Workflow and performance of intraoperative CT, cone-beam CT, and robotic cone-beam CT for spinal navigation in 503 consecutive patients

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  • 1 Department of Neurosurgery, Charité-Universitätsmedizin Berlin;
  • | 2 Department of Neurosurgery, Goethe Universität Frankfurt, Frankfurt am Main;
  • | 3 Department of Neuroradiology, Charité-Universitätsmedizin Berlin; and
  • | 4 Department of Neurosurgery, University at Oldenburg, Germany
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OBJECTIVE

A direct comparison of intraoperative CT (iCT), cone-beam CT (CBCT), and robotic cone-beam CT (rCBCT) has been necessary to identify the ideal imaging solution for each individual user’s need. Herein, the authors sought to analyze workflow, handling, and performance of iCT, CBCT, and rCBCT imaging for navigated pedicle screw instrumentation across the entire spine performed within the same surgical environment by the same group of surgeons.

METHODS

Between 2014 and 2018, 503 consecutive patients received 2673 navigated pedicle screws using iCT (n = 1219), CBCT (n = 646), or rCBCT (n = 808) imaging during the first 24 months after the acquisition of each modality. Clinical and demographic data, workflow, handling, and screw assessment and accuracy were analyzed.

RESULTS

Intraoperative CT showed image quality and workflow advantages for cervicothoracic cases, obese patients, and long-segment instrumentation, whereas CBCT and rCBCT offered independent handling, around-the-clock availability, and the option of performing 2D fluoroscopy. All modalities permitted reliable intraoperative screw assessment. Navigated screw revision was possible with each modality and yielded final accuracy rates > 92% in all groups (iCT 96.2% vs CBCT 92.3%, p < 0.001) without a difference in the accuracy of cervical pedicle screw placement or the rate of secondary screw revision surgeries.

CONCLUSIONS

Continuous training and an individual setup of iCT, CBCT, and rCBCT has been shown to permit safe and precise navigated posterior instrumentation across the entire spine with reliable screw assessment and the option of immediate revision. The perceived higher image quality and larger scan area of iCT should be weighed against the around-the-clock availability of CBCT and rCBCT technology with the option of single-handed robotic image acquisition.

ABBREVIATIONS

CBCT = cone-beam CT; CPS = cervical pedicle screw; iCT = intraoperative CT; OR = operating room; rCBCT = robotic CBCT.

OBJECTIVE

A direct comparison of intraoperative CT (iCT), cone-beam CT (CBCT), and robotic cone-beam CT (rCBCT) has been necessary to identify the ideal imaging solution for each individual user’s need. Herein, the authors sought to analyze workflow, handling, and performance of iCT, CBCT, and rCBCT imaging for navigated pedicle screw instrumentation across the entire spine performed within the same surgical environment by the same group of surgeons.

METHODS

Between 2014 and 2018, 503 consecutive patients received 2673 navigated pedicle screws using iCT (n = 1219), CBCT (n = 646), or rCBCT (n = 808) imaging during the first 24 months after the acquisition of each modality. Clinical and demographic data, workflow, handling, and screw assessment and accuracy were analyzed.

RESULTS

Intraoperative CT showed image quality and workflow advantages for cervicothoracic cases, obese patients, and long-segment instrumentation, whereas CBCT and rCBCT offered independent handling, around-the-clock availability, and the option of performing 2D fluoroscopy. All modalities permitted reliable intraoperative screw assessment. Navigated screw revision was possible with each modality and yielded final accuracy rates > 92% in all groups (iCT 96.2% vs CBCT 92.3%, p < 0.001) without a difference in the accuracy of cervical pedicle screw placement or the rate of secondary screw revision surgeries.

CONCLUSIONS

Continuous training and an individual setup of iCT, CBCT, and rCBCT has been shown to permit safe and precise navigated posterior instrumentation across the entire spine with reliable screw assessment and the option of immediate revision. The perceived higher image quality and larger scan area of iCT should be weighed against the around-the-clock availability of CBCT and rCBCT technology with the option of single-handed robotic image acquisition.

Amain driving force of successful clinical translation of spinal navigation has been the rapid evolvement of intraoperative 3D imaging solutions.1–13 In general, these can be categorized into true CT (fan beam) imaging on one side, and cone-beam CT imaging with or without robotic control on the other. Three of the most widely used, state-of-the-art solutions include the mobile AIRO (Brainlab AG) intraoperative CT (iCT),7 the mobile O-arm (Medtronic) cone-beam CT (CBCT),12 and the permanently installed Zeego (Siemens Healthcare) robotic CBCT (rCBCT).13 In this context, several studies have reported on iCT-,5,7,14,15 CBCT-,12,16–18 and rCBCT-based spinal navigation,8,10,13,19 each of which requires a certain degree of training.20,21 This is highly relevant because inadequate training is one of the main reasons cited when spine surgeons refrain from adapting image guidance.22 Exposure is the best way to ensure proper training. For this purpose, a direct comparison of workflow, handling, and performance of iCT-, CBCT-, and rCBCT-based spinal navigation could help identify the ideal imaging solution for each individual user’s need to optimize surgical and clinical results. Therefore, the aim of the present study was to report a systematic and comprehensive analysis of iCT-, CBCT-, and rCBCT-based spinal navigation during the first 24 months after clinical implementation within a single surgical environment by the same group of surgeons.

Methods

This study was conducted according to the World Medical Association Declaration of Helsinki and approved by the ethics committee of the Charité-Universitätsmedizin Berlin, Germany, and included 503 patients (260 females and 243 males) who underwent navigated pedicle screw instrumentation using iCT (n = 195), CBCT (n = 141), or rCBCT (n = 167) imaging in our department between May 2014 and December 2018. Instrumentation and intraoperative screw assessment were performed with real-time spinal navigation, and iCT, CBCT, or rCBCT imaging was performed across the entire subaxial spine. Instrumentation in the cervical spine only included the subaxial region (C2–7) and was performed exclusively with cervical pedicle screws (CPSs). All consecutive patients who underwent surgery within the first 24 months after acquisition of each individual imaging device were included. The type of intraoperative imaging was selected according to availability and logistical requirements at the 3 Berlin Charité neurosurgery sites; iCT was performed at Campus Charité Virchow and Campus Charité Mitte, CBCT at Campus Benjamin Franklin, and rCBCT at Campus Charité Mitte. Importantly, each of the involved primary spine surgeons (P.V., J.W., M.C., S.B., and N.H.) performed surgery with each imaging modality across all 3 sites. Clinical and demographic data, workflow, handling, and screw assessment and accuracy for each imaging modality were retrospectively analyzed by an independent observer who was not involved in patient care. Informed consent was waived due to the retrospective nature of the study.

Intraoperative Imaging and Navigation Setup

An overview of technical specifications of the 3 imaging modalities is presented in Table 1.

TABLE 1.

