Augmented Reality in Spine Surgery: A Case Study of Atlantoaxial Instrumentation in Os Odontoideum.

Despite advancement in surgical innovation, C1-C2 fixation remains challenging due to risks of screw malposition and vertebral artery (VA) injuries. Traditional image-based navigation, while useful, often demands that surgeons frequently shift their attention to external monitors, potentially causing distractions. In this article, we introduce a microscope-based augmented reality (AR) navigation system that projects both anatomical information and real-time navigation images directly onto the surgical field. In the present case report, we discuss a 37-year-old female who suffered from os odontoideum with C1-C2 subluxation. Employing AR-assisted navigation, the patient underwent the successful posterior instrumentation of C1-C2. The integrated AR system offers direct visualization, potentially minimizing surgical distractions. In our opinion, as AR technology advances, its adoption in surgical practices and education is anticipated to expand.

Reduction in CT scan number with the reference frame middle attachment method in intraoperative CT navigation for adolescent idiopathic scoliosis.

PURPOSE: Elucidate whether it is preferable to use the reference frame (RF) middle attachment (RFMA) method over the edge of the planned pedicle screw (PS) insertion area for RF placement in the surgery for adolescent idiopathic scoliosis (AIS) with intraoperative computed tomography (CT) navigation. METHODS: Eighty-six consecutive patients (76 female and 10 male; mean age: 15.9 years) with AIS who underwent posterior spinal fusion using intraoperative CT navigation were enrolled. The group with the RF placed at the most distal part of the CT scan range was defined as the distal group (Group D), with other placements classified into the middle group (Group M). PS perforation rate and surgical outcome were compared between the groups. RESULTS: There was no significant difference in perforation rate between Group M and Group D (3.4% vs. 3.0%, P = 0.754). The mean ± standard deviation number of instrumented vertebrae at the first CT scan was significantly higher in Group M (8.2 ± 1.2 vs. 6.3 ± 1.2, P < 0.001), while mean blood loss was significantly lower (266 ± 185 mL vs. 416 ± 348 mL, P = 0.011). The frequency of needing a second CT scan for PS insertion was significantly lower in Group M (38% vs. 69%, P = 0.04). CONCLUSION: The RFMA method in thoracic scoliosis surgery for AIS with intraoperative CT navigation could significantly decrease the number of CT scans and blood loss while maintaining a comparable PS perforation rate to RF placement at the distal end of the planned PS insertion range.

Comparison of radiation exposure and surgery time between an intraoperative CT with automatic surface registration and a preoperative CT with manual surface registration in navigated spinal surgeries.

PURPOSE: This retrospective matched case-control study was conducted to compare two CT based surgery techniques for navigated screw placement in spinal surgery, whether a reduction of radiation exposure and surgery time could be achieved. METHODS: We matched cases treated with an intraoperative CT (iCT), regarding the type and number of implants, with cases treated with a preoperative CT (pCT) of one main surgeon. Outcome measures were radiation exposure due to intraoperative control x-rays, radiation exposure due to CT images, and the duration of surgery. RESULTS: The required radiation exposure could be significantly reduced in the iCT group. For the intraoperative control X-rays by 69% (median (MED) 88.50/standard deviation (SD) 107.84 and MED 286.00/SD 485.04 for iCT and pCT respectively-in Gycm2; p < 0.001) and for the CT examinations by 25% (MED 317.00/SD 158.62 and MED 424.50/SD 225.04 for iCT and pCT respectively-in mGycm; p < 0.001) with no significant change in surgery time. The correlation between the number of segments fused and the necessary surgery time decreased significantly for the iCT group (Pearson product-moment-correlation: r = 0.569 and r = 0.804 for iCT and pCT respectively; p < 0.05). CONCLUSION: The results show that spinal navigation using an intraoperative CT with automatic registration compared to a preoperative CT and intraoperative manual surface registration, allows a significant reduction of radiation exposure, without prolonged surgery time. A significant benefit regarding cut-to-suture-time can be gained with surgeries of a larger scale.

