Real-time Surgical Navigation Research Articles

Intraoperative navigation in craniofacial surgery.

Craniofacial surgery requires comprehensive anatomical knowledge of the head and neck to ensure patient safety and surgical precision. Over recent decades, there have been significant advancements in imaging techniques and the development of real-time surgical navigation systems. Intraoperative navigation technology aligns surgical instruments with imaging-derived information on patient anatomy, enabling surgeons to closely follow preoperative plans. This system functions as a radiologic map, improving the accuracy of instrument placement and minimizing surgical complications. The introduction of first-generation navigation systems in the early 1990s revolutionized surgical procedures by enabling real-time tracking of instruments using preoperative imaging. Initially utilized in neurosurgery, intraoperative navigation has since become standard practice in otolaryngology, cranio-maxillofacial surgery, and orthopedics. Since the 2000s, second-generation navigation systems have been developed to meet the growing demand for precision across various surgical specialties. The adoption of these systems in craniofacial surgery has been slower, but their use is increasing, particularly in procedures such as foreign body removal, facial bone fracture reconstruction, tumor resection, and craniofacial reconstruction and implantation. In Korea, insurance coverage for navigation in craniofacial surgery began in 2021, and new medical technologies for orbital wall fracture treatment were approved in August 2022. These technologies have only recently become clinically available, but are expected to play an increasingly important role in craniofacial surgery. Intraoperative navigation enhances operative insight, improves target localization, and increases surgical safety. Although these systems have a steep learning curve and initially prolong surgery, efficiency improves with experience. Calibration issues, registration errors, and soft tissue deformation can introduce inaccuracies. Nonetheless, navigation technology is evolving, and the integration of intraoperative computed tomography data holds promise for further enhancements of surgical accuracy. This paper discusses the various types and applications of navigation employed in craniofacial surgery, highlighting their benefits and limitations.

Intraoperative Real-Time Image-Guided Fibular Harvest and Mandibular Reconstruction: A Feasibility Study on Cadaveric Specimens.

This study assesses the feasibility of real-time surgical navigation to plan and guide sequential steps during mandible reconstruction on a series of cadaveric specimens. An image-guided surgical (IGS) system was designed including customized mandible and fibula fixation devices with navigation reference frames and an accompanied image-guided software. The mandibular and fibular segmental osteotomies were performed using the IGS in all five cadaveric patients. Procedural time and cephalometric measurements were recorded. Five real-time IGS mandibulectomy and fibular reconstruction were successfully performed. The mean Dice score and Hausdorff-95 distance between the planned and actual mandible reconstructions was 0.8 ± 0.08 and 7.29 ± 4.81 mm, respectively. Intercoronoid width, interangle width, and mandible projection differences were 1.15 ± 1.17 mm, 0.9 ± 0.56 mm, and 1.47 ± 1.62 mm, respectively. This study presents the first demonstration of a comprehensive image-guided workflow for mandibulectomy and fibular flap reconstruction on cadaveric specimens and resulted in adequate cephalometric accuracy.

Quantitative MRI approach in the preoperative evaluation of a rare large-mass abdominal GIST tumor

Gastrointestinal stromal tumors (GISTs) are rare cancers originating from the gastrointestinal tract's interstitial cells of Cajal. This study explores the utility of quantitative Magnetic Resonance Imaging (MRI), particularly volumetric lesion segmentation, in the preoperative evaluation of large-mass abdominal GISTs. MRI offers high-resolution imaging without ionizing radiation, which is crucial for oncology patients requiring repeated scans. Advanced semi-automatic segmentation techniques were employed in this study from different MRI sequences to enhance precision in tumor boundary delineation and volumetric analysis, and aid personalized surgical planning. In addition, this study demonstrates that using different clinical imaging protocols and comparing volumetric data from CT and various MRI sequences yields consistent results with minimal volumetric error. Finally, integrating MRI data into real-time surgical navigation systems underscored the synergy between radiology, surgical oncology, and computer science, improving tumor margin assessment and reducing recurrence risk. This approach highlights a pivotal shift towards technology-enhanced healthcare, promising better patient outcomes.