Technical specifications and handling

iCTCBCTrCBCT
HandlingSurgeon & circulating staffSurgeon & circulating staffSurgeon
MobilityBtwn ORsBtwn ORs & during opPermanently installed
Gantry diameter, cm10769.981.5
Field of view, cm562026
Detector technology32-slice helical scan detector array30-cm × 40-cm digital flat panel detector30-cm × 38-cm digital flat panel detector
Perceived image qualityExcellentGoodGood
Automatic pt/image coregistrationYesYesYes
Image stackingNoNoNo
Possibility of 2D fluoroscopyNoYesYes

Pt = patient.

For iCT-based spinal navigation, the AIRO iCT (Brainlab AG) was used.7,23 This mobile system can be used in an existing operating room (OR) and consists of a CT gantry, which houses the x-ray tube, 32-slice helical scan detector array, high-voltage generator, air cooling system and battery, and a column for the OR table. The CT scan is remotely executed by a qualified radiologist or radiology technician through a handheld touchpad. For CBCT-based spinal navigation, the mobile O-arm system was used. Next to 3D cone-beam CT reconstruction, this system offers the possibility of 2D fluoroscopy and can be used in any existing OR suite. The 3D CBCT data set is generated by a stationary system that houses a rotating x-ray tube (Varian Model B100 with A132 insert) and detector (Varian Model Paxscan 4030D) to obtain fluoroscopic images at a submillimeter spatial resolution. Three-dimensional CBCT imaging was performed in high-definition mode with the L or XL setting, depending on the patient’s body size. Execution of the scan is performed remotely from outside the OR by a surgeon qualified for CBCT image acquisition. For rCBCT-based spinal navigation, we used the robotic 3D Artis Zeego II digital fluoroscopy C-arm system (Siemens Healthineers) as previously described.11 The rCBCT is a permanently installed robotic system that uses a C-arm mounted x-ray tube and 30-cm × 40-cm flat panel detector to obtain fluoroscopic images at a submillimeter spatial resolution, which are immediately postprocessed into a 3D data set. Although the device requires a dedicated hybrid OR setup, all preparations for rCBCT scanning, including positioning of the C-arm, movement of the OR table, and 2D fluoroscopic imaging for setup of the 3D scan, can be performed by a qualified surgeon alone through a sterile-draped control panel without the assistance of circulating staff. The scanning procedure is remotely executed by the surgeon from outside the OR. Data sets were automatically (iCT) or manually (rCBCT and CBCT) transferred to our in-hospital picture archiving and communication system (PACS).

For navigated pedicle screw implantation, an image-guidance system and infrared tracking camera that permitted automatic patient/image coregistration was used, depending on the software interface and manufacturer of the imaging device (for iCT and rCBCT, Brainlab Curve and Brainlab Spinal Navigation Software version 3.0 were used and for CBCT, StealthStation S7 Navigation System [Medtronic] was used). Surgery was performed on mobile, radiolucent, carbon-fiber examination tables (Trumpf Carbon FloatLine or Trumpf Carbon X-Tra [Trumpf Medical]). For all rCBCT procedures and for iCT or CBCT procedures at or above the midthoracic level, the patient’s head was fixed in a radiolucent carbon fiber 3-pin head clamp (Trumpf X-Ray [Trumpf Medical]). Surgical exposure was gained through a standard midline or paraspinal/transmuscular approach, and a spinal reference clamp (Brainlab AG) was attached to a spinous process or the iliac crest. For acquisition of the spinal navigation scan with automatic patient/image coregistration, the OR table, imaging device, and navigation tracking camera were positioned to ensure an unobstructed line of sight from the navigation tracking camera to the spinal reference clamp and the registration fiducials mounted on the gantry (iCT and CBCT) or C-arm (rCBCT) of the imaging device (Fig. 1). Draping comprised cocoon-like draping of the patient and additional draping of the rotating detector, x-ray tube, and/or gantry for O-arm and Zeego procedures, and standard patient draping without draping of the nonrotating gantry for AIRO procedures. Common technological issues were mainly due to connectivity problems between the imaging/navigation interface in Zeego and AIRO cases, leading to a failure of automatic scan upload to the navigation platform. Importantly, this was resolved with a manual data set upload and did not require additional scanning procedures.

FIG. 1.
FIG. 1.

Setup of iCT-, CBCT-, and rCBCT-based spinal navigation in the OR during surgery (A–C) and intraoperative image acquisition (D–F). The red arrows illustrate the required position change of the imaging device. For iCT- and CBCT-based imaging, the position change requires the assistance of circulating staff. In rCBCT-based imaging, the position change is performed by the surgeon alone using a draped control panel. In all cases, a clear line of sight (dashed gray line) from the tracking camera to the patient and intraoperative imaging device is required for automatic patient/image coregistration. A = anesthesiologist; C = navigation tracking camera; N = nurse; NAV = navigation unit; Resp = respirator; S = surgeon; T = OR tables.

Navigated Pedicle Screw Implantation and Intraoperative Screw Assessment

Following the navigation scan, an image-guidance probe was used to verify correct anatomical coregistration. The screw entry point and trajectory were identified with a navigated drill guide (for iCT and rCBCT, Ulrich Medical in cervical spine cases and Brainlab AG in thoracolumbosacral spine cases; for CBCT, Medtronic) under consideration of real-time inline views of the axial, coronal, and sagittal planes. Next, a battery-powered drill (Cordless Driver, Stryker) with a 2.3-mm (cervical) or 2.6-mm (thoracolumbosacral) drill bit was inserted through the drill guide and a navigated pilot hole was drilled down to a desired depth. In CBCT-based cervical pedicle screw instrumentation, the pilot hole was drilled with a navigated, 2-mm diamond burr (Midas Rex EM200 Stylus engine, Medtronic). Next, a guide wire was inserted, the pedicle was tapped and probed, and a cannulated, measured pedicle screw with a diameter from 4.0 mm to 9.5 mm (for the thoracolumbosacral spine, CD Horizon Solera [Medtronic], and for the cervical spine, Vertex [Medtronic] or Neon3 [Ulrich Medical]) was inserted. Screw positioning was directly assessed by a second, navigated iCT, CBCT, or rCBCT scan with the chance of immediate repositioning, followed by a final iCT, CBCT, or rCBCT scan, on which the presented overall and regional pedicle screw accuracies were determined.

Analysis of Screw Accuracy and Assessment

Intraoperative screw placement accuracy as well as intraoperative screw assessment ability based on image quality were retrospectively assessed by an independent observer according to previous classification systems. Considering the large variation in methods to describe pedicle screw accuracy, we decided to use the classic 2-mm increment method, initially described by Gertzbein and Robbins24 and modified according to Rampersaud et al.25 Accordingly, the screws were categorized into 4 groups: A, completely within the pedicle; B, < 2-mm pedicle breach; C, 2- to 4-mm pedicle breach; and D, > 4-mm pedicle breach. Screws that were classified into categories A and B were considered accurate.

