Intraoperative 3D Imaging Research Articles

Radiation dose and image quality comparison during spine surgery with two different, intraoperative 3D imaging navigation systems.

Careful protocol selection is required during intraoperative three‐dimensional (3D) imaging for spine surgery to manage patient radiation dose and achieve clinical image quality. Radiation dose and image quality of a Medtronic O‐arm commonly used during spine surgery, and a Philips hybrid operating room equipped with XperCT C‐arm 3D cone‐beam CT (hCBCT) are compared. The mobile O‐arm (mCBCT) offers three different radiation dose settings (low, standard, and high), for four different patient sizes (small, medium, large, and extra large). The patient's radiation dose rate is constant during the entire 3D scan. In contrast, C‐CBCT spine imaging uses three different field of views (27, 37, and 48 cm) using automatic exposure control (AEC) that modulates the patient's radiation dose rate during the 3D scan based on changing patient thickness. hCBCT uses additional x‐ray beam filtration. Small, medium, and large trunk phantoms designed to mimic spine and soft tissue were imaged to assess radiation dose and image quality of the two systems. The estimated measured “patient” dose for the small, medium, and large phantoms imaged by the mCBCT considering all the dose settings ranged from 9.4–27.6 mGy, 8.9–33.3 mGy, and 13.8–40.6 mGy, respectively. The “patient” dose values for the same phantoms imaged with hCBCT were 2.8–4.6 mGy, 5.7–10.0 mGy, and 11.0–15.2 mGy. The CNR for the small, medium, and large phantoms was 2.9 to 3.7, 2.0 to 3.0, and 2.5 to 2.6 times higher with the hCBCT system, respectively. Hounsfield unit accuracy, noise, and uniformity of hCBCT exceeded the performance of the mCBCT; spatial resolution was comparable. Added x‐ray beam filtration and AEC capability achieved clinical image quality for intraoperative spine surgery at reduced radiation dose to the patient in comparison to a reference O‐arm system without these capabilities.

The correlation between intra-operative 2D- and 3D fluoroscopy with postoperative CT-scans in the treatment of calcaneal fractures

ObjectivesThe aim of this study was to determine the correlation of the intra-operative fluoroscopic 2D- and 3D-images compared with a postoperative CT-scan, in terms of quality of reduction and fixation of calcaneal fractures. MethodsPatients requiring open reduction and internal fixation (ORIF) of a calcaneal fracture were recruited as part of the EF3X-trial. During surgery, intra-operative images of fluoroscopic 2D- and 3D-imaging were obtained to assess the quality of the reduction and implant position. All patients received a postoperative CT-scan within one week.The operating surgeon evaluated intra-operatively both 2D- and 3D-images according to a 23-item scoring protocol on a 3-point Likert scale. A scoring panel, consisting of three clinical experts, evaluated all images in a blinded and independent fashion. Intraclass correlation coefficients (ICC) with their 95% confidence intervals (CI) were calculated using a two-way-random model with absolute agreement. ResultsA total of 102 calcaneal fractures were included. Agreement of 3D-imaging for the quality of reduction was better than 2D-imaging, although still fair, but for fixation moderate to good. Agreement between the 2D-images and the CT-scans was poor to fair. Intra-operative 2D-imaging received the highest ratings for image quality and interpretability, followed by CT-scanning. ConclusionImplant position can be evaluated satisfactory with the aid of intra-operative 3D imaging. Although intra-operative 3D imaging had a better agreement with postoperative CT-scanning than 2D-imaging, there is a need to improve image quality and suppress scattering from implants to improve the additional value of intra-operative 3D imaging in calcaneal fracture reduction and fixation.

Utility of virtual three-dimensional image analysis for laparoscopic gastrectomy conducted by trainee surgeons.

