Comparative analysis of 'functional excision' of heterotopic ossification around the hip - computed tomography (CT) navigation guided versus conventional excision.

PURPOSE: We aim to analyse and compare the efficacy of the excision of HO around the hip with and without CT-guided navigation. We also aim to compare the functional outcome between CT navigation guided versus conventional excision of HO. PATIENTS AND METHODS: This study is a retrospective analysis of prospectively collected data from 2015 to 2022. There were 23 patients (24 hips) in the final cohort. Intraoperative CT navigation guided excision was performed in 7 hips and conventional excision of HO was done in 17 hips. The HO was classified by Brooker's grading in radiographs. CT scan was taken preoperatively in all patients to exactly identify the volume, location and preoperative planning. The functional outcome was analysed according to Harris Hip Score (HHS) and International Hip Outcome Tool (iHOT) for self-ambulatory patients and improvement in the sitting or nursing care was assessed in patients mobilising with wheelchair or walker support. Any complications or recurrence noted postoperatively and in follow-up were recorded. RESULTS: The mean follow-up was 41.2 months in the CT navigation-guided excision group and 55 months in the conventional excision group. According to Brooker's grading, grade IV was present in 20 hips and grade III in four hips. Twelve patients were self-ambulatory and the other 12 patients were requiring support for mobilisation. There was a significant improvement in the HHS from 21.3 ± 3.7, 18.3 ± 2.5 preoperatively to 75.2 ± 8.3, 72.2 ± 4.3 postoperatively in the CT navigation guided and conventional group respectively (p < 0.001) in the self-ambulatory group. There was one anterior wall and one partial posterior wall fracture in the conventional group. One patient in the conventional group had a deep infection and recurrence. One patient had a superficial infection and another had superficial vein thrombosis in the CT guided excision group. CONCLUSION: Intraoperative CT navigation helps to exactly localize the HO and facilitates safe excision. Functional excision of the HO leads to better nursing care and functional outcomes between both groups.

Surgical Treatment of Calcified Thoracic Herniated Disc Disease via the Transthoracic Approach with the Use of Intraoperative Computed Tomography (iCT) and Microscope-Based Augmented Reality (AR).

Background and Objectives: The aim of this study is to present our experience in the surgical treatment of calcified thoracic herniated disc disease via a transthoracic approach in the lateral position with the use of intraoperative computed tomography (iCT) and augmented reality (AR). Materials and Methods: All patients who underwent surgery for calcified thoracic herniated disc via a transthoracic transpleural approach at our Department using iCT and microscope-based AR were included in the study. Results: Six consecutive patients (five female, median age 53.2 ± 6.4 years) with calcified herniated thoracic discs (two patients Th 10-11 level, two patients Th 7-8, one patient Th 9-10, one patient Th 11-12) were included in this case series. Indication for surgery included evidence of a calcified thoracic disc on magnet resonance imaging (MRI) and CT with spinal canal stenosis of >50% of diameter, intractable pain, and neurological deficits, as well as MRI-signs of myelopathy. Five patients had paraparesis and ataxia, and one patient had no deficit. All surgeries were performed in the lateral position via a transthoracic transpleural approach (Five from left side). CT for automatic registration was performed following the placement of the reference array, with a high registration accuracy. Microscope-based AR was used, with segmented structures of interest such as vertebral bodies, disc space, herniated disc, and dural sac. Mean operative time was 277.5 ± 156 min. The use of AR improved orientation in the operative field for identification, and tailored the resection of the herniated disc and the identification of the course of dural sac. A control-iCT scan confirmed the complete resection in five patients and incomplete resection of the herniated disc in one patient. In one patient, complications occurred, such as postoperative hematoma, and wound healing deficit occurred. Mean follow-up was 22.9 ± 16.5 months. Five patients improved following surgery, and one patient who had no deficits remained unchanged. Conclusions: Optimal surgical therapy in patients with calcified thoracic disc disease with compression of dural sac and myelopathy was resectioned via a transthoracic transpleural approach. The use of iCT-based registration and microscope-based AR significantly improved orientation in the operative field and facilitated safe resection of these lesions.

Abdominal Arterial Translation in Lower Lumbar Spine Level Due to Positional Change: A Clinical Survey Using Intraoperative Computed Tomography.

