Intraoperative Scanning Research Articles

Vestibular electrode position stability over time.

In vestibular implants (VI), the electrode position is thought to be important for optimal neural activation. The objective of this study was to evaluate the stability of the vestibular electrode position over time. Seven patients implanted with a VI were followed for one year. When possible, the fenestrations of the semicircular canals were kept very small (approximately 0.8mm) to stabilize the electrode lead. Additionally, the electrodes were fixed at their fenestration sites using bone cement. A temporal bone CT scan was performed intraoperatively, and one week and one year postoperatively. In one patient reliable analysis of the intraoperative CT scan was not possible due to a technical error. A displacement of the vestibular electrodes of more than 0.5mm was considered significant. Fourteen out of 18 electrodes did not show a significant displacement between the intraoperative scan and the first postoperative scan. In the remaining four electrodes, a displacement of ≥ 0.5mm occurred (mean 0.54mm, range 0.50-0.58mm). These four electrodes were found in the two first implanted patients. In both cases, the intraoperative CT scan had a slice thickness of 0.5mm and showed severe scattering. This might imply that the measured displacement was (partially) related to a higher measurement error. None of the vestibular electrodes migrated outside of the ampulla. No displacement was observed in any of the vestibular electrodes between the first postoperative scan and the one-year follow-up scan. The current surgical technique seems to securely stabilize the vestibular VI electrodes over time.

Outcomes following endoscopic endonasal resection of craniopharyngiomas using intraoperative magnetic resonance imaging: Case series

BackgroundCraniopharyngiomas are rare tumors that originate from the squamous epithelium in Rathke's sac residues. There is a limited body of literature on the effect of using intraoperative magnetic resonance imaging (IO-MRI) in resection of craniopharyngiomas via endoscopic endonasal surgery (EES). The present study aims to assess the outcomes of EES for resection of craniopharyngiomas using IO-MRI. MethodsThis is a retrospective analysis of the data collected on the point of care, consisting of 27 patients who underwent EES for histologically confirmed craniopharingiomas. All procedures were performed by a single neurosurgeon in between 2018 and 2020. ResultsIO-MRI showed gross total resections were achieved in 25 (92.6 %) patients, and subtotal resections were achieved in 2 (7.4 %) patients. Pre-anticipated resection rate was achieved in the intraoperative scans in all patients and none of the patients required further resection. IO-MRI prolonged the anesthesia duration by an average of 32 ± 4 min. In the follow-up, 24 (88.9 %) cases of permanent diabetes insipidus and 10 (37 %) cases of panhypopituitarism were observed. Cerebrospinal fluid rhinorrhea complicated 6 (22.2 %) cases. ConclusionThis present study is the largest study evaluating the efficiency of IO-MRI in craniopharyngioma. In addition, unlike other studies, only the patients who underwent EES were included. Although it has been known that the EES for craniopharyngioma is an effective and less invasive technique, this presented early results would suggest that combining this method with IO-MRI did not make significant contributions to surgical outcome.

Two years of neurosurgical intraoperative MRI in Sweden - evaluation of use and costs.

The current shortage of radiology staff in healthcare provides a challenge for departments all over the world. This leads to more evaluation of how the radiology resources are used and a demand to use them in the most efficient way. Intraoperative MRI is one of many recent advancements in radiological practice. If radiology staff is performing intraoperative MRI at the operation ward, they may be impeded from performing other examinations at the radiology department, creating costs in terms of exams not being performed. Since this is a kind of cost whose importance is likely to increase, we have studied the practice of intraoperative MRI in Sweden. The study includes data from the first four hospitals in Sweden that installed MRI scanners adjacent to the operating theaters. In addition, we included data from Karolinska University Hospital in Solna where intraoperative MRI is carried out at the radiology department. Scanners that were moved into the operation theater and doing no or few other scans were used 11-12% of the days. Stationary scanners adjacent to the operation room were used 35-41% of the days. For scanners situated at the radiology department doing intraoperative scans interspersed among all other scans, the proportion was 92%. Our study suggests that performing exams at the radiology department rather than at several locations throughout the hospital may be an efficient approach to tackle the simultaneous trends of increasing demands for imaging and increasing staff shortages at radiology departments.

