CT Navigation Research Articles

Feasibility study of intraoperative cone‐beam CT navigation for benign bone tumour surgery

BackgroundIntraoperative cone‐beam computed tomography (CBCT) offers the advantage of navigation on the current anatomical situation and the possibility to take a control scan. We assessed the feasibility of using intraoperative CBCT for navigated intralesional curettage.MethodsNine benign bone tumour patients were studied. Feasibility was assessed by describing the workflow and indications for navigation, scoring CBCT image quality and registration accuracy, and measuring scan and navigation set‐up times. Short‐term follow‐up was described.ResultsCBCT navigation was successful in all patients. Median tumour visibility, tumour delineation, and vital structure visibility scores were good. Median registration accuracy score was very good. Median scan and verification times were 5 and 3 minutes, respectively. One patient had a tumour recurrence after 6 months.ConclusionsIntraoperative CBCT navigation is feasible and safe. Indications for use of navigation in clinical practice are closeness to vital structures, complexly shaped tumours or bone, minimally invasive surgery, and repeated surgery.

Comparison Analysis of Robot-Assisted Computed Tomography Navigation System and Manual Freehand Technique in Orthopedic Surgery

Background and Objective: At present, the robot system and CT guidance system play a significant role in minimally invasive orthopedic surgery, because it is a precise and flexible manipulator that work in confined and complex surgical environments. The robot and CT assisted operations will become increasingly important in orthopedic surgery and in residents' education. Hence, this study aimed to investigate the application value of robot system and CT guidance system in orthopedic surgery. Methods: Firstly, a predesigned questionnaire investigation was carried out in our hospital, and 12 professionals received this questionnaire. Their private opinions on robot system and CT guidance system applied in orthopedic surgery were assessed, respectively. And then, a retrospective survey was performed on the basis of 51 medical records of patients suffering from orthopedic disorders, and all the patients ever reveived orthopedic surgery, under the guidance of a robot-assisted CT navigation system, or by the freehand technique. And the detailed surgical procedures and therapeutic effect were compared between the two groups. In addition, the informed consents of patients were obtained beforehand, and this research protocol was approved by institutional review board in our hospital. Results: The robot system and CT guidance applied in orthopedic surgery has become more popular than before in recent years. In terms of questionnaire, 12 surgeons received this investigation, but the number of validated questionnaires was 11, the response rate was 91.67% (11/12). This kind of training of robot and CT assistant orthopedic surgery varied from a training program by intuitive surgical, master-apprenticeship, fellowship, and self-designed training programs. Most respondents supported the viewpoint that a professional training program and examination for the basics of robot skills were required. With respect to the comparison of detailed surgical procedures between robot-assisted CT navigation system and freehand technique, the operation time under the guidance of robot-assisted CT navigation system was shorter (189.7 ± 65.9 min vs. 298.9 ± 91.1 min, P < 0.05), the pin regulation times under the guidance of robot-assisted CT navigation system were less (1.2 ± 0.96 vs. 12.3 ± 4.28, P < 0.0001), the intraoperative fluoroscopy time under the guidance of robot-assisted CT navigation system were shorter (12.5 ± 3.69 min vs. 52.6 ± 11.1 min, P < 0.001), and the rate of good pin insertion location was higher under the guidance of robot-assisted CT navigation system were shorter (100% vs. 56.7%, P < 0.01). The incidences of postoperative complications were less among the patients who ever received CT-aided orthopedic surgery, but the complication distribution was not statiatially significant. Conclusion: The robot and CT-aided orthopedic surgery become far more popular than before, and has been accepted within a broad scope. And, the intelligent robot-assistant CT could transform the behaviour of orthopedic operations, and make them easier, faster and probably safer, whem compared with the freehand technique. In addition, the professional training still need multidisciplinary basic skills and collaboration.

Intraoperative CT and Surgical Navigation for Iliosacral Screws: Technique for Patients With Sacral Dysmorphism.

Percutaneous iliosacral screw (IS) fixation for pelvic ring injuries with the use of an O-arm imaging system has been associated with decreased procedure time and improved accuracy of IS screw placement compared with the use of fluoroscopic guidance. Specifically, patients with sacral dysmorphism require identification of safe bony sacral corridors, using specific anatomical measurements, to decrease the likelihood of complications such as screw perforation. Intraoperative computed tomography imaging and navigation can aid in safe and accurate IS screw fixation in patients with difficult anatomy.

