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00007632-200912150-0001500007632_2009_34_2919_zausinger_intraoperative_26article< 103_0_16_6 >Spine© 2009 Lippincott Williams & Wilkins, Inc.Volume 34(26)15 December 2009pp 2919-2926Intraoperative Computed Tomography With Integrated Navigation System in Spinal Stabilizations[Technique]Zausinger, Stefan MD*; Scheder, Ben MD*; Uhl, Eberhard MD*; Heigl, Thomas RN*; Morhard, Dominik MD†; Tonn, Joerg-Christian MD*From the *Department of Neurosurgery, and †Institute of Clinical Radiology, Klinikum Grosshadern, Ludwig-Maximilians-University, Munich, Germany.Acknowledgment date: February 3, 2009. Revision date: April 30, 2009. Acceptance date: May 4, 2009.The device(s)/drug(s) is/are FDA-approved or approved by corresponding national agency for this indication.No funds were received in support of this work. No benefits in any form have been or will be received from a commercial party related directly or indirectly to the subject of this manuscript.Supported by BrainLAB, Feldkirchen, Germany and Siemens Healthcare, Forchheim, Germany and Trumpf, Puchheim, Germany.Address correspondence and reprint requests to Stefan Zausinger, MD, Department of Neurosurgery, Ludwig-Maximilians-Universität, Klinikum Grosshadern, Marchioninistr 15, 81377 Munich, Germany; E-mail: Stefan.Zausinger@med.uni-muenchen.deAbstractStudy Design. A prospective interventional case-series study plus a retrospective analysis of historical patients for comparison of data.Objective. To evaluate workflow, feasibility, and clinical outcome of navigated stabilization procedures with data acquisition by intraoperative computed tomography.Summary of Background Data. Routine fluoroscopy to assess pedicle screw placement is not consistently reliable. Our hypothesis was that image-guided spinal navigation using an intraoperative CT-scanner can improve the safety and precision of spinal stabilization surgery.Methods. CT data of 94 patients (thoracolumbar [n = 66], C1/2 [n = 12], cervicothoracic instability [n = 16]) were acquired after positioning the patient in the final surgical position. A sliding gantry 40-slice CT was used for image acquisition. Data were imported to a frameless infrared-based neuronavigation workstation. Intraoperative CT was obtained to assess the accuracy of instrumentation and, if necessary, the extent of decompression. All patients were clinically evaluated by Odom-criteria after surgery and after 3 months.Results. Computed accuracy of the navigation system reached <2 mm (0.95 ± 0.3 mm) in all cases. Additional time necessary for the preoperative image acquisition including data transfer was 14 ± 5 minutes. The duration of interrupting the surgical process for iCT until resumption of surgery was 9 ± 2.5 minutes. Control-iCT revealed incorrect screw position ≥2 mm without persistent neurologic or vascular damage in 20/414 screws (4.8%) leading to immediate correction of 10 screws (2.4%). Control-iCT changed the course of surgery in 8 cases (8.5% of all patients). The overall revision rate was 8.5% (4 wound revisions, 2 CSF fistulas, and 2 epidural hematomas). There was no reoperation due to implant malposition. According to Odom-criteria all patients experienced a clinical improvement. A retrospective analysis of 182 patients with navigated thoracolumbar transpedicular stabilizations in the preiCT era revealed an overall revision rate of 10.4% with 4.4% of patients requiring screw revision.Conclusion. Intraoperative CT in combination with neuronavigation provides high accuracy of screw placement and thus safety for patients undergoing spinal stabilization. Reoperations due to implant malpositions could be completely avoided. The system can be installed into a pre-existing operating environment without need for special surgical instruments. The procedure is rapid and easy to perform without restricted access to the patient and—by replacing pre- and postoperative imaging—is not associated with an additional exposure to radiation. Multidisciplinary use increases utilization of the system and thus improves cost-efficiency relation.With increased utilization of spinal instrumentation, it was seen that routine radiography to assess pedicle screw placement is not consistently reliable. According to a recently published meta-analysis,1 the rate of penetration of the pedicle cortex by an inserted screw without the use of navigation amounted to nearly 10%. With the use of spinal navigation, the rate of screw misplacement is considerably improved, but still was 4.8%. In image-guided surgery case, positions of surgical instruments are superimposed onto intraoperatively acquired fluoroscopic images or—more often—preoperatively acquired computed tomography scans.2 However, navigation based on preoperatively acquired CT