Purpose The aim of this study was to investigate the utility the three-dimensional (3D) imaging for laparoscopic gastrectomy performed by trainee surgeons. Methods 3D-reconstruction was performed using multi-detector computed tomography (MDCT) and SYNAPSE VINCENT software. Trainee surgeons made 3D-imaging and checked the anatomical structure. Thirty-three patients who underwent laparoscopic gastrectomy (LG) for gastric cancer were examined. Trainees performed 19 LG, while specialists performed 14 LG. The vascular pattern and the surgical outcomes were evaluated. Result 3D imaging depicted the correct positional relationship between the gastric vasculatures and the organs. Regarding vascular pattern detected by 3D imaging, the origins of the infrapyloric artery were the right gastroepiploic artery in 12 cases (36%), the gastroduodenal artery in eight cases (24%), the bifurcation of the right gastroepiploic artery and gastroduodenal artery in seven cases (21%), and not detected in one case (3%). The types of confluence of the infrapyloric vein were the right gastroepiploic vein in 16 cases (48%), the anterior superior pancreatoduodenal vein in 10 cases (30%), and not detected in seven cases (21%). Surgical outcomes were not different between trainee group using intraoperative 3D image with the specialist in instruction group without the intraoperative 3D image. Conclusions Preoperative 3D imaging might contribute to successful and safe LG by trainee surgeons. J. Med. Invest. 66 : 280-284, August, 2019.

Is bony attachment necessary for dynamic reference frame in navigation-assisted minimally invasive lumbar spine fusion surgery?

This study aimed to compare the accuracy of navigation-assisted percutaneous pedicle screw insertions between traditional posterior superior iliac spine (PSIS) fixed and cutaneously fixed dynamic reference frame (DRF) in minimally invasive surgery of transforaminal lumbar interbody fusion (MIS TLIF). This is a prospective randomized clinical study. Between May 2016 and Nov 2017, 100 patients who underwent MIS TLIF were randomly divided into bone fixed group (with PSIS fixed DRF) and skin fixed group (with cutaneously fixed DRF). The pedicel screws were inserted under navigational guidance using computed tomography (CT) data acquired intraoperatively with a Ziehm 3-dimensional fluoroscopy-based navigation system. Screw positions were immediately checked by a final intraoperative scan. The accuracy of screw placement was evaluated by a sophisticated computed tomography protocol. Both groups had similar patient demographics. Totally Five-hundred Twelve pedicle screws were placed in the lumbar spine. There were 2 moderate (2–4 mm) pedicle perforations in each group. The accuracy showed no significant difference between bone fixed and skin fixed DRF. There were no significant procedure-related complications. The skin fixed DRF provides similar accuracy in pedicle screw insertions with bone fixed DRF using intraoperative 3D image guided navigation in MIS TLIF. Skin fixed DRF not only serves as an alternative method but also saves a separate incision wound for bony attachment.

Intraoperative three-dimensional imaging in the management of orbital trauma

Background: Intraoperative three-dimensional (3D) imaging can be utilized to detect bone malpositioning during facial fracture repair. Aim: This article exhibits a case of left Zygomatic maxillary complex fracture that was repaired with the aid of intraoperative 3D imaging technology. Methods: A critical size orbital floor defect was apparent on the imaging, necessitating an immediate repair avoiding a second-revision surgery. Results and Conclusion: The use of 3D imaging has historically been underutilized due to financial and time constraints. However, when comparing to costs and time utilized to undergo a second surgery, usage of 3D imaging intraoperatively is beneficial to the patient, team, and the institution.

Navigation in lumbar spinal surgery: When is it useful?

Spinal navigation has evolved greatly since its implementation in the mid-1990s and is now widely used in lumbar spine surgery. However, navigation is not yet accepted as astandard technique. In addition to the classic use in lumbar pedicle screw instrumentation, navigation technology, especially in combination with intraoperative 3D imaging, can be applied in awide range of indications and in all lumbar approaches. The technology is particularly helpful in minimally invasive operations. The concept of "total navigation" stands for an efficient use of the technique from skin incision on and aims at complete elimination of radiation exposure for the surgical team. High accuracy and low radiation exposure of the OR team are indisputable advantages of navigated operations, while time savings and economic benefits are yet to be demonstrated. Regular use and standardized workflow are essential for the safe and effective application of lumbar navigation. Currently, lumbar navigation technology is already of great importance, yet the complex technology requires intensive training. With improved user comfort and image quality, spinal navigation will continue to spread in the future.