Wednesday, September 26, 2018 7:35 AM–9:00 AM ePosters

BACKGROUND CONTEXT Several studies have shown that the use of a combination of intraoperative CT images and navigation, significantly improves pedicle screw placement accuracy. A new concept of surgical navigation system using augmented reality (AR) with intraoperative 3D cone beam CT (CBCT) was developed specifically for spinal surgery. PURPOSE To evaluate accuracy, efficiency, and safety of an AR-based surgical navigation system for pedicle screw placement. STUDY DESIGN/SETTING Prospective study. PATIENT SAMPLE Twenty patients. OUTCOME MEASURES Pedicle screw placement accuracy, procedural time, patients and occupational radiation doses. METHODS Twenty patients (1:1 male:female, 30±19 years) eligible for spine surgery with pedicle screw placement (13 scoliosis deformity cases and 7 other surgical indications) were prospectively enrolled and treated using surgical navigation with AR (Philips Healthcare, Best, the Netherlands). A total of 253 screws were placed in the patients using AR. The navigation system consists of optical video cameras integrated in a ceiling-mounted C-arm in a hybrid operating room (OR). An intraoperative CBCT was acquired from the C-arm to plan an optimal path for screw placement. The screws were navigated thanks to the planned paths augmented to the reality scene shown by the video cameras. An additional CBCT was performed to evaluate the accuracy of screw placement by independent reviewers using the Gertzbein scale. Total navigation time for screw placement, patient radiation dose as well as occupational staff dose was measured. RESULTS In average 13±6 screws per patient were placed with navigation. The accuracy of pedicle screw placement was 94% yielding 15/253 screws rated as grade 2 (2–4 mm pedicle breach) from which 13 were lateral breaches. Thirteen of these grade 2 screws had a diameter larger than the pedicle isthmus size where they were placed. The average navigation time was 5.2±4.1 minutes with a median value of 4 minutes from making the bone entry burr-hole to the final screw placement. Navigation time corresponded to an average of 16.8% of the total procedure time. The average patient radiation dose was 31±13 Gy cm2 (median 32, range: 14–51) with an average of 4 CBCT scans per procedure. During intraoperative 3D acquisitions, the OR staff was behind a leaded shield in the corner of the OR and did not wear apron lead protection during surgery. The average cumulative occupational dose of all staff member in the OR was 0.8±1.1 µSv (median 0.3, range: 0.0–3.2). CONCLUSIONS Surgical navigation using AR with intraoperative CBCT demonstrated clinical accuracy as high as 94% of pedicle screw placement with no related clinical complications. The average required time of navigation per screw placement was as short as 5.2 minutes. The use of navigation was a short fraction of the total procedure time. The CBCT intraoperative imaging available on the AR-based navigation system demonstrated negligible cumulative staff dose.

Intraoperative O-arm-navigated resection in musculoskeletal tumors

BackgroundAlthough emerging evidence has suggested that computer-assisted navigation allows surgeons to plan the optimal level of resection without compromising the surgical margins, the precise accuracy of the procedures has been unclear. The aim of this study was to investigate the accuracy and safety of the musculoskeletal tumor resection using O-arm/Stealth intraoperative navigation assistance. MethodsA retrospective study of six patients with bone and soft tissue tumors who underwent surgical resection using O-arm/Stealth navigation system was performed. The histological diagnosis was osteosarcoma, metastatic bone tumor, leiomyosarcoma, undifferentiated sarcoma, and synovial sarcoma, respectively. Tumor resection was performed according to planned osteotomy planes determined on O-arm/Stealth three-dimensional intraoperative images. The resection accuracy, length of time for the procedures, surgical margins, and perioperative complications were evaluated. ResultsThe distances between the entry and exit points for the planned and actual cuts were 1.5 ± 0.3 mm and 2.3 ± 0.3 mm, respectively, and the mean discrepancy of the osteotomy angle was 2.8 ± 1.2°. The mean length of time required for navigation was 14 min. A histological examination revealed clear margins in all patients. There were no complications related to navigation, and no patients developed local recurrence during a mean follow-up of 30.6 months. ConclusionsThe O-arm/Stealth intraoperative CT navigation system provides safe and accurate osteotomy in musculoskeletal tumor resections. However, surgeons should keep in mind and be careful of minimal errors during osteotomy, which are around 2 mm from the planned line.

