Intraoperative Computed Tomography Imaging Research Articles

Robotic-Assisted Minimally Invasive Spinopelvic Fixation for Traumatic Sacral Fractures: Case Series Investigating Early Safety and Efficacy

High-energy traumatic sacral fractures, particularly U-type or AOSpine classification type C fractures, may lead to significant functional deficits. Traditionally, spinopelvic fixation for unstable sacral fractures was performed with open reduction and fixation, but robotic-assisted minimally invasive surgical methods now present new, less invasive approaches. The objective here was to present a series of patients with traumatic sacral fractures treated with robotic-assisted minimally invasive spinopelvic fixation and discuss early experience, considerations, and technical challenges. Between June 2022 and January 2023, 7 consecutive patients met the inclusion criteria. Intraoperative fluoroscopic images were merged with intraoperative computed tomography images using a robotic system to plan the trajectories for placement of bilateral lumbar pedicle and iliac screws. Intraoperative computed tomography was performed after pedicle and pelvic screw insertion to confirm appropriate placement before insertion of rods percutaneously without the need for a side connector. The cohort consisted of 7 patients (4 female, 3 male) with ages ranging from 20 to 74. Intraoperatively, the mean blood loss was 85.7 ± 84.0 mL, and mean operative time was 178.4 ± 63.9 minutes. There were no complications in 6 patients; 1 patient experienced both a medially breached pelvic screw and a complicated rod pullout. All patients were safely discharged to their homes or an acute rehabilitation facility. Our early experience reveals that robotic-assisted minimally invasive spinopelvic fixation for traumatic sacral fractures is a safe and feasible treatment option with the potential to improve outcomes and reduce complications.

Intraoperative computed tomography during fenestrated and branched endovascular aortic repair: a feasibility study.

Endovascular aortic repair with fenestrated or branched endografts is technically challenging, and proper intraoperative assessment of all stent graft components with only angiography and fluoroscopy can be difficult. Intraoperative computed tomography (CT) imaging can be a valuable aid for the operators in the evaluation of stent grafting results prior to completion of surgery. To examine the feasibility of performing intraoperative CT imaging during fenestrated and branched endovascular aortic repair (f-bEVAR) under sterile conditions and with patients under general anesthesia. Intraoperative CT imaging was performed in 10 patients undergoing elective aortic repair with fenestrated or branched endografts. Adverse events, time consumption for CT set-up and image acquisition, and additional radiation dose to the patient were recorded. CT image quality was graded. Immediate corrective maneuvers performed based on the CT findings was registered. There were no adverse events related to intraoperative CT imaging. The median additional operating time by including intraoperative CT was 16 min (interquartile range [IQR] = 12-19), comprising 7% of the median total operating time. The median estimated additional radiation dose to the patient was 4.8 mSv (IQR = 3.8-4.9). All intraoperative CT examinations were considered to be of sufficient quality for stent graft evaluation. No immediate corrective procedures were performed on the basis of CT findings in this study cohort. CT imaging intraoperatively during f-bEVAR is feasible with an acceptable increase in operating time and radiation dose.

Combining physics-based models with deep learning image synthesis and uncertainty in intraoperative cone-beam CT of the brain.

