Intraoperative Cone-beam Computed Tomography Imaging Research Articles

Image-Guided Transbronchial Pulmonary Cryoablation with a Flexible Cryoprobe in Swine: Performance and Radiology-Pathology Correlation

PurposeTo evaluate the performance of a prototype flexible transbronchial cryoprobe compared with that of percutaneous transthoracic cryoablation and to define cone-beam computed tomography (CT) imaging and pathology cryolesion features in an in vivo swine model. Materials and MethodsTransbronchial cryoablation was performed with a prototype flexible cryoprobe (3 central and 3 peripheral lung ablations in 3 swine) and compared with transthoracic cryoablation performed with a commercially available rigid cryoprobe (2 peripheral lung ablations in 1 swine). Procedural time and cryoablation success rates for endobronchial navigation and cryoneedle deployment were measured. Intraoperative cone-beam CT imaging features of cryolesions were characterized and correlated with gross pathology and hematoxylin and eosin–stained sections of the explanted cryolesions. ResultsThe flexible cryoprobe was successfully navigated and delivered to each target through a steerable guiding sheath (6/6). At 4 minutes after ablation, 5 of 6 transbronchial and 2 of 2 transthoracic cryolesions were visible on cone-beam CT. The volumes on cone-beam CT images were 55.5 cm3 (SE ± 8.0) for central transbronchial ablations (n = 2), 72.5 cm3 (SE ± 8.1) for peripheral transbronchial ablations (n = 3), and 79.5 cm3 (SE ±11.6) for peripheral transthoracic ablations (n = 2). Pneumothorax developed in 1 animal after transbronchial ablation and during ablation in the transthoracic cryoablation. Images of cryoablation zones on cone-beam CT correlated well with the matched gross pathology and histopathology sections of the cryolesions. ConclusionsTransbronchial cryoablation with a flexible cryoprobe, delivered through a steerable guiding sheath, is feasible. Transbronchial cryoablation zones are imageable with cone-beam CT, with gross pathology and histopathology similar to those of transthoracic cryoablation.

First clinical application of image-guided intraoperative electron radiation therapy with real time intraoperative dose calculation in recurrent rectal cancer: technical procedure

Intraoperative radiation therapy (IORT) is a radiation technique applying a single fraction with a high dose during surgery. We report the first abdomino-pelvic application of an image-guided intraoperative electron radiation therapy with intraoperative real time dose calculation based on the individual intraoperative patient anatomy. A patient suffering from locoregionally recurrent rectal cancer after treatment with neoadjuvant re-chemoradiation was chosen for this approach. After surgical removal of the recurrence, an adequate IORT applicator was placed as usual. A novel mobile imaging device (ImagingRing, MedPhoton) was positioned around the patient covering the region to be treated with the IORT-applicator in place. It allowed the acquisition of three-dimensional intraoperative cone-beam computed tomography images suitable for dose calculation using an automated scaling (heuristic object and head scatter as well as hardening corrections) of Hounsfield units. After image acquisition confirmed the correct applicator position, the images were transferred to our treatment planning system for intraoperative dose calculation. Treatment could be accomplished using the calculated dose distribution. We herein describe the details of the procedure including necessary adjustments in the typically used IORT equipment and work flow. We further discuss the pros and cons of this new approach generally overcoming a decade long limitation of IORT procedures as well as future perspectives regarding IORT treatments.

PDS-MAR: a fine-grained projection-domain segmentation-based metal artifact reduction method for intraoperative CBCT images with guidewires

Objective. Since the invention of modern Computed Tomography (CT) systems, metal artifacts have been a persistent problem. Due to increased scattering, amplified noise, and limited-angle projection data collection, it is more difficult to suppress metal artifacts in cone-beam CT, limiting its use in human- and robot-assisted spine surgeries where metallic guidewires and screws are commonly used. Approach. To solve this problem, we present a fine-grained projection-domain segmentation-based metal artifact reduction (MAR) method termed PDS-MAR, in which metal traces are augmented and segmented in the projection domain before being inpainted using triangular interpolation. In addition, a metal reconstruction phase is proposed to restore metal areas in the image domain. Main results. The proposed method is tested on both digital phantom data and real scanned cone-beam computed tomography (CBCT) data. It achieves much-improved quantitative results in both metal segmentation and artifact reduction in our phantom study. The results on real scanned data also show the superiority of this method. Significance. The concept of projection-domain metal segmentation would advance MAR techniques in CBCT and has the potential to push forward the use of intraoperative CBCT in human-handed and robotic-assisted minimal invasive spine surgeries.