images inherits the problem of a change in intersegmental anatomy following final positioning for surgery. The combination of an intraoperative CT (iCT) scanner with a neuronavigation system not only permits the intraoperative control of the extent of decompression, resection of tumors, and detection of complications, but also the generation and update of the neuronavigation data set. Therefore, incorporation of iCT seems to also be useful in spinal navigation procedures, especially in cases with traumatic or degenerative luxation, or listhesis requiring surgical repositioning on the OR table.Our hypothesis was that image-guided spinal navigation using an intraoperative CT scanner can improve the safety and accuracy of spinal stabilization surgery. The aim of this study was to evaluate prospectively clinical outcome, feasibility, and workflow of navigated stabilization procedures in spinal surgery with iCT data acquisition before or during the operative procedure, and iCT-control of implant position. Furthermore, a retrospective analysis of 182 patients with navigated thoracolumbar stabilizations in the preiCT era was performed for the purpose of comparing of rates of screw malposition and incidence of revision operations.Materials and MethodsPatientsFrom February 2006 to September 2008 iCT data of 94 patients (63 female, 31 male; mean age: 61.5 ± 13.4 years (mean ± standard deviation SD); range: 19 to 85 years; 66 patients with thoracolumbar instability, 16 patients with cervicothoracic instability, 12 patients with C1/2 instability, follow-up: 7.9 months, range: 2–29 months) were acquired.Imaging ProceduresAll patients had given their informed consent to perform iCT examinations. Patients were rested in the final prone surgical position after correction of malalignment by positioning on a radiolucent adjustable flexible and rotating operating table (Jupiter, Trumpf, Puchheim, Germany). The table permits movement to a stored scanning position and then back to the operating position at any time during surgery. Either a carbon-made head plate or, if necessary for cervical stabilizations, a carbon-made radiolucent Mayfield head clamp (OMI Inc., Cincinnati, OH) was used as a headrest. A sliding gantry 40-slice CT scanner (Somatom Sensation Open, Siemens Healthcare, Forchheim, Germany) with an expanded gantry bore (82 cm) was used for image acquisition. During image acquisition the gantry moves over the patient, with the position of the catheters and ventilation tube remaining stable during the scanning procedure. (Schematic drawing and images of the OR in Figures 1, 2) Pre- and intraoperative imaging were performed using a collimation of 24 × 1.2 mm at 120 kV, 240 mAs, pitch 0.9, and a rotation time of 1 second, using automated dose-modulation software. Multiplanar reconstructions with a slice thickness and increment of 3 mm were calculated in axial and sagittal orientations. Data were imported to a frameless infrared-based neuronavigation station (Vector Vision Sky, BrainLAB, Feldkirchen, Germany). An intraoperative CT was obtained to assess the extent of decompression and the accuracy of instrumentation. All screws were evaluated on multi planar reconstructions and rated on the basis of the 2 mm increment classification suggested by Gertzbein and Robbins.3Figure 1. Left: schematic drawing of intraoperative setup during surgery. Right drawing: situation during intraoperative CT scan. A indicates anesthesia; S, surgeon; SN, scrub nurse, navigation system consisting of roof-based camera and monitor.Figure 2. Left: image-guided operating suite with radiolucent OR table, CT-scanner with sliding gantry and roof-based monitor and cameras. Right: preoperative safety check. The gantry is provided with an expanded bore. The scanning position of the table is digitally stored to enable intraoperative control-CTs without the danger of collision of the gantry with the patient or the table.Assessment of Surgical Work Flow and OutcomeOnce the instrumentation has been placed, confirmation by a second intraoperative CT scan was obtained and, if necessary, correction of screw position was achieved. The times required for preoperative scanning (navigation CT, safety checkup, data transfer), intraoperative scanning (sterile draping, scan, resumption of surgery), and for navigated screw placement (surgical exposure, navigated screw placement, iCT control) for each procedure were documented. The times for additional necessary fluoroscopy were noted. Change of surgery based on intraoperative imaging was documented for each procedure.All patients were clinically evaluated by Odom et al criteria4 and concerning neurologic deficits after surgery and after 3 months. Furthermore, all complications during the follow-up period, attributable to the operation, and number