Proof-of-concept of a robotic-driven photogrammetric scanner for intra-operative knee cartilage repair.

This work presents a proof-of-concept of a robotic-driven intra-operative scanner designed for knee cartilage lesion repair, part of a system for direct in vivo bioprinting. The proposed system is based on a photogrammetric pipeline, which reconstructs the cartilage and lesion surfaces from sets of photographs acquired by a robotic-handled endoscope, and produces 3D grafts for further printing path planning. A validation on a synthetic phantom is presented, showing that, despite the cartilage smooth and featureless surface, the current prototype can accurately reconstruct osteochondral lesions and their surroundings with mean error values of 0.199 ± 0.096mm but with noticeable concentration on areas with poor lighting or low photographic coverage. The system can also accurately generate grafts for bioprinting, although with a slight tendency to underestimate the actual lesion sizes, producing grafts with coverage errors of -12.2 ± 3.7, -7.9 ± 4.9, and -15.2 ± 3.4% for the medio-lateral, antero-posterior, and craneo-caudal directions, respectively. Improvements in lighting and acquisition for enhancing reconstruction accuracy are planned as future work, as well as integration into a complete bioprinting pipeline and validation with ex vivo phantoms.

Comparison of intraoperative CT- and cone beam CT-based spinal navigation for the treatment of atlantoaxial instability

BACKGROUND CONTEXTDue to the complexity of neurovascular structures in the atlantoaxial region, spinal navigation for posterior C1–C2 instrumentation is nowadays a helpful tool to increase accuracy of surgery and safety of patients. Many available intraoperative navigation devices have proven their reliability in this part of the spine. Two main imaging techniques are used: intraoperative CT (iCT) and cone beam computed tomography (CBCT). PURPOSEComparison of iCT- and CBCT-based technologies for navigated posterior instrumentation in C1-C2 instability. STUDY DESIGNRetrospective study. PATIENT SAMPLEA total of 81 consecutive patients from July 2014 to April 2020. OUTCOME MEASURESScrew accuracy and operating time. METHODSPatients with C1–C2 instability received posterior instrumentation using C2 pedicle screws, C1 lateral mass or pedicle screws. All screws were inserted using intraoperative imaging either using iCT or CBCT systems and spinal navigation with autoregistration technology. Following navigated screw insertion, a second intraoperative scan was performed to assess the accuracy of screw placement. Accuracy was defined as the percentage of correctly placed screws or with minor cortical breach (<2 mm) as graded by an independent observer compared to misplaced screws. RESULTSA total of 81 patients with C1–C2 instability were retrospectively analyzed. Of these, 34 patients were operated with the use of iCT and 47 with CBCT. No significant demographic difference was found between groups. In the iCT group, 97.7% of the C1–C2 screws were correctly inserted; 2.3% showed a minor cortical breach (<2 mm); no misplacement (>2 mm). In the CBCT group, 98.9% of screws were correctly inserted; no minor pedicle breach; 1.1% showed misplacement >2 mm. Accuracy of screw placement demonstrated no significant difference between groups. Both technologies allowed sufficient identification of screw misplacement intraoperatively leading to two screw revisions in the iCT and three in the CBCT group. Median time of surgery was significantly shorter using CBCT technology (166.5 minutes [iCT] vs 122 minutes [CBCT]; p<.01). CONCLUSIONSSpinal navigation using either iCT- or CBCT-based systems with autoregistration allows safe and reliable screw placement and intraoperative assessment of screw positioning. Using the herein presented procedural protocols, CBCT systems allow shorter operating time.

Comparison of functional and esthetic outcomes in digital versus analog rehabilitation of one-piece screw-retained implant crowns placed at second stage surgery.