Image-guided neurosurgery requires high localization and registration accuracy to enable effective treatment and avoid complications. However, accurate neuronavigation based on preoperative magnetic resonance (MR) or computed tomography (CT) images is challenged by brain deformation occurring during the surgical intervention. To facilitate intraoperative visualization of brain tissues and deformable registration with preoperative images, a 3D deep learning (DL) reconstruction framework (termed DL-Recon) was proposed for improved intraoperative cone-beam CT (CBCT) image quality. The DL-Recon framework combines physics-based models with deep learning CT synthesis and leverages uncertainty information to promote robustness to unseen features. A 3D generative adversarial network (GAN) with a conditional loss function modulated by aleatoric uncertainty was developed for CBCT-to-CT synthesis. Epistemic uncertainty of the synthesis model was estimated via Monte Carlo (MC) dropout. Using spatially varying weights derived from epistemic uncertainty, the DL-Recon image combines the synthetic CT with an artifact-corrected filtered back-projection (FBP) reconstruction. In regions of high epistemic uncertainty, DL-Recon includes greater contribution from the FBP image. Twenty paired real CT and simulated CBCT images of the head were used for network training and validation, and experiments evaluated the performance of DL-Recon on CBCT images containing simulated and real brain lesions not present in the training data. Performance among learning- and physics-based methods was quantified in terms of structural similarity (SSIM) of the resulting image to diagnostic CT and Dice similarity metric (DSC) in lesion segmentation compared to ground truth. A pilot study was conducted involving seven subjects with CBCT images acquired during neurosurgery to assess the feasibility of DL-Recon in clinical data. CBCT images reconstructed via FBP with physics-based corrections exhibited the usual challenges to soft-tissue contrast resolution due to image non-uniformity, noise, and residual artifacts. GAN synthesis improved image uniformity and soft-tissue visibility but was subject to error in the shape and contrast of simulated lesions that were unseen in training. Incorporation of aleatoric uncertainty in synthesis loss improved estimation of epistemic uncertainty, with variable brain structures and unseen lesions exhibiting higher epistemic uncertainty. The DL-Recon approach mitigated synthesis errors while maintaining improvement in image quality, yielding 15%-22% increase in SSIM (image appearance compared to diagnostic CT) and up to 25% increase in DSC in lesion segmentation compared to FBP. Clear gains in visual image quality were also observed in real brain lesions and in clinical CBCT images. DL-Recon leveraged uncertainty estimation to combine the strengths of DL and physics-based reconstruction and demonstrated substantial improvements in the accuracy and quality of intraoperative CBCT. The improved soft-tissue contrast resolution could facilitate visualization of brain structures and support deformable registration with preoperative images, further extending the utility of intraoperative CBCT in image-guided neurosurgery.

Sacroiliac joint fusion navigation: how accurate is pin placement?

Sacroiliac joint (SIJ) fusion utilizing intraoperative navigation requires a standard reference frame, which is often placed using a percutaneous pin. Proper placement ensures the correct positioning of SIJ fusion implants. There is currently no grading scheme for evaluation of pin placement into the pelvis. The purpose of this study was to evaluate the occurrence of ideal percutaneous pin placement into the posterior ilium during navigated SIJ fusion. After IRB approval was obtained, electronic medical records and intraoperative computed tomography images of patients who underwent navigated SIJ fusion by the senior author between October 2013 and January 2020 were reviewed. A pin placement grading scheme and the definition of "ideal" placement were developed by the authors and deemed acceptable by fellow attending surgeons. Six attending surgeons completed two rounds of pin placement grading, and statistical analysis was conducted. Of 90 eligible patients, 73.3% had ideal pin placement, 17.8% medial/lateral breach, and 8.9% complete miss. Male patients were 3.7 times more likely to have ideal placement than females (p < 0.05). There was no relationship between BMI, SIJ fusion laterality, or pin placement laterality and ideal placement. Interobserver reliability was 0.72 and 0.70 in the first and second rounds, respectively, and defined as "substantial agreement." Intraobserver reliability ranged from 0.74 (substantial agreement) to 0.92 (almost perfect agreement). Nonideal pin placement occurred in 26.7% of cases, but a true "miss" into the sacrum was rare. Ideal pin placement was more likely in males and was not associated with BMI, SIJ fusion laterality, or pin placement laterality. The grading scheme developed has high intraobserver and interobserver reliability, indicating that it is reproducible and can be used for future studies. When placing percutaneous pins, surgeons must be aware of factors that can decrease placement accuracy, regardless of location.

Dual Image Navigation to Secure Surgical Margins in Thoracoscopic Segmentectomy.