Statistical Analysis

Descriptive summary statistics are presented as mean ± SD, median and range (minimum to maximum), median and IQR, or percentage, as appropriate. Normal distribution was tested using the Shapiro-Wilk test and accordingly, demographics were analyzed with the Kruskal-Wallis test or one-way ANOVA. For contingency analysis, the chi-square test was used. For comparison of screw accuracy rates and screw revision parameters, the Kruskal-Wallis test with Dunn’s correction for multiple comparisons was used. All statistics were calculated with GraphPad Prism for Mac version 9.1 (GraphPad Software). Statistical significance was set at p < 0.05, and all tests were two-sided.

Results

Between May 2014 and December 2018, 2673 navigated pedicle screws were implanted and assessed with iCT (n = 1219), CBCT (n = 646), or rCBCT (n = 808) imaging in 503 patients. Baseline demographics were comparable, but differences between imaging modalities were noted in the indication for surgery, region of instrumentation, duration of surgery, hospital length of stay, and median instrumentation length (Table 2). In cases that required instrumentation across > 5 segments, iCT-based navigation facilitated workflow due to the larger scan area.

TABLE 2.

Demographics

iCT (n = 195)CBCT (n = 141)rCBCT (n = 167)p Value
Median age, yrs (IQR)68 (57–75)70 (59–77)69 (58–77)0.381
Sex, n (%)0.628
 F101 (52)77 (55)82 (49)
 M94 (48)64 (45)85 (51)
Median weight, kg (IQR)76 (65–90)78 (67– 90)78 (67–85)0.731
Mean height ± SD, cm169.5 ± 10169.8 ± 11168.3 ± 120.552
Median BMI (IQR)26 (23–30)27 (24–30)26.7 (24–30)0.575
Indication for op, n (%)
 Degenerative disease113 (58)114 (81)86 (52)<0.0001
 Infectious disease19 (10)10 (7)23 (14)0.149
 Tumor30 (15)7 (5)19 (11)0.011
 Trauma33 (17)10 (7)39 (23)0.0006
Instrumented region, n (%)
 Subaxial cervical spine43 (22)17 (12)24 (14)0.0325
 Thoracic spine49 (25)8 (6)35 (21)<0.0001
 Lumbosacral spine103 (53)116 (82)108 (65)<0.0001
Median instrumentation length, segments (range)3 (1–16)1 (1–7)2 (1–10)<0.0001
Median duration of op, mins (IQR)231 (188–311)157 (118–201)209 (158–272)<0.0001
Median LOS, days (IQR)16 (9–25)11 (7–17)14 (9–20)<0.0001

LOS = length of stay.

Kruskal-Wallis test or one-way ANOVA depending on the Shapiro-Wilk normality test; the chi-square test for contingency. Boldface type indicates statistical significance.

For 2672 screws, all 3 imaging modalities permitted screw placement assessment for each implanted screw across all regions of the spine, with more artifacts visible when performing imaging in the cervicothoracic region and obese patients, and generally for CBCT and rCBCT compared with iCT. Due to technical reasons, 1 iCT screw was not captured on imaging. The software-based option of setting an “inline” view offered by both navigation platforms facilitated screw assessment, particularly in the transverse plane (Fig. 2).

FIG. 2.
FIG. 2.

Transverse iCT (A), CBCT (B), and rCBCT (C) images obtained in patients undergoing lumbar fusion, illustrating the high image quality that permitted successful pedicle screw assessment in each case. Note that screw assessment is facilitated by adjusting an “inline” perspective along the axis of the screw (pink and blue lines on the CBCT image) instead of applying standard transverse views as shown in iCT and rCBCT images. R = right.

The proportion of initially misplaced screws ≥ 2 mm was fewer with iCT (4.6%) and greatest with CBCT (13.3%), followed by rCBCT (8.5%) (CBCT vs iCT, p < 0.0001; CBCT vs rCBCT, p = 0.024; and iCT vs rCBCT, p = 0.038). Accordingly, the number of intraoperatively revised screws differed significantly between groups (Table 3) and was fewest in iCT-based spinal navigation (iCT vs CBCT, p = 0.0092). Importantly, navigated screw revision was successful with all imaging modalities and yielded a final accuracy > 92% in all groups. The greatest final accuracy was noted in iCT (96.2%) compared with CBCT (92.3%; p < 0.001 vs iCT) and rCBCT (94.4%); region-specific analysis showed a greater final accuracy of iCT in the thoracic spine (iCT 97.1%, CBCT 90.0%, and rCBCT 90.8%; p < 0.001 for iCT vs CBCT and rCBCT; Fig. 3). The rate of required secondary screw revision surgeries did not differ.

TABLE 3.

Screw revision parameters

iCT (n = 195)CBCT (n = 141)rCBCT (n = 167)p Value
Total no. of navigated screws1219646808
Initial screws w/ ≥2-mm breach, n (%)56 (4.6)86 (13.3)69 (8.5)<0.0001
Intraop revised screws, n1036240.012
Final overall accuracy, %96.292.394.40.0012
2nd op due to misplaced screw, n (%)1 (0.5)3 (2.1)1 (0.6)0.277

Kruskal-Wallis test with the Dunn’s test for multiple comparisons based on the Shapiro-Wilk normality test; the chi-square test for contingency. Boldface type indicates statistical significance.

FIG. 3.
FIG. 3.

Bar graphs showing the initial and final overall (A) and final regional (B) intraoperative screw placement accuracy following navigated pedicle screw implantation using iCT, CBCT, or rCBCT. Accuracy categories were defined as follows: A, completely within the pedicle; B, < 2-mm pedicle breach; C, 2- to 4-mm pedicle breach; and D, > 4-mm pedicle breach. Categories A and B are considered as accurate placement. *p < 0.01, **p < 0.001; two-sided Kruskal-Wallis test with the Dunn’s multiple comparison test.

Discussion

Setup and Workflow

The recent technological evolution of computer-assisted spine surgery has facilitated the development of high-resolution intraoperative 3D imaging technologies based on different conceptual ideas that each require their own specific OR setup.26 In general, state-of-the art intraoperative 3D imaging solutions can be categorized into fan-beam iCT imaging (i.e., AIRO iCT) and CBCT or rCBCT imaging. Most importantly, real-time spinal navigation based on 3D intraoperative imaging has helped improve pedicle screw accuracy rates27 and reduce radiation exposure for the OR team,26,28–30 and holds promise to provide better outcomes.31,32 Considering the substantial acquisition and maintenance costs associated with intraoperative 3D imaging solutions,33,34 however, a direct comparison of state-of-the-art 3D imaging modalities is needed to highlight the strengths and weaknesses of each platform depending on the user’s individual needs and resources. Since 2013, our department has had the opportunity to implement 4 of the most commonly used technologies for intraoperative 3D imaging and real-time spinal navigation, beginning with an isocentric 3D C-arm, which was later followed by iCT (2014), CBCT (2016), and rCBCT (2017) technologies.7,11,23,35 Meanwhile, numerous studies have reported on the individual performance of these platforms,1–10,12–16,18,19 but a direct comparison between the most commonly used iCT, CBCT, and rCBCT technologies is still lacking. This is a dilemma, because different surgical environments affect setup, workflow, training, and routine and a direct workflow and performance assessment by the same group of surgeons within the same surgical environment could help uncover critical benefits and limitations of individual imaging modalities.

