A Novel System and Image Processing for Improving 3D Ultrasound-guided Interventional Cancer Procedures

Image-guided medical interventions are diagnostic and therapeutic procedures that focus on minimizing surgical incisions for improving disease management and reducing patient burden relative to conventional techniques. Interventional approaches, such as biopsy, brachytherapy, and ablation procedures, have been used in the management of cancer for many anatomical regions, including the prostate and liver. Needles and needle-like tools are often used for achieving planned clinical outcomes, but the increased dependency on accurate targeting, guidance, and verification can limit the widespread adoption and clinical scope of these procedures. Image-guided interventions that incorporate 3D information intraoperatively have been shown to improve the accuracy and feasibility of these procedures, but clinical needs still exist for improving workflow and reducing physician variability with widely applicable cost-conscience approaches. The objective of this thesis was to incorporate 3D ultrasound (US) imaging and image processing methods during image-guided cancer interventions in the prostate and liver to provide accessible, fast, and accurate approaches for clinical improvements. An automatic 2D-3D transrectal ultrasound (TRUS) registration algorithm was optimized and implemented in a 3D TRUS-guided system to provide continuous prostate motion corrections with sub-millimeter and sub-degree error in 36 ± 4 ms. An automatic and generalizable 3D TRUS prostate segmentation method was developed on a diverse clinical dataset of patient images from biopsy and brachytherapy procedures, resulting in errors at gold standard accuracy with a computation time of 0.62 s. After validation of mechanical and image reconstruction accuracy, a novel 3D US system for focal liver tumor therapy was developed to guide therapy applicators with 4.27 ± 2.47 mm error. The verification of applicators post-insertion motivated the development of a 3D US applicator segmentation approach, which was demonstrated to provide clinically feasible assessments in 0.246 ± 0.007 s. Lastly, a general needle and applicator tool segmentation algorithm was developed to provide accurate intraoperative and real-time insertion feedback for multiple anatomical locations during a variety of clinical interventional procedures. Clinical translation of these developed approaches has the potential to extend the overall patient quality of life and outcomes by improving detection rates and reducing local cancer recurrence in patients with prostate and liver cancer

Liver metastases from colorectal cancer

Introduction: Colorectal cancer (CRC) is the third most common cancer worldwide. At diagnosis of CRC 20-25% of patients have metastatic disease. The liver is the most common metastatic site and liver metastases are detected in 25-30% of all patients. A quarter of these patients are amenable for liver resection that results in a five-year survival exceeding 50%. The indications for liver resection continue to broaden and are no longer limited by number and size of liver metastases nor the presence of extrahepatic metastases. Currently liver resection is indicated when macroscopic tumour clearance can be achieved with preservation of a sufficient future liver remnant. Different strategies to improve resectability exist such as portal vein occlusion, two-stage resections, associating liver partition and portal vein ligation for staged hepatectomy and thermal ablation, mainly radiofrequency ablation or microwave ablation (MWA). Decisions on management of patients with metastatic CRC should ideally be made in a multidisciplinary team (MDT) setting. Failing to do so may result in suboptimal management and patients that could be resected are not necessarily offered curative-intended treatment. As a result of this there are known regional differences in the treatment of patients with liver metastases that may affect survival. For patients not suitable for resection, either due to the metastatic burden or comorbidity omitting extensive surgery, local ablation is an option. Aims: The aim of Study I was to provide detailed population-based data of liver metastatic patterns, treatment and survival in patients with metastatic CRC. In Study II, the potentially improved resection rates were evaluated in a scenario where all patients with liver metastatic disease, irrespective of extrahepatic metastases, were assessed by a liver MDT. Study III aimed to describe the feasibility and safety of a multiple MWA strategy in patients with initially unresectable liver metastases. The primary aim of Study IV was to evaluate the accuracy and safety of antenna placement in stereotactic computed tomography-guided MWA of primary and secondary liver tumours. The secondary aims of Study IV were to evaluate the feasibility of the navigation system, to measure the procedure-related radiation dose and to assess the safety of high-frequency jet ventilation for target motion control. Patients and Methods: In Studies I and II, a population-based cohort consisting of all patients diagnosed with CRC in the Stockholm and Gotland region during 2008, identified from the Swedish Colorectal Cancer Registry, was used. Details of metastatic spread, referral to a MDT conference and oncologic and surgical treatment were retrieved from electronic patient charts and recorded during a five-year follow-up period or until death. Predictors of survival in Studies I and III were estimated using a Cox proportional hazards model. Survival curves were illustrated using Kaplan-Meier estimates and survival functions were compared using the log-rank test (Studies I-III). For Study II, additional information on American Society of Anesthesiologists grade, comorbidity and patients’ own preferences towards treatment, were retrieved for the 272 patients with liver metastases. Each patient was presented at a fictive liver MDT conference, irrespective of previous management, and categorized as resectable, potentially resectable or unresectable. Treatment decisions were compared with the original management and factors associated with referral to the liver MDT were assessed using logistic regression. In Study III, a multiple MWA strategy was applied to 20 patients with initially unresectable liver metastases between October 2009 and September 2012. The feasibility and safety of the procedure as well as local recurrence rate was recorded. Overall and disease-free survival in the ablated group was compared with results from two historic cohorts from Study I, one treated palliatively and the other resected. In Study IV 20 patients with primary or secondary liver malignancy, where surgical resection was contraindicated or the lesions were not visible on ultrasound, were included for treatment with percutaneous MWA using a stereotactic navigation system (Cascination AG, Bern, Switzerland) that shows the actual position of the tracked antenna in real time with respect to pre-operative CT images. Descriptive statistics were used to evaluate the accuracy of antenna placement, the number of antenna readjustments, safety and radiation dose. Results: In Study I 1026 patients with CRC were identified and liver metastases were detected in 272 (26.5%). Liver and lung metastases were more often diagnosed in hindgut (splenic flexure to rectum) compared with midgut cancer (caecum to splenic flexure) (28.4% versus 22.1%, p=0.029 and 19.7% versus 13.2%, p=0.010, respectively) but the extent of liver metastases was less for hindgut compared with midgut cancer (p=0.001). Five-year OS was significantly worse in liver metastatic midgut cancer compared with hindgut cancer (6.5% vs. 21.6%, p10 liver metastases), while male gender (OR 1.39, CI 0.84-2.30) and treatment at a teaching hospital (OR 1.06, CI 0.62-1.81) were not. In Study III, the ablated group showed a four-year overall survival of 41% compared with 70% for the historic cohort of resected patients and 4% for palliatively treated patients. Eighteen patients had recurrence in the liver, 11 had extrahepatic recurrence and 10 out of 20 treated patients were alive at a median follow-up of 25 months. In Study IV, the antenna was placed with a mean target error of 5.83.2 mm in relation to the intended target at a mean total radiation dose of 958557 mGy x cm. Conclusions: Study I: Detailed population-based data on the metastatic pattern of CRC and survival could assist in more structured and individualized guidelines for follow-up of patients with CRC as well as personalized treatment, based on factors other than resectability as currently defined. Study II: A meaningful number of patients with liver metastases were not managed according to best available evidence and the potential for higher resection rates is considerable. Study III: The highly selected patients treated with a multiple MWA strategy had a survival benefit compared with patients treated with palliative chemotherapy but the recurrence rate was high. Study IV: Sufficient accuracy was achieved using percutaneous MWA with stereotactic navigation