Analog and digital impressions are established procedures for restoration of single-tooth implants. In this study, single-tooth implants were restored with definitive restorations during second-stage surgery. Analog and digital workflows were compared. Eighty single-tooth implants were examined in total. In 40 implants, an index was taken immediately after implant placement using composite resin to fabricate the final crowns (analog workflow). For the other 40 single-tooth implants, intraoral intraoperative scans were performed (digital workflow) during primary surgery. The custom-fabricated screw-retained crowns were placed during second-stage surgery. Photographs and examinations for the scores were taken at the time of the follow-up visit, 1-4 years after placement of the crowns. The number of treatment appointments required was recorded and the modified pink esthetic score (PES) was determined. Additionally, the functional implant prosthetic score (FIPS) was measured. The mean PES was 12.15/14 for the digital workflow and 11.95/14 for the analog workflow. The most common deficit was incomplete papillae for both workflows. Three treatment appointments were required for both workflows: (1) Scan and/or impressions making and patient consent, (2) implant placement, and (3) second-stage surgery with crown insertion. The FIPS was 9.1/10 for the digital workflow group and 9.2 /10 for the analog workflow group. Common deficits presented as missing papillae as well as open approximal contacts. The FIPS was not significantly different between workflows (p = 0.679). The PES also did not show a statistically significant difference for both workflows (p = 0.654), however the analog workflow showed better values for the papillae (p < 0.05). A significant difference was also found in the other PES values, with the digital workflow showing better results here (p < 0.05). A chronological analysis of the results of the digital technique showed that the cases treated last had significantly better values than the cases treated first. According to the results of this study, both workflows allowed placement of the definitive crowns on single-tooth implants during second-stage surgery. Both workflows were found to be equivalent in terms of esthetic results in this study, although the digital workflow demonstrated a learning curve. This article is protected by copyright. All rights reserved.

Ureter position and risk of ureteral injury during lateral lumbar interbody fusion

BackgroundUreteral injury during lateral lumbar interbody fusion (LLIF) is uncommon. However, it is a serious complication that may require additional surgery should it occur. The objective of this study was to evaluate whether there was any change in the position of the left ureter between preoperative biphasic contrast-enhanced CT scanned in the supine position and intraoperative scanning in the right lateral decubitus position after stent placement, to assess the risk of ureteral injury in the actual surgical position. MethodsThe position of the left ureter scanned with the O-arm navigation system with the patient in the right lateral decubitus position and its position on preoperative biphasic contrast-enhanced CT images scanned with the patient in the supine position were investigated comparing their positions at the L2/3, L3/4, and L4/5 levels. ResultsThe ureter was located along the interbody cage insertion trajectory in 25 of 44 disc levels (56.8%) in the supine position, but in only 4 (9.5%) in the lateral decubitus position. The proportion of patients in whom the left ureter was located lateral to the vertebral body (along the LLIF cage insertion trajectory) at each level was 80% in the supine position and 15.4% in the lateral decubitus position at the L2/3 level, 53.3% in the supine position and 6.7% in the lateral decubitus position at the L3/4 level, and 33.3% in the supine position and 6.7% in the lateral decubitus position at the L4/5 level. ConclusionThe proportion of patients in whom the left ureter was located on the lateral surface of the vertebral body when the patient was in the actual surgical position (lateral decubitus position) was 15.4% at the L2/3 level, 6.7% at the L3/4 level, and 6.7% at the L4/5 level, suggesting that caution is required during LLIF surgery.

360 Assessment of Pedicle Screw Placement Accuracy Utilizing a Novel Augmented Reality and Artificial Intelligence Surgical Guidance System

INTRODUCTION: The integration of artificial intelligence (AI) and augmented reality (AR) technologies in spine navigation has the potential to minimize pedicle screw misplacement, decrease radiation exposure, and improve procedural efficiency, addressing some of the challenges associated with spinal instrumentation. METHODS: Sixty lumbosacral pedicle screws were placed by 4 Orthopedics surgeons in 6 cadavers using the AR/AI surgical navigation system. Two CT intraoperative scans (before and after screw placement) of the cadaveric specimens were obtained for the study to measure the 3D positional and angular discrepancies between virtual and real screws. The validation procedure consisted of 3 steps: (1) automatic registration and 3D coordinate transformation, where the preop CT scan was aligned with the postop scan to determine the virtual screw 3D positions and orientations in postop scan; (2) analysis of the postop scan to determine the real screw 3D positions and orientations as they appeared in the scan volume; (3) automatic comparison between the 3D positions and orientations of the virtual and real screws. RESULTS: A one-sample t-test statistical analysis yielded a mean positional error of 2.16 mm ± 1.00 mm (99% CI: 1.81-2.49 mm), and a mean angular error of 1.49± 0.73° (99% CI: 1.25-1.74°). These results were independent of anatomical level, side, and surgeon. CONCLUSIONS: This study indicates that this AR/AI surgical guidance system provides mean positional and angular errors lower than 3.0 mm and 3.0° respectively, thus complying with FDA-required regulatory acceptance criteria. The system was FDA-cleared as a US 510k Orthopedic Stereotaxic Instrument.