A New Noninvasive Frameless Registration System for Stereotactic Cranial Biopsy: A Technical Note.

Although frame-based stereotactic biopsy is still considered the gold standard for brain biopsies, frameless robot-assisted stereotactic systems are now able to provide an equal level of safety and accuracy. However, both systems suffer from a lack of efficiency of the operative workflow. To describe the technique of a new frameless and noninvasive registration tool Neurolocate (Renishaw). This tool, combined with an intraoperative cone-beam computed tomography imaging system like O-ARM (Medtronic), might facilitate the achievement and workflow of robot-assisted stereotactic intracranial biopsies. Neurolocate is a 3-dimensional fiducial tool fixed directly on the Neuromate (Renishaw) robot arm. It consists of 5 radio-opaque spherical fiducials, whose geometry is constant. This tool made it possible to carry out the coregistration then the biopsy in the same operating time, following a five-step procedure described here. We retrospectively extracted selected preliminary results from our initial experience. Over 1 year, 23 consecutive adult patients were biopsied with Neurolocate in our center. The mean overall operative time, from patient's installation to skin closure, was 97 minutes ± 27 (SD). The entire procedure took place in a single location unit (operating room), which facilitated workflow and surgical planning. No invasive gesture was performed outside of the operating time. Neurolocate is a new frameless and noninvasive registration tool that could improve workflow and flexibility for operating room management and surgical planning. It may also increase the comfort of patients undergoing robot-assisted intracranial stereotactic biopsies. The accuracy and safety profile should be addressed in specific studies.

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.

Zygomaticomaxillary complex fracture repair with intraoperative CBCT imaging. A prospective cohort study

The aim of this study was to evaluate the value of intraoperative conebeam computed tomography (CBCT) imaging in the treatment of zygomaticomaxillary complex (ZMC) fractures.A prospective single center cohort study was performed. Included were consecutive patients who underwent surgery for a unilateral ZMC fracture. An intraoperative CBCT scan was performed after reduction of the ZMC fracture. Revision reduction was performed of the ZMC and/or orbital floor (OF) on indication. The preoperative and postoperative asymmetry of the outer surface of the ZMC was measured on digital 3D-models of CBCT scans, using a mirroring and surface-based matching technique. The postoperative asymmetry of the ZMC in the study group was compared to the asymmetry of the ZMC in the control group with healthy individuals.A total of 38 patients with a unilateral ZMC fracture were included. The mean postoperative asymmetry in the study group (1.67 mm, SD 0.89) was less than the mean preoperative asymmetry (2.69 mm, SD 0.95) (paired samples T-test p < 0.01) but showed no statistically significant difference with the mean asymmetry in the healthy control group (1.40 mm, SD 0.54) (independent samples T-test p = 0.31). Revision reduction of the ZMC and/or OF fracture had been performed in 11 cases after malalignment was noted on the intraoperative CBCT. The indication for intraoperative revision reduction was associated with comminuted ZMC fractures and/or fractures with indication for OF reduction (Pearson Chi Square p < 0.01).Within the limitations of the study, intraoperative CBCT imaging seemed to have a positive influence on ZMC fracture treatment, especially in the case of comminuted ZMC fractures and/or fractures with indication for OF treatment.

Intraoperative Cone Beam CT in Hybrid Operation Room for Pediatric Scoliosis Patients: Comparison of Pedicle Screw Violation Rate at Normal and Low Radiation Doses.

Retrospective observational study. This study aimed to determine the effect of reducing the radiation dose of intraoperative cone beam computed tomography (CBCT) during posterior spinal fusion (PSF) for pediatric scoliosis on the rate of pedicle screw (PS) violation. Intraoperative CBCT for pediatric scoliosis improves the accuracy of PS insertion in PSF. However, few reports have addressed the PS perforation rate from reduced radiation doses in hybrid navigation. We evaluated 855 PSs inserted into 58 pediatric scoliosis patients (11 male and 47 female, mean age: 16.6 yr) who underwent PSF using CBCT. A radiation dose of 1/3 or 1/5 of the normal dose (ND) was defined as a low dose (LD). After PS insertion, intraoperative CBCT images were reviewed to assess the degree of PS perforation. G2-3 (i.e., perforations of 4 mm or more) was defined as a violation. The PS violation rate was compared between the groups, and factors associated with violations were examined. A total of 567 and 288 screws were inserted in the ND group and LD group, respectively. The PS violation rate was comparable at 1.8% in the ND group and 1.7% in the LD group. Multiple logistic regression analysis showed that distance from the upper instrumented vertebra (UIV) was an independently associated factor of PS violation (+1 vertebra, operation room 0.73, P = 0.038). In addition, the mean height of patients with PS violations (148.8 ± 3.6 cm) was significantly shorter than that of patients without violations (157.9 ± 1.2 cm) ( P = 0.034). There was no increase in PS violation rate with lower doses of radiation for intraoperative navigation CBCT. Extra care is warranted for vertebrae close to the UIV and patients of shorter stature.Level of Evidence: 3.