Augmented reality for computer assisted orthopaedic surgery

In recent years, computer-assistance and robotics have established their presence in operating theatres and found success in orthopaedic procedures. Benefits of computer assisted orthopaedic surgery (CAOS) have been thoroughly explored in research, finding improvements in clinical outcomes, through increased control and precision over surgical actions. However, human-computer interaction in CAOS remains an evolving field, through emerging display technologies including augmented reality (AR) – a fused view of the real environment with virtual, computer-generated holograms. Interactions between clinicians and patient-specific data generated during CAOS are limited to basic 2D interactions on touchscreen monitors, potentially creating clutter and cognitive challenges in surgery. Work described in this thesis sought to explore the benefits of AR in CAOS through: an integration between commercially available AR and CAOS systems, creating a novel AR-centric surgical workflow to support various tasks of computer-assisted knee arthroplasty, and three pre–clinical studies exploring the impact of the new AR workflow on both existing and newly proposed quantitative and qualitative performance metrics. Early research focused on cloning the (2D) user-interface of an existing CAOS system onto a virtual AR screen and investigating any resulting impacts on usability and performance. An infrared-based registration system is also presented, describing a protocol for calibrating commercial AR headsets with optical trackers, calculating a spatial transformation between surgical and holographic coordinate frames. The main contribution of this thesis is a novel AR workflow designed to support computer-assisted patellofemoral arthroplasty. The reported workflow provided 3D in-situ holographic guidance for CAOS tasks including patient registration, pre-operative planning, and assisted-cutting. Pre-clinical experimental validation on a commercial system (NAVIO®, Smith & Nephew) for these contributions demonstrates encouraging early-stage results showing successful deployment of AR to CAOS systems, and promising indications that AR can enhance the clinician’s interactions in the future. The thesis concludes with a summary of achievements, corresponding limitations and future research opportunities.Open Acces

A minimally invasive surgical system for 3D ultrasound guided robotic retrieval of foreign bodies from a beating heart

The result of various medical conditions and trauma, foreign bodies in the heart pose a serious health risk as they may interfere with cardiovascular function. Particles such as thrombi, bullet fragments, and shrapnel can become trapped in a person's heart after migrating through the venous system, or by direct penetration. The severity of disruption can range from benign to fatal, with associated symptoms including anxiety, fever, cardiac tamponade, hemorrhage, infection, embolism, arrhythmia, and valve dysfunction. Injuries of this nature are common in both civilian and military populations. For symptomatic cases, conventional treatment is removal of the foreign body through open surgery via a median sternotomy, the use of cardiopulmonary bypass, and a wide incision in the heart muscle; these methods incur pronounced perioperative risks and long recovery periods. In order to improve upon the standard of care, we propose an image guided robotic system and a corresponding minimally invasive surgical approach. The system employs a dexterous robotic capture device that can maneuver inside the heart through a small incision. Visualization and guidance within the otherwise occluded internal regions are provided by 3D transesophageal echocardiography (TEE), an emerging form of intraoperative medical imaging used in interventions such as mitral valve repair and device implantation. A robotic approach, as opposed to a manual procedure using rigid instruments, is motivated by the various challenges inherent in minimally invasive surgery, which arise from attempts to perform skilled surgical tasks through small incisions without direct vision. Challenges include reduced dexterity, constrained workspace, limited visualization, and difficult hand-eye coordination, which ultimately lead to poor manipulability. A dexterous robotic end effector with real-time image guidance can help overcome these challenges and potentially improve surgical performance. However promising, such a system and approach require that several technical hurdles be resolved. The foreign body must be automatically tracked as it travels about the dynamic environment of the heart. The erratically moving particle must then be captured using a dexterous robot that moves much more slowly in comparison. Furthermore, retrieval must be performed under 3D ultrasound guidance, amidst the uncertainties presented by both the turbulent flow and by the imaging modality itself. In addressing such barriers, this thesis explores the development of a prototype system capable of retrieving a foreign body from a beating heart, culminating in a set of demonstrative in vitro experiments