Soft Tissue Navigation Research Articles

A case study: impact of target surface mesh size and mesh quality on volume-to-surface registration performance in hepatic soft tissue navigation

PurposeSoft tissue deformation severely impacts the registration of pre- and intra-operative image data during computer-assisted navigation in laparoscopic liver surgery. However, quantifying the impact of target surface size, surface orientation, and mesh quality on non-rigid registration performance remains an open research question. This paper aims to uncover how these affect volume-to-surface registration performance.MethodsTo find such evidence, we design three experiments that are evaluated using a three-step pipeline: (1) volume-to-surface registration using the physics-based shape matching method or PBSM, (2) voxelization of the deformed surface to a 1024^3 voxel grid, and (3) computation of similarity (e.g., mutual information), distance (i.e., Hausdorff distance), and classical metrics (i.e., mean squared error or MSE).ResultsUsing the Hausdorff distance, we report a statistical significance for the different partial surfaces. We found that removing non-manifold geometry and noise improved registration performance, and a target surface size of only 16.5% was necessary.ConclusionBy investigating three different factors and improving registration results, we defined a generalizable evaluation pipeline and automatic post-processing strategies that were deemed helpful. All source code, reference data, models, and evaluation results are openly available for download: https://github.com/ghattab/EvalPBSM/.

Navigation in urological surgery: Possibilities and limits of current techniques

Surgical navigation describes the concept of real-time processing and presentation of preoperative and intraoperative data from different sources to intraoperatively provide surgeons with additional cognitive support. Imaging methods such as 3D ultrasound, magnetic resonance imaging (MRI) and computed tomography (CT) and data from optical, electromagnetic or mechanical tracking methods are used. The resulting information of the navigation system will be presented by the means of visual methods. Mostly virtual reality or augmented reality visualization is used. There are different guidance systems for various disciplines introduced. Mostly it operates on rigid structures (bone, brain). For soft tissue navigation motion compensation and deformation detection are necessary. Therefore, marker-based tracking methods are used in several urological application examples; however, the systems are often still under development and have not yet arrived in the clinical routine.

Magnetic tracking in the operation room using the da Vinci® telemanipulator is feasible

In recent years, robotic assistance for surgical procedures has grown on a worldwide scale, particularly for use in more complex operations. Such operations usually require meticulous handling of tissue, involve a narrow working space and limit the surgeon’s sense of orientation in the human body. Improvement in both tissue handling and working within a narrow working space might be achieved through the use of robotic assistance. Soft tissue navigation might improve orientation by visualizing important target and risk structures intraoperatively, thereby possibly improving patient outcome. Prerequisites for navigation are its integration into the surgical workflow and accurate localization of both the instruments and patient. Magnetic tracking allows for good integration but is susceptible to distortion through metal or electro-magnetic interference, which may be caused by the operation table or a robotic system. We have investigated whether magnetic tracking can be used in combination with the da Vinci® (DV) telemanipulator in terms of stability and precision. We used a common magnetic tracking system (Aurora®, NDI Inc.) with the DV in a typical operation setup. Magnetic field distortion was evaluated using a measuring facility, with the following reference system: without any metal (R), operation table alone (T), DV in standby (D) and DV in motion (Dm). The maximum error of the entire tracking volume for R, T, D and Dm was 9.9, 32.8, 37.9 and 37.2 mm, respectively. Limiting the tracking volume to 190 mm (from cranial to caudal) resulted in a maximum error of 4.0, 8.3, 8.5 and 8.9 mm, respectively. When used in the operation room, magnetic tracking shows high errors, mainly due to the operation table. The target area should be limited to increase accuracy, which is possible for most surgical applications. The use of the da Vinci® telemanipulator only slightly aggravates the distortion and can thus be used in combination with magnetic tracking systems.