Impact of intraoperative Cone-Beam Computed Tomography use on patient satisfaction after closed nasal reduction

Background: The aim of the study was to assess, whether there is a difference in aesthetic and functional patient satisfaction between closed nasal reductions with intraoperative Cone-Beam Computed Tomography (CBCT) and without using intraoperative medical imaging. Methods: A monocentric, retrospective cohort study of 43 patients (20 patients treated with intraoperative CBCT and 23 patients treated without intraoperative imaging) was conducted. Subjective postoperative aesthetic and functional aspects of the nose were assessed. Additionally, questions comparing the aesthetics and function of the nose before and after the accident and on the desire of revision surgery were asked. Results: Both the SCHNOS-C and total SCHNOS score in the non-CBCT group were higher than the respective scores of the CBCT-group. The comparison of SCHNOS-C between male subjects of the two groups showed no statistical significance. The comparison of SCHNOS-C between male and female subjects over both groups showed significantly higher scores for female subjects. Conclusions: Patients undergoing surgery with intraoperative CBCT imaging showed better aesthetical outcomes than patients, treated without intraoperative imaging. However, the difference showed no clinical importance, so that both strategies appear to have comparable outcomes regarding postoperative aesthetics and function of the nose. Gender instead of the different strategies could contribute to the demonstrated differences. Female subjects seem to be less satisfied with the aesthetics of their nose postoperatively, potentially being more sensitive to remaining nasal deformities after surgery.

Virtual surgical planning and cone beam computed tomography in reconstruction of head and neck tumors - pilot study.

&lt;b&gt;Introduction:&lt;/b&gt; The aim of the study was to prove that a combination of visual surgical planning (VSP) and cone beam computed tomography (CBCT) is an optimal technique in fibular free flap reconstructions after complex tumor resections in the head and neck region and that it leads to better functional and aesthetic outcomes. &lt;br&gt;&lt;b&gt;Material and method:&lt;/b&gt; Six patients (3 females, 3 males) with head and neck tumors were included in the study. The region concerned midface in 2 cases and mandible in 4 patients. On the basis of computed tomography of the head, fibular free flap (FFF) reconstruction was planned with the VSP technique. The 3D-printed models were prepared. At the beginning of the operation and a few minutes after the reconstruction, an xCAT CBCT by XORAN was performed. Minor corrections of the angles of the reconstructed bony parts were made where needed. The time of the operation was assessed for each case. Functional and cosmetic results were evaluated in a 1-year follow-up. &lt;br&gt;&lt;b&gt;Results:&lt;/b&gt; The mean time of operation was 6 hours and 48 minutes, which was approximately 1hour and 40 minutes less than standard reconstructive surgery. Functional recovery was achieved in all patients. Aesthetic result was unsatisfactory for 2 patients due to insufficient soft tissue masses of FFF. &lt;br&gt;&lt;b&gt;Conclusions:&lt;/b&gt; The authors claim that intraoperative CBCT imaging, regardless of the cost, improves the accuracy of aesthetic outcome of reconstructive surgeries based on VSP, especially in the region of the midface and the mandible. Further studies on a higher number of subjects are required.

Fusion of augmented reality imaging with the endoscopic view for endonasal skull base surgery; a novel application for surgical navigation based on intraoperative cone beam computed tomography and optical tracking.

ObjectiveSurgical navigation is a well-established tool in endoscopic skull base surgery. However, navigational and endoscopic views are usually displayed on separate monitors, forcing the surgeon to focus on one or the other. Aiming to provide real-time integration of endoscopic and diagnostic imaging information, we present a new navigation technique based on augmented reality with fusion of intraoperative cone beam computed tomography (CBCT) on the endoscopic view. The aim of this study was to evaluate the accuracy of the method.Material and methodsAn augmented reality surgical navigation system (ARSN) with 3D CBCT capability was used. The navigation system incorporates an optical tracking system (OTS) with four video cameras embedded in the flat detector of the motorized C-arm. Intra-operative CBCT images were fused with the view of the surgical field obtained by the endoscope’s camera. Accuracy of CBCT image co-registration was tested using a custom-made grid with incorporated 3D spheres.ResultsCo-registration of the CBCT image on the endoscopic view was performed. Accuracy of the overlay, measured as mean target registration error (TRE), was 0.55 mm with a standard deviation of 0.24 mm and with a median value of 0.51mm and interquartile range of 0.39˗˗0.68 mm.ConclusionWe present a novel augmented reality surgical navigation system, with fusion of intraoperative CBCT on the endoscopic view. The system shows sub-millimeter accuracy.

