Intraoperative Scanning Research Articles

Do We Need Intraoperative Magnetic Resonance Imaging in All Endoscopic Endonasal Pituitary Adenoma Surgery Cases? A Retrospective Study.

There are previous reports investigating effectiveness of intraoperative magnetic resonance imaging (IO-MRI) in pituitary adenoma surgery but there is no clear data in the literature recommending when there is no need of intraoperative scan. This retrospective analysis was based on determining which patients does not need any IO-MRI scan following endoscopic endonasal pituitary adenoma surgery. Patients with functional or non-functional pituitary adenomas that were operated via endoscopic endonasal approach (EEA) between June 2017 and May 2019 were enrolled. Patients younger than 18 years old, patients who did not underwent IO-MRI procedure or not operated via EEA were excluded from the study. Hence, this study is designed to clarify if IO-MRI is useful in both functional and non-functional pituitary adenomas, functional adenomas did not split into subgroups. A total of 200 patients treated with pituitary adenoma were included. In Knosp Grade 0 – 2 group, primary surgeon’s opinion and IO-MRI findings were compatible in 150 patients (98.6%). In Knosp Grade 3 – 4 correct prediction were performed in 32 (66.6%) patients. When incorrectly predicted Knosp Grade 3 – 4 patients (n = 16) was analyzed, in 13 patients there were still residual tumor in cavernous sinus and in 3 patients there were no residual tumor. Fisher’s exact test showed there is a statistically significant difference of correct prediction between two different Knosp Grade groups (two-tailed P < 0.0001). Eighteen patients had a residual tumor extending to the suprasellar and parasellar regions which second most common site for residual tumor. Our findings demonstrate that there is no need of IO-MRI scan while operating adenomas limited in the sellae and not invading the cavernous sinus. However, we strongly recommend IO-MRI if there is any suprasellar and parasellar extension and/or cavernous sinus invasion.

Stereotactic cryoablation of large tumors of the sellar region with intraoperative CT scans\u2014technical note

BackgroundCryoablation has been used by neurosurgeons in the past and is currently being used by other disciplines to treat kidney cancer, skin lesions, and cardiac conduction defects. Because the currently available cryogenic probes can safely create large lesions and the lesion generation (in the form of ice-ball) can be monitored on intraoperative CT images, cryoablation was used to treat large tumors in and around the sella. In this paper, the author describes a technique to perform this procedure.Main bodyThree large tumors in 3 patients were treated with this method. Age of the patients was 26–58 years with a male/female ratio of 2/1. Patient 1 had a non-secreting pituitary adenoma (measuring 8 × 8 cm) and presented with long-standing total visual loss in both eyes, severe headache, and seizures. She had previous resection and radiation therapy. Patient 2 had prolactinomas (measuring 5.1 × 4.6 cm) and presented with progressive loss of vision and diplopia. Patient 3 had recurrent craniopharyngioma (measuring 7.2 × 5 cm) with prior treatment with resection radiation and frequent drainage of the cyst. He presented with headache and progressive worsening of his vision.The procedure was done on the CT table with intraoperative scans, using Patil stereotactic frame and argon cryoablation probe (Healthtronics). 3-D images were used to plan targets and trajectories. The probe was placed at the target via a trans-nasal trans-sphenoidal route. One to 3 lesions measuring 2.5–3 cm in diameter were made to ablate the tumor. Ice-ball formation was monitored live on CT images.There is no complication. One patient had near-complete resolution of the tumor, two had partial resolution of their tumors, and all had resolution of their presenting symptoms at follow-up of 3–24 months (median 6 months). In one patient, symptoms reoccurred due to the formation of new tumor masses.Short conclusionCryoablation of intracranial tumors and can be done safely and effectively. Live monitoring of lesion generation using CT imaging is a major advantage of this technique.