and cause of reoperations were noted.Additionally, in a retrospective analysis of 182 CT-navigated thoracolumbar stabilization procedures including a total of 781 pedicle screws with preoperative image acquisition and without intraoperative control-CT performed in our institution between January 1999 and January 2006, were examined and compared with the current prospective series concerning the rate of reoperations due to screw revisions and surgery related complications.ResultsSuccessful import of image data suitable for navigation was attained for all cases. Registration revealed computed accuracy <2 mm (0.95 ± 0.3 mm) in all cases, while anatomic and fluoroscopic landmark control showed sufficient accuracy even in cases of up to 5 vertebral bodies below the initially registered vertebral body. Patient characteristics and distribution of dorsal stabilization surgery are shown in Table 1.Table 1. Patient Characteristics and Distribution of Dorsal Stabilization Surgery and Number of Screws (s)Time needed for preoperative image acquisition including safety checkup and data transfer was 14 ± 5 minutes. The time-out for intraoperative scanning until continuation of surgery was 9 ± 2.5 minutes ranging from 4 to 15 minutes. Time needed for the stabilization procedure (surgical exposure, registration of the spine, screw-placement, and intraoperative control-iCT) was 83.1 ± 22.4 minutes (2 screws) for transarticular C 1/2, 77.2 ± 24.1 minute for lumbar (4 screws), and 102.7 ± 25.0 minutes (8 screws) for thoracic transpedicular screw placement.In 94 surgical procedures, an overall of 216 CT scans (100 preoperative, 116 intraoperative) were obtained resulting in 2.3 scans per case. Two scans were carried out in 70 patients, 3 in 20 and 4 scans in 4 patients. With an average time for scanning of 7.0 ± 1.8 seconds per scan, no discontinuation of ventilation was necessary. The average length of additional intraoperative fluoroscopy per patient was 98 ± 77 seconds, and 70 ± 41 seconds for lumbar single-level stabilizations (including cage-positioning).Control-iCT revealed incorrect screw position ≥2 mm with violation of the pedicle cortex in 20/414 screws (4.8%). There were 10 medial (50%), 5 lateral (25%), 4 caudal (20%), and 1 (5%) ventral misplacements. In 65/414 of the screws (15.7%), we detected a minor pedicle perforation <2 mm. In 75% of those screws, the diameter of the perforation was equal or under the distance of the screw thread (≤1 mm). Due to the small pedicle configurations the highest rate of cortical breaches was seen in the mid thoracic region (T5–T8) with 27.5% (14/51 screws). In 4 of those screws the perforation was ≥2 mm. In the whole series, there was no evidence for blow out fractures of the pedicle. Pedicle screw position and analysis of screw malpositions are shown in Tables 2 and 3.Table 2. Pedicle Screw Position and Extent of Cortical Violation After First iCT ControlTable 3. Analysis of Screws With Pedicle Cortical Violations ≥2 mmIntraoperative control imaging changed the course of surgery in 8 cases (8.5% of all patients) with immediate correction of 10 screws (2.4%) without any persistent damage to nerves or vessels. The remaining 10 screws showing pedicle wall violation over 2 mm were classified sufficient regarding stability and position towards endangered anatomic structures. In addition, in case of patients with tumorous disease, the extent of tumor resection could be confirmed. The overall reoperation rate was 8.5% (4 wound infections, 2 CSF fistulas, and 2 epidural hematomas). Two patients with postoperative wound infections and revision surgery had been operated months before due to removal and local radiotherapy of a spinal metastasis with subsequent secondary instability. Both patients had impaired wound healing after tumor surgery and atrophic skin before the stabilization. Another patient with wound infection after stabilization L5–S1 suffered from insulin-dependent diabetes. There was no reoperation due to implant malposition. There was no collision of the patient and the scanner or any new neurologic deficit related to the intraoperative scanning.There were 2 transient neurologic complications with normalization of the deficits within 3 months after the operation. One patient with temporary paresis of the L5 root, concomitant muscle weakness, and disturbance of sensitivity, and one female patient with C1/2 instability due to rheumatoid arthritis with a very thin isthmus of C2, only minimally thicker than the screw, with dissection and thrombosis of the vertebral artery and temporary right-sided dysmetria and vertigo, who recovered completely. Altogether, on the average all patients experienced a global clinical improvement after the stabilization procedure (Odom after 1 week 2.6 ± 0.6–1.9 ± 0.7 after 