Naturally, different imaging technologies have different requirements regarding logistics and space. In our experience, availability of a qualified radiologist for execution of the iCT scan, on the one hand, and accessibility to the hybrid OR for rCBCT imaging, on the other hand, represented two main factors that influenced planning under consideration of available OR capacities and staff. In our setting, the need for radiological assistance for iCT scan execution but not for cone-beam CT imaging is a legal radiation protection issue because the surgeons in our group are only certified for execution of cone-beam CT, not conventional fan-beam CT imaging. Obviously, this may differ between regions and institutions, depending on the surgeon’s radiation protection qualification and local regulations, but it remains important to recognize that different types of legal qualification may be needed to independently run different types of imaging modalities. Therefore, it appears reasonable to assume that in their country and at their institutions, surgeons are trained and certified to run the imaging modalities by themselves, but this might not actually be the case at all institutions. Regardless of radiation protection regulations, decision-making should also take into account that the O-arm and AIRO are mobile devices that can be shared between separate ORs (the O-arm even while surgery is ongoing), whereas the Zeego is a permanently installed angiography robot and only available in one OR. This is highly relevant considering the competitive environment regarding the distribution of critical OR resources and, also, for treatment of spinal emergencies 24 hours a day, 7 days a week.36 In our experience, the concept of versatile surgical mobility with mobile navigation and imaging technology that can be used in multiple ORs helped to maximize our efficiency and take advantage of spontaneously available OR resources beyond our regularly available OR capacity.

Setup and workflow of the system were other factors that required an individually tailored approach during image acquisition and real-time spinal navigation. Mobile optical navigation platforms require a direct line of sight between the infrared navigation camera, navigation tracking device, and the gantry (iCT and CBCT) or C-arm (rCBCT) of the imaging modality to permit automatic patient/image coregistration. However, particularly in our iCT imaging setup, including rotation of the patient into the CT gantry, the line of sight during scanning is different from the line of sight during surgery, which hampers workflow because rotation of the OR table from the surgery into the scanning position requires continuous training of the OR team to facilitate table rotation and camera repositioning. Of course, iCT-based spinal navigation can also be performed with the patient already rotated into the gantry,6 but this was not possible in our OR due to constructional concerns regarding patient accessibility and microscope positioning. Regardless of the imaging modality, both optical-based navigation solutions that we used remained limited by the need for a continuous, clear line of sight from the infrared navigation tracking camera to the navigated instruments. This becomes particularly challenging in anatomical regions like the ilium, sacrum, craniocervical, or cervical-thoracic region, which require diverging and/or steep trajectories that often result in an obstructed line of sight and demand frequent manual camera repositioning by the surgeon or circulating staff.

Image Quality and Screw Assessment

A main finding in our study was that all modalities provided sufficiently high image quality for reliable screw assessment across the entire spine, including the subaxial cervical spine. The fact that image quality of iCT imaging was higher in areas of difficult radiographic visualization, obese patients, those with osteopenia, or in patients who had undergone previous cervical anterior titanium cage reconstruction, mirrors recent experience from others and our group;6,7,26 importantly, the image quality of second-generation CBCT and rCBCT scanners like O-arm and Zeego was much higher compared with the imaging quality of first-generation CBCT scanners that we previously reported on.23 Also, no perceived image quality difference was noted between CBCT and rCBCT, and successful screw revision was possible with all modalities. This is highly relevant because the acquisition and maintenance costs of a second-generation mobile CBCT like the O-arm are clearly lower (approximately $600,000) than those of a mobile AIRO iCT (approximately $1,200,000), and the cost benefits of using intraoperative imaging technology needs to be investigated over the long-term under the assumption that capital costs can be offset by reducing reoperation costs of secondary screw revision surgery.31,34,37 The fact that the rate of secondary screw revision surgeries did not differ among our groups underlines the urgent need for a detailed and region-specific cost-benefit analysis of intraoperative 3D imaging technology.

Accuracy

Cone-beam CT-based spinal navigation improves pedicle screw accuracy compared with nonnavigated techniques;16,18 so far, only one group has directly compared the accuracy of O-arm CBCT against AIRO iCT with comparable accuracy in the thoracolumbar spine26 and a lower accuracy of CBCT navigation in the cervical spine.38 Although we also noted greater (overall) accuracy of iCT-based compared with CBCT-based navigation in addition to a greater number of CBCT screws requiring revision in our study, final regional accuracy of iCT compared with CBCT and rCBCT was only greater in the thoracic spine, without difference in the cervical region. The following factors could have contributed to this discrepancy compared with previous studies. First, comparability between the two previously mentioned studies and ours may be limited by the fact that different grading systems were used to classify pedicle screw accuracy. Second, navigated cervical screws in the previous study also included lateral mass screws, whereas our study focused on CPSs. Third, the previously reported lower accuracy of CBCT for navigated CPS placement could be related to more imaging artifacts in patients with previous anterior titanium cage reconstruction, which also reflects our experience using first-generation CBCT technology.23 For this reason, patients who had undergone previous cervical titanium cage reconstruction that required additional CPS were preferably scheduled for iCT-based navigation (Fig. 4) because the larger x-ray beam and semicircular beam rotation of CBCT technology generates a larger amount of scatter radiation compared with fan-beam CT imaging.39,40 Despite this selection bias, however, our findings highlight that CPS placement with second-generation CBCT and rCBCT technology appears to be reliable and safe. Regardless, it must be acknowledged that many surgeons will not have access to all 3 technologies and that the regional location of surgery may also determine which technology is used or available.

FIG. 4.
FIG. 4.

Flowchart showing the current practice of selecting either iCT or CBCT or rCBCT imaging for spinal navigation based on anatomical considerations, imaging artifacts, availability of a certified radiologist, and the number of segments requiring posterior instrumentation.

Of course, the overall accuracy difference between iCT and CBCT imaging could also be due to the different navigation platforms that were used. However, in all patients, and regardless of the imaging technology or associated navigation platform, pedicle screw insertion was performed with the same navigation technique and by the same group of surgeons who were familiar with all 3 imaging and navigation modalities. Also, no accuracy difference was detected between O-arm CBCT and Zeego rCBCT imaging, despite their different navigation interfaces; this indicates that image quality likely represents the main reason for accuracy differences between imaging modalities.