Mobile intraoperative CT-assisted frameless stereotactic biopsies achieved single-millimeter trajectory accuracy for deep-seated brain lesions in a sample of 7 patients

BackgroundBrain biopsies are crucial diagnostic interventions, providing valuable information for treatment and prognosis, but largely depend on a high accuracy and precision. We hypothesized that through the combination of neuronavigation-based frameless stereotaxy and MRI-guided trajectory planning with intraoperative CT examination using a mobile unit, one can achieve a seamlessly integrated approach yielding optimal target accuracy.MethodsWe analyzed a total of 7 stereotactic biopsy trajectories for a variety of deep-seated locations and different patient positions. After rigid head fixation, an intraoperative pre-procedural scan using a mobile CT unit was performed for automatic image fusion with the planning MRI images and a peri-procedural scan with the biopsy cannula in situ for verification of the definite target position. We then evaluated the radial trajectory error.ResultsIntraoperative scanning, surgery, computerized merging of MRI and CT images as well as trajectory planning were feasible without difficulties and safe in all cases. We achieved a radial trajectory deviation of 0.97 ± 0.39 mm at a trajectory length of 60 ± 12.3 mm (mean ± standard deviation). Repositioning of the biopsy cannula due to inaccurate targeting was not required.ConclusionIntraoperative verification using a mobile CT unit in combination with frameless neuronavigation-guided stereotaxy and pre-operative MRI-based trajectory planning was feasible, safe and highly accurate. The setting enabled single-millimeter accuracy for deep-seated brain lesions and direct detection of intraoperative complications, did not depend on a dedicated operating room and was seamlessly integrated into common stereotactic procedures.

An original method of pericardium closure after coronary artery bypass grafting

Different cardiac surgery centres have different views regarding pericardial suturing. However, there is limited scientific evidence confirming the advantage of one method over another, which disallows us from forming a general opinion regarding specialists. Here, we describe several well-known methods of suturing the pericardium and preventing traumatisation of coronary bypass grafts and analyse their weaknesses. An original technique of opening and suturing the pericardium is proposed to restore the physiological distinction between the pericardial cavity and the anterior mediastinum during coronary artery bypass grafting without the risk of compromising the functioning coronary bypass grafts and narrow mediastinal syndrome.The proposed method of suturing the pericardium received a patent for invention, No. 2733505, dated 2 October, 2020. In the A.N. Bakulev National Medical Research Center for Cardiovascular Surgery (Moscow, Russian Federation), this technique of suturing the pericardium has been routinely used since 2006. More than 2,000 intraoperative shunt scans have been performed in our department since 2009; all these scans were performed after the pericardium was closed, proving that the fear of compromising the shunts during pericardial suturing is unsupported.Received 17 December 2020. Revised 13 January 2021. Accepted 18 January 2021.Funding: The study did not have sponsorship.Conflict of interest: Authors declare no conflict of interest.Author contributionsConception and study design: G.G. Kvaratskheliya, E.P. GolubevData collection and analysis: U.S. Avkhadov, R.M. IbragimovDrafting the article: G.G. Kvaratskheliya, E.P. GolubevCritical revision of the article: E.U. Asymbekova, B.E. Rustamov, L.S. Shakhnazaryan, Yu.I. BuziashviliFinal approval of the version to be published: G.G. Kvaratskheliya, E.P. Golubev, U.S. Avkhadov, R.M. Ibragimov, B.E. Rustamov, E.U. Asymbekova, L.S. Shakhnazaryan, Yu.I. Buziashvili

The Impact of an Ultra-Early Postoperative MRI on Treatment of Lower Grade Glioma.

Simple SummaryThe decision to provide adjuvant treatment in lower grade glioma (LGG) is often based on presence of residual tumor after surgery. Differentiating tumor remnants and surgically induced artifacts can be challenging. Postoperative MRI performed 24 or 48 h after the surgery overestimates residual tumor volume. MRI scan in the first hour after surgery (ultra-early), or an intraoperative MRI after final resection, correlated best with residual tumor at 3 months follow up.The timing of MRI imaging after surgical resection may have an important role in assessing the extent of resection (EoR) and in determining further treatment. The aim of our study was to evaluate the time dependency of T2 and FLAIR changes after surgery for LGG. The Log-Glio database of patients treated at our hospital from 2016 to 2021 was searched for patients >18a and non-enhancing intra-axial lesion with complete MR-imaging protocol. A total of 16 patients matched the inclusion criteria and were thus selected for volumetric analysis. All patients received an intraoperative scan (iMRI) after complete tumor removal, an ultra-early postoperative scan after skin closure, an early MRI within 48 h and a late follow up MRI after 3–4 mo. Detailed volumetric analysis of FLAIR and T2 abnormalities was conducted. Demographic data and basic characteristics were also analyzed. An ultra-early postoperative MRI was performed within a median time of 30 min after skin closure and showed significantly lower FLAIR (p = 0.003) and T2 (p = 0.003) abnormalities when compared to early postoperative MRI (median 23.5 h), though no significant difference was found between ultra-early and late postoperative FLAIR (p = 0.422) and T2 (p = 0.575) images. A significant difference was calculated between early and late postoperative FLAIR (p = 0.005) and T2 (p = 0.019) MRI scans. Additionally, we found no significant difference between intraoperative and ultra-early FLAIR/T2 (p = 0.919 and 0.499), but we found a significant difference between iMRI and early MRI FLAIR/T2 (p = 0.027 and p = 0.035). Therefore, a postoperative MRI performed 24 h or 48 h might lead to false positive findings. An MRI scan in the first hour after surgery (ultra-early) correlated best with residual tumor at 3 months follow up. An iMRI with open skull, at the end of resection, was similar to an ultra-early MRI with regard to residual tumor.