Video-assisted thoracoscopic surgery (VATS) segmentectomy is being increasingly used for the management of non-small cell lung cancer. For non-palpable lesions, surgeons frequently find difficulty in ensuring a sufficient surgical resection margin. The purpose of this study was to evaluate the role of intraoperative dual image navigation in combination with the infrared thoracoscopy with intravenous injection of indocyanine green (IRT-ICG) method and intraoperative computed tomography (CT) in detecting oncological margins. This study involved 34 consecutive patients who underwent both IRT-ICG and intraoperative CT-assisted thoracoscopic segmentectomy between October 2017 and July 2021. The intersegmental line on the visceral pleura was visualized using the IRT-ICG method. The intersegmental line was marked by clipping, and an intraoperative CT scan was performed under bilateral lung ventilation. Intraoperative CT or three-dimensional CT reconstruction images were used by surgeons to confirm the correct anatomic segmental border and to secure a sufficient resection margin. A well-defined intersegmental line was observed in 91.2% of patients. In eight cases, the surgeon needed to make some modifications to the resection line to secure a sufficient surgical margin. The mean surgical margin assessed on gross examination by the pathologist was 23.4±9.0 mm. Complete resection was achieved in all patients using this approach. Intraoperative dual image navigation combined with the IRT-ICG method and intraoperative CT scan enables surgeons to perform definitive VATS segmentectomy for non-palpable lesions.

Intraoperative mobile computed tomography in deep brain stimulation: Comparison between Airo CT and O-arm CT.

Background: A new intraoperative mobile device, called Airo computed tomography (CT), is becoming increasingly used in surgery adding to the current most widespread intraoperative imaging in form of the O-arm CT device. Intraoperative CT imaging has the advantage to reduce the discomfort derived from the patient’s transfer from the operative room to the radiological unit and also the time of control or time of reposition in cases of lead misplacement. This is the first rapport on Airo CT device application in DBS surgery.Methods: In our retrospective study, we have evaluated 52 patients who had DBS from October 2020 to November 2021. All patients underwent a preoperative brain magnetic resonance imaging (MRI) and a stereotactic brain CT scan. We performed an intraoperative CT scan with the Airo device. Images were subsequently transferred to the neuronavigation system (BrainLab cranial software) and merged with preoperative planning images to confirm correct position of leads. Five aspects were compared: patient and surgeon comfort, surgical planning, parenchymal visualization, radioscopic lead visualization, and costs.Results: Both imaging devices are easy-to-use, precise, and safe and have their pros and cons.Conclusion: This is the first study reporting on CT-Airo application in DBS. We advise that if only DBS is considered, the O-arm application might be more suitable. If in addition to DBS cranial surgery is performed, the Airo device is more suitable.

Intraoperative computed tomography imaging for laryngoplasty

ObjectivesIntraoperative cone beam computed tomography (CBCT) imaging has the potential to facilitate the surgical procedure. The current preliminary retrospective chart review investigated the benefits of intraoperative CBCT during laryngoplasty. MethodThis study examined 26 cases that underwent intraoperative CBCT imaging during laryngoplasty, with one patient who counted twice due to first and revision surgery. The visual quality of structures of interest (glottal shape, thyroid cartilage, arytenoid cartilage, and implants) was determined using intraoperative CBCT during laryngoplasty. Each patient also underwent an aerodynamic assessment. ResultsCBCT provided unique information, such as surgical landmarks in severe scarring, the subglottal shape, and the rotation angle of the arytenoid cartilage during arytenoid adduction. Nonetheless, 26.9% (7 of 26) of cases were affected by motion artifact, due to the long acquisition time. When motion artifact-negative cases were evaluated, 100% of glottal shape and more than 89% of thyroid cartilage were well visualized. All arytenoids were well-visualized in patients ≥ 50 years of age and without motion artifact, while CBCT failed to visualize the arytenoids in 2 of 4 patients who were < 50 years, due to the lack of calcifications. After medialization surgery, the yields of improved maximal phonation times (MPTs) in the motion artifact-negative and -positive groups were 8.7 sec and 3.4 sec, respectively (p = 0.032; Welch's t test). This comparison indicates intraoperative CBCT would contribute in MPT improvement, if CBCT is taken in measurable quality. ConclusionThe potential benefits of intraoperative CBCT during laryngoplasty were demonstrated. A corollary, prospective study is warranted to further confirmation.