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

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.

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

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

Lumbar hemivertebra resection in congenital scoliosis utilizing cone-beam navigation: less radiation, more accuracy-proof of concept.

PURPOSE: To present the first known pediatric utilization of cone-beam navigation system (CBNS) for hemivertebra resection and spondylodesis CASE PRESENTATION: A 14-year-old female with congenital scoliosis, diagnosed at 8 years of age, presenting with progressive symptoms, a Cobb angle (L3-5) of 38° at time of surgery, treated historically with conservative measures. Presence of spinal intramedullary disease was excluded prior to operation via whole spine MRI. RESULTS: Patient successfully underwent surgical correction utilizing the CBNS (O-arm™, Medtronic®). Post-operative Cobb angle (L3-5) was restored to 8°. Following four different pediatric patient's radiation exposures (two receiving correction via the O-arm platform and two via the traditional method employing fluoroscopy), we show a reduction in radiation exposure using the CBNS system. CONCLUSION: We present the first known pediatric case of the utilization of the CBNS system for hemivertebra correction. We demonstrate that utilizing the CBNS platform can not only increase surgical accuracy but also decrease pediatric patient's radiation exposure as a preoperative CT scan is not needed. Future studies should continue to explore additional benefits of implementing the system into surgical practice.

[Intraoperative computed tomography and modern navigation in surgical treatment of spine and spinal cord diseases]. / Opyt primeneniya intraoperatsionnogo spiral'nogo komp'yuternogo tomografa i sovremennoi sistemy navigatsii v khirurgicheskom lechenii zabolevanii pozvonochnika i spinnogo mozga.

Surgical treatment of spine and spinal cord diseases is one of important objectives in modern neurosurgery. Patient safety is a priority in spine and spinal cord surgery. Intraoperative imaging ensures efficacy and safe surgery with and without stabilization, preoperative marking, control of decompression and correct implant placement. Surgical C-arms and intraoperative cone-beam CT scanners are the most widespread in everyday practice. The latest achievement was intraoperative spiral computed tomography. C-arms and CT scanners with intraoperative navigation increase the efficiency and safety of surgical interventions.

Intraoperative CT and cone-beam CT imaging for minimally invasive evacuation of spontaneous intracerebral hemorrhage.

BACKGROUND: Minimally invasive surgery (MIS) for evacuation of spontaneous intracerebral hemorrhage (ICH) has shown promise but there remains a need for intraoperative performance assessment considering the wide range of evacuation effectiveness. In this feasibility study, we analyzed the benefit of intraoperative 3-dimensional imaging during navigated endoscopy-assisted ICH evacuation by mechanical clot fragmentation and aspiration. METHODS: 18 patients with superficial or deep supratentorial ICH underwent MIS for clot evacuation followed by intraoperative computerized tomography (iCT) or cone-beam CT (CBCT) imaging. Eligibility for MIS required (a) availability of intraoperative iCT or CBCT, (b) spontaneous lobar or deep ICH without vascular pathology, (c) a stable ICH volume (20-90 ml), (d) a reduced level of consciousness (GCS 5-14), and (e) a premorbid mRS ≤ 1. Demographic, clinical, and radiographic patient data were analyzed by two independent observers. RESULTS: Nine female and 9 male patients with a median age of 76 years (42-85) presented with an ICH score of 3 (1-4), GCS of 10 (5-14) and ICH volume of 54 ± 26 ml. Clot fragmentation and aspiration was feasible in all cases and intraoperative imaging determined an overall evacuation rate of 80 ± 19% (residual hematoma volume: 13 ± 17 ml; p < 0.0001 vs. Pre-OP). Based on the intraoperative imaging results, 1/3rd of all patients underwent an immediate re-aspiration attempt. No patient experienced hemorrhagic complications or required conversion to open craniotomy. However, routine postoperative CT imaging revealed early hematoma re-expansion with an adjusted evacuation rate of 59 ± 30% (residual hematoma volume: 26 ± 37 ml; p < 0.001 vs. Pre-OP). CONCLUSIONS: Routine utilization of iCT or CBCT imaging in MIS for ICH permits direct surgical performance assessment and the chance for immediate re-aspiration, which may optimize targeting of an ideal residual hematoma volume and reduce secondary revision rates.