Comparative analysis of clinical factors associated with pedicle screw pull\u2010out during or immediately after surgery between intraoperative cone\u2010beam computed tomography and postoperative computed tomography

BackgroundNo studies to date have elucidated the clinical factors associated with pedicle screw pull-out during or immediately after surgery. The aim of this study was to assess the frequency of pedicle screw pull-out by comparing intraoperative scans obtained using cone-beam computed tomography (CBCT) with postoperative scans obtained using computed tomography (CT). We also sought to determine the incidence of pedicle screw pull-out and identify relevant risk factors.MethodsThis was a retrospective analysis of prospectively collected data for 742 pedicle screws placed in 76 consecutive patients who underwent at least triple-level posterior fixation for thoracic or lumbar spinal injury, spinal metastasis, or pyogenic spondylitis between April 2014 and July 2020. Pedicle screw pull-out distance in the axial and sagittal planes was compared between CT scans obtained 2 days postoperatively and CBCT images acquired intraoperatively. Risk factors associated with pedicle screw pull-out were investigated by multivariate logistic regression analysis.ResultsPedicle screw pull-out was seen with 58 pedicle screws (7.8%) in 26 patients (34.2%). There were significant differences in age, number of fused segments, frequency of diffuse idiopathic skeletal hyperostosis (DISH), and medical history of osteoporosis for pedicle screw pull-out. Risk factors for pedicle screw pull-out were older age (odds ratio 1.07, 95% confidence interval 1.02–1.130) and a diagnosis of DISH (odds ratio 3.35, 95% confidence interval 1.12–10.00). Several cases suggest that use of connecting rods was an important factor in intraoperative pedicle screw pull-out.ConclusionsOur findings suggest that age, number of fused segments, presence of DISH, and medical history of osteoporosis are risk factors for pedicle screw pull-out, with the greatest being older age and DISH.

Metal artifacts in intraoperative O-arm CBCT scans

BackgroundCone-beam computed tomography (CBCT) has become an increasingly important medical imaging modality in orthopedic operating rooms. Metal implants and related image artifacts create challenges for image quality optimization in CBCT. The purpose of this study was to develop a robust and quantitative method for the comprehensive determination of metal artifacts in novel CBCT applications.MethodsThe image quality of an O-arm CBCT device was assessed with an anthropomorphic pelvis phantom in the presence of metal implants. Three different kilovoltage and two different exposure settings were used to scan the phantom both with and without the presence of metal rods.ResultsThe amount of metal artifact was related to the applied CBCT imaging protocol parameters. The size of the artifact was moderate with all imaging settings. The highest applied kilovoltage and exposure level distinctly increased artifact severity.ConclusionsThe developed method offers a practical and robust way to quantify metal artifacts in CBCT. Changes in imaging parameters may have nonlinear effects on image quality which are not anticipated based on physics.

SURG-29. A SINGLE CENTRE EXPERIENCE OF USING INTRA-OPERATIVE MRI IN MANAGING PEDIATRIC CRANIAL NEURO-ONCOLOGY CASES

The University of Malaya Medical Centre, Kuala Lumpur had acquired a intraoperative MRI (iMRI) brain suite via a public private initiative in September 2015. The MRI brain suite has a SIEMENS 1.5T system with NORAS coil system and NORAS head clamps in a two room solution. We would like to retrospectively review the cranial paediatric neuro-oncology cases that had surgery in this facility from September 2015 till December 2019. We would like to discuss our experience with regard to the clear benefits and the challenges in using such technology to aid in the surgery. The challenges include the physical setting up the paediatric case preoperatively, the preparation and performing the intraoperative scan, the interpretation of intraoperative images and making a decision and the utilisation of the new MRI data set to assist in the navigation to locate the residue safely. Also discuss the utility of the intraoperative images in the decision of subsequent adjuvant management. The use of iMRI also has other technical challenges such as ensuring the perimeter around the patient is free of ferromagnetic material, the process of transfer of the patient to the scanner and as a consequence increased duration of the surgery. CONCLUSION: Many elements in the use of iMRI has a learning curve and it improves with exposure and experience. In some areas only a high level of vigilance and SOP (Standard operating procedure) is required to minimize mishaps. Currently, the iMRI gives the best means of determining extent of resection before concluding the surgery.

