Philip Pratt

Real-time stereo reconstruction in robotically assisted minimally invasive surgery

The recovery of 3D tissue structure and morphology during robotic assisted surgery is an important step towards accurate deployment of surgical guidance and control techniques in minimally invasive therapies. In this article, we present a novel stereo reconstruction algorithm that propagates disparity information around a set of candidate feature matches. This has the advantage of avoiding problems with specular highlights, occlusions from instruments and view dependent illumination bias. Furthermore, the algorithm can be used with any feature matching strategy allowing the propagation of depth in very disparate views. Validation is provided for a phantom model with known geometry and this data is available online in order to establish a structured validation scheme in the field. The practical value of the proposed method is further demonstrated by reconstructions on various in vivo images of robotic assisted procedures, which are also available to the community.

Augmented Reality Partial Nephrectomy: Examining the Current Status and Future Perspectives

A minimal access approach to partial nephrectomy has historically been under-utilized, but is now becoming more popular with the growth of robot-assisted laparoscopy. One of the criticisms of minimal access partial nephrectomy is the loss of haptic feedback. Augmented reality operating environments are forecast to play a major enabling role in the future of minimal access partial nephrectomy by integrating enhanced visual information to supplement this loss of haptic sensation. In this article, we systematically examine the current status of augmented reality in partial nephrectomy by identifying existing research challenges and exploring future agendas for this technology to achieve wider clinical translation.

Dynamic guidance for robotic surgery using image- constrained biomechanical models

The use of physically-based models combined with image constraints for intraoperative guidance is important for surgical procedures that involve large-scale tissue deformation. A biomechanical model of tissue deformation is described in which surface positional constraints and internally generated forces are derived from endoscopic images and preoperative 4D CT data, respectively. Considering cardiac motion, a novel technique is presented which minimises the average registration error over one or more complete cycles. Features tracked in the stereo video stream provide surface constraints, and an inverse finite element simulation is presented which allows internal forces to be recovered from known preoperative displacements. The accuracy of surface texture, segmented mesh and volumetrically rendered overlays is evaluated with detailed phantom experiments. Results indicate that by combining preoperative and intraoperative images in this manner, accurate intraoperative tissue deformation modelling can be achieved.

An effective visualisation and registration system for image-guided robotic partial nephrectomy

Robotic partial nephrectomy is presently the fastest-growing robotic surgical procedure, and in comparison to traditional techniques it offers reduced tissue trauma and likelihood of post-operative infection, while hastening recovery time and improving cosmesis. It is also an ideal candidate for image guidance technology since soft tissue deformation, while still present, is localised and less problematic compared to other surgical procedures. This work describes the implementation and ongoing development of an effective image guidance system that aims to address some of the remaining challenges in this area. Specific innovations include the introduction of an intuitive, partially automated registration interface, and the use of a hardware platform that makes sophisticated augmented reality overlays practical in real time. Results and examples of image augmentation are presented from both retrospective and live cases. Quantitative analysis of registration error verifies that the proposed registration technique is appropriate for the chosen image guidance targets.

Quantifying Innovation in Surgery

Objectives:The objectives of this study were to assess the applicability of patents and publications as metrics of surgical technology and innovation; evaluate the historical relationship between patents and publications; develop a methodology that can be used to determine the rate of innovation growth in any given health care technology. Background:The study of health care innovation represents an emerging academic field, yet it is limited by a lack of valid scientific methods for quantitative analysis. This article explores and cross-validates 2 innovation metrics using surgical technology as an exemplar. Methods:Electronic patenting databases and the MEDLINE database were searched between 1980 and 2010 for “surgeon” OR “surgical” OR “surgery.” Resulting patent codes were grouped into technology clusters. Growth curves were plotted for these technology clusters to establish the rate and characteristics of growth. Results:The initial search retrieved 52,046 patents and 1,801,075 publications. The top performing technology cluster of the last 30 years was minimally invasive surgery. Robotic surgery, surgical staplers, and image guidance were the most emergent technology clusters. When examining the growth curves for these clusters they were found to follow an S-shaped pattern of growth, with the emergent technologies lying on the exponential phases of their respective growth curves. In addition, publication and patent counts were closely correlated in areas of technology expansion. Conclusions:This article demonstrates the utility of publically available patent and publication data to quantify innovations within surgical technology and proposes a novel methodology for assessing and forecasting areas of technological innovation.