Improved Results in Closed Reduction of Zygomatic Arch Fractures by the Use of Intraoperative Cone-Beam Computed Tomography Imaging

The use of intraoperative imaging could help overcome the insufficiency of closed reduction that can result from the absence of visible feedback to evaluate the accuracy of the reduction in isolated zygomatic arch fractures. The aim of the present study was to evaluate the use of intraoperative 3-dimensional cone-beam computed tomography (CBCT) to improve the accuracy of reduction, by measuring the remaining cortical step and dislocation angle. We also evaluated the effect of CBCT on the need for repeat surgery. We performed a retrospective cohort study of patients who had undergone zygomatic arch reduction surgery from January 2008 to May 2018. The patients were grouped according to the predictor variables into group A (postoperative radiologic follow-up studies) and group B (intraoperative CBCT imaging studies). The primary outcome variables were the remaining cortical step and dislocation angle compared with the ideal virtually mirrored position. These were assessed as measures of reduction accuracy. The secondary variables included age, gender, surgery duration, and fracture type. Statistical analysis was performed using a robust multiple regression analysis. The 45 patients were divided into 2 subgroups with 18 patients in the no intraoperative imaging (control) group and 27 patients in the intraoperative imaging group. Insufficient reduction occurred in 1 patient in the group without intraoperative imaging, leading to repeat surgery. No repeat surgery was necessary in the intraoperative imaging group. The remaining cortical step of the intraoperative imaging group was significantly lower than that of the control group (0.18 vs 2.03mm; P<.001). For the remaining dislocation angle, similar findings were observed but without statistical significance (3.93° vs 7.75°; P=.58). The use of intraoperative CBCT significantly increased the accuracy of the reduction. Furthermore, the need for repeat surgery was not required for any patient in the intraoperative imaging group with CBCT-guided reduction.

Radiation exposure to the patients in thoracic and lumbar spine fusion using a new intraoperative cone-beam computed tomography imaging technique: a preliminary study.

The goals of this paper are to assess the ionizing radiation exposure to the patients during thoracic and lumbar spinal fusion using a new intraoperative 3D imaging system and to evaluate the factors that could explain the variability in the observed doses. We retrospectively reviewed 97 patients who underwent posterior instrumented thoracic and/or lumbar spinal fusion from December 2013 to November 2014. Primary data were the total dose area product (total DAP, Gycm2) and total skin dose (total SD, mGy). Influence of different variables (patient characteristics, surgical technique, and intraoperative imaging system parameters) that could influence patients' exposure was analyzed. Radiation dose imparted to patients depended on four parameters including acquisition protocol, surgical technique, patient's BMI and operative time. Minimally invasive surgery (MIS) resulted in twofold higher dose for patients, compared to open surgery. The use of low dose acquisition protocols reduced patient exposure by a factor three. Patient exposure was highly variable. Four parameters were found to explain about 68% of its variance when using a multi-axis robotic C-arm system. MIS technique (with navigation or not) as well as the acquisition protocol dramatically increases the radiation dose for patients. These results show the necessity to develop specific strategies adapted to patients and surgical procedures.

Usefulness of Intraoperative Cone Beam CT Images on Video-assisted Thoracic Surgery.

For the resection of pulmonary ground glass opacity (GGO) or non-palpable nodule on video-assisted thoracic surgery (VATS), preoperative computed tomography (CT)-guided VATS marker pricking is usually performed. Recently, air embolisms after VATS marker pricking have been reported to be serious problems. The purpose of this study was to evaluate the usefulness of intraoperative cone beam CT images on VATS to avoid preoperative VATS marker pricking. The CT number of the both GGO and nodule indicate the range from -200 to -800 HU in general. We evaluated the detection ability of the lesion in seven elements and the simulated lungs. The result indicated that there was a linear equation of "y=1.0599×-2.1492" and the degree of correlation was "R2=0.9826" for the relationship between CT number and W number [voxel number in cone beam computed tomography (CBCT)]. Evaluation of low contrast resolution has been performed. The contrast noise ratios were 2.86 on CBCT and 1.50 on multi detector-row computed tomography (MDCT), while the relative contrast ratios were same both on CBCT and MDCT (0.19) as the lowest CT number (-700 HU). In clinical situation, four types of pulmonary lesions (pure GGO, mixed GGO, solid nodule, and cyst) were detected on MDCT, and intraoperative CBCT could identify all lesions as same configuration as on MDCT. The contrast noise ratio (CNR) and relative contrast ratio (RCR) could not admit the significant difference. In conclusion, the intraoperative CBCT can be used as a non-invasive image navigator for VATS, and the preoperative CT-guided VATS marker pricking can be avoided.