PO-1476: Monte Carlo based 3D treatment planning using intraoperative CBCT scanning for image guided IORT

PO-1476: Monte Carlo based 3D treatment planning using intraoperative CBCT scanning for image guided IORT

Does Intraoperative Computed Tomography Scanning in Maxillofacial Trauma Surgery Affect the Revision Rate?

The purpose of this study was to determine how intraoperative computed tomography affects the intraoperative revision rate and consequently the post-operative, secondary corrective surgery in maxillofacial trauma surgeries. A retrospective study composed of patients with facial fractures was conducted in Prince Sultan Military Medical City in Riyadh, Saudi Arabia. The predictor variables were age, gender, site of facial fracture, type of treatment, number of scans per patient, and discharge time. The primary outcome variable was immediate intraoperative revision rate. Secondary outcome variable was total scanning time (recorded from the moment surgery was halted until it was resumed after image acquisition). Descriptive statistics were used; numerical data presented as mean±SD and categorical variables as frequency (%). A total of 22 patients underwent 25 intraoperative scans while undergoing different maxillofacial surgeries. Eleven (50%) required intraoperative revisions after the scans, and 3 (13.6%) cases had another intraoperative scan after revision. Eighteen were men and 4 were women. The mean age was 30years and age range was 19 to 76. Cases were categorized by fracture location and treatment preformed. The mean scanning time was 18.9±4.6minutes. The highest rate of revisions was seen in zygomaticomaxillary complex fractures (63.6%), they were also the only cases that required a second intraoperative scan after revision to confirm final reduction. No complications were seen postoperatively, and all patients recovered uneventfully. None of the patients required a secondary corrective surgery. All patients were discharged on the following day, except 1 case which was admitted under another service. The use of intraoperative computed tomography imaging in treating maxillofacial fractures results in a higher rate of intraoperative revisions, which in turn leads to more accurate fracture reduction and consequently reduces the possibility of a postoperative, secondary corrective surgery.

Management of Zygomaticomaxillary Complex Fractures Utilizing Intraoperative 3-Dimensional Imaging: The ZYGOMAS Protocol

Utilization of technology to aid in the assessment, planning, and management of complex craniomaxillofacial injuries is increasingly common. Limited data exist regarding the implication of intraoperative CT/3-Dimensional imaging on decision making in the management of zygomaticomaxillary complex (ZMC) fractures. This study characterizes the utilization of the intraoperative CT scanner for ZMC fracture surgery and analyzes the impact of the intraoperative CT scanner on fracture management. Using these findings, we sought to propose an algorithm to guide the appropriate utilization of intraoperative 3-Dimensional imaging in ZMC fracture surgery. This retrospective case series evaluates the use of the intraoperative CT scanner for orbitozygomatic trauma surgery at a level 1 trauma center from February 2011 to September 2016. We evaluated the preoperative CT images assessing for the number of displaced sutures, the presence of adjacent fractures requiring fixation, the presence of comminution of the zygomaticomaxillary buttress or body of the zygoma, as well as the number of axes displaced ≥ 5mm. This information was evaluated to provide guidance on the appropriate utilization of the intraoperative scanner in ZMC fracture management. A total of 71 patients were identified to have intraoperative facial CT scans and surgery for ZMC fractures over the study time period. There was a 23.9% (17/71) CT directed revision rate. There was a significantly increased likelihood of CT directed revision for fractures with adjacent fractures requiring fixation, and those with ≥ 2 axes displaced ≥ 5mm. Using these findings, we proposed the ZYGOMAS algorithm outlining the indications for use of intraoperative CT in management of ZMC fractures. If available, intraoperative CT/3-Dimensional imaging should be utilized in the management of ZMC fractures with the requirement for orbital floor reconstruction, where adjacent fractures require fixation and/or when ≥ 2 axes are displaced ≥ 5mm.