Subtalar coalition resection utilizing live navigation: a technique tip.

PurposeDescribe the surgical technique of talocalcaneal coalition resection using live CT navigation.MethodsA ten-year-old female with left talocalcaneal coalition hindfoot pain refractory to conservative management underwent surgical coalition resection using live CT navigation. The procedure and discussion of this technique is described in detail.ResultsWith minimal radiation exposure to the patient, CT navigation for this complex talocalcaneal coalition was both helpful and potentially timesaving by allowing immediate localization and guided resection of the coalition.ConclusionIn the case of a complex subtalar coalition resection, CT navigation poses minimal patient radiation exposure and allows immediate localization and guided resection of the coalition.Level of EvidenceLevel V

Assistance with multimodal image fusion in surgery of vestibular schwannomas

Objective To discuss the assistance with multimodal image fusion technology in surgery of vestibular schwannomas to improve the rate of total resection as well as preservation of nerve function and achieve precise surgical treatment. Methods This retrospective study involved 30 patients who underwent surgical treatment of vestibular schwannomas with the assistance of multimodal image fusion at Neurosurgery Department of PLA General Hospital from January 2016 to August 2016. The facial nerve was reconstructed through Fast Imaging Employing Steady State Acquisition With Cycled Phases (FIESTA-C) and Diffusion Tensor Imaging (DTI), and the accuracy of reconstructed facial nerve was verified by intraoperative findings under microscope. The images of facial nerve, internal auditory canal water imaging and temporal bone CT were 3D-reconstructed and fused to determine the relationship between tumors and surrounding structures. CT navigation was used to determine the exact location of posterior wall of the internal auditory canal and areas to be removed. Continuous intraoperative neuroelectrophysiological monitoring was conducted to determine the location of the nerve to avoid its injury. Results Total tumor resection was achieved in 28 cases (93.3%) and subtotal resection in 2 cases (6.7%). The anatomical integrity of facial nerve was preserved in 28 cases (93.3%), and 26 cases (86.7%) had excellent or good facial functions. The successful rate of facial nerve reconstruction was 100%, and 93.3% of all patients demonstrated consistence between reconstructed and actual positions of the nerve. Navigation was performed in 17 patients with the registration error ranging from 0.30 mm to 0.92 mm (mean: 0.47±0.15 mm). None of the patients had preoperative functional hearing, and no one retained or improved hearing postoperatively. During the perioperative period, there was no death, cerebrospinal fluid leakage, intracranial hematoma or lower cranial nerve palsy. Conclusion The application of multimodal image fusion in surgical treatment of acoustic neuromas could improve the rates of total resection and facial function retention and help reduce operative complications. Key words: Neuroma, acoustic; Neuronavigation; Diffusion tensor imaging; Neurophysiology monitoring; Facial nerve; Internal auditory canal

Accuracy of pedicle screw insertion by AIRO® intraoperative CT in complex spinal deformity assessed by a new classification based on technical complexity of screw insertion.

To develop a classification based on the technical complexity encountered during pedicle screw insertion and to evaluate the performance of AIRO® CT navigation system based on this classification, in the clinical scenario of complex spinal deformity. 31 complex spinal deformity correction surgeries were prospectively analyzed for performance of AIRO® mobile CT-based navigation system. Pedicles were classified according to complexity of insertion into five types. Analysis was performed to estimate the accuracy of screw placement and time for screw insertion. Breach greater than 2mm was considered for analysis. 452 pedicle screws were inserted (T1-T6: 116; T7-T12: 171; L1-S1: 165). The average Cobb angle was 68.3° (range 60°-104°). We had 242 grade 2 pedicles, 133 grade 3, and 77 grade 4, and 44 pedicles were unfit for pedicle screw insertion. We noted 27 pedicle screw breach (medial: 10; lateral: 16; anterior: 1). Among lateral breach (n=16), ten screws were planned for in-out-in pedicle screw insertion. Among lateral breach (n=16), ten screws were planned for in-out-in pedicle screw insertion. Average screw insertion time was 1.76±0.89min. After accounting for planned breach, the effective breach rate was 3.8% resulting in 96.2% accuracy for pedicle screw placement. This classification helps compare the accuracy of screw insertion in range of conditions by considering the complexity of screw insertion. Considering the clinical scenario of complex pedicle anatomy in spinal deformity AIRO® navigation showed an excellent accuracy rate of 96.2%.