Efficacy of navigation system-assisted distraction osteogenesis for hemifacial microsomia based on artificial intelligence for 3 to 18 years old: study protocol for a randomized controlled single-blind trial

BackgroundMandibular distraction osteogenesis (MDO) is a major part of the treatment for hemifacial microsomia patients. Due to the narrow surgical field of the intraoral approach, osteotomy accuracy is highly dependent on the surgeons’ experience. Electromagnetic (EM) tracking systems can achieve satisfying accuracy to provide helpful real-time surgical navigation. Our research team developed an EM navigation system based on artificial intelligence, which has been justified in improving the accuracy of osteotomy in the MDO in animal experiments. This study aims to clarify the effect of the EM navigation system in improving the MDO accuracy for hemifacial microsomia patients.MethodsThis study is designed as a single-centered and randomized controlled trial. Altogether, 22 hemifacial microsomia patients are randomly assigned to the experiment and control groups. All patients receive three-dimensional CT scans and preoperative surgical plans. The EM navigation system will be set up for those in the experiment group, and the control group will undergo traditional surgery. The primary outcome is the surgical precision by comparing the osteotomy position of pre- and postoperative CT scan images through the Geomagic Control software. The secondary outcomes include mandibular symmetry (occlusal plane deviation angle, mandibular ramus height, and body length), pain scale, and complications. Other indications, such as the adverse events of the system and the satisfactory score from patients and their families, will be recorded.DiscussionThis small sample randomized controlled trial intends to explore the application of an EM navigation system in MDO for patients, which has been adopted in other surgeries such as orthognathic procedures. Because of the delicate structures of children and the narrow surgical view, accurate osteotomy and protection of nearby tissue from injury are essential for successful treatment. The EM navigation system based on artificial intelligence adopted in this trial is hypothesized to provide precise real-time navigation for surgeons and optimally improve patient outcomes, including function and aesthetic results. The results of this trial will extend the application of new navigation technology in pediatric plastic surgery.Trial registrationChinese Clinical Trial Registry ChiCTR2200061565. Registered on 29 June 2022.

Real-time Navigation for Vascularized Lymph-node Transplantation Using Projection Mapping with Indocyanine Green Fluorescence.

The medical imaging projection system (MIPS) is a real-time surgical navigation device using indocyanine green (ICG) emission signals and active projection mapping. The difference between the object and the projected image is within 1 mm, and the time lag is within 0.1 seconds. We herein report the application of the MIPS to vascularized lymph-node transplantation (VLNT) surgery for lower extremity lymphedema to detect inguinal lymph nodes and perform color-coded navigation surgery for lymph-node resection. A left superficial inguinal lymph node was planned to be used as a donor for VLNT to the right lower leg in a 73-year-old woman with lower extremity lymphedema. Under general anesthesia, multiple intradermal injections of 0.1 ml of ICG were administered around the left inguinal donor site. The MIPS showed a clear linear projection image from a lateral injected point connecting to a lateral superficial inguinal lymph node. The left superficial circumflex iliac artery and vein were dissected for vascularized VLNT. Intraoperative real-time MIPS navigation continuously guided the transection plane colored by ICG fluorescence signals without shifting the visual focus from the surgical field. This is the first report of the intraoperative use of ICG projection mapping for VLNT donor-site surgery. The MIPS was able to visualize functional lymph nodes to facilitate minimally invasive donor-site surgery.

Automatic Real-Time Space Registration Application for Simulating Dental and Maxillofacial Surgery.

Real-time surgical navigation systems are important for preoperative planning and intraoperative navigation. Automatic preoperative multimodal data registration and postoperative spatial registration are extremely crucial in such surgical navigation systems. However, existing automatic multimodal data registration methods have extremely limited application scope due to the lack of accuracy and speed. In addition, the registration results obtained by existing methods are practically lacking and are rarely applied in clinics. To address the above issues, this paper proposes a novel real-time teeth registration algorithm with computed tomography (CT) data and optical tracking scanning data. The proposed method is based on the weighted iterative closest point (ICP) algorithm with 3 improvements: (1) the multilayer spherical point set is generated inside the laser scanning marker sphere, (2) the weight decreases from inside to outside layer by layer, and (3) the weight of the voxel center point set is combined with the CT data of the marker sphere. Specifically, the proposed iCP registration method can overcome the limitation of surface point set registration and tackle the problem of high surface deformity of laser scanning marker spheres. For the registration result of CT and scanning data, the authors employ the real-time spatial registration algorithm based on optical tracking to complete the navigation of the simulated surgical instruments on the multimodal fusion image. The experimental results show that the proposed ICP algorithm reduces the mean square error by 1 order of magnitude and that our method has strong practical value.