The Use of Intraoperative CT Hounsfield Unit Values for the Assessment of Bone Quality in Patients Undergoing Lumbar Interbody Fusion.

Retrospective Cohort Study. To evaluate the accuracy of intraoperatively measured computed tomography (CT) Hounsfield unit (HU) values by comparison with preoperative CT HU values and to compare the radiation exposure between preoperative and intraoperative CT scans. HU values of lumbar vertebrae were measured and compared between preoperative and intraoperative CT scans in patients undergoing lumbar interbody fusion. In patient group one, Canon CT scanners were used preoperatively and the AIRO CT scanner was used intraoperatively. In patient group two, Canon CT scanners were used preoperatively and the O-arm Cone Beam CT (CBCT) scanner was used intraoperatively. In a subgroup analysis of patient group one, radiation by means of CT Dose Index (CTDI) was compared between Canon and AIRO CT scanners. In the first patient group, a total of 250 vertebrae were analysed in 74 patients showing a strong Pearson correlation of >.94 between pre- and intraoperative HU values. Bland-Altman analysis indicated consistency and equivalence with a bias of 3.9 and 95% limits of agreement from -27.17 to 34.97 when comparing all pre- and intraoperative HU values of L1-5. In the second patient group, a total of 27 vertebrae were analysed in 10 patients showing weak Pearson correlation and Bland-Altman analysis indicated no equivalence. CTDI did not differ between Canon and AIRO CT scanners. Correct and reliable CT HU measurement as mandatory key factor for the intraoperative assessment of bone quality and robotic-assisted surgery is feasible with intraoperative AIRO CT imaging without increase of radiation exposure.

Vertebrae segmentation in reduced radiation CT imaging for augmented reality applications.

There is growing evidence for the use of augmented reality (AR) navigation in spinal surgery to increase surgical accuracy and improve clinical outcomes. Recent research has employed AR techniques to create accurate auto-segmentations, the basis of patient registration, using reduced radiation dose intraoperative computed tomography images. In this study, we aimed to determine if spinal surgery AR applications can employ reduced radiation dose preoperative computed tomography (pCT) images. We methodically decreased the imaging dose, with the addition of Gaussian noise, that was introduced into pCT images to determine the image quality threshold that was required for auto-segmentation. The Gaussian distribution's standard deviation determined noise level, such that a scalar multiplier (L: [0.00, 0.45], with steps of 0.03) simulated lower doses as L increased. We then enhanced the images with denoising algorithms to evaluate the effect on the segmentation. The pCT radiation dose was decreased to below the current lowest clinical threshold and the resulting images produced segmentations that were appropriate for input into AR applications. This held true at simulated dose L = 0.06 (estimated 144 mAs) but not at L = 0.09 (estimated 136 mAs). The application of denoising algorithms to the images resulted in increased artifacts and decreased bone density. The pCT image quality that is required for AR auto-segmentation is lower than that which is currently employed in spinal surgery. We recommend a reduced radiation dose protocol of approximately 140 mAs. This has the potential to reduce the radiation experienced by patients in comparison to procedures without AR support. Future research is required to identify the specific, clinically relevant radiation dose thresholds required for surgical navigation.

Three-dimensional intraoperative computed tomography imaging for zygomatic fracture repair.

