Current Projects
Image Registration for Intra-operative Guidance in the iMR Scanner
Medical images obtained from different sources such as Magnetic Resonance Imaging (MR), x-Rays (XR), Positron Emission Tomography (PET), etc. are increasingly being used simultaneously via image registration techniques for medical diagnosis, treatment, surgery and research. Depending on the application, registration can be used for different modalities, for different patients and/or for different time points. In this project we will deal with the registration of MRI images from the same patient at different times. Before the surgery, an MR scanner provides high-resolution images from the patient and, during the surgery, an interventional MR (iMR) scanner provides near real time low-resolution images. Due to the fact that the MR scanner provides better soft tissue contrast and overall better quality images, it is desirable to register images from the iMR with images from the MR scanner during the surgery to allow the surgeon to make use of the detailed anatomy present in the high resolution images. The iMR scanner at St Mary’s Hospital is mainly used for Gastro-intestinal surgery. This type of surgery involves considerable deformation of anatomical structures; therefore, adequate non-rigid registration algorithms able to cope with such deformation are required in order to use pre-operative MR data during a procedure.
Modelling and assessment of surgical dexterity using synchronised video-motion analysis and Hidden Markov Models
The introduction of Minimally Invasive Surgery (MIS) in the early 1980s changed the way operations are performed. Smaller incisions, trauma minimization, faster recovery time and less pain are some of the advantages of MIS. Endoscopic surgery also brought difficulties to the surgeons including instrument manipulation problems, hand movement constraints and the need for continuous training and assessment. The role of an objective system providing feedback regarding surgical dexterity has become critical and various techniques have been investigated including motion analysis, video scoring, etc. Analysis of the movements performed by the hands of the surgeon has been thoroughly validated and is widely used to assess technical skill due to its reliability and speed of calculation. However, this type of analysis provides quantitative metrics that are only indirectly related to the quality of the task/operation. Video-based assessment tools such as the Objective Structured Assessment of Technical Skills (OSATS) are also commonly used as they enable a more qualitative assessment of performance, but they are time consuming and reliability between observers can be an issue. A system combining these two methodologies to provide an integrated assessment tool that allows for the generation of both global and task specific reliable quantitive metrics and facilitates the indexation of the video footage for qualitative evaluation is thus highly desirable. It is the aim of this project to develop an integrated surgical assessment system for laparoscopic and robotic surgery using synchronised video-motion analysis and stochastic modelling based on Hidden Markov Models.
Robotic and Haptic Systems for Minimally Invasive Surgery: telemanipulator approach
The introduction of surgical robots in minimally invasive surgery and changes in instrumentation are aimed at improving the dexterity in a confined surgical space. Improvements in endoscopic technology, such as the introduction of video direct 3-D vision, are helping the transformation of conventional “open” procedures into minimally invasive robotically assisted ones. Nevertheless, when internal organs are not in view, more information is required to make a decision. During robotically assisted cardiac surgery where only an enclosed and small area of the heart is visible, there are forbidden regions (such as those containing veins and arteries) which must be protected, as well as regions in which the robot can freely move. Excessive force can damage or completely destroy tissues or objects. On the other hand, a minimal amount of force is needed for decisive gripping, particularly when gripping solid objects such as needles. The aim of this project is to investigate the requirements for a haptic system in robotically assisted cardiac surgery and to develop the concepts of active constraints in the spatial and force domains.