Background: Abdominal vascular injury, a fatal complication of lumbar disc surgery, should concern spine surgeons. This study aimed to compare the position of the abdominal arteries in the supine and prone positions and the factors involved. Thirty patients who underwent lumbar surgery by posterior approach were included. Methods: All patients underwent computed tomography (CT) preoperatively in the supine position and intraoperatively in the prone position. In the CT axial image, at the L4, L4/5 disc, L5, and L5/S1 disc level, we measured the shortest distance between the abdominal arteries and the vertebral body (SDA: shortest distance to the aorta), and the amount of abdominal arterial translation, defined as "SDA on intraoperative CT" minus "SDA on preoperative CT". Additionally, the preoperative CT axial images were evaluated for the presence of aortic calcification. Results: No significant difference in SDA values based on patients' positions was observed at each level. In males, the supine position brought the abdominal artery significantly closer to the spine at the left side of the L5/S level (p = 0.037), and, in cases of calcification of the abdominal artery, the abdominal artery was found to be closer to the spine at the left side of the L4/5 level (p = 0.026). Conclusions: It is important to confirm preoperative images correctly to prevent great vessel injuries in lumbar spine surgery using a posterior approach.

Comparison of iCT-based navigation and fluoroscopic-guidance for atlantoaxial screw placement in 78 patients with traumatic cervical spine injuries.

BACKGROUND CONTEXT: Studies have shown biomechanical superiority of cervical pedicle screw placement over other techniques. However, accurate placement is challenging due to the inherent risk of neurovascular complications. Navigation technology based on intraoperative 3D imaging allows highly accurate screw placement, yet studies specifically investigating screw placement in patients with traumatic atlantoaxial injuries are scarce. The aim of this study was to compare atlantoaxial screw placement as treatment of traumatic instabilities using iCT-based navigation or fluoroscopic-guidance with intraoperative 3D control scans. METHODS: This was a retrospective review of patients with traumatic atlantoaxial injuries treated operatively with dorsal stabilization of C1 and C2. Patients were either assigned to the intraoperative navigation or fluoroscopic-guidance group. Screw accuracy, procedure time, and revisions were compared. RESULTS: Seventy-eight patients were included in this study with 51 patients in the navigation group and 27 patients in the fluoroscopic-guidance group. In total, 312 screws were placed in C1 and C2. Screw accuracy was high in both groups; however, pedicle perforations > 1 mm occurred significantly more often in the fluoroscopic-guidance group (P = 0.02). Procedure time was on average 23 min shorter in the navigation group (P = 0.02). CONCLUSIONS: This study contributes to the available data showing that navigated atlantoaxial screw placement proves to be feasible as well as highly accurate compared to the fluoroscopic-guidance technique without prolonging the time needed for surgery. When comparing these data with other studies, the application of different classification systems for assessment of screw accuracy should be considered.

Comparison of intraoperative imaging guided versus microelectrode recording guided deep brain stimulation for Parkinson's disease: A meta-analysis / Comparativa entre la cirugía guiada por imágenes y la estimulación cerebral profunda guiada por microelectrodos en el tratamiento de la enfermedad de Parkinson: un metaanálisis

Background Traditionally, most centers would use microelectrode recording (MER) to refine targeting in deep brain stimulation (DBS) surgery. In recent years, intraoperative imaging (IMG) guided DBS has become an alternative way to verify lead placement. Currently, there is still controversy surrounding the necessity of MER or IMG for DBS. This meta-analysis aims to explore lead accuracy, clinical efficacy and safety between IMG and MER guided DBS for Parkinson's disease (PD). Methods PubMed, Embase, Web of Science, Cochrane Library were searched up to Mar, 2021 for studies reporting comparisons between IMG and MER guided DBS for PD. Subgroup analysis was conducted to assess effects of different IMG technology and DBS targeting site. Results Six studies, comprising of 478 patients were included in our analysis. The mean difference between the two implantation techniques in stereotactic accuracy, lead passes per trajectory, improvement% of Unified Parkinson's Disease Rating Scale part III and levodopa equivalent daily dose were −0.45 (95% confidence interval, CI=−1.11 to 0.20), −0.18 (95% CI=−0.41 to 0.06), 3.40 (95% CI=−5.36 to 12.16), and 5.00 (95% CI=−1.40 to 11.39), respectively. No significant differences were observed in each adverse event and operation/procedure time between the two implantation techniques. Conclusions Both IMG and MER guided DBS offered effective control of motor symptoms for PD. Besides, IMG guided is comparable to MER guided DBS, in terms of safety, accuracy and efficiency. It is recommended for each hospital to select DBS guidance technology based on available resources and equipment (AU)