Intraoperative Imaging in Pelvic Surgery.

Pelvic fractures may range from highly severe, life-threatening injuries to less acute clinical entities. There are several sub-entities that are summed up as pelvic injuries. Anatomically, there are fractures of the anterior or posterior pelvic ring. Apart from these, there are fractures of the acetabulum that make up about one fifth of all pelvic injuries. The indication for surgical treatment of pelvic ring injuries depends on the type of injury, involvement of anterior and/or posterior elements of the pelvic ring, demands and the general condition of the patient. In acetabular fractures, indications depend on the dislocation of the fracture and of course also the needs of the patient and his general condition. An intraarticular step-off of more than 2 mm is usually considered as an indication for open reduction and osteosynthesis. Usually in all these injuries, a preoperative CT scan is mandatory to allow precise planning of the operative approach and technique. Intraoperatively, the surgeon should be familiar with the acquisition of the 2D standard views, including 2D imaging of the pelvic ring and the acetabulum. These consist of the anteroposterior view for both pelvic ring and acetabular osteosyntheses. For further assessment of pelvic ring treatments, inlet and outlet views are achievable by angulating the C-arm cranially and caudally. To assess aspects of the anterior and posterior column of the acetabulum, iliac oblique views are used. Here, the C-arm is rotated laterally. As evaluation of 2D views can be limited due to anatomy and superposing structures, intraoperative 3D imaging has become common in the last decade. Special C-arms allow the automatic acquisition of large numbers of projections and create CT-like views of the central volume. Although this method has significantly widened the possibilities of intraoperative imaging, some issues remain. Depending on the amount of implants placed in the imaging field, assessment can be seriously impaired due to artefacts caused by the implants. Intraoperative CT imaging promises enhanced image quality for artefacts and allows a considerably larger field of view. The use of radiation-free navigation facilitates implant placement in minimally invasive procedures like screw placement in the sacroiliacal joint or the acetabulum by visualisation of instruments and implants in a pre- or intraoperative 3D data set.

Intraoperative CT Scan Verification of Pedicle Screw Placement in AIS to Prevent Malpositioned Screws: Safety Benefit and Cost

Study DesignProspective database review. ObjectivesDetermine if use of intraoperative 3D imaging of pedicle screw position provides clinical and cost benefit. Summary of BackgroundInjury or reoperation from malpositioned pedicle screws in adolescent idiopathic scoliosis (AIS) surgery occurs but is increasingly considered to be a never-event. To avoid complications, intraoperative 3D imaging of screw position may be obtained. MethodsA prospective, consecutive AIS database at a high-volume pediatric spine center was examined three years before and after implementation of an intraoperative low-dose computed tomographic (CT) scan protocol. All screws were placed via freehand technique and corrected if found to be outside optimal trajectory on the postplacement CT scan. Demographic and outcome data were compared between cohorts, along with number, location, and reason for screw change. Cost analysis was based on the average cost of revision surgery for screw malposition versus intraoperative CT use. ResultsThere were 153 patients in the pre-CT and 153 in the post-CT cohorts with a minimum 2-year follow-up. Two reoperations were needed for revision of improper screw placement in the pre-CT group and none in the post-CT group. Number of patients needed to harm was 76 (absolute risk increase = 1.31% [–0.49%, 3.11%]). Of those who had intraoperative CT scans, 80 (52.3%) needed on average 1.75 screw trajectories/lengths changed. Forty-three percent were medial breaches; of these, 39% were in the concavity. There were no differences between patients who did and did not need screw repositioning with regard to body mass index (BMI), age, curve size, surgeon/trainee side, screw density, or preoperative and one-year postoperative Scoliosis Research Society–22 patient questionnaire (SRS-22) scores. The average cost of reoperation for malposition was $4,900, whereas the cost of a single intraoperative CT was $232. ConclusionIntraoperative CT is an effective tool to prevent reoperation in AIS surgery for incorrect screw placement. Despite high volume, experience, and specialty training, incorrect trajectories occur and systems should be in place for preventable error. Level of EvidenceLevel II.