3 months).The retrospective analysis of 182 patients with navigated thoracolumbar transpedicular screw-placement (781 pedicle screws) in the preiCT era revealed an overall revision rate of 10.4% with 4.4% of the patients requiring screw revision due to implant malposition (Table 4). The average time interval between stabilization and screw revision surgery was 52.6 days, ranging from 1 to 225 days.Table 4. Rates of Screw Malposition and Incidence of Revision Operations of a Retrospective Analysis of Navigated Stabilizations Without Intraoperative CT and of the Present Series (Navigated Stabilizations With Intraoperative CT)Discussion and ConclusionIt was shown that image-guided spinal instrumentation procedures in the cervical, thoracic, and lumbar spine have lower rates of screw misplacement than do those performed without image guidance.1,2 In the present study, we could show that intraoperative CT in combination with neuronavigation provides high accuracy of screw placement and thus safety for patients undergoing spinal stabilization. The procedure is rapid and easy to perform and—by replacing pre- and postoperative imaging—is not associated with additional exposure to radiation.FluoroscopyThe standard intraoperative visualizing system in spine surgery is fluoroscopy by C-arm. However, despite its longstanding and widespread use there are still several disadvantages in daily routine especially under more difficult conditions such as adipositas, scoliosis or instrumentations of the cervicothoracic region. Because conventional fluoroscopy is generally limited by 2-dimensional imaging, techniques have been developed to enable fluoroscopic scanning software to produce 3-dimensional images to identify inadvertent fracture malreductions or implant malpositions which may be overlooked by routine C-arm fluoroscopy. In its most advanced variation, fluoroscopy enables axial cuts and 2- or 3-dimensional reconstructions to be generated that can be combined with navigation.5 Generally, several authors stated that ISO-C-3-dimensional adds little operative time to the procedure and enables the surgeon to evaluate the extent of bony decompression and placement of cages, plates, and screws intraoperatively, possibly precluding the need for postoperative CT scans in selected cases.6–8 Restrictions are based on the limited length of the scan volume which leads to several scans in multilevel interventions. Furthermore, restricted imaging quality in comparison to high-definition CT has to be considered,9,10 especially in case of very fine anatomic structures, obese patients, or complex instrumentation. Therefore, several authors still use postoperative CT for final assessment of the instrumentation.11,12 Finally, even 3-dimensional fluoroscopy does not offer the possibility of display of soft tissue, e.g., for illustration of presumed intraspinal hematoma, tumor remnants, or violation of paraspinal organs.Intraoperative Computed TomographyIntraoperative computed tomography was introduced into neurosurgery in the early 80's,13–17 predominantly for resection control of brain tumors or combining CT scans with a stereotactic system for brain biopsies. Up to now this technology has not reached great acceptance in the neurosurgical community because of limited image quality, comprehensive time-consuming modifications of the intraoperative work flow and the limited slice orientation with the lack of reconstructive software. Furthermore, the gantry aperture was cramped, in many settings not mobile and the patient had to be placed on the ordinary table of the scanner thus limiting positioning of the patient and space for the surgical team and devices. However, the conventional procedure with a sliding table also has a major impact on anesthesia management. During the procedure the patient is moved extensively with danger of tube or catheter dislocation and limited patient access. Furthermore, there is inadequate separation between operating field and anesthetic area.18In our case, a CT scanner with a sliding gantry concept was installed within a preexisting operating room. The spatial resolution in z-axis of the system of 0.4 to 0.6 mm corresponds to usual modern nonmovable scanners. During image acquisition the gantry moves over the patient on a fixed carbon-made OR-table, avoiding any danger of dislocation of catheters or of the ventilation tube during the scanning procedure due to table movements. The gantry is provided with an expanded bore to allow scanning of obese patients, patients positioned on pillows or frames or patients with a mounted radiolucent skull clamp, e.g., for C1/2 fusion procedures. All areas of the body can be scanned, thus making the system useful for numerous surgical subspecialties which improve the cost benefit ratio. Positioning