Real-time 3-D model-based navigation system for endoscopic paranasal sinus surgery

Foot-Controlled Robot-Enabled EnDOscope Manipulator (FREEDOM) for Sinus Surgery: Design, Control, and Evaluation

Despite successful clinical applications, teleoperated robotic surgical systems face particular limitations in the functional endoscopic sinus surgery (FESS) in terms of incompatible instrument dimensions and robot set-up. The endoscope remains manually handled by an assistant when the surgeon performs bimanual operations. This paper introduces the development of the Foot-controlled Robot-Enabled EnDOscope Manipulator (FREEDOM) designed for FESS. The system features clinical considerations that inform the design for providing reliable and safe endoscope positioning with minimal obstruction to the routine practice. The robot structure is modular and compact to ensure coaxial instrument manipulation through the nostril for manual procedures. To avoid rigid endoscope motions, a new compliant endoscope holder is proposed that passively limits the lens-tissue contact forces under collisions for patient-side protection. To facilitate hands-free endoscope manipulation that imposes minimal distractions to the surgeon, a foot-wearable interface is further designed to relieve the assistant's workload. The foot control method owns a short learning curve (mean 3.4 mins), and leads the task to be more ergonomic and surgeon-centered. Cadaver and clinical studies were both conducted to evaluate the surgical applicability of the FREEDOM to assist endoscope manipulation in FESS. The system was validated to be safe (IEC-60601-1) and easy for set up (mean 3.6 mins), from which the surgeon could perform various three-handed procedures alone in FESS without disrupting the routine practice.

Virtual reality training for improving the skills needed for performing surgery of the ear, nose or throat

BACKGROUND

Virtual reality simulation uses computer-generated imagery to present a simulated training environment for learners. This review seeks to examine whether there is evidence to support the introduction of virtual reality surgical simulation into ear, nose and throat surgical training programmes.

OBJECTIVES

1. To assess whether surgeons undertaking virtual reality simulation-based training achieve surgical ('patient') outcomes that are at least as good as, or better than, those achieved through conventional training methods.2. To assess whether there is evidence from either the operating theatre, or from controlled (simulation centre-based) environments, that virtual reality-based surgical training leads to surgical skills that are comparable to, or better than, those achieved through conventional training.

SEARCH METHODS

The Cochrane Ear, Nose and Throat Disorders Group (CENTDG) Trials Search Co-ordinator searched the CENTDG Trials Register; Central Register of Controlled Trials (CENTRAL 2015, Issue 6); PubMed; EMBASE; ERIC; CINAHL; Web of Science; ClinicalTrials.gov; ICTRP and additional sources for published and unpublished trials. The date of the search was 27 July 2015.

SELECTION CRITERIA

We included all randomised controlled trials and controlled trials comparing virtual reality training and any other method of training in ear, nose or throat surgery.

DATA COLLECTION AND ANALYSIS

We used the standard methodological procedures expected by The Cochrane Collaboration. We evaluated both technical and non-technical aspects of skill competency.