Real-Time Dynamic Navigation System for the Precise Quad-Zygomatic Implant Placement in a Patient with a Severely Atrophic Maxilla.

Zygomatic implants (ZIs) are an ideal way to address cases of a severely atrophic edentulous maxilla and maxilla defects because they replace extensive bone augmentation and shorten the treatment cycle. However, there are risks associated with the placement of ZIs, such as penetration of the orbital cavity or infra-temporal fossa. Furthermore, the placement of multiple ZIs makes this surgery risky and more difficult to perform. Potential intraoperative complications are extremely dangerous and may cause irreparable losses. Here, we describe a practical, feasible, and reproducible protocol for a real-time surgical navigation system for precisely placing quad-zygomatic implants in the severely atrophic maxilla of patients with residual bone that does not meet the requirements of conventional implants. Hundreds of patients have received ZIs at our department based on this protocol. The clinical outcomes have been satisfactory, the intraoperative and postoperative complications have been low, and the accuracy indicated by infusion of the designed image and postoperative three-dimensional image has been high. This method should be utilized during the entire surgical procedure to ensure ZI placement safety.

Real-Time Dynamic Navigation System for the Precise Quad-Zygomatic Implant Placement in a Patient with a Severely Atrophic Maxilla

Zygomatic implants (ZIs) are an ideal way to address cases of a severely atrophic edentulous maxilla and maxilla defects because they replace extensive bone augmentation and shorten the treatment cycle. However, there are risks associated with the placement of ZIs, such as penetration of the orbital cavity or infra-temporal fossa. Furthermore, the placement of multiple ZIs makes this surgery risky and more difficult to perform. Potential intraoperative complications are extremely dangerous and may cause irreparable losses. Here, we describe a practical, feasible, and reproducible protocol for a real-time surgical navigation system for precisely placing quad-zygomatic implants in the severely atrophic maxilla of patients with residual bone that does not meet the requirements of conventional implants. Hundreds of patients have received ZIs at our department based on this protocol. The clinical outcomes have been satisfactory, the intraoperative and postoperative complications have been low, and the accuracy indicated by infusion of the designed image and postoperative three-dimensional image has been high. This method should be utilized during the entire surgical procedure to ensure ZI placement safety.

Application of real-time surgical navigation for zygomatic fracture reduction and fixation

Inappropriate treatment of zygomatic fractures can reduce esthetic and functional outcomes. The aim of this study was to answer the research question: "Among patients with a unilateral zygomatic fracture, is the use of computer-assisted real-time navigation system during fracture reduction precise and accurate to create postoperative facial symmetry?"Using a retrospective cohort study design, we enrolled a cohort of unilateral zygomatic fractures undergoing open reduction and internal fixation (ORIF) with the aid of the computer-based navigation system at Chang Gung Memorial Hospital, Taiwan, during January 2015 and March 2018. The predictor variable was the comparison before and after surgery. The main outcome variables included (1) two-dimensional (2D) reduction of the displacement at five anatomical landmarks: zygomaticofrontal, inferior orbital rim, zygomaticosphenoidal, zygomaticomaxillary, and zygomaticotemporal lines/buttresses and (2) three-dimensional (3D) differences on distances between zygomatic surface to the porion plane and the midpoint of zygomatic arch (ZA) to the mid-porion (MP) plane. The Wilcoxon signed-rank test was computed to compare between pre- and postoperative data, and a p-value less than 0.05 was considered statistically significant.The cohort comprised 24 subjects (50% females, 75% left-sided) with a mean age of 30.5 +/- 13.8 years. On 2D analysis, the significant fracture reduction was found: 4.78 vs. 1.22 mm, 1.78 vs. 0.40 mm, 3.50 vs. 0.07 mm, 3.06 vs. 0.55 mm, and 2.55 vs. 0.50 mm at zygomaticomaxillary, zygomaticofrontal, inferior orbital rim, zygomaticosphenoidal, and zygomaticotemporal landmarks. The 3D evaluations revealed the significant reduction of the differences between the left and right zygomatic surface to the porion plane (4.09 ± 2.12 vs. 0.46 ± 0.35 mm) and between the left and right ZA midpoints to the MP plane (4.89 ± 2.59 vs. 0.71 ± 0.44 mm) (p<0.001 for both 2D and 3D analyses).The results of this study suggest that the real-time surgical navigation system can effectively guide the ORIF of zygomatic fractures. Future research studies should focus on the learning curve and cost-effectiveness analysis of this technique.