Research and application progress of surgical robot in spine surgery

Open and percutaneous pedicle screw insertion would have the risk of damaging the nerve or blood vessels, due to the complexity of the spine structure. Despite the aid of various means of preoperative CT and intraoperative navigation, pedicle screw insertion failure rate is still 4.1%-28.9%. In recent years, the development of spine surgical robots might bring new solutions to this problem. The use of the spine surgical robots has been more than 20 years, and developed rapidly with the development of intraoperative navigation and intraoperative CT in recent years. Some robots have been certified by the FDA or the CE. And the number of reported robot-assisted surgeries such as scoliosis surgeries or severe lumbar spondylolisthesis surgeries has increased rapidly as well. Current literatures have verified the robot-assisted pedicle screw insertion has high accuracy, good stability and short learning curve, which may be able to become one of the main trend of spinal surgery in the future. This article mend to review some developed spine surgery robot and their clinical application indication and results.

Percutaneous screw placement in the lumbar spine with a modified guidance technique based on 3D CT navigation system.

Several guidance techniques have been employed to increase accuracy and reduce surgical time during percutaneous placement of pedicle screws (PS). The purpose of our study was to present a modified technique for percutaneous placement of lumbar PS that reduces surgical time. We reviewed 23 cases of percutaneous PS placement using our technique for minimally invasive lumbar surgeries and 24 control cases where lumbar PS placement was done via common technique using Jamshidi needles (Becton, Dickinson and Company, Franklin Lakes, NJ, USA). An integrated computer-guided navigation system was used in all cases. In the technique modification, a handheld drill with a navigated guide was used to create the path for inserting guidewires through the pedicles and into the vertebral bodies. After drill removal, placement of the guidewires through the pedicles took place. The PS were implanted over the guidewires, through the pedicles and into the vertebral bodies. Intraoperative computed tomography was performed after screw placement to ensure optimal positioning in all cases. There were no intraoperative complications with either technique. PS placement was correct in all cases. The average time for each PS placement was 6.9 minutes for the modified technique and 9.2 minutes for the common technique. There was no significant difference in blood loss. In conclusion, this modified technique is efficient and contributes to reduced operative time.

245 - Accuracy of Three Different Methods of Cervical Pedicle Screw Insertion

BACKGROUND CONTEXT: Many methods about how to insert the cervical pedicle screw (CPS) for improving safety have been reported since Abumi et al. first reported on CPSs in 1994. These reports suggest the usage of fluoroscopy, aiming device or CT navigation can improve the accuracy of CPS insertion, and the vertebral artery or nerve injury that will cause the severe postoperative complication can be avoided by these surgical assistive device for CPS insertion.

A novel technique for placement of sacro-alar-iliac (S2AI) screws by K-wire insertion using intraoperative navigation

Sacral-iliac fixation techniques may be indicated in the management of various lumbosacral pathologies including spinal degeneration, infection, tumour resection, fracture, pseudarthrosis, correction of spinal deformities involving long fusion constructs to the sacrum and cases with poor sacral fixation. There are a number of options for lumbosacral fixation each with their own advantages and disadvantages. Though S2-alar-iliac (S2AI) have demonstrated promising advantages over alternatives, the complex anatomy of the spinopelvic region demands precise insertion of the screws to create a biomechanically robust construct safely. As such, we present a novel technique of using intra-operative CT navigation and K-wires to establish and secure a planned trajectory, thereby ensuring solid spinopelvic fixation with S2AI screws. This was performed as part of a long fusion construct for correction of kyphosis deformity in a male patient.

Radiation dose reduction in thoracic and lumbar spine instrumentation using navigation based on an intraoperative cone beam CT imaging system: a prospective randomized clinical trial.