Intraoperative ultrasound guidance for transanal endoscopic microsurgery

Local excision of rectal cancer with transanal endoscopic microsurgery has proved to be a viable alternative to conventional, more radical techniques, but the reduced sensory experience presents significant challenges for the surgeon. Accurate identification and complete removal of lesions and subsurface targets is currently a difficult task, often exacerbated by intraoperative tissue deformation. This work describes novel ultrasound calibration and effective visualisation methods designed to meet these requirements, relying solely on optical measurements and pattern tracking. Detailed quantitative phantom and porcine validation experiments confirm that the technique is both practical and an accurate means for assessing lesion thickness intraoperatively, leading directly to human clinical trials.

Comparative effectiveness of 3-dimensional vs 2-dimensional and high-definition vs standard-definition neuroendoscopy: a preclinical randomized crossover study.

BACKGROUND: Although the potential benefits of 3-dimensional (3-D) vs 2-dimensional (2-D) and high-definition (HD) vs standard-definition (SD) endoscopic visualization have long been recognized in other surgical fields, such endoscopes are generally considered too large and bulky for use within the brain. The recent development of 3-D and HD neuroendoscopes may therefore herald improved depth perception, better appreciation of anatomic details, and improved overall surgical performance. OBJECTIVE: To compare simultaneously the effectiveness of 3-D vs 2-D and HD vs SD neuroendoscopy. METHODS: Ten novice neuroendoscopic surgeons were recruited from a university hospital. A preclinical randomized crossover study design was adopted to compare 3-D vs 2-D and HD vs SD neuroendoscopy. The primary outcomes were time to task completion and accuracy. The secondary outcomes were perceived task workload using the NASA (National Aeronautics and Space Administration) Task Load Index and subjective impressions of the endoscopes using a 5-point Likert scale. RESULTS: Time to task completion was significantly shorter when using the 3-D vs the 2-D neuroendoscopy (P = .001), and accuracy of probe placement was significantly greater when using the HD vs the SD neuroendoscopy (P = .009). We found that 3-D endoscopy significantly improved perceived depth perception (P < .001), HD endoscopy significantly improved perceived image quality (P < .001), and both improved participants’ overall impression (P < .001). CONCLUSION: Three-dimensional neuroendoscopy and HD neuroendoscopy have differing but complementary effects on surgical performance, suggesting that neither alone can completely compensate for the lack of the other. There is therefore strong preclinical evidence to justify 3-D HD neuroendoscopy. ABBREVIATIONS: HD, high definition SD, standard definition

Intraoperative Ultrasound Overlay in Robot-assisted Partial Nephrectomy: First Clinical Experience

Portable workstation with NVIDIA Quadro SDI capture and output cards (NVIDIA, Santa Clara, CA, USA) Hitachi Aloka ProSound ALPHA 10 cart (Hitachi Aloka Medical Ltd., Tokyo, Japan) Hitachi Aloka UST-533 multifrequency linear array microsurgery probe with attached KeySurgical marker dots (KeySurgical Inc., Eden Prairie, MN, USA) Custom probe clip 3D printed in sterilisable Cobalt-Chrome alloy Intraoperative Ultrasound Overlay in Robot-assisted Partial Nephrectomy: First Clinical Experience

Image-guided robotic interventions for prostate cancer

Robotic prostatectomy is a common surgical treatment for men with prostate cancer, with some studies estimating that 80% of prostatectomies now performed in the USA are done so robotically. Despite the technical advantages offered by robotic systems, functional and oncological outcomes of prostatectomy can still be improved further. Alternative minimally invasive treatments that have also adopted robotic platforms include brachytherapy and high-intensity focused ultrasonography (HIFU). These techniques require real-time image guidance—such as ultrasonography or MRI—to be truly effective; issues with software compatibility as well as image registration and tracking currently limit such technologies. However, image-guided robotics is a fast-growing area of research that combines the improved ergonomics of robotic systems with the improved visualization of modern imaging modalities. Although the benefits of a real-time image-guided robotic system to improve the precision of surgical interventions are being realized, the clinical usefulness of many of these systems remains to be seen.

A hand-held instrument for in vivo probe-based confocal laser endomicroscopy during Minimally Invasive Surgery

Probe-based confocal laser endomicroscopy (pCLE) provides high resolution imaging of tissue in vivo. Maintaining a steady contact between target tissue and pCLE probe tip is important for image consistency. In this paper, a new prototype hand-held instrument for in vivo pCLE during Minimally Invasive Surgery (MIS) is presented. The proposed instrument incorporates adaptive force sensing and actuation, allowing improved image consistency and force control, thus minimizing tissue deformation and induced micro-structural variations. The performance and accuracy of the contact force control are evaluated in detailed laboratory settings and in vivo validation of the device during transanal microsurgery in a live porcine model further demonstrates the potential clinical value of the device.