ObjectivesZygomatic complex (ZMC) fractures comprise up to 40% of all facial fractures. Misaligned bone fragments and misplaced fixation hardware traditionally detected postoperatively on plain radiographs of the skull might require re-operation. The intraoperative O-Arm (Medtronic, USA) is a three-dimensional (3D) computed tomographic imaging system.Materials and MethodsThis retrospective single-center study evaluated the utility of O-Arm scanning during corrective surgeries for ZMC and zygomatic arch (ZA) fractures from 2018 to 2020. Three females and 16 males (mean age, 31.52 years; range, 22-48 years) were included. Fracture instability (n=6) and facial deformity (n=15) were the most frequent indications for intraoperative 3D O-Arm scan.ResultsThe images demonstrated that all fracture lines were properly reduced and fixed. Another scan performed at the end of the fixation or reduction stage, however, revealed suboptimal results in five of the 19 cases, and further reduction and fixation of the fracture lines were required.ConclusionImplementation of an intraoperative O-Arm system in ZMC and ZA fracture surgeries assists in obtaining predictable and accurate results and obviates the need for revision surgeries. The device should be considered for precise operations such as ZMC fracture repairs.

Utility of a Computer-assisted Rod Bending System to Avoid Pull-out and Loosening of Percutaneous Pedicle Screws.

This was a retrospective observational study of a cohort of consecutive patients. To compare the influence of (1) manual and (2) computer-assisted (CA) rod bending techniques on pedicle screw pull-out resulting in loosening during rod reduction and final tightening. Our recent study showed screw pull-out during rod reduction might be a risk factor for loosening of percutaneous pedicle screws (PPSs) postoperatively, resulting in worse postoperative back pain. We retrospectively analyzed data from 53 consecutive patients who underwent minimally invasive lumbar or thoracic spinal stabilization using intraoperative computed tomography image (CT)-guided navigation with conventional manual rod bending or CA rod bending and were followed up for 1 year. Screw pull-out length was measured on axial CT images obtained immediately after screw insertion and postoperatively. Loosening of screws and clinical outcome were evaluated radiographically, clinically, and by CT 1 year after surgery. The frequencies of screw pull-out and screw loosening between the 2 rod bending techniques were compared. Lumbar pain-related factors for both groups of patients were determined preoperatively and 1 year after surgery. Overall, 360 pedicle screws were placed in the manual group and 124 pedicle screws were placed in the CA group. There was no significant difference in the mean age, sex, bone mineral density, mean stabilized length, or smoking habits of patients between the groups. The diameters, lengths, and trajectory angle (axial and sagittal) of the screws placed were not significantly different between the groups. Screw pull-out rate/length and loosening in the CA group was significantly lower than that in the manual group. Postoperative low back pain improved significantly in the CA group compared with that in the manual group. CA bending is useful to avoid PPS pull-out during rod reduction and screw loosening postoperatively. CA bending is useful to avoid PPS pull-out during rod reduction and screw loosening postoperatively. This result might have been a factor leading to reduced postoperative back pain in the CA group, however, that future studies are need to investigate this association.

Does Intraoperative Computed Tomography Scanning in Maxillofacial Trauma Surgery Affect the Revision Rate?

The purpose of this study was to determine how intraoperative computed tomography affects the intraoperative revision rate and consequently the post-operative, secondary corrective surgery in maxillofacial trauma surgeries. A retrospective study composed of patients with facial fractures was conducted in Prince Sultan Military Medical City in Riyadh, Saudi Arabia. The predictor variables were age, gender, site of facial fracture, type of treatment, number of scans per patient, and discharge time. The primary outcome variable was immediate intraoperative revision rate. Secondary outcome variable was total scanning time (recorded from the moment surgery was halted until it was resumed after image acquisition). Descriptive statistics were used; numerical data presented as mean±SD and categorical variables as frequency (%). A total of 22 patients underwent 25 intraoperative scans while undergoing different maxillofacial surgeries. Eleven (50%) required intraoperative revisions after the scans, and 3 (13.6%) cases had another intraoperative scan after revision. Eighteen were men and 4 were women. The mean age was 30years and age range was 19 to 76. Cases were categorized by fracture location and treatment preformed. The mean scanning time was 18.9±4.6minutes. The highest rate of revisions was seen in zygomaticomaxillary complex fractures (63.6%), they were also the only cases that required a second intraoperative scan after revision to confirm final reduction. No complications were seen postoperatively, and all patients recovered uneventfully. None of the patients required a secondary corrective surgery. All patients were discharged on the following day, except 1 case which was admitted under another service. The use of intraoperative computed tomography imaging in treating maxillofacial fractures results in a higher rate of intraoperative revisions, which in turn leads to more accurate fracture reduction and consequently reduces the possibility of a postoperative, secondary corrective surgery.