of the patients remains as usual and the surgical work flow is basically unchanged. There is no need for special surgical instruments or for dedicated anesthesiological devices. The scanning position of the table is digitally stored after a preoperative safety-check to enable intraoperative control CTs without the danger of collision of the gantry with the patient or the table, even under impaired visual control due to the draped patient and table. With this concept, we had no case of collision or tube dislocation due to the scanning procedure in the present series. A large working space between the mobile CT gantry and the operating table allows the regular use of an operating microscope. Electrophysiological monitoring is not altered by the scanner nor does it interfere with the image acquisition.iCT and Spinal NavigationImage-guided spinal instrumentation procedures in the cervical, thoracic, and lumbar spine have lower rates of screw misplacement compared to those performed without image guidance.1 However, registration of conventionally generated preoperative images for navigation leaves a substantial risk of inaccurate screw placement due to the patient being in the prone position during surgery, although they were in the supine position during data acquisition. Our setup with a scanner in the OR allows imaging data being acquired after correction of instable segments or fragments and final prone positioning of the patient without further changes of the intervertebral relations. This is advantageous especially in case of spondylolisthesis or an unstable upper cervical spine injury where the likelihood of change in the intersegmental relationship is at a maximum before and after positioning on the OR table. The constant relation between images and the actual intersegmental position of the vertebrae is especially advantageous in case of a previously laminectomized patient with very limited bony areas for the registration procedure. In addition, an intraoperative update at any time during surgery based on an intraoperatively acquired CT imaging date set, e.g., for control of screw position, can be used for successful recalibration of neuronavigation, accounting for any anatomic changes caused by surgical manipulations.Considering the large variation of methods reported to identify screw placement accuracy, we decided to use the classic 2 mm increment method, initially presented by Gertzbein and Robbins.3 Clinical sequelae of screw misplacement can be derived quite safely since deviations <4 mm are considered as tolerable usually not being associated with relevant neural or vascular lesions.3,19 Accuracy reached in the present study for transarticular C1/2 screws was 95.8%, which is comparable to other studies about the use of neuronavigation.20,21 In a meta-analysis1 a mean screw accuracy of only 91.3% was found without neuronavigation, which underlines the advantage of this method in this highly sensitive region. Especially screw placement in the thoracic spine can be extremely challenging and restrictions have to be made using conventional 2D radiograph projections by C-arm. The intraoperative usage of a CT allows additional gain of information during surgery, e.g., concerning intraspinal or intrathoracic hematoma. Kosmopoulos and Schizas1 revealed a median accuracy of 94.3% with the use of neuronavigation. Our rate of 5.6% screw malpositions in the thoracic spine compares favorably with the literature. In this context, it has to be mentioned that most of our patients suffered from a local destructive tumor which often involved the dorsal structures as lamina and spinous processes, and other patients had already been laminectomized in previous operations with subsequent development of instability. In both scenarios, the area that could be used for the registration procedure was reduced. For lumbar pedicle screw fixation noncortical breach rates of 79.0% of non-navigated and up to 96.1% of image-based screw fixations (95.2% in the current study) are reported.1 Despite residual malplaced screws, the revision rate due to implant malposition was 0% as a sequel of immediate intraoperative control and correction. Intraoperative control imaging changed the course of surgery in 8 of 94 cases with immediate correction of 10 screws. In conclusion, we found that having the option of making an intraoperative quality check at any time leads to significantly increased efficiency.Comparing our results with other groups using iCT and spinal navigation is difficult since intraoperative CT scanners so far have only been installed in a few hospitals and respective studies are rare:Haberland et al22 reported on the first successful incorporation of iCT in spinal navigation procedures. A total of 161 pedicle screws have been inserted in 35 patients