Antecedentes Tradicionalmente, la mayoría de los centros usaban los microelectrodos de registro (microelectrode recording [MER]) para mejorar la orientación en la cirugía mediante la estimulación cerebral profunda (deep brain stimulation [DBS]). En los últimos años, la DBS orientada mediante imágenes intraoperatorias (intraoperative imaging guided [IMG]) se ha convertido en una forma alternativa de verificar la colocación de los electrodos. Hoy en día, todavía existe controversia en torno al uso de MER o IMG para realizar una DBS. Este metaanálisis tiene como objetivo explorar la precisión de los electrodos, la eficacia clínica y la seguridad entre la DBS guiada mediante IMG y MER en el tratamiento de la enfermedad de Parkinson (EP). Métodos Se realizaron búsquedas en PubMed, Embase, Web of Science y Cochrane Library hasta marzo de 2021 para localizar estudios que informasen sobre comparaciones entre la DBS guiada mediante IMG y la guiada mediante MER en la EP. Se realizó un análisis de subgrupos para evaluar los efectos de una tecnología IMG y una ubicación DBS guiada diferentes. Resultados En nuestro análisis hemos incluido seis estudios con 478 pacientes. La diferencia media entre las dos técnicas de implantación en la precisión estereotáctica, los pasos del electrodo por trayectoria, el porcentaje de mejora de la escala unificada de clasificación de la enfermedad de Parkinson, parteIII, y la dosis diaria equivalente de levodopa fueron −0,45 (intervalo de confianza del 95% [IC 95%]: −1,11 a 0,20), −0,18 (IC 95%: −0,41 a 0,06), 3,40 (IC 95%: −5,36 a 12,16) y 5,00 (IC 95%: −1,40 a 11,39), respectivamente. No se observaron diferencias significativas en cada evento adverso y tiempo de operación/procedimiento entre las dos técnicas de implantación (AU)

Comparison of intraoperative imaging guided versus microelectrode recording guided deep brain stimulation for Parkinson's disease: A meta-analysis.

BACKGROUND: Traditionally, most centers would use microelectrode recording (MER) to refine targeting in deep brain stimulation (DBS) surgery. In recent years, intraoperative imaging (IMG) guided DBS has become an alternative way to verify lead placement. Currently, there is still controversy surrounding the necessity of MER or IMG for DBS. This meta-analysis aims to explore lead accuracy, clinical efficacy and safety between IMG and MER guided DBS for Parkinson's disease (PD). METHODS: PubMed, Embase, Web of Science, Cochrane Library were searched up to Mar, 2021 for studies reporting comparisons between IMG and MER guided DBS for PD. Subgroup analysis was conducted to assess effects of different IMG technology and DBS targeting site. RESULTS: Six studies, comprising of 478 patients were included in our analysis. The mean difference between the two implantation techniques in stereotactic accuracy, lead passes per trajectory, improvement% of Unified Parkinson's Disease Rating Scale part III and levodopa equivalent daily dose were -0.45 (95% confidence interval, CI=-1.11 to 0.20), -0.18 (95% CI=-0.41 to 0.06), 3.40 (95% CI=-5.36 to 12.16), and 5.00 (95% CI=-1.40 to 11.39), respectively. No significant differences were observed in each adverse event and operation/procedure time between the two implantation techniques. CONCLUSIONS: Both IMG and MER guided DBS offered effective control of motor symptoms for PD. Besides, IMG guided is comparable to MER guided DBS, in terms of safety, accuracy and efficiency. It is recommended for each hospital to select DBS guidance technology based on available resources and equipment.

iCT Navigation for Transpedicular Screw Fixation in the Thoracolumbar Spine: Experience in 100 Consecutive Cases.

Background: Various guidance techniques have been developed for optimal pedicle screw placement. We present our initial experience with intraoperative CT (iCT) navigation for transpedicular screw fixation in the thoracolumbar spine. Objective: This study aimed to describe the accuracy and reliability of iCT navigation for transpedicular screw fixation. Material and Methods: One hundred consecutive patients underwent thoracolumbar pedicle screw fixation under iCT navigation. After iCT registration of the local bony anatomy with a firmly attached spinous process tracker, pedicle screw placement was performed under navigation with an infrared camera and infrared reflectors on insertion instruments. Screw trajectories of the intraoperative verification CT were matched against the navigation paths. Radiological and clinical follow-up was prospectively documented and retrospectively analyzed. The study included 47 women and 53 men with a mean age of 66 years. Indications for thoracolumbar pedicle fixation were degenerative instability with stenosis, cyst or disc herniation (82), spondylolytic instability (9), scoliosis with stenosis (6), and traumatic fractures (3). A total of 443 pedicle screws were inserted: 22 in the thoracic spine, 371 in the lumbar spine, and 50 in S1. Results and Conclusions: Four hundred thirty-five out of 443 screws (98%) were correctly placed. Misplacement was explained by loosened infrared reflectors on pedicle awl or probe, or by the displacement of the spinous process tracker; misplaced screws were re-inserted intraoperatively and showed correct placement on the second verification CT. Based on our first 100 cases, iCT navigation for transpedicular screw fixation in the thoracolumbar spine seems to be very accurate and reliable.