Accuracy of Thoracolumbar Pedicle Screw Insertion Based on Routine Use of Intraoperative Imaging and Navigation.

Study DesignRetrospective review.PurposeTo determine the accuracy of thoracolumbar pedicle screw insertion with the routine use of three-dimensional (3D) intraoperative imaging and navigation over a large series of screws in an Asian population.Overview of LiteratureThe use of 3D intraoperative imaging and navigation in spinal surgery is aimed at improving the accuracy of pedicle screw insertion. This study analyzed 2,240 pedicle screws inserted with the routine use of intraoperative navigation. It is one of very few studies done on an Asian population with a large series of screws.MethodsPatients who had undergone thoracolumbar pedicle screws insertion using intraoperative imaging and navigation between 2009 and 2017 were retrospectively analyzed. Computed tomography (CT) images acquired after the insertion of pedicle screws were analyzed for breach of the pedicle wall. The pedicle screw breaches were graded according to the Gertzbein classification. The breach rate and revision rate were subsequently calculated.ResultsA total of 2,240 thoracolumbar pedicle screws inserted under the guidance of intraoperative navigation were analyzed, and the accuracy of the insertion was 97.41%. The overall breach rate was 2.59%, the major breach rate was 0.94%, and the intraoperative screw revision rate was 0.7%. There was no incidence of return to the operating theater for revision of screws.ConclusionsThe routine use of 3D navigation and intraoperative CT imaging resulted in consistently accurate pedicle screw placement. This improved the safety of spinal instrumentation and helped in avoiding revision surgery for malpositioned screws.

The Application of Intraoperative Computed Tomography in Surgical Management of Temporomandibular Joint Ankylosis

To investigate the application and value of intraoperative computed tomography (CT) in the surgical management of temporomandibular joint (TMJ) ankylosis. Patients who underwent surgery of TMJ ankylosis with the aid of intraoperative CT scan from July 2016 to December 2018 were retrospectively studied. Demographics, type of ankylosis, surgical method, intraoperative CT scan time, radiographic evidence, the CT-directed revision rate, and clinical outcomes were analyzed. Four patients (5 sides) were successfully operated with the aid of intraoperative CT imaging, and CT-directed revisions were made in 3 of them during surgery. The average time spent in CT scanning was (10.2±3.3) minutes. No surgical complications were noted, and a good satisfaction rate (with an average maximum mouth opening of 38.8mm and no recurrence during the follow-up period) was obtained. Intraoperative CT scanning is a helpful tool in the evaluation of the radiographic result of TMJ ankylosis, and a real-time revision could be made. It increased the precision and safety of the surgery of TMJ ankylosis.

Clinical outcome following intraoperative computed tomography-assisted secondary orbital reconstruction

