Thomas Looi

Use of 3-Dimensional Printing Technology and Silicone Modeling in Surgical Simulation: Development and Face Validation in Pediatric Laparoscopic Pyeloplasty

OBJECTIVES Pediatric laparoscopy poses unique training challenges owing to smaller workspaces, finer sutures used, and potentially more delicate tissues that require increased surgical dexterity when compared with adult analogs. We describe the development and face validation of a pediatric pyeloplasty simulator using a low-cost laparoscopic dry-laboratory model developed with 3-dimensional (3D) printing and silicone modeling. DESIGN AND SETTING The organs (the kidney, renal pelvis, and ureter) were created in a 3-step process where molds were created with 3D modeling software, printed with a Spectrum Z510 3D printer, and cast with Dragon Skin 30 silicone rubber. The model was secured in a laparoscopy box trainer. A pilot study was conducted at a Canadian Urological Association meeting. A total of 24 pediatric urology fellows and 3 experienced faculty members then assessed our skills module during a minimally invasive surgery training course. Participants had 60 minutes to perform a right-side pyeloplasty using laparoscopic tools and 5-0 VICRYL suture. Face validity was demonstrated on a 5-point Likert scale. PARTICIPANTS AND RESULTS The dry-laboratory model consists of a kidney, a replaceable dilated renal pelvis and ureter with an obstructed ureteropelvic junction, and an overlying peritoneum with an inscribed fundamentals of laparoscopic surgery pattern-cutting exercise. During initial validation at the Canadian Urological Association, participants rated (out of 5) 4.75 ± 0.29 for overall impression, 4.50 ± 0.41 for realism, and 4.38 ± 0.48 for handling. During the minimally invasive surgery course, 22 of 24 fellows and all the faculty members completed the scoring. Usability was rated 4 or 5 by 14 participants (overall, 3.6 ± 1.22 by novices and 3.7 ± 0.58 by experts), indicating that they would use the model in their own training and teaching. Esthetically, the model was rated 3.5 ± 0.74 (novices) and 3.3 ± 0.58 (experts). CONCLUSIONS We developed a pediatric pyeloplasty simulator by applying a low-cost reusable model for laparoscopic training and skills acquisition. The models usability, realism, and feel are good, it can be imaged under common modalities, and it shows promise as an educational tool.

Application of CAD/CAM prefabricated age-matched templates in cranio-orbital remodeling in craniosynostosis.

Infants with craniosynostosis involving the metopic and coronal sutures require cranio-orbital reshaping to correct craniofacial dysmorphologic feature and to improve facial balance. Currently, surgical techniques to create a balanced fronto-orbital region are based on the surgeons subjective approach and artistic vision in creating a normal shape to the forehead. To date, the use of age-matched templates and computer-assisted design/computer-assisted manufacturing techniques in optimizing the outcomes of surgical intervention in this area have not been explored. The aim of this article was to describe the process of template generation and application based on age-matched controls using computer-assisted design/computer-assisted manufacturing technology and to present this application in 2 cases.

A single arm, single camera system for automated suturing

In this paper, a novel approach for automated suturing is introduced and experimental results are presented. Unlike other similar works, the proposed approach adopts a single arm to implement a suturing task with a standard laparoscopic needle holder and curved suture needle. 3D information is obtained from a clinical (single camera) endoscope through an elliptical/circular pose measurement algorithm, which dynamically tracks the suture needle and surface markers. This drives robotic needle steering through a set of surgeon-defined entry/exit points on a tissue pad phantom. Implementation results indicate good depth resolution (1.5mm) and task repeatability (85%) for a variety of consistency, lighting, and location variation scenarios.

Design and evaluation of a new synthetic brain simulator for endoscopic third ventriculostomy.

OBJECT Endoscopic third ventriculostomy (ETV) is an effective but technically demanding procedure with significant risk. Current simulators, including human cadavers, animal models, and virtual reality systems, are expensive, relatively inaccessible, and can lack realistic sensory feedback. The purpose of this study was to construct a realistic, low-cost, reusable brain simulator for ETV and evaluate its fidelity. METHODS A brain silicone replica mimicking normal mechanical properties of a 4-month-old child with hydrocephalus was constructed, encased in the replicated skull, and immersed in water. Realistic intraventricular landmarks included the choroid plexus, veins, mammillary bodies, infundibular recess, and basilar artery. The thinned-out third ventricle floor, which dissects appropriately, is quickly replaceable. Standard neuroendoscopic equipment including irrigation is used. Bleeding scenarios are also incorporated. A total of 16 neurosurgical trainees (Postgraduate Years 1-6) and 9 pediatric and adult neurosurgeons tested the simulator. All participants filled out questionnaires (5-point Likert-type items) to rate the simulator for face and content validity. RESULTS The simulator is portable, robust, and sets up in minutes. More than 95% of participants agreed or strongly agreed that the simulators anatomical features, tissue properties, and bleeding scenarios were a realistic representation of that seen during an ETV. Participants stated that the simulator helped develop the required hand-eye coordination and camera skills, and the training exercise was valuable. CONCLUSIONS A low-cost, reusable, silicone-based ETV simulator realistically represents the surgical procedure to trainees and neurosurgeons. It can help them develop the technical and cognitive skills for ETV including dealing with complications.

MatMRI and MatHIFU: software toolboxes for real-time monitoring and control of MR-guided HIFU

BackgroundThe availability of open and versatile software tools is a key feature to facilitate pre-clinical research for magnetic resonance imaging (MRI) and magnetic resonance-guided high-intensity focused ultrasound (MR-HIFU) and expedite clinical translation of diagnostic and therapeutic medical applications.In the present study, two customizable software tools that were developed at the Thunder Bay Regional Research Institute are presented for use with both MRI and MR-HIFU. Both tools operate in a MATLAB®; environment. The first tool is named MatMRI and enables real-time, dynamic acquisition of MR images with a Philips MRI scanner. The second tool is named MatHIFU and enables the execution and dynamic modification of user-defined treatment protocols with the Philips Sonalleve MR-HIFU therapy system to perform ultrasound exposures in MR-HIFU therapy applications.MethodsMatMRI requires four basic steps: initiate communication, subscribe to MRI data, query for new images, and unsubscribe. MatMRI can also pause/resume the imaging and perform real-time updates of the location and orientation of images. MatHIFU requires four basic steps: initiate communication, prepare treatment protocol, and execute treatment protocol. MatHIFU can monitor the state of execution and, if required, modify the protocol in real time.ResultsFour applications were developed to showcase the capabilities of MatMRI and MatHIFU to perform pre-clinical research. Firstly, MatMRI was integrated with an existing small animal MR-HIFU system (FUS Instruments, Toronto, Ontario, Canada) to provide real-time temperature measurements. Secondly, MatMRI was used to perform T2-based MR thermometry in the bone marrow. Thirdly, MatHIFU was used to automate acoustic hydrophone measurements on a per-element basis of the 256-element transducer of the Sonalleve system. Finally, MatMRI and MatHIFU were combined to produce and image a heating pattern that recreates the word ‘HIFU’ in a tissue-mimicking heating phantom.ConclusionsMatMRI and MatHIFU leverage existing MRI and MR-HIFU clinical platforms to facilitate pre-clinical research. MatMRI substantially simplifies the real-time acquisition and processing of MR data. MatHIFU facilitates the testing and characterization of new therapy applications using the Philips Sonalleve clinical MR-HIFU system. Under coordination with Philips Healthcare, both MatMRI and MatHIFU are intended to be freely available as open-source software packages to other research groups.

Structurally-redesigned concentric-tube manipulators with improved stability

Concentric-tube manipulators could experience a snapping-through motion that negatively impacts their smooth operation. This may limit their adoption in the operating room, despite their advantage of enabling dexterity within a highly confined space. In this paper, we demonstrate through the kinematics of concentric-tube robots, how this adverse effect of torsion could be reduced or potentially eliminated. As proof of principle, we demonstrate experimentally and numerically that by adopting tubular composite structures, such as multi-layer helical tubes or cellular tubes, that could be designed to exhibit higher torsional-to-bending stiffness ratio, the stability margin of concentric-tube robots can be improved up to 40%. This will allow concentric-tube robots to achieve even a higher dexterity within a more confined space.