Early Outcomes in Renal Transplantation With Routine Intraoperative Duplex Ultrasound

While intra-operative duplex ultrasound scanning can be readily performed in renal transplantation, the value of this intervention in routine practice is not established. Three hundred thirty-one consecutive single renal transplants in adult recipients underwent intraoperative scanning at implantation. Early graft losses were compared with those recorded in the ANZDATA Registry. Nine overt vascular abnormalities were corrected prior to scanning. Four further suspected venous outflow restrictions were confirmed by ultrasound and revised. Another 11 major vascular revisions were performed following intraoperative ultrasound consisting of 7 otherwise unsuspected inflow abnormalities, all corrected, and 4 anastomoses redone to reposition the graft. Thirty-two (9.7%) grafts were repositioned under ultrasound guidance to improve cortical perfusion but without vascular revision. One graft with hyperacute rejection was explanted 4 days postimplantation and one graft with primary nonfunction remained well perfused. Two patients died within 90 days, both with functioning grafts. Twenty-three grafts were re-explored within 7 days, including 9 solely for graft hypoperfusion. There were no postoperative arterial thromboses and, at re-exploration, no arterial anastomoses required revision. There were no postoperative venous thromboses, although one venous anastomosis was revised. No grafts were lost within 90 days for surgical or technical reasons compared with 76 (1.0%) of 7603 contemporaneous grafts in the ANZDATA Registry (P=.077 Fisher's exact test, P=.069 χ2 test). The routine use of intraoperative ultrasound appears to be of benefit by identifying otherwise unrecognized vascular abnormalities, leading to a reduction in early graft losses because of surgical factors.

Intraoperative Ultrasonography in Endoscopic Approaches for Orbital Lesions: A Single-Center Case Series.

Recently, endoscopic approaches for orbital lesions have been proposed. Their results seem promising; however, orbital surgery remains challenging with possible significant morbidity, mostly because of orbital structures manipulation. Ultrasonography is an innovative intraoperative imaging technique that can assist the surgeon in these approaches. To assess the role of intraoperative ultrasound (IOUS) in endoscopic orbital surgery. All consecutive patients with orbital tumors operated in our institution through an endoscopic approach with IOUS have been prospectively collected from 2019 to May 2021. Fifteen patients were included. Based on tumor location, evaluated on preoperative MRI, the endoscopic endonasal approach was preferred in 7 tumors in medial quadrants while the endoscopic transpalpebral in 8 lateral ones. During surgery, IOUS allowed us to identify the tumors and the most relevant anatomic structures in all cases. Time spent for IOUS preparation before the first scan was 8 ± 6 minutes on average, and each intraoperative scan took approximately 30 to 120 seconds. Gross tumor removal was achieved in 8 patients, subtotal in 3, while in 4 patients, surgery was limited to a biopsy. No surgical complications were observed. IOUS has allowed us to localize the lesion and to identify the straighter surgical corridor and assess the tumor resection, effectively helping the surgeon and potentially reducing operative complications. This tool provides a real-time image, not affected by the orbital structures shift, which can be dynamically assessed multiple times during surgery. However, it is hampered by the need of specific training and possible artifacts.

Augmented Reality to Improve Surgical Workflow in Minimally Invasive Transforaminal Lumbar Interbody Fusion - A Feasibility Study With Case Series.

ObjectiveMinimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) is a highly reproducible procedure for the fusion of spinal segments. We recently introduced the concept of “total navigation” to improve workflow and eliminate fluoroscopy. Image-guided surgery incorporating augmented reality (AR) may further facilitate workflow. In this study, we developed and evaluated a protocol to integrate AR into the workflow of MIS-TLIF. MethodsA case series of 10 patients was the basis for the evaluation of a protocol to facilitate tubular MIS-TLIF by the application of AR. Surgical TLIF landmarks were marked on a preoperative computed tomography (CT)-scan using dedicated software. This marked CT scan was fused intraoperatively with the low-dose navigation CT scan using elastic image fusion, and the markers were transferred to the intraoperative scan. Our experience with this workflow and the surgical outcomes were collected. ResultsOur AR protocol was safely implemented in all cases. The TLIF landmarks could be preoperatively planned and transferred to the intraoperative imaging. Of the 10 cases, 1 case had additionally a synovial cyst resection and in 2 cases an additional bony decompression was performed due to central stenosis. The average procedure time was 160.6±31.9 minutes. The AR implementation added 1.72±0.37 minutes to the overall procedure time. No complications occurred. ConclusionOur findings support the idea that total navigation with AR may further facilitate the workflow, especially in cases with more complex anatomy and for teaching and training purposes. More work is needed to simplify the software and make AR integration more user-friendly.

Soft-tissue simulation of the breast for intraoperative navigation and fusion of preoperative planning.

Computational preoperative planning offers the opportunity to reduce surgery time and patient risk. However, on soft tissues such as the breast, deviations between the preoperative and intraoperative settings largely limit the applicability of preoperative planning. In this work, we propose a high-performance accurate simulation model of the breast, to fuse preoperative information with the intraoperative deformation setting. Our simulation method encompasses three major elements: high-quality finite-element modeling (FEM), efficient handling of anatomical couplings for high-performance computation, and personalized parameter estimation from surface scans. We show the applicability of our method on two problems: 1) transforming high-quality preoperative scans to the intraoperative setting for fusion of preoperative planning data, and 2) real-time tracking of breast tumors for navigation during intraoperative radiotherapy. We have validated our methodology on a test cohort of nine patients who underwent tumor resection surgery and intraoperative radiotherapy, and we have quantitatively compared simulation results to intraoperative scans. The accuracy of our simulation results suggest clinical viability of the proposed methodology.

Computed Tomography Intraoperative Navigation in Spinal Surgery: Assessment of Patient Radiation Exposure in Current Practices.

Patient radiation exposure associated with the use of computed tomography (CT) navigation during spinal surgeries was widely compared with other intraoperative imaging techniques. The aim of this study is to explore the use of navigation with regard to current spinal surgery practices and the technical limitations of such imaging systems. Dosimetric data from 101 patients who underwent intraoperative, CT-navigated spine surgery were retrospectively collected. The study population was divided into 3 groups according to the primary surgical indication. The number of CT image acquisitions per patient, the field length, and the time of exposure per acquisition during a single surgery were compared as well as the radiation dose emitted to patients. Dose-length products (DLP) per acquisition were 678.52, 656.8, and 649.36 mGy·cm with no significant difference for spinal deformity (SD), degenerative disease (DD), and vertebral fracture (VF) procedures, respectively. Analyzing the number of CT image acquisitions per patient revealed that repeated intraoperative scans were often performed for patients who were suffering from an SD due to technical limitations of the navigation. As a consequence, the cumulative dose was higher in the SD group (DLP total = 1175 mGy·cm) than in the DD (DLP total = 762.74 mGy·cm) and VF (DLP total = 649.36 mGy·cm) groups. CT navigation is an efficient intraoperative imaging technique that reduces the rate of surgical complications, but its technical limitations lead to an increased risk of patient radiation exposure, especially for complex surgeries where multiple scanning acquisitions are needed. To avoid patient's overexposure, spine surgeons should minimize the number of intraoperative acquisitions while considering the complexity of the surgery and the limitations of the guidance system. The use of dual guidance systems has also to be considered according to the benefit-risk balance between patient's outcomes and radiation dose exposure.

Optical coherence tomography and convolutional neural networks can differentiate colorectal liver metastases from liver parenchyma ex vivo