Limitations

Despite these performance differences, a major limitation of our study is that individual radiation exposure was not assessed. Patient radiation exposure with 3D imaging remains controversial, given the exponential increase compared with standard fluoroscopy. However, this increase needs to be weighed against the benefit that all scanning procedures were executed without personnel inside the OR, so that radiation exposure for the OR team was essentially reduced to zero. Also, the effective dose of a single AIRO iCT scan per patient has been reported to range between 5.5 and 7.4 mSv (approximately 13–15 mSv per procedure including the first navigation and second screw placement control scan)6,26 and the AIRO iCT allows for graded radiation exposure settings that range between 25% and 75% of the typical radiation exposure of conventional CT, which can be omitted both pre- and postoperatively if only intraoperative 3D imaging is used for planning and screw assessment. For second-generation CBCT technology, radiation exposure similar to that of iCT and equivalent to approximately 19 mSv per spinal navigation procedure has been reported,26 which is less than the radiation dose of commonly used 64-multislice CT scanners.12,41

Furthermore, we only assessed intraoperative 3D imaging in the context of real-time spinal navigation for pedicle screw insertion using titanium implants. This is relevant, because intraoperative 3D imaging also offers the benefit of providing information on soft tissue, bone structure,42 and the underlying pathology, which in combination with augmented reality and machine learning applications can improve planning, execution, and judgement during spinal procedures.43–45 Additionally, carbon fiber–reinforced PEEK increases the quality of radiological follow-up and adjuvant irradiation planning through the reduction of imaging artifacts compared with standard titanium implants.46 Therefore, it remains to be determined how iCT, CBCT, and rCBCT perform in the context of spinal augmented reality applications and real-time navigation using new implant materials.

Conclusions

In this study, for the first time, we describe the setup and performance of navigated spinal instrumentation using iCT, CBCT, or rCBCT imaging within the same surgical environment. We have shown that each of these modalities is feasible for safe and precise navigated posterior instrumentation across the entire spine, and we currently follow the algorithm illustrated in Fig. 4 to determine the best-suited imaging modality based on anatomical considerations, imaging artifacts, length of instrumentation, and the availability of radiological assistance. Importantly, all imaging modalities permitted reliable implant control with the option of direct screw revision, and the rate of secondary screw revision surgeries did not differ among groups. Together, the benefit of a perceived higher image quality and a larger scan area of iCT needs to be weighed against the around-the-clock availability of CBCT and rCBCT with the option of completely independent handling of robotic imaging solutions.

Acknowledgments

Dr. Hecht is a Berlin Institute of Health Clinical Fellow, funded by Stiftung Charité.

Disclosures

The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.

Author Contributions

Conception and design: Hecht, Vajkoczy. Acquisition of data: Hecht, Kendlbacher, Tkatschenko, Bayerl, Bohner. Analysis and interpretation of data: Hecht, Kendlbacher, Tkatschenko, Czabanka, Woitzik. Drafting the article: Kendlbacher. Critically revising the article: Hecht, Czabanka, Bayerl, Bohner, Woitzik, Vajkoczy. Reviewed submitted version of manuscript: all authors. Approved the final version of the manuscript on behalf of all authors: Hecht. Statistical analysis: Hecht, Kendlbacher. Study supervision: Hecht.

Supplemental Information

Previous Presentations

Portions of this work were presented orally at the 14th Annual Meeting of the German Spine Society (DWG) in Munich, Germany, November 28–30, 2019.

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    • Export Citation
  • 6

    Navarro-Ramirez R, Lang G, Lian X, Berlin C, Janssen I, Jada A, et al. Total navigation in spine surgery; a concise guide to eliminate fluoroscopy using a portable intraoperative computed tomography 3-dimensional navigation system. World Neurosurg. 2017;100:325335.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 7

    Hecht N, Kamphuis M, Czabanka M, Hamm B, König S, Woitzik J, et al. Accuracy and workflow of navigated spinal instrumentation with the mobile AIRO® CT scanner. Eur Spine J. 2016;25(3):716723.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 8

    Cordemans V, Kaminski L, Banse X, Francq BG, Cartiaux O. Accuracy of a new intraoperative cone beam CT imaging technique (Artis zeego II) compared to postoperative CT scan for assessment of pedicle screws placement and breaches detection. Eur Spine J. 2017;26(11):29062916.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 9

    Scheufler KM, Franke J, Eckardt A, Dohmen H. Accuracy of image-guided pedicle screw placement using intraoperative computed tomography-based navigation with automated referencing, part I: cervicothoracic spine. Neurosurgery. 2011;69(4):782795.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 10

    Richter PH, Gebhard F, Dehner C, Scola A. Accuracy of computer-assisted iliosacral screw placement using a hybrid operating room. Injury. 2016;47(2):402407.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 11

    Tkatschenko D, Kendlbacher P, Czabanka M, Bohner G, Vajkoczy P, Hecht N. Navigated percutaneous versus open pedicle screw implantation using intraoperative CT and robotic cone-beam CT imaging. Eur Spine J. 2020;29(4):803812.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 12

    Oertel MF, Hobart J, Stein M, Schreiber V, Scharbrodt W. Clinical and methodological precision of spinal navigation assisted by 3D intraoperative O-arm radiographic imaging. J Neurosurg Spine. 2011;14(4):532536.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 13

    Czerny C, Eichler K, Croissant Y, Schulz B, Kronreif G, Schmidt R, et al. Combining C-arm CT with a new remote operated positioning and guidance system for guidance of minimally invasive spine interventions. J Neurointerv Surg. 2015;7(4):303308.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 14

    Ganguly R, Minnema A, Singh V, Grossbach A. Retrospective analysis of pedicle screw accuracy for patients undergoing spinal surgery assisted by intraoperative computed tomography (CT) scanner AIRO® and BrainLab© navigation. Clin Neurol Neurosurg. 2020;198:106113.

    • Search Google Scholar
    • Export Citation
  • 15

    Rajasekaran S, Bhushan M, Aiyer S, Kanna R, Shetty AP. Accuracy of pedicle screw insertion by AIRO® intraoperative CT in complex spinal deformity assessed by a new classification based on technical complexity of screw insertion. Eur Spine J. 2018;27(9):23392347.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 16

    Rivkin MA, Yocom SS. Thoracolumbar instrumentation with CT-guided navigation (O-arm) in 270 consecutive patients: accuracy rates and lessons learned. Neurosurg Focus. 2014;36(3):E7.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 17

    Verma SK, Singh PK, Agrawal D, Sinha S, Gupta D, Satyarthee GD, Sharma BS. O-arm with navigation versus C-arm: a review of screw placement over 3 years at a major trauma center. Br J Neurosurg. 2016;30(6):658661.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 18

    Silbermann J, Riese F, Allam Y, Reichert T, Koeppert H, Gutberlet M. Computer tomography assessment of pedicle screw placement in lumbar and sacral spine: comparison between free-hand and O-arm based navigation techniques. Eur Spine J. 2011;20(6):875881.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 19