Soft-tissue balancing navigation used in total knee arthroplasty for the varus knee

Objective To use soft-tissue balancing navigation for real-time quantitative observation of medial soft-tissue releasing in total knee arthroplasty (TKA) for the varus knee. Methods From October 2006 through September 2010,25 patients with knee osteoarthritis plus knee varus received TKA under soft-tissue balancing navigation.The soft-tissue balancing navigation system was used in the knee after routine bone cutting.The soft tissue stresses and balancing status observed and documented before and during the releasing under the guidance of the navigation system.Clinical outcomes were followed up. Results In this series,the mean operating time was 62 minutes (from 48 to 80 minutes) and the mean intraoperative blood loss was 320 mL ( from 100 to 500 mL).An average follow-up of 36.4 months (from 12 to 54 months)revealed no revision due to infection or loosening.The mean HSS scores were imuproved significantly from preoperative 53.4 ± 12.8 to 89.2 ± 17.3 at the last follow-up( t =17.411,P =0.000 ).The alignment of the lower limb decreased significantly from preoperative varus of 16.4°± 10.0° to postopcrative varus of 1.8° ± 2.1°(t=7.526,P=0.000).The differences in the medial and lateral stresses of the soft tissue at the knee extension and flexion were significant between pre-releasing and post-releasing ( P ＜ 0.05).In releasing the posterior portion of medial collateral ligament (MCL),the decreasc in medial and lateral stresses at the knee extension (42.33％ ± 20.88％ ) was significantly greater than that at the knee flexion ( 12.33％ ± 9.75％ ) ( t =6.714,P =0.000).In releasing both the anterior and posterior portions of MCL.the decrease in medial and lateral stresses at the knee extension (50.33％ ± 18.82％ ) was significantly smaller than that at the knee flexion (59.42％ ± 21.46％ ) ( t =2.492,p =0.021 ). Conclusion The soft-tissue balancing uavigation system is capable of real-time quantitative measurement of the soft tissue stress and balance in TKA for the varus knee. Key words: Osteoarhritis, knee; Surgcry, computer-assisted; Arthroplasty, replacement,knee; Soft tissue balamce

Navigated Liver Biopsy Using a Novel Soft Tissue Navigation System versus CT-Guided Liver Biopsy in a Porcine Model: A Prospective Randomized Trial

The aim of this prospective, randomized animal study was to compare a new computer guided needle-based navigation system for liver biopsy with conventional computed tomography (CT)-guided liver biopsy. Computer-navigated interventions provide continuous needle tracking during motion and deformation from patient respiration and movement. Twenty artificial tumors of about 5 mm in diameter were injected into the livers of five pigs, each at a different site. Each tumor was targeted by conventional CT-guided and computer navigated intervention. Intervention was considered complete after successful tumor biopsy. Data on procedure time, number of CT scans performed, accuracy, and success rate were recorded. All tumors (100%) were biopsied successfully. Mean procedural time was comparable between the two techniques (20 ± 9 minutes conventional versus 20 ± 8 minutes navigation). Mean number of CT scans were 1.2 ± 0.4 with navigation and 6.1 ± 3.8 with the conventional technique (P < .01). The dose-length product in the conventional group was significantly higher (212 ± 116 mGy × cm) than in the navigated group (78 ± 22 mGy × cm; P < .001). Mean number of capsule penetrations was 4 ± 1 with navigation versus 2 ± 1 with the conventional technique (P < .001). Computer-navigated liver biopsy may provide a promising and innovative device for easy, rapid, and successful liver biopsies with low morbidity. Further technical improvements and clinical studies in humans are required.

New trends in minimally invasive urological surgery. What is beyond the robot?

To review the minimal-invasive development of surgical technique in urology focusing on nomenclature, history and outcomes of Laparo-Endoscopic Single-site Surgery (LESS), Natural Orifice Translumenal Endoscopic Surgery (NOTES) and Computer-Assisted Surgery (CAS). A comprehensive literature search was conducted in order to find article related to LESS, NOTES and CAS in urology. The most relevant papers over the last 10 years were selected in base to the experience from the panel of experts, journal, authorship and/or content. Seven hundred and fifty manuscripts were found. Papers on LESS describe feasibility/safety in most of the procedures with a clinical experience of more than 300 cases and five compared results to standard laparoscopy without showing significant differences. NOTES accesses have been proved their feasibility/safety in experimental study. In human, the only procedures performed are on kidney and through a hybrid-Transvaginal route. New robots overcome the main drawbacks of the DaVinci® platform. The use of CAS is increasing its popularity in urology. LESS has been applied in clinical practice, but only ongoing technical and instrumental refinement will define its future role and overall benefit. The transition to a clinical application of NOTES seems at present only possible with multiple NOTES access and transvaginal access. Robot and Soft Tissue Navigation appear to be important to improve surgical skills. We are already witness to the advantages offered by the former even if costs need to be redefined based on pending long-term results. The latter will probably upgrade the quality of surgery in a near future.