PurposeOptical coherence tomography (OCT) is an imaging technology based on low-coherence interferometry, which provides non-invasive, high-resolution cross-sectional images of biological tissues. A potential clinical application is the intraoperative examination of resection margins, as a real-time adjunct to histological examination. In this ex vivo study, we investigated the ability of OCT to differentiate colorectal liver metastases (CRLM) from healthy liver parenchyma, when combined with convolutional neural networks (CNN).MethodsBetween June and August 2020, consecutive adult patients undergoing elective liver resections for CRLM were included in this study. Fresh resection specimens were scanned ex vivo, before fixation in formalin, using a table-top OCT device at 1310 nm wavelength. Scanned areas were marked and histologically examined. A pre-trained CNN (Xception) was used to match OCT scans to their corresponding histological diagnoses. To validate the results, a stratified k-fold cross-validation (CV) was carried out.ResultsA total of 26 scans (containing approx. 26,500 images in total) were obtained from 15 patients. Of these, 13 were of normal liver parenchyma and 13 of CRLM. The CNN distinguished CRLM from healthy liver parenchyma with an F1-score of 0.93 (0.03), and a sensitivity and specificity of 0.94 (0.04) and 0.93 (0.04), respectively.ConclusionOptical coherence tomography combined with CNN can distinguish between healthy liver and CRLM with great accuracy ex vivo. Further studies are needed to improve upon these results and develop in vivo diagnostic technologies, such as intraoperative scanning of resection margins.

Autofluorescence detection and co-axial projection for intraoperative localization of parathyroid gland

BackgroundNear-infrared (NIR) autofluorescence detection is an effective method for identifying parathyroid glands (PGs) in thyroidectomy or parathyroidectomy. Fiber optical probes provide quantitative autofluorescence measurements for PG detection owing to its high sensitivity and high excitation light cut-off efficiency at a fixed detection distance. However, an optical fiber probe lacks the imaging capability and cannot map the autofluorescence distribution on top of normal tissue background. Therefore, there is a need for intraoperative mapping of PGs with high sensitivity and imaging resolution.MethodsWe have developed a fluorescence scanning and projection (FSP) system that combines a scanning probe and a co-axial projector for intraoperative localization and in situ display of PGs. Some of the key performance characteristics, including spatial resolution and sensitivity for detection, spatial resolution for imaging, dynamic time latency, and PG localization capability, are characterized and verified by benchtop experiments. Clinical utility of the system is simulated by a fluorescence-guided PG localization surgery on a tissue-simulating phantom and validated in an ex vivo experiment.ResultsThe system is able to detect indocyanine green (ICG) solution of 5 pM at a high signal-to-noise ratio (SNR). Additionally, it has a maximal projection error of 0.92 mm, an averaged projection error of 0.5 ± 0.23 mm, and an imaging resolution of 748 μm at a working distance ranging from 35 to 55 cm. The dynamic testing yields a short latency of 153 ± 54 ms, allowing for intraoperative scanning on target tissue during a surgical intervention. The simulated fluorescence-guided PG localization surgery has validated the system’s capability to locate PG phantom with operating room ambient light interference. The simulation experiment on the PG phantom yields a position detection bias of 0.36 ± 0.17 mm, and an area intersection over unit (IoU) of 76.6% ± 6.4%. Fluorescence intensity attenuates exponentially with the thickness of covered tissue over the PG phantom, indicating the need to remove surrounding tissue in order to reveal the weak autofluorescence signal from PGs. The ex vivo experiment demonstrates the technical feasibility of the FSP system for intraoperative PG localization with accuracy.ConclusionWe have developed a novel probe-based imaging and navigation system with high sensitivity for fluorescence detection, capability for fluorescence image reconstruction, multimodal image fusion and in situ PG display function. Our studies have demonstrated its clinical potential for intraoperative localization and in situ display of PGs in thyroidectomy or parathyroidectomy.

The XVS System During Open Spinal Fixation Procedures in Patients Requiring Pedicle Screw Placement in the Lumbosacral Spine

This pilot study was undertaken to evaluate the safety, performance, and usability of the Xvision-Spine (XVS) System (Augmedics, Arlington Heights, IL) during open spinal fixation procedures in patients requiring pedicle screw placement in the lumbosacral spine. The XVS System is an augmented reality head-mounted display (HMD) based on a computer navigation system designed to assist surgeons in accurately placing pedicle screws. It uses an HMD-mounted tracking camera to provide optical tracking technology, and provides the surgeon a translucent direct near-eye display of the navigated surgical instrument's location relative to the computed tomographic image. We report the preliminary results of a prospective series of all consecutive patients who underwent augmented reality-assisted pedicle screw placement in the lumbosacral vertebrae at 3 institutions. Clinical accuracy for each pedicle screw was graded with Gertzbein-Robbins scores by 2 independent and blinded neuroradiologists. The 19 study participants included 8 men and 11 women with a mean age of 59.13 ± 12.09 and 59.91 ± 12.89 years, respectively. Seventeen procedures were successfully completed via the XVS System. Two procedures were not completed due to technical issues with the system's intraoperative scanner. A total of 86 screws were inserted. The accuracy of the XVS System was 97.7%. The XVS System's performance in accurate placement of pedicle screws in the lumbosacral vertebrae had an overall accuracy of 97.7%. These preliminary results were comparable to the accuracy of other manual computer-assisted navigation systems reported in the literature.