Infant Robotic Cleft Palate Surgery: A Feasibility Assessment Using a Realistic Cleft Palate Simulator

Background: A surgical robot offers enhanced precision, visualization, and access and the potential to improve outcomes in cleft palate surgery. The goal of this study was to investigate the feasibility of using the da Vinci robot for cleft palate repair in infants using a cleft palate simulator test bed. Methods: A high-fidelity cleft palate simulator was developed that allows performance of a robotic cleft palate repair procedure. A complete cleft palate repair was performed with the da Vinci Si with 5-mm instruments and the da Vinci Xi with 8-mm instruments. The advantages of the robotic approach were assessed in comparison with using standard instruments. For each system, arm repositioning, collisions, instrument and endoscope excursion, wrist orientation, and vision were compared for 12 steps of the repair. Results: The cleft palate simulator provided a reproducible platform for testing robotic cleft palate surgery. The advantages of the robotic approach were the ability to articulate a miniature wrist intraorally with superior visualization, increased ambidexterity, and improved ergonomics compared with using standard instruments. Cleft palate repair with the Xi was superior to the Si with respect to arm repositioning, instrument collisions and excursion, and wrist orientation. However, Xi performance remained suboptimal because of the larger instruments. Conclusions: Robotic cleft palate repair using the da Vinci system offers advantages compared with the traditional approach. Cleft palate repair is more feasible with the Xi and 8-mm instruments. However, performance is limited by the instrumentation, which requires modification to ensure safety and efficacy. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, V.

Extraction of liver vessel centerlines under guidance of patient-specific models

Fast extraction of blood vessels of abdominal organs is still a challenging task especially in intra-procedural treatments due to large tissue deformation. In this study, we propose a novel joint vessel extraction and registration framework. This vessel extraction technique is under the guidance of prior knowledge patient specific models. The proposed technique automatically provides correspondence between extracted vessels and pre-procedural vessels, which is important for image guidance such as labeled vessels from pre-procedural models, improves the quality of disease diagnosis using multiple images and follow-up, and provides important information for nonrigid image registration. Another key component in our framework is to dynamically update mapped pre-procedural models by rapidly registering the patient model to the current image based on strain energy, point marks and 3D extracted vessels currently available. We have demonstrated the effectiveness of our technique in extraction of vessels from liver MR images. Validation shows a extraction error of 3.99 mm. This technique has the potential to significantly improve the quality of intra-procedural image guidance, diagnosis of disease and treatment planning.

Magnetic resonance imaging properties of multimodality anthropomorphic silicone rubber phantoms for validating surgical robots and image guided therapy systems

The development of image guided robotic and mechatronic platforms for medical applications requires a phantom model for initial testing. Finding an appropriate phantom becomes challenging when the targeted patient population is pediatrics, particularly infants, neonates or fetuses. Our group is currently developing a pediatricsized surgical robot that operates under fused MRI and laparoscopic video guidance. To support this work, we describe a method for designing and manufacturing silicone rubber organ phantoms for the purpose of testing the robotics and the image fusion system. A surface model of the organ is obtained and converted into a mold that is then rapid-prototyped using a 3D printer. The mold is filled with a solution containing a particular ratio of silicone rubber to slacker additive to achieve a specific set of tactile and imaging characteristics in the phantom. The expected MRI relaxation times of different ratios of silicone rubber to slacker additive are experimentally quantified so that the imaging properties of the phantom can be matched to those of the organ that it represents. Samples of silicone rubber and slacker additive mixed in ratios ranging from 1:0 to 1:1.5 were prepared and scanned using inversion recovery and spin echo sequences with varying TI and TE, respectively, in order to fit curves to calculate the expected T1 and T2 relaxation times of each ratio. A set of infantsized abdominal organs was prepared, which were successfully sutured by the robot and imaged using different modalities.

Evaluation and Implementation of a High-Fidelity Cleft Palate Simulator.

Background: Cleft palate repair is a challenging procedure to learn because of the delicate tissue handling required and the small confines of the infant oral cavity. As a result, cleft palate simulators have previously been described to augment cleft palate repair training. Although valuable, they lack the fidelity for this complex procedure. Methods: A high-fidelity cleft palate simulator was evaluated by staff and fellows in pediatric plastic surgery who provided feedback on its realism, anatomical accuracy, and effectiveness as a training tool. The simulator was implemented within a training workshop following a didactic session on cleft palate repair and anatomy. A test was administered to each participant before and immediately after the workshop to assess knowledge transfer. Perceived confidence of performing a repair following the workshop was also assessed, as was the workshop’s effectiveness. Results: Overall, participants agreed that the simulator is anatomically accurate and realistic and strongly agreed that the simulator is a valuable training tool. The average test score increased from 25 percent before the workshop to 77.27 percent after the workshop. Overall, participants of the workshop felt more confident performing a repair and strongly agreed that the workshop was valuable and effective. Conclusions: A high-fidelity cleft palate simulator has been evaluated as realistic, anatomically accurate, and valuable as a training tool. The simulator was successfully integrated into a training workshop, which resulted in significant knowledge increase on anatomy and the procedure and perceived confidence and comfort in performing a cleft palate repair.