NIR‐II J‐Aggregates Labelled Mesoporous Implant for Imaging‐Guided Osteosynthesis with Minimal Invasion

AbstractMedical implants are widely used in clinical practice, such as cardiovascular stenting, maxillofacial surgery, and orthopedics. However, most of the traditional implant operations are open and invasive, resulting in massive dissection of soft tissue and interruption of blood supply. The accurate navigation for the implant operations is considered as one of the most effective ways to reduce the damage, which is urgently desired in clinic. Herein, a biocompatible NIR‐II J‐aggregates labelled mesoporous implant for imaging‐guided osteosynthesis with minimal invasion is reported. Mesoporous silica layer with vertical channels is grown on the surface of titanium plate, which can provide the confining space for the formation of the FD‐1080 J‐aggregates. Both the absorption and fluorescence peaks of the FD‐1080 J‐aggregates are located in NIR‐II window (beyond 1300 nm), which are ideal for high resolution and real time surgical navigation in deep tissue. NIR‐II imaging can clearly display the location and outline of the implant both in vitro and in vivo. This NIR‐II imaging‐guided osteosynthesis can effectively reduce the surgical wound and operational duration, which is crucial for the implant surgeries.

Real-time navigation by three-dimensional virtual reconstruction models in robot-assisted laparoscopic pyeloplasty for ureteropelvic junction obstruction: our initial experience.

BackgroundThe aim of this study was to evaluate the effectiveness and safety of real-time surgical navigation by three-dimensional (3D) virtual reconstruction models in robot-assisted laparoscopic pyeloplasty (RALP).MethodsBetween November 2018 and January 2020, 38 patients with ureteropelvic junction obstruction (UPJO) who underwent RALP were retrospectively enrolled. The operations were assisted in real time by 3D models in 16 patients, while 22 patients underwent surgery without navigation. Based on whether patients had a prior intervention history, crossing vessels or congenital deformities, we further divided them into the “complicated UPJO” cohort and the “regular UPJO” cohort for subgroup analysis. The demographic characteristics, intraoperative parameters, perioperative data and follow-up data were recorded and compared between the groups.ResultsAll of the procedures were successfully performed without open or laparoscopic conversion. The mean dissection time to the UPJ was shorter in the navigation group than in the non-navigation group, both in the whole cohort (15.3 vs. 24.8 min, P=0.011) and in the complicated cohort (15.4 vs. 27.5 min, P=0.004), while there was no significant difference in the regular cohort. The overall operative time and estimated blood loss in the navigation group tended to be less, although the difference was not statistically significant. No difference in anastomosis time, postoperative hospital stay or complications was noted between the two groups in either cohort. At a mean follow-up of 11.2 months, the overall success rate was 94.7% (36/38), and there was no significant difference between the two groups.ConclusionsReal-time navigation by 3D virtual reconstruction models might be helpful to improve surgical efficiency and safety of RALP by facilitating the dissection around the UPJ, especially for cases of complicated UPJO. However, the prospective study with larger sample size is further needed to confirm the results.

Accuracy and clinical outcome of a real-time surgical navigation system for the placement of quad zygomatic implants