Systematic review of intra-operative duplex scanning during renal transplantation.

A systematic review of the value of intra-operative duplex scanning during renal transplantation was undertaken. Studies assessing intra-operative renal cortical flow in the arcuate vessels with outcomes of ultrasound directed interventions during the initial procedure, delayed graft function, post-operative resistive indices, graft losses and early returns to theatre for graft hypoperfusion were reviewed. PROSPERO registration: (https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42020203873). Literature searching identified 2069 articles for screening, with 131 reviewed and 12 selected for analysis comprising 5 individual case reports, one case series of 11 patients and 6 non-randomised controlled trials. Studies with similar methodologies were pooled because of the low number of studies and outcomes. Outcomes of interest were not reported for all patients. Intra-operative interventions comprising graft repositioning in 18 (16%) and vascular revision in 2 (2%) were performed in 115 patients undergoing intra-operative scans. There were no graft losses or returns to theatre for graft hypoperfusion (0 of 108 cases) compared to 7 of 71 (10%) without intraoperative scanning (P = 0.003). Three of 8 (38%) patients with high intra-operative resistive indices (RIs) were returned to theatre for hypoperfusion compared to 1 of 110 (1%) patients with normal resistive indices (P = <0.001). Ten of 13 (77%) patients with high RIs had delayed graft function compared to 10 of 40 (25%) with normal RIs (P = 0.001). Despite the absence of randomised controlled trials, and heterogeneous small studies, adverse outcomes were reduced with intra-operative scanning. High intraoperative RIs were predictive of both delayed graft function and return to theatre for hypoperfusion.

Efficacy and safety for combination of t-EMG with O-arm assisted pedicle screw placement in neurofibromatosis type I scoliosis surgery

BackgroundDue to the characteristics of neurofibromatosis type I (NF-1) scoliosis, the precise placement of pedicle screws still remains to be a challenge. Triggered screw electromyography (t-EMG) has been proved to exhibit high sensitivity to identify mal-positioned pedicle screws, but no previous study assessed the combination of t-EMG with O-arm-assisted pedicle screw placement in NF-1 scoliosis surgery.ObjectiveTo evaluate efficacy and safety for combination of t-EMG with O-arm-assisted pedicle screw placement in NF-1 scoliosis surgery.Materials and methodsFrom March 2018 to April 2020, sixty-five NF-1 scoliosis patients underwent t-EMG and O-arm-assisted pedicle screw fixation were retrospectively reviewed. The channel classification system was applied to classify the pedicle morphology based on pedicle width measurement by preoperative computed tomography scans. The minimal t-EMG threshold for screw path inspection was used as 8 mA, and operative screw redirection was also recorded. All pedicle screws were verified using a second intraoperative O-arm scan. The correlation between demographic and clinical data with amplitude of t-EMG were also analyzed.ResultsA total of 652 pedicle screws (T10-S1) in 65 patients were analyzed. The incidence of an absent pedicle (channel classification type C or D morphology) was 150 (23%). Overall, abnormal t-EMG threshold was identified in 26 patients with 48 screws (7.4%), while 16 out of the 48 screws were classified as G0, 14 out of the 48 screws were classified as G1, and 18 out of the 48 screws were classified as G2. The screw redirection rate was 2.8% (18/652). It showed that t-EMG stimulation detected 3 unacceptable mal-positioned screws in 2 patients (G2) which were missed by O-arm scan. No screw-related neurological or vascular complications were observed.ConclusionsCombination of t-EMG with O-arm-assisted pedicle screw placement was demonstrated to be a safe and effective method in NF-1 scoliosis surgery. The t-EMG could contribute to detecting the rupture of the medial wall which might be missed by O-arm scan. Combination of t-EMG with O-arm could be recommended for routine use of screw insertion in NF-1 scoliosis surgery.