Clinical Application of CT Navigation in treatment of Lumbar Spondylolisthesis with Minimally Invasive Surgery - Transforaminal Lumbar Interbody Fusion.

OBJECTIVE: To explore the clinical effect of the application of CT navigation in the treatment of lumbar spondylolisthesis with minimally invasive surgery - transforaminal lumbar interbody fusion (MIS-TLIF). METHODS: A retrospective study was conducted on 30 patients with lumbar spondylolisthesis who were continuously treated in linyi central hospital from May 2018 to March 2019.The patients were divided into two groups,15 patients treated with MIS-TLIF with the aid of CT navigation during the operation were included into an observation group. Another 15 patients were treated with open transforaminal lumbar interbody fusion as the control group. The baseline information, including gender, age and course of disease, perioperative period and imaging conditions, and VAS and ODI scores of patients in the two groups were collected and analyzed. RESULTS: Fifteen patients were included into the observation group, including 9 male and 6 female patients with an average age of 52.60 ± 6.31 and a course of disease of 16.33 ± 6.00 months. The other 15 patients were included into the observation group, including seven male and eight female patients with an average age of 52.87 ± 7.38 and a course of disease of 19.13 ± 9.89 months. The difference in the gender, age and course of disease between the two groups had no statistical significance (P > 0.05). However, the difference in the duration of operation and intraoperative blood loss between the two groups had statistical significance (P< 0.05). There were no statistically significant differences in wound complications, neurological complications, preoperative slippage rate, postoperative slippage rate, slippage reduction rate and screw placement accuracy (P > 0.05). VAS scores of the two groups were statistically significant from six months after surgery (P < 0.01). There was no significant difference in ODI between the two groups at any time point (P >, 0.05). VAS and ODI scores were improved at each time point compared with those before surgery. CONCLUSION: The minimally invasive transforaminal lumbar fusion performed with the aid of CT navigation during the operation shortens the duration of operation and the amount of bleeding, reduces the back pain, is beneficial to the early postoperative functional exercise, and speeds up the postoperative recovery.

Utilization of the Intraoperative Mobile AIRO® CT Scanner in Stereotactic Surgery: Workflow and Effectiveness.

BACKGROUND: In frame-based stereotactic surgery, intraoperative imaging is crucial. It generally follows a workflow including preoperative MRI and intraoperative frame-based CT. The intraoperative transport of the anesthetized and intubated patient to and from the CT unit can be time-consuming and cumbersome. Here, we report the first 50 patients who underwent stereotactic biopsies using the mobile AIRO® intraoperative CT (iCT) scanner. METHODS: A conventional stereotactic frame was mounted to the AIRO® carbon table via carbon adapter. 0°gantry thin-slice iCT was performed. The imaging data were transferred to a conventional stereotaxy working unit. After fusion of the preoperative MRI and AIRO® iCT, the stereotactic system was built based on the iCT, and trajectories were calculated accordingly. RESULTS: The frame-based stereotactic iCT was easy to implement and successfully accomplished in all patients. The MRI/iCT image fusion was feasible in all of the studies. A conclusive histological result was obtained in 46 of the 50 cases included. There was no bleeding complication. Net surgery time was reduced by 38 min, on average. CONCLUSION: We conclude that the AIRO® system is a safe, easy-to-use, and sufficiently accurate iCT for CT frame-based stereotactic biopsy planning that results in a considerable reduction of surgery time. In the future, it remains to be evaluated if the accuracy rates and intraoperative workflow will permit its application in deep brain stimulation and other functional procedures as well.