Objective: To evalute the accuracy and clinical outcome of a real-time navigation system for the placement of quad zygomatic implants. Methods: Twenty-four patients [9 males and 15 females, mean age was (50.8±14.7) years old], from January 2015 to December 2019, with 96 zygomatic implants placed under a real-time navigation system in Department of Second Dental Center and Department of Oral Implantology of Ninth People's Hospital, Shanghai Jiaotong University School of Medicine were included in the study. The preoperative and the postoperative multislice CT or cone-beam CT were fused to measure and record the entry, exit and angle deviation between the planned and placed implants. The implants were divided into groups according to implant insertion approach (real-time navigation and free-hand), implant length (<47.5 mm and ≥47.5 mm) and implant position (proximal and distal implant). And the differences of implant accuracy were analyzed. The intraoperative and postoperative complications were also recorded. The implant survival rate was evaluated after 6 months follow-up. A P value<0.05 indicates statistical significance. Results: The mean entry, exit and angle deviation of zygomatic implants were (1.49±0.64) mm, [2.03(1.58, 2.40)] mm and (2.49°±1.12°), respectively. The average entry, exit and angle deviation of the navigation guided implant insertion group were (1.45±0.60) mm, (1.96±0.44) mm and (2.66±1.13°) respectively, while those of the free-hand group were (1.50±0.64) mm, (2.04±0.79) mm and (2.50°±1.13°) respectively. There was no significant difference between the two groups (P>0.05). The average entry, exit and angle deviation of the group with length<47.5 mm were (1.42±0.60) mm, (2.13±0.60) mm and (2.61°±1.08°) respectively and those of the group with length ≥ 47.5 mm were (1.52±0.65) mm, (1.98±0.82) mm and (2.43°±1.14°) respectively. No significant difference was found between the two groups (P>0.05). In proximal implant group, the average entry, exit and angle deviation were (1.55±0.69) mm, (2.05±0.92) mm and (2.48°±1.16 °) respectively while those of distal implant group were (1.43±0.57) mm, (2.01±0.57) mm and (2.49°±1.10°), respectively. No significant difference was detected between the two groups (P>0.05). All zygomatic implants were placed uneventfully. There were no intra-operative complications, and post-operative reversible complications developed in 3 patients. Two zygomatic implants were lost and the overall zygomatic implant survival rate was 97.9% (94/96) within a follow-up of 6 months. Conclusions: Quad zygomatic implant placement can be achieved with high accuracy and predictable clinical outcome under guidance of a real-time navigation system.

RespiTrack: Patient-specific real-time respiratory tumor motion prediction using magnetic tracking

PurposeAn intraoperative real-time respiratory tumor motion prediction system with magnetic tracking technology is presented. Based on respiratory movements in different body regions, it provides patient and single/multiple tumor-specific prediction that facilitates the guiding of treatments.MethodsA custom-built phantom patient model replicates the respiratory cycles similar to a human body, while the custom-built sensor holder concept is applied on the patient’s surface to find optimum sensor number and their best possible placement locations to use in real-time surgical navigation and motion prediction of internal tumors. Automatic marker localization applied to patient’s 4D-CT data, feature selection and Gaussian process regression algorithms enable off-line prediction in the preoperative phase to increase the accuracy of real-time prediction.ResultsTwo evaluation methods with three different registration patterns (at fully/half inhaled and fully exhaled positions) were used quantitatively at all internal target positions in phantom: The statical method evaluates the accuracy by stopping simulated breathing and dynamic with continued breathing patterns. The overall root mean square error (RMS) for both methods was between 0.32pm 0.06~hbox {mm} and 3.71pm 0.79~hbox {mm}. The overall registration RMS error was 0.6pm 0.4~hbox {mm}. The best prediction errors were observed by registrations at half inhaled positions with minimum 0.27pm 0.02~hbox {mm}, maximum 2.90pm 0.72~hbox {mm}. The resulting accuracy satisfies most radiotherapy treatments or surgeries, e.g., for lung, liver, prostate and spine.ConclusionThe built system is proposed to predict respiratory motions of internal structures in the body while the patient is breathing freely during treatment. The custom-built sensor holders are compatible with magnetic tracking. Our presented approach reduces known technological and human limitations of commonly used methods for physicians and patients.

Computerized Navigation: A Useful Tool in Total Knee Replacement.