MAIN RESULTS

We included nine studies involving 210 participants. Out of these, four studies (involving 61 residents) assessed technical skills in the operating theatre (primary outcomes). Five studies (comprising 149 residents and medical students) assessed technical skills in controlled environments (secondary outcomes). The majority of the trials were at high risk of bias. We assessed the GRADE quality of evidence for most outcomes across studies as 'low'. Operating theatre environment (primary outcomes) In the operating theatre, there were no studies that examined two of three primary outcomes: real world patient outcomes and acquisition of non-technical skills. The third primary outcome (technical skills in the operating theatre) was evaluated in two studies comparing virtual reality endoscopic sinus surgery training with conventional training. In one study, psychomotor skill (which relates to operative technique or the physical co-ordination associated with instrument handling) was assessed on a 10-point scale. A second study evaluated the procedural outcome of time-on-task. The virtual reality group performance was significantly better, with a better psychomotor score (mean difference (MD) 1.66, 95% CI 0.52 to 2.81; 10-point scale) and a shorter time taken to complete the operation (MD -5.50 minutes, 95% CI -9.97 to -1.03). Controlled training environments (secondary outcomes) In a controlled environment five studies evaluated the technical skills of surgical trainees (one study) and medical students (three studies). One study was excluded from the analysis. Surgical trainees: One study (80 participants) evaluated the technical performance of surgical trainees during temporal bone surgery, where the outcome was the quality of the final dissection. There was no difference in the end-product scores between virtual reality and cadaveric temporal bone training. Medical students: Two other studies (40 participants) evaluated technical skills achieved by medical students in the temporal bone laboratory. Learners' knowledge of the flow of the operative procedure (procedural score) was better after virtual reality than conventional training (SMD 1.11, 95% CI 0.44 to 1.79). There was also a significant difference in end-product score between the virtual reality and conventional training groups (SMD 2.60, 95% CI 1.71 to 3.49). One study (17 participants) revealed that medical students acquired anatomical knowledge (on a scale of 0 to 10) better during virtual reality than during conventional training (MD 4.3, 95% CI 2.05 to 6.55). No studies in a controlled training environment assessed non-technical skills.

AUTHORS' CONCLUSIONS

There is limited evidence to support the inclusion of virtual reality surgical simulation into surgical training programmes, on the basis that it can allow trainees to develop technical skills that are at least as good as those achieved through conventional training. Further investigations are required to determine whether virtual reality training is associated with better real world outcomes for patients and the development of non-technical skills. Virtual reality simulation may be considered as an additional learning tool for medical students.

New system for tracking a device for diagnosing scalp skin

In scalp skin examinations, it is difficult to find a previously treated region on a patient's scalp through images captured by a camera attached to a diagnostic device because the zoom lens on camera has a small field of view. Thus, doctors manually record the region on a chart or manually mark the region. However, this process is slow and inconveniences the patient. Thus, we propose a new system for tracking the diagnostic device for the scalp skin of patients. Our research is novel in four ways. First, our proposed system consists of two cameras to capture the face and the diagnostic device. Second, the user can easily set the position of camera to capture the diagnostic device by manually moving a frame to which the camera is attached. Third, the position of patient's nostrils and corners of the eyes are detected to align the position of his/her head more accurately with the recorded position from previous sessions. Fourth, the position of the diagnostic device is continuously tracked during the examination through images that help detect the position of the color marker attached to the device. Experimental results show that our system has a higher performance than conventional method.

Design of the image-guided biopsy marking system for gastroscopy

Endoscopists currently rely on an invasive biopsy tattooing method to identify previously biopsied sites. In order to better guide endoscopists to find the biopsy positions in follow-ups, we proposed a non-invasive image guided biopsy marking system for gastroscopy. Using an electromagnetic tracking device, the position of the gastroscope relative to the stomach was acquired and displayed in the guidance interface. The biopsy positions were recorded in computer for the use of guidance in follow-ups. The accuracy of the system was evaluated by both phantom experiments and in vivo experiments. The average target registration errors on the test animal and the volunteer are 13.4 mm and 11.2 mm respectively. Although the positioning error is slightly larger than current biopsy tattooing method, it satisfies the need for guidance. In the near future, we will validate the system by measuring how much it saves examination time.

Autonomous avoidance based on motion delay of master-slave surgical robot

Safe use of master-slave robots for endoscopic surgery requires autonomous motions to avert contact with vital organs, blood vessels, and nerves. Here we describe an avoidance control algorithm with delay compensation that takes the dynamic characteristics of the robot into account. To determine the operating parameters, we measured frequency characteristics of each joint of the slave-manipulator. The results suggest this delay compensation program improves avoidance performance.

Intra-operative virtual endoscopy for image guided endonasal transsphenoidal pituitary surgery

PURPOSE

Virtual endoscopy has already proven its benefit for pre-operative planning of endoscopic pituitary surgery. The translation of such a system into the operating room is a logical consequence, but only a few general intra-operative image guided systems providing virtual endoscopic images have been proposed so far. A discussion of related visualization and interaction problems occurring during sinus and pituitary surgery is still missing.