Accuracy and revision rate of intraoperative computed tomography point-to-point navigation for lateral mass and pedicle screw placement: 11-year single-center experience in 1054 patients.

High accuracy in intraoperative computed tomography (iCT) navigation utilizing an intraoperatively acquired dataset for screw placement in the spine has been reported in the literature. To further improve the accuracy and counteract any intraoperative movement of predefined registration points, we introduce an iCT point-to-point navigation, where marker screws are inserted intraoperatively to increase patient safety. In all, 1054 patients who underwent iCT point-to-point navigation for lateral mass and pedicle screw placement were retrospectively analyzed between 09/2005 and 09/2016. Implant-related complications such as screw misplacement, screw loosening, and revision rate were determined. Furthermore, we investigated the rate of complications and the clinical outcome. In total, 6059 screws were inserted in 1054 patients. There were 553 (52.5%) female and 501 (47.5%) male patients. Average age was 63.5 years, mean BMI 27.5 (SD 13.9). Here, 1427 (23.5%) screws were inserted in the cervical, 995 (16.4%) in the thoracic, 3167 (52.3%) in the lumbar, and 470 (7.8%) in the sacral spine. Eight patients required a revision procedure for screw misplacement (0.8%). Total screw misplacement rate was 0.3% (16/6059). With the use of reference markers in iCT-based, spinal, point-to-point navigation, we achieved a high accuracy of screw placement with a low revision rate (0.8%) and a total screw misplacement rate of 0.3%.

Reliable navigation registration in cranial and spine surgery based on intraoperative computed tomography.

OBJECTIVE: Low registration errors are an important prerequisite for reliable navigation, independent of its use in cranial or spinal surgery. Regardless of whether navigation is used for trajectory alignment in biopsy or implant procedures, or for sophisticated augmented reality applications, all depend on a correct registration of patient space and image space. In contrast to fiducial, landmark, or surface matching-based registration, the application of intraoperative imaging allows user-independent automatic patient registration, which is less error prone. The authors' aim in this paper was to give an overview of their experience using intraoperative CT (iCT) scanning for automatic registration with a focus on registration accuracy and radiation exposure. METHODS: A total of 645 patients underwent iCT scanning with a 32-slice movable CT scanner in combination with navigation for trajectory alignment in biopsy and implantation procedures (n = 222) and for augmented reality (n = 437) in cranial and spine procedures (347 craniotomies and 42 transsphenoidal, 56 frameless stereotactic, 59 frame-based stereotactic, and 141 spinal procedures). The target registration error was measured using skin fiducials that were not part of the registration procedure. The effective dose was calculated by multiplying the dose length product with conversion factors. RESULTS: Among all 1281 iCT scans obtained, 1172 were used for automatic patient registration (645 initial registration scans and 527 repeat iCT scans). The overall mean target registration error was 0.86 ± 0.38 mm (± SD) (craniotomy, 0.88 ± 0.39 mm; transsphenoidal, 0.92 ± 0.39 mm; frameless, 0.74 ± 0.39 mm; frame-based, 0.84 ± 0.34 mm; and spinal, 0.80 ± 0.28 mm). Compared with standard diagnostic scans, a distinct reduction of the effective dose could be achieved using low-dose protocols for the initial registration scan with mean effective doses of 0.06 ± 0.04 mSv for cranial, 0.50 ± 0.09 mSv for cervical, 4.12 ± 2.13 mSv for thoracic, and 3.37 ± 0.93 mSv for lumbar scans without impeding registration accuracy. CONCLUSIONS: Reliable automatic patient registration can be achieved using iCT scanning. Low-dose protocols ensured a low radiation exposure for the patient. Low-dose scanning had no negative effect on navigation accuracy.

Technical note: accuracy and precision in stereotactic stem cell transplantation.