    Cordemans V, Kaminski L, Banse X, Francq BG, Detrembleur C, Cartiaux O. Pedicle screw insertion accuracy in terms of breach and reposition using a new intraoperative cone beam computed tomography imaging technique and evaluation of the factors associated with these parameters of accuracy: a series of 695 screws. Eur Spine J. 2017;26(11):29172926.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 20

    Ryang YM, Villard J, Obermüller T, Friedrich B, Wolf P, Gempt J, et al. Learning curve of 3D fluoroscopy image-guided pedicle screw placement in the thoracolumbar spine. Spine J. 2015;15(3):467476.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 21

    Rahmathulla G, Nottmeier EW, Pirris SM, Deen HG, Pichelmann MA. Intraoperative image-guided spinal navigation: technical pitfalls and their avoidance. Neurosurg Focus. 2014;36(3):E3.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 22

    Härtl R, Lam KS, Wang J, Korge A, Kandziora F, Audigé L. Worldwide survey on the use of navigation in spine surgery. World Neurosurg. 2013;79(1):162172.

  • 23

    Hecht N, Yassin H, Czabanka M, Föhre B, Arden K, Liebig T, Vajkoczy P. Intraoperative computed tomography versus 3D C-arm imaging for navigated spinal instrumentation. Spine (Phila Pa 1976).2018;43(5):370377.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 24

    Gertzbein SD, Robbins SE. Accuracy of pedicular screw placement in vivo. Spine (Phila Pa 1976).1990;15(1):1114.

  • 25

    Rampersaud YR, Pik JHT, Salonen D, Farooq S. Clinical accuracy of fluoroscopic computer-assisted pedicle screw fixation: a CT analysis. Spine (Phila Pa 1976).2005;30(7):E183E190.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 26

    Scarone P, Vincenzo G, Distefano D, Del Grande F, Cianfoni A, Presilla S, Reinert M. Use of the Airo mobile intraoperative CT system versus the O-arm for transpedicular screw fixation in the thoracic and lumbar spine: a retrospective cohort study of 263 patients. J Neurosurg Spine. 2018;29(4):397406.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 27

    Shin BJ, James AR, Njoku IU, Härtl R. Pedicle screw navigation: a systematic review and meta-analysis of perforation risk for computer-navigated versus freehand insertion. J Neurosurg Spine. 2012;17(2):113122.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 28

    Villard J, Ryang YM, Demetriades AK, Reinke A, Behr M, Preuss A, et al. Radiation exposure to the surgeon and the patient during posterior lumbar spinal instrumentation: a prospective randomized comparison of navigated versus non-navigated freehand techniques. Spine (Phila Pa 1976).2014;39(13):10041009.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 29

    Pennington Z, Cottrill E, Westbroek EM, Goodwin ML, Lubelski D, Ahmed AK, Sciubba DM. Evaluation of surgeon and patient radiation exposure by imaging technology in patients undergoing thoracolumbar fusion: systematic review of the literature. Spine J. 2019;19(8):13971411.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 30

    Mendelsohn D, Strelzow J, Dea N, Ford NL, Batke J, Pennington A, et al. Patient and surgeon radiation exposure during spinal instrumentation using intraoperative computed tomography-based navigation. Spine J. 2016;16(3):343354.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 31

    Dea N, Fisher CG, Batke J, Strelzow J, Mendelsohn D, Paquette SJ, et al. Economic evaluation comparing intraoperative cone beam CT-based navigation and conventional fluoroscopy for the placement of spinal pedicle screws: a patient-level data cost-effectiveness analysis. Spine J. 2016;16(1):2331.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 32

    Xiao R, Miller JA, Sabharwal NC, Lubelski D, Alentado VJ, Healy AT, et al. Clinical outcomes following spinal fusion using an intraoperative computed tomographic 3D imaging system. J Neurosurg Spine. 2017;26(5):628637.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 33

    Hussain I, Cosar M, Kirnaz S, Schmidt FA, Wipplinger C, Wong T, Härtl R. Evolving navigation, robotics, and augmented reality in minimally invasive spine surgery. Global Spine J. 2020;10(2)(suppl):22S33S.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 34

    Malham GM, Wells-Quinn T. What should my hospital buy next?-Guidelines for the acquisition and application of imaging, navigation, and robotics for spine surgery. J Spine Surg. 2019;5(1):155165.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 35

    Czabanka M, Haemmerli J, Hecht N, Foehre B, Arden K, Liebig T, et al. Spinal navigation for posterior instrumentation of C1-2 instability using a mobile intraoperative CT scanner. J Neurosurg Spine. 2017;27(3):268275.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 36

    Hecht N, Wessels L, Werft FO, Schneider UC, Czabanka M, Vajkoczy P. Need for ensuring care for neuro-emergencies—lessons learned from the COVID-19 pandemic. Acta Neurochir (Wien). 2020;162(8):17951801.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 37

    Noriega DC, Hernández-Ramajo R, Rodríguez-Monsalve Milano F, Sanchez-Lite I, Toribio B, Ardura F, et al. Risk-benefit analysis of navigation techniques for vertebral transpedicular instrumentation: a prospective study. Spine J. 2017;17(1):7075.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 38

    Habib N, Filardo G, Distefano D, Candrian C, Reinert M, Scarone P. Use of intraoperative CT improves accuracy of spinal navigation during screw fixation in cervico-thoracic region. Spine (Phila Pa 1976).2021;46(8):530537.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 39

    Zhang J, Weir V, Fajardo L, Lin J, Hsiung H, Ritenour ER. Dosimetric characterization of a cone-beam O-arm imaging system. J XRay Sci Technol. 2009;17(4):305317.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 40

    Garayoa J, Castro P. A study on image quality provided by a kilovoltage cone-beam computed tomography. J Appl Clin Med Phys. 2013;14(1):3888.

  • 41

    Van de Kelft E, Costa F, Van der Planken D, Schils F. A prospective multicenter registry on the accuracy of pedicle screw placement in the thoracic, lumbar, and sacral levels with the use of the O-arm imaging system and StealthStation Navigation. Spine (Phila Pa 1976).2012;37(25):E1580E1587.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 42

    Knez D, Likar B, Pernus F, Vrtovec T. Computer-assisted screw size and insertion trajectory planning for pedicle screw placement surgery. IEEE Trans Med Imaging. 2016;35(6):14201430.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 43

    Elmi-Terander A, Burström G, Nachabe R, Skulason H, Pedersen K, Fagerlund M, et al. Pedicle screw placement using augmented reality surgical navigation with intraoperative 3d imaging: a first in-human prospective cohort Study. Spine (Phila Pa 1976).2019;44(7):517525.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 44

    Peh S, Chatterjea A, Pfarr J, Schäfer JP, Weuster M, Klüter T, et al. Accuracy of augmented reality surgical navigation for minimally invasive pedicle screw insertion in the thoracic and lumbar spine with a new tracking device. Spine J. 2020;20(4):629637.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 45

    Carl B, Bopp M, Saß B, Voellger B, Nimsky C. Implementation of augmented reality support in spine surgery. Eur Spine J. 2019;28(7):16971711.

