Proximity Map Projection: Interactive Visualisation for Image-Guided Surgery

Abstract

This thesis describes a new interface technique for neurosurgeons and interventional radiologists performing image-guided therapies such as the ablation of brain tumours. This new technique is called Proximity Map Projection (PMP).

Based on an analysis of related work, including the documented recent progress in enabling technologies, a case is made that present-day interactive visualisations supporting image-guided treatment of tumours will need to be dramatically improved to take advantage of the increased image refresh rates available as soon as 2020. This probable requirement for improved visualisation technology in the very near future motivated the invention and investigation of the PMP technique described in this thesis. The PMP technique is an interactive 2-D visual projection of the proximity of two 3-D surfaces – in particular, the surface representing the boundary of a thermal treatment region, and the surface of a tumour that is the target of this treatment. By clicking on interesting points in the PMP, surgeons are able to quickly select the 2-D MRI slices corresponding to those interesting points. The PMP provides a quick way of selecting a desired image from a large stack of 2-D MRI data, thus freeing up surgeons to spend a greater proportion of their time applying their expertise to decision making, rather than to navigating through image data.

In this thesis, the PMP technique is presented and then refined as user studies are undertaken. In a series of investigations exploring its effectiveness, it is shown that the PMP technique enables non-expert users to quickly and accurately navigate to, and observe, desired individual medical images within large stacks of such images. A further experiment finds no significant differences in the way that medically experienced and inexperienced users use PMP to complete tasks. That study also verifies that users pay visual attention to PMP, regardless of whether or not they have interacted with it via the mouse. Observation of the visual attention of users during simulated tasks is used to provide further explanation of why PMP is effective. PMP’s potential to be used by medical professionals is then assessed via a series of semi-structured interviews with surgeons and interventional radiologists. Such experts are found to be optimistic about the potential for PMP to be incorporated into their workflows. This last phase of the research then culminates with observations of a number of medical procedures on human patients that are similar to the kinds of procedures to which PMP might be applied. From these observations it appears that, while they do enable life-saving therapies, present software interfaces are not entirely satisfying for the surgeons who use them. Opportunities for significant future research collaborations were identified during these interviews and observations.

This thesis concludes by describing a practical path towards achieving its ultimate goal: the use of PMP in real-time image-guided medical procedures on human patients. Key activities on this path include: integration of PMP into the training and simulation version of a collaborator’s therapy system; conducting a case study to allow further refinement of the PMP technique; and inclusion of PMP in a clinical trial with surgeons. Show more