Pedicle Screw Placement Using Augmented Reality Surgical Navigation With Intraoperative 3D Imaging: A First In-Human Prospective Cohort Study.

Prospective observational study. The aim of this study was to evaluate the accuracy of pedicle screw placement using augmented reality surgical navigation (ARSN) in a clinical trial. Recent cadaveric studies have shown improved accuracy for pedicle screw placement in the thoracic spine using ARSN with intraoperative 3D imaging, without the need for periprocedural x-ray. In this clinical study, we used the same system to place pedicle screws in the thoracic and lumbosacral spine of 20 patients. The study was performed in a hybrid operating room with an integrated ARSN system encompassing a surgical table, a motorized flat detector C-arm with intraoperative 2D/3D capabilities, integrated optical cameras for augmented reality navigation, and noninvasive patient motion tracking. Three independent reviewers assessed screw placement accuracy using the Gertzbein grading on 3D scans obtained before wound closure. In addition, the navigation time per screw placement was measured. One orthopedic spinal surgeon placed 253 lumbosacral and thoracic pedicle screws on 20 consenting patients scheduled for spinal fixation surgery. An overall accuracy of 94.1% of primarily thoracic pedicle screws was achieved. No screws were deemed severely misplaced (Gertzbein grade 3). Fifteen (5.9%) screws had 2 to 4 mm breach (Gertzbein grade 2), occurring in scoliosis patients only. Thirteen of those 15 screws were larger than the pedicle in which they were placed. Two medial breaches were observed and 13 were lateral. Thirteen of the grade 2 breaches were in the thoracic spine. The average screw placement time was 5.2 ± 4.1 minutes. During the study, no device-related adverse event occurred. ARSN can be clinically used to place thoracic and lumbosacral pedicle screws with high accuracy and with acceptable navigation time. Consequently, the risk for revision surgery and complications could be minimized. 3.

Intraoperative 3d-image guidance in laparoscopic and open liver resection. initial experience

Intraoperative 3d-image guidance in laparoscopic and open liver resection. initial experience

Wednesday, September 26, 2018 7:35 AM–9:00 AM ePosters: P73. Economic study: a cost-effectiveness study of an intraoperative compared with a preoperative image-guided system in spine surgery fixation. Analysis of 10years of experience