Secondary post-traumatic orbital reconstructions are challenging. Portable computed tomography (CT) provides the option to acquire real-time, intraoperative images that help to detect the insufficient reconstruction of the orbit immediately. We retrospectively analyzed patients who received intraoperative CT imaging and analyzed the effect of intraoperative CT scans on revision rates and orbital volume changes before, during, and after surgery. From August 2014 to September 2016, eleven patients received intraoperative cone-beam CT scans to evaluate the results of secondary orbit reconstruction using Medpor + titanium implants. Patient demographics, surgical details, CT scanning protocol, and follow-up results were analyzed. 3D CT volumetry was used to analyze the orbital volume based on OsiriX MD software. Based on intraoperative CT findings, seven cases required intraoperative revision to further augment the orbital cavity or adjust implants. The mean preoperative measured enophthalmos was 3.41±1.4 mm (range: 2-6 mm), which decreased to 0.73±0.4 mm (range: 0-1 mm) at postop assessment (p<0.0001). On the fracture side, there was a significant difference between preoperative vs. intraoperative and preoperative vs. postoperative volume measurements (p<0.01 for both subsets), but no significant difference between intraoperative vs. postoperative measurements. Intraoperative CT is a valuable tool in secondary orbital reconstruction cases based on clinical enophthalmos evaluation and 3D CT volumetry. For these patients, the avoidance of another revision surgery may outweigh the disadvantage of increased operation time and additional radiation exposure.

Comparative Analysis of Surgical Outcomes of C1–2 Fusion Spine Surgery between Intraoperative Computed Tomography Image Based Navigation-Guided Operation and Fluoroscopy-Guided Operation

ObjectiveFixation of the C1–2 segment is challenging because of the complex anatomy in the region and the need for a high degree of accuracy to avoid complications. Preoperative 3D-computed tomography (CT) scans can help reduce the risk of complications in the vertebral artery, spinal cord, and nerve roots. However, the patient may be susceptible to injury if the patient’s anatomy does not match the preoperative CT scans. The intraoperative 3D image-based navigation systems have reduced complications in instrument-assisted techniques due to greater accuracy. This study aimed to compare the radiologic outcomes of C1–2 fusion surgery between intraoperative CT image-guided operation and fluoroscopy-guided operation. MethodsWe retrospectively reviewed the radiologic images of 34 patients who underwent C1–2 fusion spine surgery from January 2009 to November 2018 at our hospital. We assessed 17 cases each of degenerative cervical disease and trauma in a study population of 18 males and 16 females. The mean age was 54.8 years. A total of 139 screws were used and the surgical procedures included 68 screws in the C1 lateral mass, 58 screws in C2 pedicle, nine screws in C2 lamina and C2 pars screws, four lateral mass screws in sub-axial level. Of the 34 patients, 19 patients underwent screw insertion using intraoperative mobile CT. Other patients underwent atlantoaxial fusion with a standard fluoroscopy-guided device. ResultsA total of 139 screws were correctly positioned. We analyzed the positions of 135 screws except for the four screws that performed the lateral mass screws in C3 vertebra. Minor screw penetration was observed in seven cases (5.2%), and major pedicle screw penetration was observed in three cases (2.2%). In one case, the malposition of a C2 pedicle screw was confirmed, which was subsequently corrected. There were no complications regarding vertebral artery injury or onset of new neurologic deficits. The screw malposition rate was lower (5.3%) in patients who underwent intraoperative CT-based navigation than that for fluoroscopy-guided cases (10.2%). And we confirmed that the operation time can be significantly reduced by surgery using intraoperative O-arm device. ConclusionSpinal navigation using intraoperative cone-beam CT scans is reliable for posterior fixation in unstable C1-2 pathologies and can be reduced the operative time.

Intraoperative computed tomography imaging for dose calculation in intraoperative electron radiation therapy: Initial clinical observations.