In-Vitro Evaluation of a Soft-Tissue Navigation System for Laparoscopic Prostatectomy

We introduce a custom-designed phantom model for the in-vitro evaluation of an augmented reality-based soft-tissue navigation system for ultrasound-guided prostate interventions. Transrectal ultrasound segmentation of the prostate, navigation aid placement, initial registration, endoscope tracking, and enhanced visualization steps in the navigation procedure were performed to accommodate the actual prostatic motion. In-vitro laparoscopic manipulations simulating surgical procedures were performed by a physician using human prostate specimens. The target visualization error, defining the accuracy of the tracking, is determined by means of a leave-out test strategy by alternately using four navigation aids for endoscope registration and the remaining two navigation aids for accuracy verification. The introduction of the navigation aids lasted approximately 3 minutes. The navigation aids and especially their barbs were visible because of their ultrasound reflecting nature. For each organ, 1000 endoscope registrations were calculated, in which two randomly chosen navigation aids served the purpose of verifying the pose. We were able to demonstrate that the superimposed image could follow automatically the videoendoscopic real-time view. The mean target visualization errors for the respective trials were determined as 0.81 (±0.12) mm, 0.62 (±0.14) mm, and 0.98 (±0.23) mm. The ultrasound-based inside-out navigation system for laparoscopic prostatectomy overcomes the problem of tissue shift and deformation in an in-vitro model. In case of organ movement, the augmented picture with the detected navigation aids could follow the videoendoscopic image using the navigation aids as landmarks.

T1651 Soft Tissue Navigation: An Ex-Vivo Porcine Liver Model for Multimodality Imaging of Deformations to Validate Techniques for Image-Guided Liver Surgery

T1651 Soft Tissue Navigation: An Ex-Vivo Porcine Liver Model for Multimodality Imaging of Deformations to Validate Techniques for Image-Guided Liver Surgery

Image-guided surgery in minimally invasive urology

Image-guided surgery (IGS) is a new type of surgery in which indirect visualization of the surgical anatomy helps the surgeon to enable minimally invasive percutaneous, laparoscopic, or robotic-aided treatment more precisely and safely, to achieve complete tumor removal and sparing of the function of critical organs. Although 2D ultrasonography has played a main role as conventional intraoperative image guidance, image-fusion system of ultrasonography with computed tomography (CT) or MRI, 3D ultrasonography imaging, MRI-compatible navigation system, and image-overlay technology of augmented reality navigation system have emerged with computer aid. Development of augmented reality in soft tissue navigation is challenging, especially in tracking of organ motion and deformation. In IGS, the surgeon may see any angled tomogram of the patient's body, or 3D anatomies beyond the direct vision. IGS would not only provide the delivery of energy or medicines to the therapeutic target, but also monitor the precision and effectiveness of the treatment. Emerging imaging technology gives surgeons a new powerful opportunity to realize where surgical pathological targets and vital healthy anatomies are located beyond the surgeon's direct vision.