BACKGROUND CONTEXT Spinal navigation and image-guided system (IGS) are, up to now, well establish technologies, and thanks to their excellent results their spread is growing. In the latest years many publications and meta-analyses demonstrate their accuracy and safety, and even more center adopted IGS in daily activity. However, the acquisition and maintenance costs of these systems are high, and not all the hospital and clinics can effort its purchase. In an era when health expenditure is rising exponentially, cost-effectiveness analyses are mandatory to responsibly manage the scarce health care resources and to define if this technology is economically sustainable and which criteria must be respect to justify its acquisition. PURPOSE The purpose of the present study was to perform a detailed cost-effectiveness analysis to determine the value of a navigation system coupled with intra-operative 3D imaging in adult spinal surgery analyzed thought a micro costing approach in a period of 10years. STUDY DESIGN/SETTING Retrospective cost-effectiveness study. PATIENT SAMPLE Patients operated on our surgical department between 2003 and 2013. METHODS A retrospective cost-effectiveness study was conducted to analyze the overall costs of a population of patients admitted to our Neurosurgical department for spine fixation surgery. In the present study the authors have analyzed the entire population of patients treated for spinal instrumentation with the aid of an IGS system from January 2003 to March 2013. The cost-effectiveness study compared two different type of spinal navigation: system based on a preoperative CT scan (from January 2003 to April 2009 – group I) and the intraoperative CT like scan system (from April 2009 to March 2013 – group II). The economic evaluation is conducted from a hospital perspective. Costs of the two procedures are measured and valued using a microcosting approach. All costs incurred by the hospital are collected from the hospital's accounting service. The evaluation took into consideration all of the phases, from preadmission testing to discharge. Cost of the complications are considered and analyzed as well. RESULTS The study includes 499 patients with a total of 2,542 screws inserted with IGS. Baseline data were similar for the two groups, as were hospitalization and complications. The full cost of the two procedures was analysed: mean cost with intraoperative CT scan system procedure was 6.545 € (±525.9) and 6.853 (±564.3) with preoperative image-guided system. The screws' accuracy were respectively 98.5% and 96.1%. Higher costs were identified for human resources, disposable and implanted materials (more than 1.000 €); in particular, cost of human source were higher for the use of preoperative scan. The higher total cost of the procedure with preoperative scan is related for the major part to the cost of CT scan (preoperative for navigation and postoperative for control). CONCLUSIONS The results of our study show a cost difference that is not statistically significant between the two procedures. However, the use of the intraoperative CT scan system suggests an economic advantage in a long-term point of view. It consent to reduce surgical time and complications bringing to a better clinical result; consent an economics saving in term of human resource and number and type of radiological imaging. A break-even point is estimated after almost 150 procedures. Moreover, nowadays this system is used for more than only screws insertion reducing the financial impact of this technology on the hospital.

A novel technique of cervical pedicle screw placement with a pilot screw under the guidance of intraoperative 3D imaging from C-arm cone-beam CT without navigation for safe and accurate insertion.

The cervical pedicle screw (CPS) requires careful and accurate placement because of the critical risk for neurovascular injury. This study aimed to introduce and evaluate the safety and efficacy of a new CPS placement technique using intraoperative C-arm cone-beam CT (CBCT) and a pilot screw without navigation system. This was a case-control study to compare the accuracy and safety of intraoperative C-arm CBCT-guided CPS placement with freehand CPS placement under lateral fluoroscopy using control data from a previous multicenter study. A total of 166 CPSs were inserted under intraoperative C-arm CBCT guidance in 48 consecutive patients (20 rheumatoid arthritis, 16 degenerative spinal disorders, 6 spinal tumor, 2 congenital deformity, 2 ossification of posterior longitudinal ligament, and 2 fracture dislocation). Accuracy and safety of CPS placement were assessed. The overall malposition rate was 2.4% (4 screws in grade 1: malposition by less than half-screw diameter, 0 in grade 2: malposition by more than half-screw diameter), which was significantly lower than the reported malposition rate of 14.8% in lateral fluoroscopy-guided freehand placement. There were no complications directly related to CPS insertion. The average estimated effective radiation dose per surgery was 14.7mSv. The novel technique enables intraoperative adjustment of the trajectory of the CPS as well as confirmation of the CPS path before penetrating the isthmus of the pedicle, resulting in accurate and safe CPS placement, which outweighs the demerits of radiation exposure. These slides can be retrieved under Electronic Supplementary Material.

Development of a 3D ultrasound guidance system for permanent breast seed implantation.