Spine surgery still remains a challenge for every spine surgeon, aware of the potential serious outcomes of misplaced instrumentation. Though many studies have highlighted that using intraoperative cone beam CT imaging and navigation systems provides higher accuracy than conventional freehand methods for placement of pedicle screws in spine surgery, few studies are concerned about how to reduce radiation exposure for patients with the use of such technology. One of the main focuses of this study is based on the ALARA principle (as low as reasonably achievable). A prospective randomized trial was conducted in the hybrid operating room between December 2015 and December 2016, including 50 patients operated on for posterior instrumented thoracic and/or lumbar spinal fusion. Patients were randomized to intraoperative 3D acquisition high-dose (standard dose) or low-dose protocol, and a total of 216 pedicle screws were analyzed in terms of screw position. Two different methods were used to measure ionizing radiation: the total skin dose (derived from the dose-area product) and the radiation dose evaluated by thermoluminescent dosimeters on the surgical field. According to Gertzbein and Heary classifications, low-dose protocol provided a significant higher accuracy of pedicle screw placement than the high-dose protocol (96.1 versus 92%, respectively). Seven screws (3.2%), all implanted with the high-dose protocol, needed to be revised intraoperatively. The use of low-dose acquisition protocols reduced patient exposure by a factor of five. This study emphasizes the paramount importance of using low-dose protocols for intraoperative cone beam CT imaging coupled with the navigation system, as it at least does not affect the accuracy of pedicle screw placement and irradiates drastically less.

Wiltse approach assisted by O-arm three-dimensional CT navigation in treatment of Lenke 5C Idiopathic Scoliosis

Objective To explore the feasibility and efficacy of posterior minimally invasive scoliosis surgery in Lenke 5C adolescent idiopathic scoliosis (AIS). Methods From November 2012 to March 2014, a total of 16 patients underwent posteri-or minimally invasive scoliosis surgery assisted by O-arm three-dimensional CT navigation were included. There were 14 female and 2 male, with an average age of (16.7±1.6) years (ranged from 14 to 18 years). The mean Cobb angles of lumbar and thoracic curve were 48.7°±5.6°and 24.1°±5.4°, respectively. Results 16 patients were successfully completed the operation, the average operation time was (246±89) min, the average intraoperative blood loss was (192±105) ml, and the fusion level was 4.9±0.5 on av-erage. A total of 155 screws were inserted in the 16 patients, with a mean implant density of 98.9%±4.9%. All the patients were fol-lowed up for (26.4±3.9) months on average. The following radiographic parameters were evaluated before surgery, immediately af-ter surgery and at the last follow-up: curve magnitude, apical vertebral translation (AVT), apical vertebral rotation (AVR), trunk shift, thoracic kyphosis (TK), thoracolumbar kyphosis (TLK), lumbar lordosis (LL) and sagittal vertical axis (SVA). The accuracy of pedicle screw placement was assessed according to postoperative CT scans. SRS-22 scores and complications were also recorded during the follow-up. Immediately after surgery, the correction rate of main lumbar curve was 80.1%±8.3%, and thoracic curve was 59.3%±8.7%, and a obvious improvement was noted in terms of AVT, AVR, trunk shift and TLK. At the last follow-up, except the increase of SVA from (-27.6±19.5) mm to (-12.3±6.6) mm, no obvious changes of AVT, AVR, trunk shift, TK, TLK and LL were observed during the follow-up. According to CT evaluation, the satisfactory rate of pedicle screw placement was 94.2%, while the perforation rate was 5.8% (9/155). Fusion across the facet joint were satisfactory. In SRS-22 assessment, the mean scores of func-tional, pain, self-image, mental state and satisfaction were (4.3 ± 0.5) points, (4.7 ± 0.6) points, (4.2 ± 0.7) points, (4.2 ± 0.5) points and (4.4 ± 0.6) points. No wound infection, implant failure and neurologic complications were found after surgery. Conclusion Wiltse approach assisted by O-arm three-dimensional CT navigation has the characteristics of small injury, less bleeding, high accuracy placement of pedicle screws and high self-satisfaction of patients. It is a feasible, safe and effective way to treat Len-ke 5C AIS. Key words: Scoliosis; Surgical procedures, minimally iInvasive; Surgery, computer-assisted

Improved surgical procedure using intraoperative navigation for the implantation of the SPG microstimulator in patients with chronic cluster headache.