METHODS

This paper aims at filling this gap and proposes a system that integrates an existing virtual endoscopy system originally designed for pre-operative planning of pituitary surgery with a professional intra-operative navigation system. Visualization and interaction possibilities of the pre-operative planning system have been extended to fulfill the special requirements to the system if used for intra-operative navigation of endonasal transsphenoidal pituitary surgery.

RESULTS

The feasibility of the system has been successfully tested on 1 cadaver and 12 patients. The virtual endoscopic images were found useful (1) during the endonasal transsphenoidal approach in cases of anatomic variations and for the individually tailored opening of the sellar floor, and (2) during tumor resection for respecting the internal carotid artery. The visualization of hidden anatomical structures behind the bony walls of the sphenoid sinus during the sellar phase of the surgery has been found most beneficial.

DISCUSSION

According to our data, intra-operative virtual endoscopy provides additional anatomical information to the surgeon. By depicting individual anatomical variations in advance, it may add to the safety of this frequent neurosurgical procedure.

Computer assistance for intraoperative navigation in ENT surgery

The intraoperative need for exact orientation during interventions in the paranasal sinuses and the augmented need for navigational aids in lateral skull base surgery have lead to the development of computer-aided tools during the last fifteen years. These tools, which provide the position of a tool or a pointer in the patient's preoperative radiologic imaging, have quickly gained a wide acceptance for revision surgeries and the surgical treatment of complex pathologies in Ear-, Nose- and Throat (ENT-) surgery. Currently, the use of such systems is spreading from academic centers to smaller hospitals and will become a standard tool in the near future. We review the present state of computer-aided surgery (CAS) systems, based on our experience as clinical and research centers with a long experience in the field, provide some technological background information and, based on selected cases, show the merits of this technology. The systems we have been working with cover a wide variety of intraoperative navigational systems in ENT surgery (Easy Guide, MedScan II, MKM, SNN, STN, SurgiGATE ORL, Treon, VectorVision, Viewing Wand, [without claiming completeness]), and virtually the whole area of ENT surgeries: macroscopic, (video-)endoscopic and microscopic procedures. The 3D tracking technologies involved cover mechanical, optical (active and passive), magnetic and robotic principles. The visualization tools used are computer monitors, video monitors, head-up-displays and the microscope's oculars, thus spanning the area from pointer-systems to real navigators and a surgical telepresence demonstrator, implementing the majority of available patient-to-image referencing strategies. Clinically, the systems can be operated with an acceptable accuracy of around 1 mm, whereas in laboratory settings and in cadaver studies application accuracy may be pushed to its limits: the physical resolution of the radiologic imaging used for navigation.

CT-based manual segmentation and evaluation of paranasal sinuses

Manual segmentation of computed tomography (CT) datasets was performed for robot-assisted endoscope movement during functional endoscopic sinus surgery (FESS). Segmented 3D models are needed for the robots' workspace definition. A total of 50 preselected CT datasets were each segmented in 150-200 coronal slices with 24 landmarks being set. Three different colors for segmentation represent diverse risk areas. Extension and volumetric measurements were performed. Three-dimensional reconstruction was generated after segmentation. Manual segmentation took 8-10 h for each CT dataset. The mean volumes were: right maxillary sinus 17.4 cm(3), left side 17.9 cm(3), right frontal sinus 4.2 cm(3), left side 4.0 cm(3), total frontal sinuses 7.9 cm(3), sphenoid sinus right side 5.3 cm(3), left side 5.5 cm(3), total sphenoid sinus volume 11.2 cm(3). Our manually segmented 3D-models present the patient's individual anatomy with a special focus on structures in danger according to the diverse colored risk areas. For safe robot assistance, the high-accuracy models represent an average of the population for anatomical variations, extension and volumetric measurements. They can be used as a database for automatic model-based segmentation. None of the segmentation methods so far described provide risk segmentation. The robot's maximum distance to the segmented border can be adjusted according to the differently colored areas.