Thomas Stüdeli

Use of the Resection Map system as guidance during hepatectomy

BackgroundThe objective of this work is to evaluate a new concept of intraoperative three-dimensional (3D) visualization system to support hepatectomy. The Resection Map aims to provide accurate cartography for surgeons, who can therefore anticipate risks, increase their confidence and achieve safer liver resection.MethodsIn an experimental prospective cohort study, ten consecutive patients admitted for hepatectomy to three European hospitals were selected. Liver structures (portal veins, hepatic veins, tumours and parenchyma) were segmented from a recent computed tomography (CT) study of each patient. The surgeon planned the resection preoperatively and read the Resection Map as reference guidance during the procedure. Objective (amount of bleeding, tumour resection margin and operating time) and subjective parameters were retrieved after each case.ResultsThree different surgeons operated on seven patients with the navigation aid of the Resection Map. Veins displayed in the Resection Map were identified during the surgical procedure in 70.1% of cases, depending mainly on size. Surgeons were able to track resection progress and experienced improved orientation and increased confidence during the procedure.ConclusionsThe Resection Map is a pragmatic solution to enhance the orientation and confidence of the surgeon. Further studies are needed to demonstrate improvement in patient safety.

Augmented Reality for Minimally Invasive Surgery: Overview and Some Recent Advances

Pablo Lamata1,2, Wajid Ali3, Alicia Cano1, Jordi Cornella3, Jerome Declerck2, Ole J. Elle3, Adinda Freudenthal4, Hugo Furtado5, Denis Kalkofen6, Edvard Naerum3, Eigil Samset3, Patricia Sanchez-Gonzalez1, Francisco M. Sanchez-Margallo7, Dieter Schmalstieg6, Mauro Sette8, Thomas Studeli4, Jos Vander Sloten8 and Enrique J. Gomez1 1Universidad Politecnica de Madrid, Spain 2Siemens, United Kingdom 3University of Oslo, Norway 4Delft University of Technology, Netherlands 5Medical Centre Ljubljana, Slovenia 6 Graz University of Technology, Austria 7Minimally Invasive Surgery Centre Jesus Uson, Spain 8University of Leuven, Belgium

Surgical wayfinding and navigation processes in the human body

During minimally invasive therapies (MITs), surgeons and interventionists rely on medical images as cartographic overviews over the working and navigation area in the patient’s body. MITs are reported as highly demanding for the surgeon’s fine motor skills as well as for his cognitive capacities (Berguer 1999). Buess (2008) reports that many surgeons only master know-how for simple MITs and points out that different skill are needed for MITs than for open surgical procedures. MITs are characterized by limited access to the working area and thus also by limited and indirect spatial information. Cognitive load of the surgeon arises from the need not only to maintain spatial awareness but also to make correct decisions and solve problems. Cao and Milgram (2000) could show that the abdominal surgeons use considerable cognitive spatial capacities to maintain spatial awareness in the inner space of the anatomical cavity while operating in the colon with the help of an endoscopic video (colonoscopy). Dominguez (2001) could show differences in decision making and problem solving of experienced surgeons and surgeons in training and highlights their importance for surgical competency and excellence. In order to reduce surgeons and interventionists cognitive workload during MITs, considerable amount of effort is actually undertaken in the development of surgical information and navigation systems. In order to design intuitive tools that support medical experts in their time critical wayfinding and navigation tasks (in a working environment with high risks), a deeper understanding of safe and effective navigation and wayfinding strategies is mandatory. The development process of surgical information and navigation systems and their user interfaces could be substantially supported with a plain model that makes the complex information need–spatial–orientational as well as safety-strategical—comprehensible for designers and engineers. In earlier work (within ARISER network), a plain model has been introduced based on the observed similarities in navigation strategies of surgeons (Studeli et al. 2007) and classical maritime navigators (Bowditch 1995, p. 371ff). Both experts rely on prudent navigation strategies which are described in the model as iterative and multifactor problem solving and quality control cycles (Studeli 2008, 2009). This model has been evaluated positively by four surgeons from different fields (abdominal, cardiac and pelvic surgery). One of the remaining questions was how to incorporate the prominent role of spatial mental models in surgery (e.g. Cao and Milgram 2000). The here presented research describes the analysis of ethnographic data to link the ‘‘iterative and multifactor problem solving and quality control cycles’’ with the five elements of mental models of Lynch (1960). T. Studeli (&) Faculty of Industrial Design Engineering, Delft University of Technology, Landbergstraat 15, 2628 CE Delft, The Netherlands e-mail: t.p.studeli@tudelft.nl

Endoclamp Balloon Visualization and Automatic Placement System

OBJECTIVES Aortic occlusion is one of the most important open discussions in minimally invasive cardiac surgery. Different techniques can be employed, and all have benefits and drawbacks. The objective of our work is to improve the safety of internal aortic occlusion with the Port Access technique, which employs an endoclamp balloon catheter. We propose a combined information and positioning system based on augmented reality technology and robotics in which the position of the balloon can be seen at all times and can be automatically controlled by a robotic actuator. METHODS The system was designed by a multidisciplinary team of engineers, medical doctors, and human factor specialists in a human-centered design approach. We measure the balloon position in real time with a magnetic tracking system. This position is superimposed on a 3-dimensional scan of the patients thorax, with the balloon in the artery shown at all times. The position measurement is also used to control the robotic catheter inserter that places and maintains the balloon position at a specified target. The system was evaluated in 2 user studies that compared it with other visual aids. RESULTS The user tests have shown that the system effectively supports the surgeon in the placement task, with an increase in placement accuracy and a reduction in time compared with the current visualization technique. The users also rated the system as supporting them well. CONCLUSIONS The clinical feasibility of the system was proved. The system provides better visualization and position control and can effectively increase the safety of the procedure. This system has the potential of making Port Access a more attractive technique.

Physiological Parameters Based Control Scheme for Automatic Intravascular Balloon Inflation

A control scheme based on physiological parameters for the inflation of an intra-aortic clamping balloon is presented. Automatic volumetric pumps for the inflation of balloon catheter have been largely developed, although the process modelling for catheter mounted balloon’s inflation has never been discussed. Automatic inflation is a key issue for autonomous positioning and navigation of an intra-aortic catheter. This work explores the possibility of modelling the inflation process for a catheter mounted balloon, proposing a first order model. The pole’s position depends by the catheter’s hydraulic resistance and by the sum of the aorta’s and balloon’s compliance. Main advance of this control scheme is the fact of taking into account a physiological parameter, integrating it in the control algorithm. The estimation of the aorta’s compliance can be done either with in-vitro experiments or at the same time while controlling the pump by means of an adaptive control scheme. The scheme was applied to control a volumetric pump and tested in vitro and in vivo, showing a reasonable settling time, rise time and overshoot.