The ATI SPG microstimulator is designed to be fixed on the posterior maxilla, with the integrated lead extending into the pterygopalatine fossa to electrically stimulate the sphenopalatine ganglion (SPG) as a treatment for cluster headache. Preoperative surgical planning to ensure the placement of the microstimulator in close proximity (within 5mm) to the SPG is critical for treatment efficacy. The aim of this study was to improve the surgical procedure by navigating the initial dissection prior to implantation using a passive optical navigation system and to match the post-operative CBCT images with the preoperative treatment plan to verify the accuracy of the intraoperative placement of the microstimulator. Custom methods and software were used that result in a 3D rotatable digitally reconstructed fluoroscopic image illustrating the patient-specific placement with the ATI SPG microstimulator. Those software tools were preoperatively integrated with the planning software of the navigation system to be used intraoperatively for navigated placement. Intraoperatively, the SPG microstimulator was implanted by completing the initial dissection with CT navigation, while the final position of the stimulator was verified by 3D CBCT. Those reconstructed images were then immediately matched with the preoperative CT scans with the digitally inserted SPG microstimulator. This method allowed for visual comparison of both CT scans and verified correct positioning of the SPG microstimulator. Twenty-four surgeries were performed using this new method of CT navigated assistance during SPG microstimulator implantation. Those results were compared to results of 21 patients previously implanted without the assistance of CT navigation. Using CT navigation during the initial dissection, an average distance reduction of 1.2mm between the target point and electrode tip of the SPG microstimulator was achieved. Using the navigation software for navigated implantation and matching the preoperative planned scans with those performed post-operatively, the average distance was 2.17mm with navigation, compared to 3.37mm in the 28 surgeries without navigation. Results from this new procedure showed a significant reduction (p=0.009) in the average distance from the SPG microstimulator to the desired target point. Therefore, a distinct improvement could be achieved in positioning of the SPG microstimulator through the use of intraoperative navigation during the initial dissection and by post-operative matching of pre- and post-operatively performed CBCT scans.

Interactive 3D Virtual Colonoscopic Navigation For Polyp Detection From CT Images

Optical colonoscopy is an invasive procedure used to examine surface lining of the colon, by inserting a flexible tube with a light and camera into the body. Virtual colonoscopy is emerging as a non-invasive alternative to optical colonoscopy. This paper describes 3D reconstruction of colon structure from patient specific CT images, interactive visualization and navigation through the reconstructed colon, automated computation of the navigation path and automated polyp detection with 90.91% sensitivity. This enables a doctor to perform a fast diagnosis through virtual exploration of the colon and resort to invasive colonoscopy procedures only if suspicious polyps are detected.

Accuracy of pedicle screw placement using intraoperative CT navigation system

Accuracy of pedicle screw placement using intraoperative CT navigation system

Operační korekce skoliózy: prodlužuje peroperační CT navigace trvání operace?

Operační korekce skoliózy: prodlužuje peroperační CT navigace trvání operace?

Percutaneous internal fixation of pelvic fractures.

Percutaneous internal fixation of pelvic fractures is increasing in popularity with multiple new techniques reported. The purpose of this article is to outline the imaging, indication, planning, equipment, surgical technique and complications of these methods. Areview of the literature is provided and the techniques for anterior and posterior pelvic stabilisation are discussed. High-quality preoperative CT scans are essential in planning for this technique. The anterior internal fixator ("InFix") is an effective method for stabilising the anterior ring and should be usually used in conjunction with posterior fixation. Good technique avoids neurovascular injury, which can be adevastating complication. The retrograde anterior column screw (RACS) is atechnique that can be used in most patients, although in smaller patients smaller screw diameters may be needed. The entry point for the screw is more lateral in women than men. Iliosacral screws (ISS) are an effective method of posterior stabilisation and can be placed using 2D or 3D fluoroscopy, computer navigation or CT navigation. Percutaneous fixation of pelvic fractures requires high-quality imaging and can be aided by computer navigation. Safe techniques are reproducible; however, not all patients and fracture patterns can be treated using these techniques.

The role of Intraoperative 3D navigation for pelvic bone tumor resection

Interventional 3D analysis is often used for surgery of the spine. The goal of this study was to describe the technique and initial results of intraoperative 3D CT navigation (O-Arm, Medtronic, Louisville, CO, USA) for surgery of the pelvis. Six patients were included, five with primary bone tumors and one with post-traumatic non-union. All CT procedures were completed without modifying the surgical technique, except one case in which the device had to be reinstalled during surgery. The duration of surgery was not increased and lasted for a mean 224minutes (96–380). Recorded radiation was between 450–1125mGrey/cm. All procedures were performed according to the preoperative plan resulting in systematic resection with a safe surgical margin (R0). One surgical site infection occurred. Although these operations could have been performed without 3-D navigation, this technique provided continuous intraoperative control and safety. Level of evidenceIV.