  • 46

    Ringel F, Ryang YM, Kirschke JS, Müller BS, Wilkens JJ, Brodard J, et al. Radiolucent carbon fiber-reinforced pedicle screws for treatment of spinal tumors: advantages for radiation planning and follow-up imaging. World Neurosurg. 2017;105:294301.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • View in gallery

    Setup of iCT-, CBCT-, and rCBCT-based spinal navigation in the OR during surgery (A–C) and intraoperative image acquisition (D–F). The red arrows illustrate the required position change of the imaging device. For iCT- and CBCT-based imaging, the position change requires the assistance of circulating staff. In rCBCT-based imaging, the position change is performed by the surgeon alone using a draped control panel. In all cases, a clear line of sight (dashed gray line) from the tracking camera to the patient and intraoperative imaging device is required for automatic patient/image coregistration. A = anesthesiologist; C = navigation tracking camera; N = nurse; NAV = navigation unit; Resp = respirator; S = surgeon; T = OR tables.

  • View in gallery

    Transverse iCT (A), CBCT (B), and rCBCT (C) images obtained in patients undergoing lumbar fusion, illustrating the high image quality that permitted successful pedicle screw assessment in each case. Note that screw assessment is facilitated by adjusting an “inline” perspective along the axis of the screw (pink and blue lines on the CBCT image) instead of applying standard transverse views as shown in iCT and rCBCT images. R = right.

  • View in gallery

    Bar graphs showing the initial and final overall (A) and final regional (B) intraoperative screw placement accuracy following navigated pedicle screw implantation using iCT, CBCT, or rCBCT. Accuracy categories were defined as follows: A, completely within the pedicle; B, < 2-mm pedicle breach; C, 2- to 4-mm pedicle breach; and D, > 4-mm pedicle breach. Categories A and B are considered as accurate placement. *p < 0.01, **p < 0.001; two-sided Kruskal-Wallis test with the Dunn’s multiple comparison test.

  • View in gallery

    Flowchart showing the current practice of selecting either iCT or CBCT or rCBCT imaging for spinal navigation based on anatomical considerations, imaging artifacts, availability of a certified radiologist, and the number of segments requiring posterior instrumentation.

  • 1

    Richter M, Mattes T, Cakir B. Computer-assisted posterior instrumentation of the cervical and cervico-thoracic spine. Eur Spine J. 2004;13(1):5059.

  • 2

    Waschke A, Walter J, Duenisch P, Reichart R, Kalff R, Ewald C. CT-navigation versus fluoroscopy-guided placement of pedicle screws at the thoracolumbar spine: single center experience of 4,500 screws. Eur Spine J. 2013;22(3):654660.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 3

    Zausinger S, Scheder B, Uhl E, Heigl T, Morhard D, Tonn JC. Intraoperative computed tomography with integrated navigation system in spinal stabilizations. Spine (Phila Pa 1976).2009;34(26):29192926.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 4

    Tormenti MJ, Kostov DB, Gardner PA, Kanter AS, Spiro RM, Okonkwo DO. Intraoperative computed tomography image-guided navigation for posterior thoracolumbar spinal instrumentation in spinal deformity surgery. Neurosurg Focus. 2010;28(3):E11.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 5

    Lian X, Navarro-Ramirez R, Berlin C, Jada A, Moriguchi Y, Zhang Q, Härtl R. Total 3D Airo® navigation for minimally invasive transforaminal lumbar interbody fusion. BioMed Res Int. 2016;2016:5027340.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 6

    Navarro-Ramirez R, Lang G, Lian X, Berlin C, Janssen I, Jada A, et al. Total navigation in spine surgery; a concise guide to eliminate fluoroscopy using a portable intraoperative computed tomography 3-dimensional navigation system. World Neurosurg. 2017;100:325335.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 7

    Hecht N, Kamphuis M, Czabanka M, Hamm B, König S, Woitzik J, et al. Accuracy and workflow of navigated spinal instrumentation with the mobile AIRO® CT scanner. Eur Spine J. 2016;25(3):716723.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 8

    Cordemans V, Kaminski L, Banse X, Francq BG, Cartiaux O. Accuracy of a new intraoperative cone beam CT imaging technique (Artis zeego II) compared to postoperative CT scan for assessment of pedicle screws placement and breaches detection. Eur Spine J. 2017;26(11):29062916.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 9

    Scheufler KM, Franke J, Eckardt A, Dohmen H. Accuracy of image-guided pedicle screw placement using intraoperative computed tomography-based navigation with automated referencing, part I: cervicothoracic spine. Neurosurgery. 2011;69(4):782795.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 10

    Richter PH, Gebhard F, Dehner C, Scola A. Accuracy of computer-assisted iliosacral screw placement using a hybrid operating room. Injury. 2016;47(2):402407.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 11

    Tkatschenko D, Kendlbacher P, Czabanka M, Bohner G, Vajkoczy P, Hecht N. Navigated percutaneous versus open pedicle screw implantation using intraoperative CT and robotic cone-beam CT imaging. Eur Spine J. 2020;29(4):803812.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 12

    Oertel MF, Hobart J, Stein M, Schreiber V, Scharbrodt W. Clinical and methodological precision of spinal navigation assisted by 3D intraoperative O-arm radiographic imaging. J Neurosurg Spine. 2011;14(4):532536.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 13

    Czerny C, Eichler K, Croissant Y, Schulz B, Kronreif G, Schmidt R, et al. Combining C-arm CT with a new remote operated positioning and guidance system for guidance of minimally invasive spine interventions. J Neurointerv Surg. 2015;7(4):303308.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 14

    Ganguly R, Minnema A, Singh V, Grossbach A. Retrospective analysis of pedicle screw accuracy for patients undergoing spinal surgery assisted by intraoperative computed tomography (CT) scanner AIRO® and BrainLab© navigation. Clin Neurol Neurosurg. 2020;198:106113.