Use of Neuronavigation and Augmented Reality in Transsphenoidal Pituitary Adenoma Surgery.

The aim of this study was to report on the clinical experience with microscope-based augmented reality (AR) in transsphenoidal surgery compared to the classical microscope-based approach. AR support was established using the head-up displays of the operating microscope, with navigation based on fiducial-/surface- or automatic intraoperative computed tomography (iCT)-based registration. In a consecutive single surgeon series of 165 transsphenoidal procedures, 81 patients underwent surgery without AR support and 84 patients underwent surgery with AR support. AR was integrated straightforwardly within the workflow. ICT-based registration increased AR accuracy significantly (target registration error, TRE, 0.76 ± 0.33 mm) compared to the landmark-based approach (TRE 1.85 ± 1.02 mm). The application of low-dose iCT protocols led to a significant reduction in applied effective dosage being comparable to a single chest radiograph. No major vascular or neurological complications occurred. No difference in surgical time was seen, time to set-up patient registration prolonged intraoperative preparation time on average by twelve minutes (32.33 ± 13.35 vs. 44.13 ± 13.67 min), but seems justifiable by the fact that AR greatly and reliably facilitated surgical orientation and increased surgeon comfort and patient safety, not only in patients who had previous transsphenoidal surgery but also in cases with anatomical variants. Automatic intraoperative imaging-based registration is recommended.

High Accuracy and Safety of Intraoperative CT-Guided Navigation for Transpedicular Screw Placement in Revision Spinal Surgery.

BACKGROUND: Intraoperative CT-guided navigation (iCT-navigation) has been reported to improve the accuracy and safety of transpedicular screw placement in primary spinal surgery. However, due to a disrupted bony anatomy and scarring tissue, revision spinal surgery can be challenging. The purpose of this study was to evaluate the accuracy and safety of iCT-navigation for screw placement at the virgin site versus the revision site in revision thoracolumbar spinal surgery. METHOD: In total, 254 screws were inserted in 27 revision surgeries, in which 114 (44.9%) screws were inserted at the site with previous laminectomy or posterolateral fusion (the revision site), 64 (25.2%) were inserted at the virgin site, and 76 (29.9%) were inserted to replace the pre-existing screws. CT scans were conducted for each patient after all screws were inserted to intraoperatively confirm the screw accuracy. RESULTS: In total, 248 (97.6%) screws were considered accepted. The rate of accepted screws at the virgin site was 98.4% (63/64) versus 95.6% (109/114) at the revision site (p: 0.422). There were six (2.4%) unaccepted screws, which were immediately revised during the same operation. There was no neurological injury noted in our patients. CONCLUSION: With the use of iCT-navigation, the rate of accepted screws at the revision site was found to be comparable to that at the virgin site. We concluded that iCT-navigation could achieve high accuracy and safety for transpedicular screw placement in revision spinal surgery and allow for the immediate revision of unaccepted screws.

Computed Tomography Intraoperative Navigation in Spinal Surgery: Assessment of Patient Radiation Exposure in Current Practices.

BACKGROUND: Patient radiation exposure associated with the use of computed tomography (CT) navigation during spinal surgeries was widely compared with other intraoperative imaging techniques. The aim of this study is to explore the use of navigation with regard to current spinal surgery practices and the technical limitations of such imaging systems. METHODS: Dosimetric data from 101 patients who underwent intraoperative, CT-navigated spine surgery were retrospectively collected. The study population was divided into 3 groups according to the primary surgical indication. The number of CT image acquisitions per patient, the field length, and the time of exposure per acquisition during a single surgery were compared as well as the radiation dose emitted to patients. RESULTS: Dose-length products (DLP) per acquisition were 678.52, 656.8, and 649.36 mGy·cm with no significant difference for spinal deformity (SD), degenerative disease (DD), and vertebral fracture (VF) procedures, respectively. Analyzing the number of CT image acquisitions per patient revealed that repeated intraoperative scans were often performed for patients who were suffering from an SD due to technical limitations of the navigation. As a consequence, the cumulative dose was higher in the SD group (DLP total = 1175 mGy·cm) than in the DD (DLP total = 762.74 mGy·cm) and VF (DLP total = 649.36 mGy·cm) groups. CONCLUSIONS: CT navigation is an efficient intraoperative imaging technique that reduces the rate of surgical complications, but its technical limitations lead to an increased risk of patient radiation exposure, especially for complex surgeries where multiple scanning acquisitions are needed. CLINICAL RELEVANCE: To avoid patient's overexposure, spine surgeons should minimize the number of intraoperative acquisitions while considering the complexity of the surgery and the limitations of the guidance system. The use of dual guidance systems has also to be considered according to the benefit-risk balance between patient's outcomes and radiation dose exposure.