Permanent breast seed implantation (PBSI) is a promising radiotherapy technique for early-stage breast cancer, completed in a single visit by permanently implanting 103 Pd seeds using needles inserted through a template and guided by two-dimensional (2D) ultrasound (US). However, operator dependence has been highlighted as a limitation of this procedure. Consequently, we propose and have developed an intraoperative guidance system using three-dimensional (3D) US and an instrumented mechanical arm to provide intraoperative 3D imaging and needle template tracking. A mechatronic 3D US scanner reconstructs a 3D image from 150 2D images. A tracked mechanical arm mounted to the scanner locates four fiducial points on the template, registering the template to the 3D image. 3D reconstruction was validated for linear and volumetric measurement accuracy using phantoms of known geometry. In vivo breast US image quality was evaluated in a healthy volunteer. The encoded arm was calibrated and validated using a jig with divots at known locations relative to the scanner and the scanner registered to the 3D US image using intersecting strings in a fluid-filled test jig. Template registration accuracy was assessed using a machined test jig. Tracking accuracy was assessed in a liquid medium by comparing tracked and imaged needle tip positions. Finally, the system was used to guide a mock procedure in a patient-specific phantom and micro-CT imaging used to evaluate its accuracy. Geometric validation showed median distances within ±1.1% of expected values and volumetric validation showed differences of ≤4.1%. Tracking arm point measurements showed an average error of 0.43mm and 3D US volume registration showed target registration error ≤0.9mm. Mean template registration accuracy in each axis of translation/rotation was ≤1.3mm/1.0°. Mean needle-targeting error was 2.5mm and 1.6° for needle tips and trajectories, respectively. Mean needle tip and angular errors of the phantom procedure were 2.1mm and 2.6°. Modeled seed displacement of the phantom procedure showed mean error of 2.6mm and a maximum of 3.8mm. A 3D US guidance system for PBSI has been developed. Benchtop performance and image quality in volunteer scans are satisfactory. A phantom PBSI procedure was successfully delivered using the system with maximum seed error within dosimetric benchmarks (<5mm). Translation of the device into the clinic is forthcoming.

Comprehensive Assessment of Mitral Valve Geometry and Cardiac Remodeling With 3-Dimensional Echocardiography After Percutaneous Mitral Valve Repair

MitraClip is a validated treatment for significant mitral regurgitation (MR) in high-risk patients. Aims of the study were to evaluate immediate changes in mitral valve (MV) geometry induced by MitraClip and correlations between baseline geometry and cardiac remodeling. Eighty patients who underwent MitraClip for primary (48%) or secondary (52%) MR were enrolled. Intraoperative transesophageal echocardiographic 3D images were acquired immediately before and after the procedure for MV annulus (MVA) morphology analysis. Transthoracic 3D echocardiography was performed preoperatively and at 6 months follow-up (6MFU). Patients were classified on the basis of MR reduction (ΔMR) at 6MFU as Optimal (ΔMR ≥ 2) or Suboptimal (ΔMR < 2). An optimal result was reached in 60 (75%) patients, whereas 20 subjects showed a ΔMR< 2 at 6MFU. The Optimal showed significantly smaller baseline MVA (antero-posterior diameter 4.05 ± 0.59 vs 4.43 ± 0.68 cm; anterolateral-posteromedial diameter 4.38 ± 0.56 vs 4.70 ± 0.73 cm; MVA circumference 14.1 ± 1.7 vs 15.1 ± 2.3 cm; and 3D area 14.8 ± 3.9 vs 17.4 ± 5.3 cm2), lower sphericity index and nonplanar angle compared with Suboptimal. A value of antero-posterior diameter ≥4.44cm was identified (receiver-operating characteristic curve) as a possible cut-off for preoperative identification of Suboptimal patients. Postoperatively, MitraClip induced reduction of MVA flattening (nonplanar angle), sphericity index, and size (as expressed by antero-posterior diameter, MVA circumference and area). At 6MFU, the Optimal showed significant decrease in left ventricular volumes and pulmonary artery systolic pressure. In conclusion, MitraClip induces remarkable changes in MVA geometry and favorable left ventricular remodeling is detected in patients with optimal mid-term outcome; a preprocedural antero-posterior diameter <4.44cm seems to be a potential predictor of mid-term optimal result.

Feasibility and Accuracy of Thoracolumbar Minimally Invasive Pedicle Screw Placement With Augmented Reality Navigation Technology.

