.MethodsIn this work, we present a novel LRS-based IGS system for laparoscopic liver procedures. A triangulation process is formulated to compute the 3D coordinates of laser points by using the existing IGS system tracking devices. This allows the use of a compact and cost-effective LRS and therefore facilitates the integration into the laparoscopic setup. The 3D laser points are then reconstructed into a surface to register to the preoperative liver model using a multi-level registration process.ResultsExperimental results show that the proposed system provides submillimeter scanning precision and accuracy comparable to those reported in the literature. Further quantitative analysis shows that the proposed system is able to achieve a patient-to-image registration accuracy, described as target registration error, of

Multi-Operational Selective Computer-Assisted Targeting of hepatocellular carcinoma—Evaluation of a novel approach for navigated tumor ablation

3.2\pm 0.57\,\hbox {mm}

Design and implementation of an electromagnetic ultrasound-based navigation technique for laparoscopic ablation of liver tumors

3.2±0.57mm.ConclusionsWe believe that the presented approach will lead to a faster integration of LRS-based registration techniques in the surgical environment. Further studies will focus on optimizing scanning time and on the respiratory motion compensation.

Feasibility of stereotactic MRI-based image guidance for the treatment of vascular malformations: a phantom study

Abstract Background: The benefits of using navigation technology for percutaneous local ablation of selected hepatocellular carcinoma (HCC) have been shown. Due to additional efforts in the procedural workflow, barriers to introducing navigation systems on a broad clinical level remain high. In this work, initial steps toward a novel concept for simple and precise targeting of HCC are evaluated. Material and methods: The proposed technique is based on an angiographic approach using an intrahepatic electromagnetic (EM) reference, for consecutive percutaneous navigated positioning of ablation probes. We evaluated the environmental influence of the angiography suite on EM tracking accuracy, the measurement of a 3 D offset from two 2 D fluoroscopy images, and the accuracy and efficiency of the proposed approach in a porcine liver model. Results: The C-arm had a major influence on EM tracking accuracy, with an error up to 3.8 mm. The methodology applied for measurement of a 3 D offset from 2 D fluoroscopy images was confirmed to be feasible with a mean error of 0.76 mm. In the porcine liver model experiment, the overall target positioning error (TPE) was 2.0 mm and time for navigated targeting was 17.9 seconds, when using a tracked ablation probe. Conclusions: The initial methodology of the proposed technique was confirmed to be feasible, introducing a novel concept for simple and precise navigated targeting of HCC.

CURAC 2016 Tagungsband: 15. Jahrestagung der Deutschen Gesellschaft für Computer- und Roboterassistierte Chirurgie e.V., 29.09. – 01.10.2016, Bern

Objective To facilitate precise local ablation of hepatocellular carcinoma (HCC) in a setting of combined ablation and transarterial chemoembolization (TACE), we evaluated accuracy and efficiency of a novel technique for navigated positioning of ablation probes using intrahepatic tumor referencing and electromagnetic (EM) guidance, in a porcine model. Methods An angiographic wire with integrated EM reference sensor at its tip was inserted via a transarterial femoral access and positioned in the vicinity of artificial liver tumors. The resulting offset distance between the tumor center and the intrahepatic endovascular EM reference was calculated. Subsequently, EM tracked ablation probes were inserted percutaneously and navigated toward the tumor center, relying on continuous EM guidance via the intrahepatic reference. Targeting accuracy was assessed as the Euclidean distance between the tip of the ablation probe and the tumor center (Target Positioning Error, TPE). Procedural efficiency was assessed as time efforts for tumor referencing and tumor targeting. Results In 6 animals, 124 targeting measurements were performed with an offset distance < 30 mm (clinically most feasible position), resulting in a mean TPE of 2.9 ± 1.6 mm. No significant correlation between the TPE and different intrahepatic offset distances (range 21 to 61 mm, n = 365) was shown as long as the EM reference was placed within the liver. However, the mean TPE increased when placing the EM reference externally on the animal skin (p < 0.01). TPE was similar when targeting under continuous ventilation or in apnea (p = 0.50). Mean time for tumor referencing and navigated targeting was 6.5 ± 3.8 minutes and 14 ± 8 seconds, respectively. Conclusion The proposed technique allows precise and efficient navigated positioning of ablation probes into liver tumors in the animal model. We introduce a simple approach suitable for combined ablation and TACE of HCC in a single treatment session.

Virtual angiography of complex vascular networks to assist arteriovenous malformation therapy

The treatment of vascular malformations requires the placement of needles in anatomically non-well defined, pathological vessels that can be as small as 1 mm. The procedure currently relies primarily on two-dimensional fluoroscopic and ultrasonic images for guidance. We hypothesize that the combination of stereotactic image guidance with existing targeting methods can achieve a reliable and fast placement of the needle while resulting in low radiation exposure and contrast agent dosages. We herein present an evaluation of the integration of a stereotactic image guidance system into the workflow for the treatment of these malformations in a clinical pilot study. Specifically, we evaluated the supported placement of percutaneous needles for the treatment of the malformations. Preliminary results of the first four patients are presented.