BACKGROUND: While multiple trials have employed stereotactic stem cell transplantation, injection techniques have received little critical attention. Precise cell delivery is critical for certain applications, particularly when targeting deep nuclei. METHODS: Ten patients with a history of ischemic stroke underwent CT-guided stem cell transplantation. Cells were delivered along 3 tracts adjacent to the infarcted area. Intraoperative air deposits and postoperative T2-weighted MRI fluid signals were mapped in relation to calculated targets. RESULTS: The deepest air deposit was found 4.5 ± 1.0 mm (mean ± 2 SEM) from target. The apex of the T2-hyperintense tract was found 2.8 ± 0.8 mm from target. On average, air pockets were found anterior (1.2 ± 1.1 mm, p = 0.04) and superior (2.4 ± 1.0 mm, p < 0.001) to the target; no directional bias was noted for the apex of the T2-hyperintense tract. Location and distribution of air deposits were variable and were affected by the relationship of cannula trajectory to stroke cavity. CONCLUSIONS: Precise stereotactic cell transplantation is a little-studied technical challenge. Reflux of cell suspension and air, and the structure of the injection tract affect delivery of cell suspensions. Intraoperative CT allows assessment of delivery and potential trajectory correction.

Accuracy of Intraoperative Computed Tomography in Deep Brain Stimulation-A Prospective Noninferiority Study.

INTRODUCTION: Clinical response to deep brain stimulation (DBS) strongly depends on the appropriate placement of the electrode in the targeted structure. Postoperative MRI is recognized as the gold standard to verify the DBS-electrode position in relation to the intended anatomical target. However, intraoperative computed tomography (iCT) might be a feasible alternative to MRI. MATERIALS AND METHODS: In this prospective noninferiority study, we compared iCT with postoperative MRI (24-72 hours after surgery) in 29 consecutive patients undergoing placement of 58 DBS electrodes. The primary outcome was defined as the difference in Euclidean distance between lead tip coordinates as determined on both imaging modalities, using the lead tip depicted on MRI as reference. Secondary outcomes were difference in radial error and depth, as well as difference in accuracy relative to target. RESULTS: The mean difference between the lead tips was 0.98 ± 0.49 mm (0.97 ± 0.47 mm for the left-sided electrodes and 1.00 ± 0.53 mm for the right-sided electrodes). The upper confidence interval (95% CI, 0.851 to 1.112) did not exceed the noninferiority margin established. The average radial error between lead tips was 0.74 ± 0.48 mm and the average depth error was determined to be 0.53 ± 0.40 mm. The linear Deming regression indicated a good agreement between both imaging modalities regarding accuracy relative to target. CONCLUSIONS: Intraoperative CT is noninferior to MRI for the verification of the DBS-electrode position. CT and MRI have their specific benefits, but both should be considered equally suitable for assessing accuracy.

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.

PURPOSE: To develop a classification based on the technical complexity encountered during pedicle screw insertion and to evaluate the performance of AIRO® CT navigation system based on this classification, in the clinical scenario of complex spinal deformity. MATERIALS AND METHODS: 31 complex spinal deformity correction surgeries were prospectively analyzed for performance of AIRO® mobile CT-based navigation system. Pedicles were classified according to complexity of insertion into five types. Analysis was performed to estimate the accuracy of screw placement and time for screw insertion. Breach greater than 2 mm was considered for analysis. RESULTS: 452 pedicle screws were inserted (T1-T6: 116; T7-T12: 171; L1-S1: 165). The average Cobb angle was 68.3° (range 60°-104°). We had 242 grade 2 pedicles, 133 grade 3, and 77 grade 4, and 44 pedicles were unfit for pedicle screw insertion. We noted 27 pedicle screw breach (medial: 10; lateral: 16; anterior: 1). Among lateral breach (n = 16), ten screws were planned for in-out-in pedicle screw insertion. Among lateral breach (n = 16), ten screws were planned for in-out-in pedicle screw insertion. Average screw insertion time was 1.76 ± 0.89 min. After accounting for planned breach, the effective breach rate was 3.8% resulting in 96.2% accuracy for pedicle screw placement. CONCLUSION: This classification helps compare the accuracy of screw insertion in range of conditions by considering the complexity of screw insertion. Considering the clinical scenario of complex pedicle anatomy in spinal deformity AIRO® navigation showed an excellent accuracy rate of 96.2%.