Study Design.Cadaveric laboratory study.Objective.To assess the feasibility and accuracy of minimally invasive thoracolumbar pedicle screw placement using augmented reality (AR) surgical navigation.Summary of Background Data.Minimally invasive spine (MIS) surgery has increasingly become the method of choice for a wide variety of spine pathologies. Navigation technology based on AR has been shown to be feasible, accurate, and safe in open procedures. AR technology may also be used for MIS surgery.Methods.The AR surgical navigation was installed in a hybrid operating room (OR). The hybrid OR includes a surgical table, a motorized flat detector C-arm with intraoperative 2D/3D imaging capabilities, integrated optical cameras for AR navigation, and patient motion tracking using optical markers on the skin. Navigation and screw placement was without any x-ray guidance. Two neurosurgeons placed 66 Jamshidi needles (two cadavers) and 18 cannulated pedicle screws (one cadaver) in the thoracolumbar spine. Technical accuracy was evaluated by measuring the distance between the tip of the actual needle position and the corresponding planned path as well as the angles between the needle and the desired path. Time needed for navigation along the virtual planned path was measured. An independent reviewer assessed the postoperative scans for the pedicle screws’ clinical accuracy.Results.Navigation time per insertion was 90 ± 53 seconds with an accuracy of 2.2 ± 1.3 mm. Accuracy was not dependent on operator. There was no correlation between navigation time and accuracy. The mean error angle between the Jamshidi needles and planned paths was 0.9° ± 0.8°. No screw was misplaced outside the pedicle. Two screws breached 2 to 4 mm yielding an overall accuracy of 89% (16/18).Conclusion.MIS screw placement directed by AR with intraoperative 3D imaging in a hybrid OR is accurate and efficient, without any fluoroscopy or x-ray imaging during the procedure.Level of Evidence: N/A

Posterior C1C2 harms fusion with 3D surgical navigation.

Several types of atlantoaxial instability can justify surgical fixation. The instrumented fusion procedure described by Harms with screw fixation of the C1 lateral masses and C2 pedicles is a demanding technique that provides lasting stabilization. However, it has been associated with nerve and vascular complications due to the local anatomical configuration. Surgical navigation systems can help improve the procedure's accuracy. We describe a series of 11 cases of C1C2 Harms fusion performed with surgical navigation and intraoperative 3D imaging checks. All procedures were carried out completely with satisfactory implant placement. There were no adverse events related to the procedure during the peri-operative period. No cortical breach was detected using cone-beam CT at the end of the procedure. The technical challenges and risks associated with C1C2 Harms fusion have led to the use of 3D intraoperative imaging systems, when available.

Intraoperative assessment of reduction and implant placement in acetabular fractures\u2014limitations of 3D-imaging compared to computed tomography

BackgroundIn acetabular fractures, the assessment of reduction and implant placement has limitations in conventional 2D intraoperative imaging. 3D imaging offers the opportunity to acquire CT-like images and thus to improve the results. However, clinical experience shows that even 3D imaging has limitations, especially regarding artifacts when implants are placed. The purpose of this study was to assess the difference between intraoperative 3D imaging and postoperative CT regarding reduction and implant placement.MethodsTwenty consecutive cases of acetabular fractures were selected with a complete set of intraoperative 3D imaging and postoperative CT data. The largest detectable step and the largest detectable gap were measured in all three standard planes. These values were compared between the 3D data sets and CT data sets. Additionally, possible correlations between the possible confounders age and BMI and the difference between 3D and CT values were tested.ResultsThe mean difference of largest visible step between the 3D imaging and CT scan was 2.0 ± 1.8 mm (0.0–5.8, p = 0.02) in the axial, 1.3 ± 1.4 mm (0.0–3.7, p = 0.15) in the sagittal and 1.9 ± 2.4 mm (0.0–7.4, p = 0.22) in the coronal views. The mean difference of largest visible gap between the 3D imaging and CT scan was 3.1 ± 3.6 mm (0.0–14.1, p = 0.03) in the axial, 4.6 ± 2.7 mm (1.2–8.7, p = 0.001) in the sagittal and 3.5 ± 4.0 mm (0.0–15.4, p = 0.06) in the coronal views. A positive correlation between the age and the difference in gap measurements in the sagittal view was shown (rho = 0.556, p = 0.011).ConclusionsIntraoperative 3D imaging is a valuable adjunct in assessing reduction and implant placement in acetabular fractures but has limitations due to artifacts caused by implant material. This can lead to missed malreduction and impairment of clinical outcome, so postoperative CT should be considered in these cases.