Background:The purpose of computer assistance in a total knee replacement is to achieve optimal alignment, size, and positioning of the implant. The method is safe and accurate and may be particularly useful in cases with abnormal anatomy.Description:The classical computer-assisted system for total knee replacement was developed with real-time surgical navigation using infrared optical tracking arrays. The tracking arrays are attached to the tibial and femoral shafts, as well as to surgical tools, allowing the surgeon to move the tools relative to the knee. The computer-assisted systems allow the surgeon to combine the “measured resection” and “gap balancing” techniques.Step 1: Preoperative planning. Set up the computer and software with the manufacturer implant features and personal preferences.Step 2: Positioning and surgical exposure. Position the patient in order to optimize the camera view.Step 3: Fixation of marker pins. Fix the marker pins to the tibial and femoral shafts.Step 4: Registration of anatomical landmarks and mechanical axes. Move the limb and mark out the anatomical landmarks according to the instructions given by the computer.Step 5: Adaption to the best model. Continue to register the joint surface and anatomy to adapt the fittest pre-registered model to the knee.Step 6: Fine-tuning. The femoral and tibial components are adjusted in size, flexion, extension, rotation, slope, and positioning along the anterior-posterior axis.Step 7: Navigation of cutting blocks and ligament balancing. The cutting blocks are positioned with the assistance of computerized navigation, adjusting for the mechanical axis and ligament tension. The cuts are then performed. Implant trials are inserted, and remaining soft-tissue releases may be performed assisted by the computer. Final implantation is performed.Alternatives:Conventional knee replacement using intramedullary rods as guidance.Rationale:The alignment and positioning of the implant are improved with the use of computer navigation1-5. Abnormal anatomy, anatomical variants and deformities, and presence of previous fractures are easy to manage with the precise assistance from the computer. Thus, in many cases, computer assistance may be a useful tool.Expected Outcomes:Computer-assisted navigation may optimize the precision and accuracy of the surgical procedure. Given the correct target, the outcome of total knee replacement may be more predictable with use of this tool; however, the impact on functional outcomes has not yet been proven to be clinically relevant in clinical trials, and the implant longevity has not been improved6-11.Important Tips:Use two 3-mm drill pins for fixation of the optical array to the tibia and femur.If pins are placed within the wound (not through separate stab incisions), plan the positioning relative to the implant to avoid obstruction of the trials.In severely osteoporotic patients, use bicortical fixation and handle the tissues and limb gently to avoid bumping or displacing the optical array as this will negatively alter the registration and reduce navigational accuracy.Make sure the reflective beads on the optical array are clean at all times and remove them (if using clip-on beads) when using the saw to avoid blood splatter.Train an assistant to press the screen buttons in the correct order and in accordance with the surgical progress.

Pilot study of a surgical robot system for zygomatic implant placement

Zygomatic implant technology has been regarded as an alternative treatment to massive grafting surgery in the severe atrophic maxillary. Nowadays, the assistant method with a real-time surgical navigation has been applied to reduce the risks of zygomatic implant placement. However, the accuracy of the complex operation is highly dependent on the experience of the surgeon. In order to avoid disadvantages of traditional surgical navigation systems, a novel surgical robot system for the zygomatic implant placement has been designed and developed. Firstly, the drilling trajectory of the zygomatic implant placement is designed through the pre-operative planning system. Secondly, the real-time positions of the surgical instruments are constantly updated with the guidance of the optical tracker. Finally, through a coordinate transformation algorithm, the drilling performance can be conducted with the control of a six degree of freedom robot. In order to evaluate the accuracy of the robot, phantom experiments had been carried out. The angle, entry point and exit point deviation of the robotic system are 1.52 ± 0.58°, 0.79 ± 0.19 mm, and 1.49 ± 0.48 mm, respectively. Meanwhile, a comparison between the robotic and manual operation demonstrates that the use of the surgical robot system for the zygomatic implant placement can improve the accuracy of the operation.

The effect of the configurations of fiducial markers on accuracy of surgical navigation in zygomatic implant placement: An in vitro study.

Real-time surgical navigation has been increasingly applied in implant placement. The initial registration procedures were found to substantially affect the overall accuracy of the system for zygomatic implant placement, but the exact number and distribution of fiducial markers was yet undetermined. This study aimed to determine the minimal numbers and optimal distributions of fiducial markers to achieve clinically acceptable accuracy in surgical navigation, through systematically analyzing the effects of different setups of fiducial markers on target registration errors (TRE). A maxillary phantom with bone-anchored fiducial markers was scanned using cone beam computed tomography, followed by data processing on Brainlab, a commercially available navigation system. A total of 10 mini-screws were inserted in the edentulous maxilla for configuration of fiducial markers, with another two mini-screws as implant targets to assess TRE in zygomatic bone. Data were then collected in nine configurations with distinct fiducial numbers and positions. Statistical analyses were performed with SPSS. Accuracy of the surgical navigation system was found to depend on both the numbers and positions of fiducial markers. No significant difference was observed in accuracy among groups with eight fiducials and with polygon span distribution (P > .05). When the fiducial numbers decreased to less than six, the markers inserted in a regular triangle area were more precise than in an inverse triangle configuration. When the number of fiducials was five with a polygonal distribution, a low TRE value of 0.59 mm was detected, which was comparable to the accuracy with more than eight fiducials in the study. A scattered distribution with a polygon span with at least five fiducial markers in the edentulous maxilla for registration seems to achieve an acceptable TRE value with a high accuracy for navigation in zygomatic implant placement.

Perception enhancement using importance-driven hybrid rendering for augmented reality based endoscopic surgical navigation.