Cervical pedicle screw placement using intraoperative computed tomography imaging with a mobile scanner gantry.

PURPOSE: A multi-detector computed tomography (CT) imaging system with a mobile scanner gantry in the operating room can provide intraoperative reconstructed images with a high resolution. We devised a technique for cervical pedicle screw (CPS) placement using the mobile CT system and evaluated the accuracy of this technique. METHODS: Forty-eight patients who underwent cervical fixation using CPSs were prospectively enrolled in this study. Initial pedicle probing was performed approximately to the depth of the posterior aspect of the vertebral body using fluoroscopic lateral view, and a marking pin was put in place. Intraoperative CT images were obtained to confirm whether the position of the marking pin was accurate. After adequate modification of the trajectory was performed, an appropriately sized CPS was inserted. The accuracy of the CPS was evaluated using postoperative reconstructed CT images, and compared with a historical control group of 22 patients (CPS insertion using only fluoroscopy). RESULTS: A total of 193 CPSs were inserted. Intraoperative CT images demonstrated that 12.4 % of the initial probings were not accurate, and modification of the trajectory was required. On postoperative CT, 92.7 % of the CPSs were found to be placed accurately: the accuracy was significantly higher than the control group (80.9 %). In the cases using intraoperative CT images, only 1.0 % of the screws were judged to show grade 2 screw misplacement; no neurovascular complications associated with screw placement were observed. CONCLUSIONS: The technique of CPS placement using mobile CT was shown to be safe and effective in preventing catastrophic complications associated with CPS insertion.

Accuracy and workflow of navigated spinal instrumentation with the mobile AIRO(®) CT scanner.

PURPOSE: Current solutions for navigated spine surgery remain hampered by restrictions in surgical workflow as well as a limited versatility and applicability. Against this background, we report the first experience of navigated spinal instrumentation with the mobile AIRO(®) intraoperative computed tomography (iCT) scanner. METHODS: AIRO(®) iCT was used for navigated posterior spinal instrumentation of 170 screws in 23 consecutive patients operated on in our Department between the first use of the system in May 2014 and August 2014. The indications for AIRO(®) were based on the surgical region, anatomical complexity and the need for >3 segment instrumentation. Following navigated screw insertion, screw positions were confirmed intraoperatively by a second iCT scan. CT data on screw placement accuracy were retrospectively reviewed and analyzed by an independent observer. RESULTS: AIRO(®)-based spinal navigation was easy to implement and successfully accomplished in all patients, adding around 18-34 min to the net surgery time. A systematic description of the authors' approach, setup in the OR and workflow integration of the AIRO(®) is presented. Analysis of screw placement accuracy revealed 9 (5.3%) screws with minor pedicle breaches (<2 mm). A total of 7 screws (4.1%) were misplaced >2 mm, resulting in an accuracy rate of 95.9%. CONCLUSIONS: The AIRO(®) system is an easy-to-use and versatile iCT for navigated spinal instrumentation and provides high pedicle screw accuracy rates. Although the authors' experience suggests that the learning curve associated with AIRO(®)-based spinal navigation is steep, a systematic user-based approach to the technology is required.

Optimizing ventriculoperitoneal shunt placement in the treatment of idiopathic intracranial hypertension: an analysis of neuroendoscopy, frameless stereotaxy, and intraoperative CT.