Augmented Reality: A New Tool To Improve Surgical Accuracy during Laparoscopic Partial Nephrectomy? Preliminary In Vitro and In Vivo Results

BackgroundUse of an augmented reality (AR)–based soft tissue navigation system in urologic laparoscopic surgery is an evolving technique. ObjectiveTo evaluate a novel soft tissue navigation system developed to enhance the surgeon's perception and to provide decision-making guidance directly before initiation of kidney resection for laparoscopic partial nephrectomy (LPN). Design, setting, and participantsCustom-designed navigation aids, a mobile C-arm capable of cone-beam imaging, and a standard personal computer were used. The feasibility and reproducibility of inside-out tracking principles were evaluated in a porcine model with an artificially created intraparenchymal tumor in vitro. The same algorithm was then incorporated into clinical practice during LPN. InterventionsEvaluation of a fully automated inside-out tracking system was repeated in exactly the same way for 10 different porcine renal units. Additionally, 10 patients underwent retroperitoneal LPNs under manual AR guidance by one surgeon. MeasurementsThe navigation errors and image-acquisition times were determined in vitro. The mean operative time, time to locate the tumor, and positive surgical margin were assessed in vivo. Results and limitationsThe system was able to navigate and superpose the virtually created images and real-time images with an error margin of only 0.5mm, and fully automated initial image acquisition took 40ms. The mean operative time was 165min (range: 135–195min), and mean time to locate the tumor was 20min (range: 13–27min). None of the cases required conversion to open surgery. Definitive histology revealed tumor-free margins in all 10 cases. ConclusionsThis novel AR tracking system proved to be functional with a reasonable margin of error and image-to-image registration time. Mounting the pre- or intraoperative imaging properties on real-time videoendoscopic images in a real-time manner will simplify and increase the precision of laparoscopic procedures.

The Role of Imaging and Navigation for Natural Orifice Translumenal Endoscopic Surgery

One of the next frontiers of minimally invasive surgery is natural orifice translumenal endoscopic surgery (NOTES). This article focuses on the perspectives and limitations of imaging and navigation in NOTES soft-tissue surgery. Based on our in-vitro and in-vivo studies, with the applicability of different systems for image-guided soft-tissue endoscopic surgery, early experience with NOTES, and long-term experience with advanced endoluminal, laparoscopic robot-assisted endoscopic surgery, we performed a review of the literature. The aim was a critical analysis of the current role of imaging during NOTES. There are several steps/problems with NOTES that might be significantly alleviated by use of imaging and soft-tissue navigation. One has to distinguish between preoperative planning and intraoperative imaging or navigation. NOTES represents a hybrid technique of laparoscopy and endoscopy with similar limitations in perception and two-dimensional imaging; however, the use of flexible instruments increases the complexity with respect to the spatial orientation. This applies not only for the surgeon, but also for tracking devices for surgical navigation systems. Unlike optical navigation systems, electromagnetic and endoscopic (inside-out) tracking devices might be best suited to NOTES. The safe realization and standardization of NOTES represents a real challenge that necessitates close and effective interdisciplinary collaboration of surgeon, technicians, informatics, and endoscopic and applied industries. Image-guided soft-tissue navigation may be very helpful to minimize the hazards of the technically challenging procedure.

Robotic and imaging in urological surgery

New imaging modalities and tissue navigation systems, which are adoptable to minimally invasive robotic urological surgical systems and prone to make the procedures more precise and easy, are reviewed. Image-guided surgery as the general name of combining information of imaging modalities with real-time surgery has already found a place in open and minimally invasive procedures. Soft tissue navigation is a complex type of computer-assisted surgery for soft tissue interventions. Robotic surgery has advantages of superior degrees of freedom and three-dimensional stereotactic user interface. A combination of surgical robotics with image-assisted surgery and soft tissue navigation may offer advantages of more precise anatomical target localization and dissection with minimal damage to the tissue. Solving the problem of organ shift and as a result, unpredictable changing of intraoperative anatomy soft tissue navigation has the potential to increase the precision of minimally invasive robotic surgery. Apart from less invasiveness, the concomitant use of minimal invasive robotic systems with soft tissue navigation enhances surgical precision. However, at present, abdominal navigation systems are in experimental use and not perfect enough for daily surgical routine.