Generalized 3-D Point Set Registration With Hybrid Mixture Models for Computer-Assisted Orthopedic Surgery: From Isotropic to Anisotropic Positional Error

Registering two point sets (PSs) is an essential problem in medical robotics and computer-assisted surgery (CAS). As one typical example, in computer-assisted orthopedic surgery (CAOS), the preoperative scan has to be aligned with the intraoperative scan accurately. In this article, we first formally formulate the generalized PS registration problem in a probabilistic manner. Especially, not only positional but also orientational information is incorporated into the registration. Notably, the positional error is assumed to obey a multivariate Gaussian distribution to accommodate the anisotropic noise. The expectation–maximization (EM) framework is utilized to solve the maximum likelihood (ML) problem. In the E-step, the correspondence probabilities between points in two generalized PSs are computed. In the M-step, the constrained optimization problem with respect to the rigid transformation matrix is reformulated as an unconstrained one. This is achieved by utilizing the Rodrigues parameterization to represent the rotation matrix. Both extensive simulated and real experiments are conducted to validate the proposed algorithm by comparing it with state-of-the-art registration methods. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Note to Practitioners</i> —This article was motivated by considering the anisotropic positional uncertainty into the rigid point set (PS) registration in the application of preoperative-to-intraoperative registration within image-guided surgery. We provide iterative solutions that compute the rotation and translation vector that aligns two 3-D PSs. The correspondences between points in two PSs are not known and regarded as hidden variables in the optimization process. Expectation–maximization technique is utilized to solve the maximum likelihood problem. We have demonstrated through experiments that our proposed approach can achieve lower registration error values than the compared state-of-the-art registration methods on various data sets. The readers should note that the proposed method is particularly suitable for cases that anisotropic noise is involved.

The interest of intraoperative scanner coupled to neuronavigation in traumatic or oncologic fractures of the cervical and upper thoracic spine requiring vertebral body height restoring procedures

ObjectIn recent years, the classical vertebroplasty has tended to be replaced by vertebral augmentation procedures. This article discusses the reliability of vertebral augmentation procedures using balloon kyphoplasty or a spine jack system, with intraoperative CT scan control coupled with the neuronavigation system as a treatment option for cervical and upper thoracic spine lesions. MethodsIn our neurosurgical department, in the past two years, 11 patients underwent either a kyphoplasty or a vertebral augmentation by a Spine Jack via a transpedicular route, under perioperative 3D imaging, for a total of 15 cervical/upper thoracic lesions. For these patients, we evaluated the clinical symptoms before and after surgery, the intraoperative and postoperative complications as well as the radiation exposure and the duration of their hospitalisation. ResultsWe noted for all of the patients an improvement of the mean Karnofsky index, which improved from 50 to 80, and of the VAS that decreased from a mean of 75 to 15, as they were clearly alleviated after the operation. The radiation was lower for patients that were treated for 2 or more vertebrae, and much lower for the medical staff. The intraoperative complications rate (4 cement leakages for 15 vertebrae, 26%), was low and completely asymptomatic in all cases. The radiological follow-up examinations were satisfactory for all the patients. ConclusionsOur results suggest that percutaneous transpedicular vertebral augmentation techniques using intraoperative CT scan are a viable treatment for secondary lesions or traumatic compression fractures of the cervical and upper thoracic spine.

One-step insertion of navigated pedicle screws in minimally invasive transforaminal lumbar interbody fusion (MITLIF): preliminary results of a novel technique

Objective To describe a novel technique modification and evaluate initial results of pedicle screw insertion in minimally invasive transforaminal lumbar interbody fusion (MITLIF), using self-drilling self-tapping one-step screws. Patients and Methods All patients who were operated for MITLIF using the one-step technique over the last 6 months period at a single institute, were retrospectively identified. The surgical technique is described and depicted. Outcome evaluation was performed, including screw misplacement, screw insertion time, and post-operative complications. Results We describe a novel technique modification in which self-drilling self-tapping navigated screws incorporate an embedded K-wire that enables a one-step insertion which obviates the need for instrument exchange. The first four patients in whom this technique was implemented were included (mean age was 55). All patients had been previously operated at the fused level. The mean surgical duration was 142 minutes and the calculated mean screw insertion time was 8.2 minutes. The mean estimated blood loss was 66 cc. An intraoperative 3D scan demonstrated no screw pedicle breach. There were no neurological complications or wound healing disturbances. The clinical course was uneventful for all patients. Conclusion To our knowledge, the use of one-step navigation-assisted self-drilling self-tapping pedicle screws with an embedded K-wire has not been previously described. Our initial experience with this novel technique modification was efficient and safe. Navigated surgery allows for newer and safer techniques to be incorporated into the surgeon’s toolbox. Further studies should be performed to thoroughly evaluate this technique.