OBJECTIVE: Cerebrospinal fluid shunting can effectively lower intracranial pressure and improve the symptoms of idiopathic intracranial hypertension (IIH). Placement of ventriculoperitoneal (VP) shunts in this patient population can often be difficult due to the small size of the ventricular system. Intraoperative adjuvant techniques can be used to improve the accuracy and safety of VP shunts for these patients. The purpose of this study was to analyze the efficacy of some of these techniques, including the use of intraoperative CT (iCT) and frameless stereotaxy, in optimizing postoperative ventricular catheter placement. METHODS: The authors conducted a retrospective review of 49 patients undergoing initial ventriculoperitoneal shunt placement for the treatment of IIH. The use of the NeuroPEN Neuroendoscope, intraoperative neuronavigation, and iCT was examined. To analyze ventricular catheter placement on postoperative CT imaging, the authors developed a new grading system: Grade 1, catheter tip terminates optimally in the ipsilateral frontal horn or third ventricle; Grade 2, catheter tip terminates in the contralateral frontal horn; Grade 3, catheter terminates in a nontarget CSF space; and Grade 4, catheter tip terminates in brain parenchyma. All shunts had spontaneous CSF flow upon completion of the procedure. RESULTS: The average body mass index among all patients was 37.6 ± 10.9 kg/m2. The NeuroPEN Neuroendoscope was used in 44 of 49 patients. Intraoperative CT scans were obtained in 24 patients, and neuronavigation was used in 32 patients. Grade 1 or 2 final postoperative shunt placement was achieved in 90% of patients (44 of 49). In terms of achieving optimal postoperative ventricular catheter placement, the use of iCT was as effective as neuronavigation. Two patients had their ventricular catheter placement modified based on an iCT study. The use of neuronavigation significantly increased time in the operating room (223.4 ± 46.5 vs. 190.8 ± 31.7 minutes, p = 0.01). There were no shunt infections in this study. CONCLUSIONS: The use of iCT appears to be equivalent to the use of neuronavigation in optimizing ventricular shunt placement in IIH. Additionally, it may shorten operating room time and limit overall costs.

Identification of residual tumor with intraoperative contrast-enhanced ultrasound during glioblastoma resection.

OBJECTIVE: The purpose of this study was to assess the capability of contrast-enhanced ultrasound (CEUS) to identify residual tumor mass during glioblastoma multiforme (GBM) surgery, to increase the extent of resection. METHODS: The authors prospectively evaluated 10 patients who underwent surgery for GBM removal with navigated ultrasound guidance. Navigated B-mode and CEUS were performed prior to resection, during resection, and after complete tumor resection. Areas suspected for residual tumors on B-mode and CEUS studies were localized within the surgical field with navigated ultrasound and samples were sent separately for histopathological analysis to confirm tumor presence. RESULTS: In all cases tumor remnants were visualized as hyperechoic areas on B-mode, highlighted as CEUS-positive areas, and confirmed as tumoral areas on histopathological analysis. In 1 case only, CEUS partially failed to demonstrate residual tumor because the residual hyperechoic area was devascularized prior to ultrasound contrast agent injection. In all cases CEUS enhanced B-mode findings. CONCLUSIONS: As has already been shown in other neoplastic lesions in other organs, CEUS is extremely specific in the identification of residual tumor. The ability of CEUS to distinguish between tumor and artifacts or normal brain on B-mode is based on its capacity to show the vascularization degree and not the echogenicity of the tissues. Therefore, CEUS can play a decisive role in the process of maximizing GBM resection.

Minimally invasive transforaminal lumbar interbody fusion with the ROSA(TM) Spine robot and intraoperative flat-panel CT guidance.

BACKGROUND: Circumferential arthrodesis is commonly used to treat degenerative lumbar diseases. Minimally invasive techniques may enable faster recovery and reduce the incidence of postoperative infections. METHODS: We report on the surgical technique of a transforaminal lumbar interbody fusion (TLIF) procedure performed with the assistance of a new robotic device (ROSA(TM) Spine) and intraoperative flat-panel CT guidance. CONCLUSIONS: The combined use of this new robotic device and intraoperative CT enables accurate and safe arthrodesis in the treatment of degenerative lumbar disc diseases.