Weichteilnavigation im Kopf-Hals-Bereich und navigierte Fremdkörperentfernung

Soft tissue navigation has traditionally been neglected in computer-aided surgery (CAS) because of unpredictable margins of error. In our study, we examined clinical cases in which standard CAS was applied in soft tissue surgery in the head and neck region. Its extended applicability, margins of error, and general performance are described and discussed. CAS was applied in surgical procedures for six patients. Five patients had foreign bodies in the head and neck region, and one patient displayed uncertain cervical lymph node enlargement. An optoelectrical navigation system (VectorVision(2), BrainLAB) was used in all cases. Using CAS, 10 out of 11 total foreign bodies were identified. Only one glass splinter attached to the eyeball could not be detected by the navigation system. One glass splinter that was deeply buried within the sphenoid bone was easily found but was left untouched. The parapharyngeal lymph node was identified and extracted in a minimally invasive transpalatinal approach. Soft tissue navigation was successfully applied in all but one case; the success was due to the altered demands in soft tissue navigation as opposed to skull-base surgery. Easy identification of foreign bodies and lymph nodes was possible in the soft tissues of the head and neck, with an acceptable margin of error.

Single and Double Anterior Cruciate Ligament Reconstruction With Use of a Navigation System: The French Experience

Soft-tissue navigation and anatomic double-bundle anterior cruciate ligament reconstruction (AACLR) have developed in tandem. Navigation is now recognized as a reference in 3-dimensional measurement of laxity, but AACLR has not been proven to be superior to single-bundle reconstruction. It is now recognized that the anterior cruciate ligament (ACL) does not behave as a simple bundle of fibers with constant tension, as anteromedial bundle and posterolateral bundle fibers have been described and widely accepted. Anatomic reconstruction is becoming more popular among surgeons but, despite their expertise, surgeons have difficulty in accurately placing the tunnels and, as a result, many different techniques have been reported. These techniques can be classified in 4 groups depending on the number of bone tunnels. Navigation for ACL reconstruction was developed in France in 1994 for isometry and laxity measurement. It also can be used to predict graft impingement. A new software version was perfected in 2007 and adapted to the concept of AACLR. Virtual grafts were created to better analyze behavior within the intercondylar notch. This system is based on modular software that can be adapted to all different techniques. The French concept of AACLR was developed in 2001 and based on 2 bundles and 4 tunnels. We undertook cadaver and clinical studies and reported rotational laxity control improvement after the addition of the posterolateral bundle to standard anteromedial bundle reconstruction. However, there are limitations to our studies: the tests were performed under manual, uncontrolled forces, and we currently lack the tool to perform an instrumental pivot-shift. Randomized controlled studies have been reported and collected in a meta-analysis. Most of these studies assessed only the tibial anterior translation for laxity measurement and did not consider the coupled rotation. The rotational laxity is essential to be considered first for the selection of patients to compare a homogenous group of patients and also the final result. None of these randomized controlled studies have demonstrated the superiority of the AACLR on traditional single-bundle reconstruction. We conclude that navigation is the appropriated tool for this clinical assessment.

Soft tissue navigation for laparoscopic partial nephrectomy

Purpose Minimally invasive surgery of kidney cancer has become a standard therapy method for renal carcinomas. Due to improvements in diagnosis, carcinomas tend to be detected with a smaller size, which often allows for a tissue sparing, laparoscopic partial nephrectomy (LPN). Successful LPN requires a safe resection line inside the kidney, which spares most of healthy tissue, while assuring the complete tumor removal. This paper proposes an approach for a real-time visualization aid during LPN.

Respiration tracking in radiosurgery without fiducials

In robotic radiosurgery, a focused beam of radiation is moved by a robot arm. We investigated methods for soft-tissue navigation using robotic radiosurgery. In previous work we described a method for real-time tracking based on correlation between the motion of implanted fiducial markers and external skin markers. In this work we extend our method of correlation-based tracking to tracking without implanted fiducials. We propose to use deformation algorithms on CT data sets combined with registration of digitally reconstructed radiographs and intra-treatment X-ray images to obtain intermittent information on the target location. This information is then combined with our basic correlation method to achieve real-time tracking. Our study investigates the feasibility of this approach from the point of view of computing time and required level of user interaction. The term 7D registration is coined to describe the underlying method for performing this task.