Renal biopsy under augmented reality guidance.

Kidney biopsies are currently performed using preoperative imaging to identify the lesion of interest and intraoperative imaging used to guide the biopsy needle to the tissue of interest. Often, these are not the same modalities forcing the physician to perform a mental cross-modality fusion of the preoperative and intraoperative scans. This limits the accuracy and reproducibility of the biopsy procedure. In this study, we developed an augmented reality system to display holographic representations of lesions superimposed on a phantom. This system allows the integration of preoperative CT scans with intraoperative ultrasound scans to better determine the lesion's real-time location. An automated deformable registration algorithm was used to increase the accuracy of the holographic lesion locations, and a magnetic tracking system was developed to provide guidance for the biopsy procedure. Our method achieved a targeting accuracy of 2.9 ± 1.5 mm in a renal phantom study.

Computer-assisted navigation in complex cervical spine surgery: tips and tricks.

Stereotactic navigation is quickly establishing itself as the gold standard for accurate placement of spinal instrumentation and providing real-time anatomic referencing. There have been substantial improvements in computer-aided navigation over the last decade producing improved accuracy with intraoperative scanning while shortening registration time. The newest iterations of modeling software create robust maps of the anatomy while tracking software localizes instruments in multiple display modes. As a result, stereotactic navigation has become an effective adjunct to spine surgery, particularly improving instrumentation accuracy in the setting of atypical anatomy. This article provides an overview of stereotactic navigation applied to complex cervical spine surgery, details the means for registration and direct referencing, and shares our preferred methods to implement this promising technology.

Evaluating an Image-Guided Operating Room with Cone Beam CT for Skull Base Surgery.

Importance Skull base surgery requires precise preoperative assessment and intraoperative management of the patient. Surgical navigation is routinely used for complex skull base cases; however, the image guidance is commonly based on preoperative scans alone. Objective The primary objective of this study was to assess the image quality of intraoperative cone-beam computed tomography (CBCT) within anatomical landmarks used in sinus and skull base surgery. The secondary objective was to assess the registration error of a surgical navigation system based on intraoperative CBCT. Design Present study is a retrospective case series of image quality after intraoperative cone beam CT. Setting The study was conducted at Toronto General Hospital and Princess Margaret Cancer Centre, University Health Network, Toronto. Participants A total of 46 intraoperative scans (34 patients, 21 skull base, 13 head and neck) were studied. Main Outcome and Measures Thirty anatomical landmarks (vascular, soft tissue, and bony) within the sinuses and anterior skull base were evaluated for general image quality characteristics: (1) bony detail visualization; (2) soft-tissue visualization; (3) vascular visualization; and (4) freedom from artifacts (e.g., metal). Levels of intravenous (IV) contrast enhancement were quantified in Hounsfield's units (HU). Standard paired-point registration between imaging and tracker coordinates was performed using 6 to 8 skin fiducial markers and the corresponding fiducial registration error (FRE) was measured. Results Median score for bony detail on CBCT was 5, remaining at 5 after administration of IV contrast. Median soft-tissue score was 2 for both pre- and postcontrast. Median vascular score was 1 precontrast and 3 postcontrast. Median score for artifacts on CBCT were 2 for both pre-and postcontrast, and metal objects were noted to be the most significant source of artifact. Intraoperative CBCT allowed preresection images and immediate postresection images to be available to the skull base surgeon. There was a significant improvement in mean (standard deviation [SD]) CT intensity in the left carotid artery postcontrast 334 HU (67 HU) ( p < 10 -10 ). The mean FRE was 1.8 mm (0.45 mm). Conclusion Intraoperative CBCT in complex skull base procedures provides high-resolution bony detail allowing immediate assessment of complex resections. The use of IV contrast with CBCT improves the visualization of vasculature. Image-guidance based on CBCT yields registration errors consistent with standard techniques.

Spinal Navigation for Cervical Pedicle Screws: Surgical Pearls and Pitfalls.