In intraoperative electron radiation therapy (IOERT) the energy of the electron beam is selected under the conventional assumption of water-equivalent tissues at the applicator end. However, the treatment field can deviate from the theoretic flat irradiation surface, thus altering dose profiles. This patient-based study explored the feasibility of acquiring intraoperative computed tomography (CT) studies for calculating three-dimensional dose distributions with two factors not included in the conventional assumption, namely the air gap from the applicator end to the irradiation surface and tissue heterogeneity. In addition, dose distributions under the conventional assumption and from preoperative CT studies (both also updated with intraoperative data) were calculated to explore whether there are other alternatives to intraoperative CT studies that can provide similar dose distributions. The IOERT protocol was modified to incorporate the acquisition of intraoperative CT studies before radiation delivery in six patients. Three studies were not valid to calculate dose distributions due to the presence of metal artefacts. For the remaining three cases, the average gamma pass rates between the doses calculated from intraoperative CT studies and those obtained assuming water-equivalent tissues or from preoperative CT studies were 73.4% and 74.0% respectively. The agreement increased when the air gap was included in the conventional assumption (98.1%) or in the preoperative CT images (98.4%). Therefore, this factor was the one mostly influencing the dose distributions of this study. Our experience has shown that intraoperative CT studies are not recommended when the procedure includes the use of shielding discs or surgical retractors unless metal artefacts are removed. IOERT dose distributions calculated under the conventional assumption or from preoperative CT studies may be inaccurate unless the air gap (which depends on the surface irregularities of the irradiated volume and on the applicator pose) is included in the calculations.

Surgical Management of Panfacial Fractures.

The evaluation and management of a patient with panfacial fractures are multifaceted. Herein, we describe basic facial skeletal anatomy, considerations for airway securing, and common concurrent injuries. Finally, we discuss primary and secondary reconstructions of facial trauma including sequencing of repair, available landmarks, and the utility of intraoperative computed tomography imaging and virtual surgical planning with custom implants.

Development of mobile intraoperative computed tomography imaging system and assessment of its performance in a brain and body phantom study

Intraoperative computed tomography (iCT) system has been developed focusing on combining the advanced imaging techniques for the best imaging modality. However, the use of iCT system in the operating rooms is limited due to the lack of flexible mobility. This study aims to develop a mobile iCT imaging system and assess its imaging performance in a phantom study. The mobile iCT system with mecanum omni-directional wheels has three major components namely, a rotating gantry, a slip-ring and a stationary gantry. Performance of mecanum iCT system was evaluated using the indices of signal-to-noise (SNR), contrast-to noise (CNR), and spatial resolution (MTF). Anatomical landmarks on phantom images were assessed using a 5-point scale (5 = definitely seen; 4 = probably seen; 3 = equivocal; 2 = probably not seen; and 1 = definitely not seen). The mecanum iCT system can be conveniently used for a whole-body scan under intraoperative conditions even in narrow operating rooms due to a smaller turning radius. The image quality of the mecanum iCT system was found to be acceptable for clinical applications (with SNR = 162.72, CNR = 134.29 and MTF = 694 μm). The diagnostic scores on the phantom images were 'definitely seen' value. The proposed mecanum iCT system achieved the improved flexible mobility and has potential to better serve as a useful imaging tool in the clinical intraoperative setting.

Navigated minimally invasive facet fusion during percutaneous lumbar pedicle screw insertion: Technical note

ObjectiveMinimally invasive surgery (MIS), or percutaneous, lumbar pedicle screw placement is commonly done, but the percutaneous nature of this makes posterior arthrodesis extremely difficult. Many times, surgeons will simply forego posterior arthrodesis, place posterior pedicle screws, and rely only on the interbody area for arthrodesis. We describe our technique of adding facet arthrodesis via the same corridor through which the pedicle screw is inserted with minimal addition of time or steps. MethodsWe demonstrate our technique of how we use navigation and tubular retractors to perform posterior facet arthrodesis during percutaneous pedicle screw placement. We illustrate this technique with a case of a patient with scoliosis, intraoperative photos, and an illustrative video. We also show an intraoperative computed tomography image to help visualize the arthrodesis surfaces. With this technique, we show how there are a few additional steps that are not very time consuming to add posterior arthrodesis. ResultsMIS facet fusion can be performed in a relatively straightforward manner during percutaneous pedicle fixation without significant addition of intraoperative time or steps. ConclusionsIt is possible to add posterior arthrodesis to percutaneous lumbar pedicle screw fusion with few added steps and minimal addition of time using navigation and MIS tubular retractors.