Microscope-Based Augmented Reality with Intraoperative Computed Tomography-Based Navigation for Resection of Skull Base Meningiomas in Consecutive Series of 39 Patients.

BACKGROUND: The aim of surgery for skull base meningiomas is maximal resection with minimal damage to the involved cranial nerves and cerebral vessels; thus, implementation of technologies for improved orientation in the surgical field, such as neuronavigation and augmented reality (AR), is of interest. METHODS: Included in the study were 39 consecutive patients (13 male, 26 female, mean age 64.08 ± 13.5 years) who underwent surgery for skull base meningiomas using microscope-based AR and automatic patient registration using intraoperative computed tomography (iCT). RESULTS: Most common were olfactory meningiomas (6), cavernous sinus (6) and clinoidal (6) meningiomas, meningiomas of the medial (5) and lateral (5) sphenoid wing and meningiomas of the sphenoidal plane (5), followed by suprasellar (4), falcine (1) and middle fossa (1) meningiomas. There were 26 patients (66.6%) who underwent gross total resection (GTR) of the meningioma. Automatic registration applying iCT resulted in high accuracy (target registration error, 0.82 ± 0.37 mm). The effective radiation dose of the registration iCT scans was 0.58 ± 1.05 mSv. AR facilitated orientation in the resection of skull base meningiomas with encasement of cerebral vessels and compression of the optic chiasm, as well as in reoperations, increasing surgeon comfort. No injuries to critical neurovascular structures occurred. Out of 35 patients who lived to follow-up, 33 could ambulate at their last presentation. CONCLUSION: A microscope-based AR facilitates surgical orientation for resection of skull base meningiomas. Registration accuracy is very high using automatic registration with intraoperative imaging.

Frameless Stereotactic Biopsy with Intraoperative Computed Tomography "Assessment of Efficacy and Real Target Registration Error".

Frameless stereotactic brain biopsy (FSB) with navigation system has been widely used. We reported preliminary experience of FSB with intraoperative computed tomography (iCT) and examined the usefulness of this novel adjuvant technique and real target registration error (rTRE) of FSB. The FSB with 5-aminolevulinic acid (5-ALA) and iCT was performed on 10 patients. The gadolinium-enhanced lesions on magnetic resonance image were defined as the biopsy target. In the procedure, iCTs were scanned twice, for autoregistration of the navigation system and for confirmation of the position of the actual inserted biopsy needle. The red fluorescence of the samples was observed under excitation with violet-blue light through a low-cut filter of neurosurgical microscope. The distance between the planned target and the tip of the biopsy needle in the image of iCT was calculated in a workstation for the assessment of rTRE. The median volume of the target was 12.13 mL (0.06-39.15 mL). We performed the surgical procedure in a prone position in four patients. None to faint 5-ALA-induced fluorescence was observed in six samples. There existed no sampling errors. The mean target distance between the planned and real targets of the mean rTRE of FSB was 2.7 ± 0.56 mm. The real TRE of FSB was first reported and was larger than the reported rTRE exactly calculated from the fiducial registration error. iCT guarantees accurate tumor sampling with autoregistration regardless of the surgical position and prevents inaccurate biopsy to occur even with ALA fluorescence assistance.

Usefulness of Intraoperative Computed Tomography on Extent of Resection of Large and Giant Pituitary Adenomas. Experience from a Developing Country.