Abstract 12030: Impact of High-Resolution Epiaortic Ultrasonographic Imaging on Evaluating Aortic Wall Pathology

Introduction: Innovative imaging modality for preclinical diagnosis of aortic dissection (AD) has been awaited. Hypothesis: We previously reported that synchrotron radiation-based X-ray phase-contrast tomography (XPCT) imaging revealed densitometrical changes in the tunica media in the aortic wall (TM) of AD. To replicate XPCT findings in clinical practice, we investigated the application of high-resolution ultrasound in intraoperative epi-aortic scan (EAS) imaging. Methods: Twelve patients (normal aorta (5), chronic AD (3), acute type-A AD(4)) were selected. Before beginning cardiopulmonary bypass, the mid-ascending aorta was exposed and an EAS was conducted using EPIQ CVx and an eL18-4 transducer. After aortic repairs, the aortic samples of AD were fixed and applied XPCT, to compare ultrasonographic intensity (UI) of EAS and densitometric changes in XPCT in the same samples. Results: In normal aorta, UI remained unchanged throughout the TM (Figure-1A). In chronic AD, high linear changes in the UI in the middle of the TM was observed in the aorta that had not been dissected (yellow arrow in Figure-1B). In acute AD, high linear changes in the UI were clearly observed in the middle of TM, and aortic dissection was observed as an extension of those liner changes (Figure-1C). A line profile of the UI between the intima and the adventitia showed that the UI remained unchanged in normal aorta, and exhibited a high peak in the middle of the TM in chronic and acute AD (Figure-1A,B,C). These results indicated differences in the UI throughout the TM between normal and pathological aortas. These findings were well consistent with changes in the TM of patients with AD, which were obtained using XPCT (Figure-1D,E). Conclusions: High-resolution ultrasonographic imaging could replace XPCT findings in clinical settings and lead to significant improvements in the presymptomatic diagnosis of various aortic wall pathologies, including aortic dissection.

Cone beam computed tomography for detecting residual stones in percutaneous nephrolithotomy, a randomized controlled trial (CAPTURE) protocol

IntroductionPercutaneous nephrolithotomy (PCNL) is the standard surgical treatment method for large kidney stones. Its aim is to achieve a stone-free status, since any residual fragments (RFs) after PCNL are likely to cause additional morbidity or stone growth. Enhancing intraoperative detectability of RFs could lead to increased stone-free rates and decreased re-intervention rates. Cone beam computed tomography (CBCT) has recently been introduced in urology as a feasible method for intraoperatively imaging RFs. The aim of this trial is to determine the added value of CBCT in percutaneous nephrolithotomy, by measuring differences in stone-related morbidity for patients with procedures in which a CBCT is used versus patients with procedures without the use of CBCT.MethodsThe CAPTURE trial is an investigator-initiated single-center, randomized controlled trial (RCT) in adult patients who have an indication for percutaneous nephrolithotomy. A contemporary percutaneous nephrolithotomy is performed. Once the surgeon is convinced of a stone-free status by means of fluoroscopy and nephroscopy, randomization allocates patients to either the study group in whom an intraoperative CBCT scan is performed or to the control group in whom no intraoperative CBCT scan is performed. The main endpoint is the stone-free status as assessed four weeks postoperatively by low-dose non-contrast abdominal CT, as a standard follow-up procedure. Secondary endpoints include the number of PCNL procedures required and the number of stone-related events (SREs) registered. The total study population will consist of 320 patients that undergo PCNL and are eligible for randomization for an intraoperative CBCT scan.DiscussionWe deem a randomized controlled trial to be the most effective and reliable method to assess the efficacy of CBCT in PCNL. Though some bias may occur due to the impossibility of blinding the urologist at randomization, we estimate that the pragmatic nature of the study, standardized circumstances, and follow-up methods with pre-defined outcome measures will result in a high level of evidence.Trial registrationNetherlands Trial Register (NTR) NL8168, ABR NL70728.042.19. Registered on 15 October 2019. Prospectively registered.