Analysis of the learning curve of the surgical procedure for the treatment of thoracic disc herniation using anterolateral transthoracic approach with the aid of image-guided system.

In surgery, the learning process represents one of the critical topics in the development of a young surgeon where there is often no standardized learning program. The learning curve is defined by plotting proficiency as a function of time, or the number of repetitions. In this study, we analyzed the learning process for a rare and surgically demanding pathology such as thoracic disc herniations (TDHs) treated with an antero-lateral trans-thoracic approach. We analyzed a consecutive series of patients admitted with a diagnosis of TDHs. All patients underwent surgery using a standard antero-lateral trans-thoracic approach, assisted by navigation system based on intraoperative 3D imaging performed with O-Arm™ (Medtronic; Dublin, Ireland) system. Twenty-one patients underwent surgery from January 2012 to June 2017. The time analysis shows a progressive reduction in time from the first to the last case with continued improvement in operating time but progressively less dramatic, this is explicable considering the classic learning curve model. Predictably, a slow learning curve was charted - typical for a technically demanding procedure associated with a rare incidence of pathology. A learning curve is an easy and efficient way to gauge the growth of a surgeon. After 21 cases we obtained an intermediate profile of learning curve between steep and shallow. Despite different alternatives for speeding up the learning process it is not always possible to standardize and reflect them in a learning process. Today, the use of technology is often considered in this but does not always affect the process itself.

Patient-specific model-based segmentation of brain tumors in 3D intraoperative ultrasound images.

Intraoperative ultrasound (iUS) imaging is commonly used to support brain tumor operation. The tumor segmentation in the iUS images is a difficult task and still under improvement because of the low signal-to-noise ratio. The success of automatic methods is also limited due to the high noise sensibility. Therefore, an alternative brain tumor segmentation method in 3D-iUS data using a tumor model obtained from magnetic resonance (MR) data for local MR-iUS registration is presented in this paper. The aim is to enhance the visualization of the brain tumor contours in iUS. A multistep approach is proposed. First, a region of interest (ROI) based on the specific patient tumor model is defined. Second, hyperechogenic structures, mainly tumor tissues, are extracted from the ROI of both modalities by using automatic thresholding techniques. Third, the registration is performed over the extracted binary sub-volumes using a similarity measure based on gradient values, and rigid and affine transformations. Finally, the tumor model is aligned with the 3D-iUS data, and its contours are represented. Experiments were successfully conducted on a dataset of 33 patients. The method was evaluated by comparing the tumor segmentation with expert manual delineations using two binary metrics: contour mean distance and Dice index. The proposed segmentation method using local and binary registration was compared with two grayscale-based approaches. The outcomes showed that our approach reached better results in terms of computational time and accuracy than the comparative methods. The proposed approach requires limited interaction and reduced computation time, making it relevant for intraoperative use. Experimental results and evaluations were performed offline. The developed tool could be useful for brain tumor resection supporting neurosurgeons to improve tumor border visualization in the iUS volumes.

218 Innovative uses of real-time intraoperative 3d imaging

Purpose of studyIn the past few years, cheaper and more accessible forms of portable 3D sensors have become available on the market, such as the Structure Sensor. While the effectiveness of larger scale scanners has been analysed pre and post operatively in the field of plastic surgery, there is ess