BACKGROUND AND OBJECTIVE: The literature on the use of intraoperative computed tomography (iCT) is sparse. We provide our experience of the usefulness of iCT in extent of resection in large and giant pituitary adenomas. METHODS: A retrospective review was performed of cases using the endonasal endoscopic technique in which iCT was used. Demographic factors, number of scans, and impact on the extent of resection are reported, with visual acuity and field changes. Tumors were graded according to the Hardy classification. Patients with cavernous sinus invasion were excluded. RESULTS: All patients received a perioperative computed tomography scan with our iCT scanner. Thirty patients are reported, including 14 large and 16 giant pituitary adenomas, including 14 nonfunctional and 16 growth hormone-secreting tumors. The overall gross total resection (GTR), near-total resection, and subtotal resection rates were 83.3%, 16.7%, and 3.3%, respectively. iCT scanning detected residual in 13 of 30 patients, including 4 with 14 large (29%) and 9 with 16 (56.3%) giant adenomas promoting further surgery. iCT use improved GTR from 43.8% to 81.3% in giant adenomas and from 71% to 86% in large adenomas. Of the 13 patients in whom iCT detected residual disease, none required >2 iCT scans. No intraoperative complications were observed. CONCLUSIONS: iCT can improve extent of resection in large and giant pituitary adenomas and facilitate maximum safe resection such as GTR or near-total resection in patients where such should be attempted. iCT use may reduce iatrogenic complications and has select financial benefits in our patients' socioeconomic demographics. However, further prospective controlled studies are required to affirm our conclusions.

Cost-Effectiveness of Intraoperative CT Scanning in Cochlear Implantation in Fee-for-Service and Bundled Payment Models.

OBJECTIVE: Electrode array tip fold-over is a complication of cochlear implant surgery that results in poor hearing outcomes and often leads to revision surgery. However, tip fold-over can be corrected immediately if identified through intraoperative computed tomography, which also potentially provides information about final intracochlear positioning. Our objective was to provide the first economic analysis of intraoperative computed tomography by generating models in fee-for-service and bundled payment reimbursement structures of payer and institutional cost-effectiveness of this technology used in cochlear implantation over 1, 5, and 10-year time periods. METHODS: Cost data specific to a commerically available intraoperative computed tomography machine was obtained from the manufacturer, Xoran Technologies. Institutional tip fold-over rate was obtained from already published data. Medicare reimbursement rate for cochlear implantation was obtained from institutional accountants. Private payer reimbursement for and cost of revision cochlear implantation were estimated based on available data. RESULTS AND CONCLUSION: At large volume centers, cost-effectiveness of this technology is possible in both fee-for-service and bundled payment reimbursement structures at various time points dependent on payer mix. Even low volume cochlear implantation centers (<150 per year) can financially benefit from intraoperative computed tomography in bundled payment models at 5- and 10-year periods regardless of payer mix. This model demonstrates key factors at play in determining cost-effectiveness of this technology including institutional factors and payer type and suggests this technology can align incentives both to improve patient care and outcomes with institutional and payer financial well-being.

Detection of impending perfusion deficits by intraoperative computed tomography (iCT) in aneurysm surgery of the anterior circulation.

BACKGROUND: The aim of our study was to evaluate the additional benefit of intraoperative computed tomography (iCT), intraoperative computed tomography angiography (iCTA), and intraoperative computed tomography perfusion (iCTP) in the intraoperative detection of impending ischemia to established methods (indocyanine green videoangiography (ICGVA), microDoppler, intraoperative neuromonitoring (IONM)) for initiating timely therapeutic measures. METHODS: Patients with primary aneurysms of the anterior circulation between October 2016 and December 2019 were included. Data of iCT modalities compared to other techniques (ICGVA, microDoppler, IONM) was recorded with emphasis on resulting operative conclusions leading to inspection of clip position, repositioning, or immediate initiation of conservative treatment strategies. Additional variables analyzed included patient demographics, aneurysm-specific characteristics, and clinical outcome. RESULTS: Of 194 consecutive patients, 93 patients with 100 aneurysms received iCT imaging. While IONM and ICGVA were normal, an altered vessel patency in iCTA was detected in 5 (5.4%) and a mismatch in iCTP in 7 patients (7.5%). Repositioning was considered appropriate in 2 patients (2.2%), where immediate improvement in iCTP could be documented. In a further 5 cases (5.4%), intensified conservative therapy was immediately initiated treating the reduced CBP as clip repositioning was not considered causal. In terms of clinical outcome at last FU, mRS0 was achieved in 85 (91.4%) and mRS1-2 in 7 (7.5%) and remained mRS4 in one patient with SAH (1.1%). CONCLUSIONS: Especially iCTP can reveal signs of impending ischemia in selected cases and enable the surgeon to promptly initiate therapeutic measures such as clip repositioning or intraoperative onset of maximum conservative treatment, while established tools might fail to detect those intraoperative pathologic changes.

Does the use of intraoperative CT scan improve outcomes in Orthopaedic surgery? A systematic review and meta-analysis of 871 cases.