Study Design:Retrospective cohort study.Objective:We intend to evaluate the accuracy and safety of cervical pedicle screw (CPS) insertion under O-arm-based 3-dimensional (3D) navigation guidance.Methods:This is a retrospective study of patients who underwent CPS insertion under intraoperative O-arm-based 3D navigation during the years 2009 to 2018. The radiological accuracy of CPS placement was evaluated using their intraoperative scans.Results:A total of 297 CPSs were inserted under navigation. According to Gertzbein classification, 229 screws (77.1%) were placed without any pedicle breach (grade 0). Of the screws that did breach the pedicle, 51 screws (17.2%) had a minor breach of less than 2 mm (grade 1), 13 screws (4.4%) had a breach of between 2 and 4 mm (grade 2), and 4 screws (1.3%) had a complete breach of 4 mm or more (grade 3). Six screws were revised intraoperatively. There was no incidence of neurovascular injury in this series of patients. 59 of the 68 breaches (86.8%) were found to perforate laterally, and the remaining 9 (13.2%) medially. It was noted that the C5 cervical level had the highest breach rate of 33.3%.Conclusions:O-arm-based 3D navigation can improve the accuracy and safety of CPS insertion. The overall breach rate in this study was 22.9%. Despite these breaches, there was no incidence of neurovascular injury or need for revision surgery for screw malposition.

Augmented reality and artificial intelligence-assisted surgical navigation: Technique and cadaveric feasibility study.

Purpose:Augmented reality-based image overlay of virtual bony spine anatomy can be projected onto real spinal anatomy using computer tomography-generated DICOM images acquired intraoperatively. The aim of the study was to develop a technique and assess the accuracy and feasibility of lumbar vertebrae pedicle instrumentation using augmented reality-assisted surgical navigation.Subjects and Methods:An augmented reality and artificial intelligence (ARAI)-assisted surgical navigation system was developed. The system consists of a display system which hovers over the surgical field and projects three-dimensional (3D) medical images corresponding with the patient's anatomy. The system was registered to the cadaveric spine using an optical tracker and arrays with reflective markers. The virtual image overlay from the ARAI system was compared to 3D generated images from intraoperative scans and used to percutaneously navigate a probe to the cortex at the corresponding pedicle starting point. Intraoperative scan was used to confirm the probe position. Virtual probe placement was compared to the actual probe position in the bone to determine the accuracy of the navigation system.Results:Four cadaveric thoracolumbar spines were used. The navigated probes were correctly placed in all attempted levels (n = 24 levels), defined as Zdichavsky type 1a, Ravi type I, and Gertzbein type 0. The virtual overlay image corresponded to the 3D generated image in all the tested levels.Conclusions:The ARAI surgical navigation system correctly and accurately identified the starting points at all the attempted levels. The virtual anatomy image overlay precisely corresponded to the actual anatomy in all the tested scenarios. This technology may lead more uniform outcomes between surgeons and decrease minimally invasive spine surgery learning curves.

Using lean principles to introduce intraoperative navigation for scoliosis surgery.

Intraoperative 3D navigation (ION) allows high accuracy to be achieved in spinal surgery, but poor workflow has prevented its widespread uptake. The technical demands on ION when used in patients with adolescent idiopathic scoliosis (AIS) are higher than for other more established indications. Lean principles have been applied to industry and to health care with good effects. While ensuring optimal accuracy of instrumentation and safety, the implementation of ION and its associated productivity was evaluated in this study for AIS surgery in order to enhance the workflow of this technique. The aim was to optimize the use of ION by the application of lean principles in AIS surgery. A total of 20 consecutive patients with AIS were treated with ION corrective spinal surgery. Both qualitative and quantitative analysis was performed with real-time modifications. Operating time, scan time, dose length product (measure of CT radiation exposure), use of fluoroscopy, the influence of the reference frame, blood loss, and neuromonitoring were assessed. The greatest gains in productivity were in avoiding repeat intraoperative scans (a mean of 248 minutes for patients who had two scans, and a mean 180 minutes for those who had a single scan). Optimizing accuracy was the biggest factor influencing this, which was reliant on incremental changes to the operating setup and technique. The application of lean principles to the introduction of ION for AIS surgery helps assimilate this method into the environment of the operating theatre. Data and stakeholder analysis identified a reproducible technique for using ION for AIS surgery, reducing operating time, and radiation exposure. Cite this article: Bone Joint J. 2020;102-B(1):5-10.