without severe misplacements. The authors concluded that the combination of iCT and spinal navigation allows a high application accuracy. Ebmeier et al23 further published results on accuracy of iCT with spinal navigation in pedicle screw placement of the thoracic spine. About 112 patients have been operated and 365 screws were inserted. There were 23 (6.3%) misplacements of pedicle screws and 42 cases (11.5%) with a minimal lateral perforation (<2 mm) of the pedicle wall. No neurologic, cardiovascular, or pulmonary injury occurred.Freidberg et al24 used iCT to improve the accuracy in case of inadequate bony removal during anterior spinal surgery by broaden the extend of decompression. Nineteen patients underwent cervical corpectomy and 12 discectomy. Of the 31 patients, assessment of iCT scans obtained in 17 indicated further bone removal was required.Therefore, from the present literature and our results it can be concluded that iCT-based generation of image date for spinal navigation and image monitoring are considered a useful surgical aid with the chance of immediate change of the surgical strategy.Scanning Time and Radiation ExposureAdditional time necessary for the preoperative image acquisition including data transfer was 14 ± 5 minutes and surgery time-out for iCT until resumption of surgery was not longer than 9 ± 2.5 minutes, which is comparable to imaging times needed with ISO-C-3-dimensional or fluoroscopy under difficult conditions. Before the intraoperative scanning procedure there is no necessity of moving bulky equipment and the draping of the patient can be easily and quickly performed with one large drape. Furthermore, scanning position of the operating table and definition of the area to be scanned is already determined before control-iCT. As a consequence, the scanning procedure itself is very quick and easy. However, to reach these very limited periods of interruption, a clear workflow has to be established and a special training of the OR personnel is required. Wendl et al25 recorded 111 minutes for navigated lumbar stabilizations with preoperatively acquired CT data, and 105 minutes for the conventional fluoroscopic approach. In this context, we favorably compare with 96 ± 39 minutes including control-iCT. Respective data for radiation time due to intraoperative fluoroscopy are very rare. Villavicencio et al12 quote an average of 93 seconds of biplanar fluoroscopy in Iso-C-3-dimensional navigated 1-level TLIF procedures. In our series, fluoro time required for the same operation was 70 seconds on average. The main reason for this is that it was not necessary to perform intraoperative time-demanding a.p. or screw-orthograde fluoroscopic imaging in any of the cases. Altogether, the time span for scanning was greatly compensated by fast and accurate screw placement due to excellent image data and consequently a reduced necessity for additional fluoroscopic control.It has been stated that percutaneous pedicle screw insertion in the lumbar region of the spine, performed using fluoroscopic control, requires a lower radiation dose compared to CT-guided navigation.26 However, CT-data based navigated screw placement has evolved to become a standard procedure to improve accuracy of surgery and to avoid resurgery, especially under difficult anatomic conditions.2 Since pre-OP scanning outside the OR is no longer necessary with the new setup, no additional exposure to radiation evolves from the fact that image data for navigation are generated in the OR. Second, the intraoperative control-CT completely replaces the usual and recommended control-imaging of screw position. In addition, the new generation high-end scanner, like the one in our system, uses less radiation than previous technologies due to e.g., 4D dose modulation (respectively tube-current-modulation) and filtering. This ensures that the amount of radiation exposure to the patient is comparable to standard scanners with a comparable bore size.Analysis of Navigated Stabilizations in PreiCT-Era and Clinical OutcomeIn the current series all patients experienced a global clinical improvement after the stabilization procedure. Odom-score after 1 week improved from 2.6 ± 0.6 (Grade III: sufficient—subjective improvement, significant impairment of physical activities) to 1.9 ± 0.7 (Grade II: good—intermittent complaints, no impairment concerning daily work) after 3 months. A retrospective analysis of 182 patients with navigated stabilizations operated on in our institution in the preiCT era revealed an overall revision rate of 10.4% with 4.4% of patients requiring screw revision after malposition (8.5% and 0% in the current series). Thus, in addition to the medical and medicolegal advantages, there are also economical aspects in favor of iCT. By using iCT, we could not