Misleading depth perception may greatly affect the correct identification of complex structures in image-guided surgery. In this study, we propose a novel importance-driven hybrid rendering method to enhance perception for navigated endoscopic surgery. First, the volume structures are enhanced using gradient-based shading to reduce the color information in low-priority regions and improve the distinctions between complicated structures. Second, an importance sorting method based on the order-independent transparency rendering is introduced to intensify the perception of multiple surfaces. Third, volume data are adaptively truncated and emphasized with respect to the perspective orientation and the illustration of critical information for viewing range extension. Various experimental results prove that with the combination of volume and surface rendering, our method can effectively improve the depth distinction of multiple objects both in simulated and clinical scenes. Our importance-driven surface rendering method demonstrates improved average performance and statistical significance as rated by 15 participants (five clinicians and ten non-clinicians) on a five-point Likert scale. Further, the average frame rate of hybrid rendering with thin-layer sectioning reaches 42 fps. Given that the process of the hybrid rendering is fully automatic, it can be utilized in real-time surgical navigation to improve the rendering efficiency and information validity.

The application of real time surgical navigation for zygomatic implant insertion in severely atrophic maxilla patients

The application of real time surgical navigation for zygomatic implant insertion in severely atrophic maxilla patients

Application of Real-Time Surgical Navigation for Zygomatic Implant Insertion in Patients With Severely Atrophic Maxilla

Computer-aided treatment technology has extended its applications to oral implantology. This report describes the authors' initial clinical experience on the application of a commercially available navigation system (VectorVision) in zygomatic implant (ZI) insertion in the severely atrophic maxilla. This was a retrospective longitudinal study. Eligible patients with maxillary edentulism who were treated with ZI placement were enrolled. Treatment planning was performed on the computer based on previously obtained 3-dimensional imaging data. The surgical procedure was carried out under the guidance of a surgical navigation system. The outcome variable was safety and additional variables were ZI survival rate and radiologic bone-to-implant contact (rBIC) area in the zygoma. Statistical analysis was performed with SPSS 16.0 for Windows (SPSS, Inc, Chicago, IL). Fifteen patients (8 men, 7 women; age range, 30 to 69yr; average age, 43±3.5yr) were eligible for the study and were enrolled from May 2015 through September 2016. Of the included patients, each of 4 patients received 1 ZI on each side of the zygomatic bone and 2 to 4 standard implants in the edentulous anterior maxilla; the other 11 received a ZI "quad approach" without standard implant insertion. All ZIs were anchored in the site of the maxillary alveolar process and zygomatic bone, and no critical anatomic structure injuries occurred during insertion and postoperative radiographic examination. All ZIs achieved osseointegration, for an overall survival rate of 100% after early healing. The overall rBIC area of ZIs in the study was 4.1 to 24.7mm (average, 14.5±4.6mm). For the limited clinical cases treated in this study, the procedure for ZI placement was feasible and reliable with the guidance of the surgical navigation system. In addition, the potential risk of complications was minimized and ZIs were placed to make the best possible use of the available bone volume.

Accuracy of a real-time surgical navigation system for the placement of quad zygomatic implants in the severe atrophic maxilla: A pilot clinical study.

A real-time surgical navigation system potentially increases the accuracy when used for quad-zygomatic implant placement. To evaluate the accuracy of a real-time surgical navigation system when used for quad zygomatic implant placement. Patients with severely atrophic maxillae were prospectively recruited. Four trajectories for implants were planned, and zygomatic implants were placed using a real-time surgical navigation system. The planned-placed distance deviations at entry (entry deviation）points, exit (exit deviation) points, and angle deviation of axes (angle deviation) were measured on fused operation images. The differences of all the deviations between different groups, classified based on the lengths and locations of implants, were analysed. A P value of < 0.05 indicated statistical significance. Forty zygomatic implants were placed as planned in 10 patients. The entry deviation, exit deviation and angle deviation were 1.35 ± 0.75 mm, 2.15 mm ± 0.95 mm, and 2.05 ± 1.02 degrees, respectively. The differences of all deviations were not significant, irrespective of the lengths (P = .259, .158, and .914, respectively) or locations of the placed implants (P = .698, .072, and .602, respectively). A real-time surgical navigation system used for the placement of quad zygomatic implants demonstrated a high level of accuracy with only minimal planned-placed deviations, irrespective of the lengths or locations of the implants.