BACKGROUND: Intraoperative imaging is frequently made use of in Orthopaedic surgery. Historically, conventional 2-dimensional fluoroscopy has been extensively used for this purpose. However, 2D imaging falls short when it is required to visualise complex anatomical regions such as pelvis, spine, foot and ankle etc. Intraoperative 3D imaging was introduced to counter these limitations, and is increasingly being employed in various sub-specialities of Orthopaedic Surgery. OBJECTIVES: This review aims to outline the clinical and radiological outcomes of surgeries done under the guidance of intraoperative 3D imaging and compare them to those done under conventional 2D fluoroscopy. METHODS: Three electronic databases (PubMed, Embase and Scopus) were searched for relevant studies that directly compared intraoperative 3D imaging with conventional fluoroscopy. Case series on intraoperative 3D imaging were also included for qualitative synthesis. The outcomes evaluated included accuracy of implant placement, mean surgical duration and rate of revision surgery due to faulty implants. RESULTS: A total of 31 studies from sub-specialities of spine surgery, pelvi-acetabular surgery, foot and ankle surgery and trauma surgery, having data on a total of 658 patients were analysed. The study groups which had access to intraoperative 3D imaging was found to have significantly increased accuracy of implant positioning (Odds Ratio 0.35 [0.20, 0.62], p = 0.0002) without statistically significant difference in mean surgical time (p = 0.57). Analysis of the studies that included clinical follow up showed that the use of intraoperative 3D imaging led to a significant decrease in the need for revision surgeries due to faulty implant placement. CONCLUSION: There is sufficient evidence that the application of intraoperative 3D imaging leads to precise implant positioning and improves the radiological outcome. Further research in the form of prospective studies with long term follow up is required to determine whether this superior radiological outcome translates to better clinical results in the long run.

Effect of Intraoperative Computed Tomography in Microelectrode Recording during Frameless Stereotactic Deep Brain Stimulation for Parkinson Disease.

BACKGROUND: Microelectrode recording (MER)-guided deep brain stimulation (DBS) remains the standard electrophysiological procedure to place the DBS lead at the optimal target. When single-track MER or test stimulation yields suboptimal results, trajectory adjustments are needed. Intraoperative computed tomography (iCT) can be useful to visualize the microelectrode and verify possible adjustments. The aim of this study was to evaluate the effect of iCT in MER during frameless stereotactic DBS for Parkinson disease (PD). METHODS: We retrospectively collected 28 PD patients, of whom 19 received iCT and 9 did not, and measured intracranial volume, cerebral volume, cerebrospinal fluid volume, and pneumocephalus volume. Euclidean distance was assessed according to merged preoperative brain CT and magnetic resonance imaging and postoperative brain CT. RESULTS: Fifty-six hemispheres in the 28 patients were analyzed for MER tracks. The patients who received iCT had a significantly lower mean number of MER tracks (1.6 vs. 2.6, P = 0.013) and lower mean Euclidean distance (2.2 mm vs. 2.7 mm, P = 0.033) compared with those who did not receive iCT. Although there was a trend of a decrease in pneumocephalus using intraoperative imaging, there was no significant difference in surgical time. CONCLUSIONS: iCT can reduce the number of MER tracks and increase surgical accuracy. Further studies are warranted to investigate whether iCT can reduce surgical complications and improve surgical outcomes.

Intraoperative Computed Tomography-Assisted Spinal Navigation in Dorsal Cervical Instrumentation: A Prospective Study on Accuracy Regarding Different Pathologies and Screw Types.

BACKGROUND: Intraoperative computed tomography (iCT) navigated dorsal instrumentation has been successfully introduced as a new clinical standard. The proximity of vital anatomic structures makes cervical spine instrumentation an especially delicate task. Therefore, navigated approaches might prove to be beneficial. In this study, the accuracy of conventional instrumentation was compared with iCT navigated dorsal cervical spine instrumentation with focus on cervical pedicle screws (CPSs) versus lateral mass screws (LMSs) and pathologies. METHODS: We analyzed a prospective consecutive series of patients undergoing cervical dorsal instrumentation with iCT and spinal navigation and retrospectively analyzed a cohort that received conventional cervical instrumentation with C-arm fluoroscopy (control group). Accuracy was assessed with a modified Gertzbein-Robbins classification. Underlying pathologies were taken into account regarding accuracy in different entities. RESULTS: Fifty-nine patients were treated using iCT (357 screws: 238 CPSs, 119 LMSs), and 98 patients underwent conventional instrumentation (632 screws: 69 CPSs, 563 LMSs). We achieved an initial accuracy of 93.28% (n = 220 screws) in the iCT group and 80.9% (n = 511 screws) in the control group (P < 0.001). Significant differences were found regarding the accuracy of CPS placement in cases of degenerative disorders (iCT vs. control; 94% vs. 63%; P < 0.001) and trauma (iCT vs. control; 88% vs. 72%; P < 0.05). iCT yielded favorable precision rates in regard to LMS placement (iCT vs. control; 94.2% vs. 82%; P < 0.05). CONCLUSIONS: Accuracy of iCT navigated instrumentation was significantly higher than conventional instrumentation. An overall tendency toward the use of CPSs with iCT navigation is evident, increasing the mechanical properties of the construct. iCT appears to be especially beneficial in elective surgery cases of degenerative spinal disorders.