    • Search Google Scholar
    • Export Citation
  • 15

    Rajasekaran S, Bhushan M, Aiyer S, Kanna R, Shetty AP. Accuracy of pedicle screw insertion by AIRO® intraoperative CT in complex spinal deformity assessed by a new classification based on technical complexity of screw insertion. Eur Spine J. 2018;27(9):23392347.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 16

    Rivkin MA, Yocom SS. Thoracolumbar instrumentation with CT-guided navigation (O-arm) in 270 consecutive patients: accuracy rates and lessons learned. Neurosurg Focus. 2014;36(3):E7.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 17

    Verma SK, Singh PK, Agrawal D, Sinha S, Gupta D, Satyarthee GD, Sharma BS. O-arm with navigation versus C-arm: a review of screw placement over 3 years at a major trauma center. Br J Neurosurg. 2016;30(6):658661.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 18

    Silbermann J, Riese F, Allam Y, Reichert T, Koeppert H, Gutberlet M. Computer tomography assessment of pedicle screw placement in lumbar and sacral spine: comparison between free-hand and O-arm based navigation techniques. Eur Spine J. 2011;20(6):875881.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 19

    Cordemans V, Kaminski L, Banse X, Francq BG, Detrembleur C, Cartiaux O. Pedicle screw insertion accuracy in terms of breach and reposition using a new intraoperative cone beam computed tomography imaging technique and evaluation of the factors associated with these parameters of accuracy: a series of 695 screws. Eur Spine J. 2017;26(11):29172926.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 20

    Ryang YM, Villard J, Obermüller T, Friedrich B, Wolf P, Gempt J, et al. Learning curve of 3D fluoroscopy image-guided pedicle screw placement in the thoracolumbar spine. Spine J. 2015;15(3):467476.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 21

    Rahmathulla G, Nottmeier EW, Pirris SM, Deen HG, Pichelmann MA. Intraoperative image-guided spinal navigation: technical pitfalls and their avoidance. Neurosurg Focus. 2014;36(3):E3.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 22

    Härtl R, Lam KS, Wang J, Korge A, Kandziora F, Audigé L. Worldwide survey on the use of navigation in spine surgery. World Neurosurg. 2013;79(1):162172.

  • 23

    Hecht N, Yassin H, Czabanka M, Föhre B, Arden K, Liebig T, Vajkoczy P. Intraoperative computed tomography versus 3D C-arm imaging for navigated spinal instrumentation. Spine (Phila Pa 1976).2018;43(5):370377.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 24

    Gertzbein SD, Robbins SE. Accuracy of pedicular screw placement in vivo. Spine (Phila Pa 1976).1990;15(1):1114.

  • 25

    Rampersaud YR, Pik JHT, Salonen D, Farooq S. Clinical accuracy of fluoroscopic computer-assisted pedicle screw fixation: a CT analysis. Spine (Phila Pa 1976).2005;30(7):E183E190.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 26

    Scarone P, Vincenzo G, Distefano D, Del Grande F, Cianfoni A, Presilla S, Reinert M. Use of the Airo mobile intraoperative CT system versus the O-arm for transpedicular screw fixation in the thoracic and lumbar spine: a retrospective cohort study of 263 patients. J Neurosurg Spine. 2018;29(4):397406.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 27

    Shin BJ, James AR, Njoku IU, Härtl R. Pedicle screw navigation: a systematic review and meta-analysis of perforation risk for computer-navigated versus freehand insertion. J Neurosurg Spine. 2012;17(2):113122.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 28

    Villard J, Ryang YM, Demetriades AK, Reinke A, Behr M, Preuss A, et al. Radiation exposure to the surgeon and the patient during posterior lumbar spinal instrumentation: a prospective randomized comparison of navigated versus non-navigated freehand techniques. Spine (Phila Pa 1976).2014;39(13):10041009.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 29

    Pennington Z, Cottrill E, Westbroek EM, Goodwin ML, Lubelski D, Ahmed AK, Sciubba DM. Evaluation of surgeon and patient radiation exposure by imaging technology in patients undergoing thoracolumbar fusion: systematic review of the literature. Spine J. 2019;19(8):13971411.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 30

    Mendelsohn D, Strelzow J, Dea N, Ford NL, Batke J, Pennington A, et al. Patient and surgeon radiation exposure during spinal instrumentation using intraoperative computed tomography-based navigation. Spine J. 2016;16(3):343354.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 31

    Dea N, Fisher CG, Batke J, Strelzow J, Mendelsohn D, Paquette SJ, et al. Economic evaluation comparing intraoperative cone beam CT-based navigation and conventional fluoroscopy for the placement of spinal pedicle screws: a patient-level data cost-effectiveness analysis. Spine J. 2016;16(1):2331.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 32

    Xiao R, Miller JA, Sabharwal NC, Lubelski D, Alentado VJ, Healy AT, et al. Clinical outcomes following spinal fusion using an intraoperative computed tomographic 3D imaging system. J Neurosurg Spine. 2017;26(5):628637.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 33

    Hussain I, Cosar M, Kirnaz S, Schmidt FA, Wipplinger C, Wong T, Härtl R. Evolving navigation, robotics, and augmented reality in minimally invasive spine surgery. Global Spine J. 2020;10(2)(suppl):22S33S.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 34

    Malham GM, Wells-Quinn T. What should my hospital buy next?-Guidelines for the acquisition and application of imaging, navigation, and robotics for spine surgery. J Spine Surg. 2019;5(1):155165.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 35

    Czabanka M, Haemmerli J, Hecht N, Foehre B, Arden K, Liebig T, et al. Spinal navigation for posterior instrumentation of C1-2 instability using a mobile intraoperative CT scanner. J Neurosurg Spine. 2017;27(3):268275.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 36

    Hecht N, Wessels L, Werft FO, Schneider UC, Czabanka M, Vajkoczy P. Need for ensuring care for neuro-emergencies—lessons learned from the COVID-19 pandemic. Acta Neurochir (Wien). 2020;162(8):17951801.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 37

    Noriega DC, Hernández-Ramajo R, Rodríguez-Monsalve Milano F, Sanchez-Lite I, Toribio B, Ardura F, et al. Risk-benefit analysis of navigation techniques for vertebral transpedicular instrumentation: a prospective study. Spine J. 2017;17(1):7075.

    • Crossref
    • PubMed
    • Search Google Scholar
    • Export Citation
  • 38

    Habib N, Filardo G, Distefano D, Candrian C, Reinert M, Scarone P. Use of intraoperative CT improves accuracy of spinal navigation during screw fixation in cervico-thoracic region. Spine (Phila Pa 1976).2021;46(8):530537.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 39

    Zhang J, Weir V, Fajardo L, Lin J, Hsiung H, Ritenour ER. Dosimetric characterization of a cone-beam O-arm imaging system. J XRay Sci Technol. 2009;17(4):305317.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 40

    Garayoa J, Castro P. A study on image quality provided by a kilovoltage cone-beam computed tomography. J Appl Clin Med Phys. 2013;14(1):3888.

  • 41

    Van de Kelft E, Costa F, Van der Planken D, Schils F. A prospective multicenter registry on the accuracy of pedicle screw placement in the thoracic, lumbar, and sacral levels with the use of the O-arm imaging system and StealthStation Navigation. Spine (Phila Pa 1976).2012;37(25):E1580E1587.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 42

    Knez D, Likar B, Pernus F, Vrtovec T. Computer-assisted screw size and insertion trajectory planning for pedicle screw placement surgery. IEEE Trans Med Imaging. 2016;35(6):14201430.

    • Crossref
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