only reduce additional strain and danger to the patient, but moreover costly surgical revisions prolonging the duration of hospitalization could be avoided. Thus, in times of increasingly important medico-economic aspects with firm reimbursement rates for therapy, the investment into an iCT can be very interesting, depending on the frequency of stabilization and tumor surgery. For neurosurgical patients, iCT is especially useful for control of cranial tumor resection (osseous tumors and contrast enhancing tumors such as meningiomas, metastases or high grade gliomas), control of catheter placement (shunt surgery) or intraoperative examination of brain perfusion (e.g., in aneurysm surgery). Furthermore, the system can be used in a multidisciplinary environment with orthopedic or general surgeons (e.g., hip/sacrum surgery) or ENT surgeons (e.g., maxillary reconstruction surgery).27Conclusion and PerspectiveIntraoperative CT in combination with neuronavigation provides high accuracy of screw placement and thus safety for patients undergoing spinal stabilization in all areas of the spine without relevant additional time required. Images for referencing the navigation system are obtained with the patient being in the final position for surgery. Furthermore, iCT provides valuable information for surgical decision-making that is predominantly related to detection of positioning of implanted material, exclusion of complications, and detection of residual tumor or otherwise neural compression. The setup allows update of the navigation during surgery by repeated image acquisition during the operation in case of intraoperative changes of the surgical situs. The system can be installed into a pre-existing operating environment without need for special surgical instruments. The procedure is rapid and easy to perform without restricted access to the patient and—by replacing pre- and postoperative imaging—is not associated with additional exposure to radiation. Multidisciplinary use increases utilization of the system and thus improves cost-effectiveness. New software generating an automatic registration will, in the future, further ease and speed-up intraoperative update of image-guided navigation using iCT.Key Points * Prospective study to evaluate feasibility and outcome of 94 navigated stabilizations of the whole spine with data acquisition by intraoperative computed tomography. * Additional effort was low and accuracy of screw positioning was high. There was immediate detection of intraoperative complications and no reoperation due to malposition. * Multidisciplinary use increases utilization of the system and improves cost-efficiency relation.References1. Kosmopoulos V, Schizas C. Pedicle screw placement accuracy: a meta-analysis. Spine 2007;32:E111–20. [CrossRef] [Full Text] [Medline Link] Request Permissions [Context Link]2. Holly LT, Foley KT. Intraoperative spinal navigation. Spine 2003;28:S54–61. [CrossRef] [Full Text] [Medline Link] Request Permissions [Context Link]3. Gertzbein SD, Robbins SE. 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Fluoroscopic method versus computer-assisted surgery. Spine 1999;24:975–82. [CrossRef] [Full Text] [Medline Link] Request Permissions [Context Link]27. Uhl E, Zausinger S, Morhard D, et al. Intraoperative computer tomography with integrated navigation system in a multidisciplinary operating suite. Neurosurgery 2009;64:231–9. 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Link]|00007632-200912150-00015#xpointer(id(R26-15))|11065213||ovftdb|00007632-199905150-00009SL0000763219992497511065213P93[CrossRef]|00007632-200912150-00015#xpointer(id(R26-15))|11065404||ovftdb|00007632-199905150-00009SL0000763219992497511065404P93[Full Text]|00007632-200912150-00015#xpointer(id(R26-15))|11065405||ovftdb|00007632-199905150-00009SL0000763219992497511065405P93[Medline Link]|00007632-200912150-00015#xpointer(id(R26-15))|130||ovftdb|00007632-199905150-00009SL00007632199924975130P93Request|00007632-200912150-00015#xpointer(id(R27-15))|11065405||ovftdb|SL0000612320096423111065405P94[Medline Link]|00007632-200912150-00015#xpointer(id(R27-15))|130||ovftdb|SL00006123200964231130P94Request PermissionsA prospective study to evaluate navigated stabilizations of the whole spine in combination with intraoperative computed tomography. We found high accuracy of screw placement (immediate repositioning of 2.4%), immediate detection of intraoperative complications and no reoperation due to malposition. Multidisciplinary use increases utilization of the system and improves cost-efficiency relation.Intraoperative Computed Tomography With Integrated Navigation System in Spinal StabilizationsZausinger, Stefan MD; Scheder, Ben MD; Uhl, Eberhard MD; Heigl, Thomas RN; Morhard, Dominik MD; Tonn, Joerg-Christian MDTechnique2634