Use of Intraoperative Computed Tomography Improves Outcome of Minimally Invasive Transforaminal Lumbar Interbody Fusion: A Single-Center Retrospective Cohort Study.

OBJECTIVE: To provide data about surgical workflow, accuracy, complications, radiation exposure, and learning curve effect in patients who underwent minimally invasive (MIS) transforaminal lumbar interbody fusion with navigation coupled with mobile intraoperative computed tomography. METHODS: A retrospective analysis was performed of data from consecutive patients who underwent single- or double-level MIS transforaminal lumbar interbody fusion at a single institution; mobile intraoperative computed tomography combined with a navigation system was used as the sole intraoperative imaging method to place pedicular screws; decompression and interbody fusion were performed through a 22-mm tubular retractor. Clinical data, perioperative complications, accuracy of pedicular screw placement, and radiation exposure were analyzed. A learning curve effect on surgical time and accuracy was assessed. RESULTS: A total of 408 screws in 100 patients were analyzed. In all cases, spinal navigation allowed for identification of pedicular trajectories and greatly facilitated nerve root decompression through the MIS approach. Overall accuracy according to Heary classification was 95.3%. Nineteen screws (4.7%) presented a minor lateral breach (<2 mm), not clinically significant. Surgical time, blood loss, and patient radiation exposure compared favorably with reported values from other series using three-dimensional navigation. A learning curve effect on surgical time, but not on screw accuracy, was identified. CONCLUSIONS: MIS transforaminal lumbar interbody fusion can now be performed without any radiation exposure to the surgeon and operating room staff, with almost absolute accuracy during screw positioning and tubular decompression. A learning curve effect on surgical time, but not on overall screw accuracy, may be expected.

Recurrent high-grade glioma surgery: a multimodal intraoperative protocol to safely increase extent of tumor resection and analysis of its impact on patient outcome.

OBJECTIVE: No consensus exists on the best treatment for recurrent high-grade glioma (HGG), particularly in terms of surgical indications, and scant data are available on the integrated use of multiple technologies to overcome intraoperative limits and pitfalls related to artifacts secondary to previous surgery and radiotherapy. Here, the authors report on their experience with the integration of multiple intraoperative tools in recurrent HGG surgery, analyzing their pros and cons as well as their effectiveness in increasing the extent of tumor resection. In addition, they present a review of the relevant literature on this topic. METHODS: The authors reviewed all cases in which recurrent HGG had been histologically diagnosed after a first surgery and the patient had undergone a second surgery involving neuronavigation with MRI, intraoperative CT (iCT), 11C-methionine-positron emission tomography (11C-MET-PET), 5-aminolevulinic acid (5-ALA) fluorescence, intraoperative neurophysiological monitoring (IONM), and intraoperative navigated ultrasound (iUS). All cases were classified according to tumor functional grade (1, noneloquent area; 2, near an eloquent area; 3, eloquent area). RESULTS: Twenty patients with recurrent HGG were operated on using a multimodal protocol. The recurrent tumor functional grade was 1 in 4 patients, 2 in 8 patients, and 3 in the remaining 8 patients. In all patients but 2, 100% EOTR was obtained. Intraoperative 5-ALA fluorescence and navigated iUS showed low specificity and sensitivity. iCT detected tumor remnants in 3 cases. Postoperatively, 6 patients (30%) had worsening neurological conditions: 4 recovered within 90 days, 1 partially recovered, and 1 experienced a permanent deficit. The median Karnofsky Performance Status remained substantially unchanged over the follow-up period. The mean progression-free survival after the second surgery was 7.7 months (range 2-11 months). The mean overall survival was 25.4 months (range 10-52 months), excluding 2 long survivors. Two patients died within 60 days after surgery, and 3 patients were still under follow-up at the end of this study. CONCLUSIONS: This is the first study reporting the integration of neuronavigation, 5-ALA fluorescence, iUS, iCT, 11C-MET-PET, and IOM during microsurgical resection of recurrent glioma. The authors believe that the proposed multimodal protocol is useful to increase the safety, effectiveness, and EOTR in patients with recurrent HGG and brain alterations secondary to radio- and chemotherapy.