Clinical applications of cone beam computed tomography in endodontics: A comprehensive review.

The use of cone beam computed tomography (CBCT) in endodontics has been extensively reported in the literature. Compared with the traditional spiral computed tomography, limited field of view (FOV) CBCT results in a fraction of the effective absorbed dose of radiation. The purpose of this manuscript is to review the application and advantages associated with advanced endodontic problems and complications, while reducing radiation exposure during complex endodontic procedures. The benefits of the added diagnostic information provided by intraoperative CBCT images in select cases justify the risk associated with the limited level of radiation exposure.

Value of intra- and post-operative cone beam computed tomography (CBCT) for positioning control of a sphenopalatine ganglion neurostimulator in patients with chronic cluster headache

IntroductionThe objective of this study was to determine whether postoperative control of the neurostimulator placement within the pterygopalatine fossa (PPF) by means of 3-dimensional (3D) cone beam computed tomography (CBCT) was of therapeutic relevance compared to intraoperative CBCT imaging alone. Material and methodsImmediately after implantation of the sphenopalatine ganglion (SPG) neurostimulator, intraoperative CBCT datasets were generated in order to visualize the position of the probe within the PPF. Postoperatively, all patients received a CBCT for comparison with intraoperatively acquired radiographs. ResultsTwenty-four patients with cluster headache (CH) received an SPG neurostimulator. In 4 patients, postoperative CBCT images detected misplacement not found in intraoperative CBCT. In 3 cases, electrode tips were misplaced into the maxillary sinus and in 1 case into the apex of the PPF superior to the suspected location of the SPG. Immediate revision with successful repositioning within 3 days was done in 2 patients and a deferred reimplantation in 1 patient within 6 months. One patient declined revision. ConclusionWe were able to demonstrate the clinical value of postoperative dental CBCT imaging with a wide region of interest (ROI) due to a superior image quality compared with that achieved with intraoperative medical CBCT. Although intraoperative 3D CBCT imaging of electrode placement is helpful in the acute surgical setting, resolution is, at present, too low to safely exclude misplacement, especially in the maxillary sinus. High-resolution postoperative dental CBCT allows rapid detection and revision of electrode misplacement, thereby avoiding readmission and recurrent tissue trauma.

Evaluation of intraoperative cone beam computed tomography and optical drill tracking in temporal bone surgery

A prototype system for intraoperative cone beam computed tomography (CBCT) imaging has been developed and augmented with real time optical tracking of a surgical drill. We hypothesize that this system provides sufficient accuracy for guidance of temporal bone surgery. Basic research. Measurements of drill localization accuracy using CBCT imaging were obtained with a custom three-dimensional calibration object. Integrated CBCT imaging and drill tracking were prospectively evaluated on 12 cadaver temporal bones. Six inexperienced and six experienced surgeons conducted four surgical tasks: cortical mastoidectomy, posterior tympanotomy, cochleostomy, and a translabyrinthine approach to the internal auditory canal. Questionnaires provided expert feedback on tracking accuracy and system usability. Target registration error measurements of drill tracking accuracy and precision yielded a mean of 0.76 mm, a maximum of 1.30 mm, and a standard deviation of 0.21 mm. Anatomical landmark identification tasks (e.g., facial nerve, incus, semicircular canals, cochlea) provided additional validation of system accuracy. The usability and utility of the guidance system were positively rated by both groups of surgeons, with further modifications underway to improve tracking line of sight and registration workflow. Experienced but in particular inexperienced surgeons indicated significant benefits in cases involving extensive disease, abnormal anatomy, and loss of anatomical landmarks. The integration of intraoperative CBCT imaging with optical tracking provides sufficient accuracy to localize anatomical structures within the temporal bone using an otological drill. Future studies will explore the role of this technology in complex oncological resections, in surgery for congenital anomalies, and as a tool for teaching.

Intraoperative Endodontic Applications of Cone-Beam Computed Tomography

IntroductionThe use of cone-beam computed tomography (CBCT) in endodontics for diagnosis, treatment planning, and follow-up has been extensively reported in the literature. Compared with the traditional spiral computed tomography, high-resolution limited CBCT results in a fraction of the effective absorbed dose of radiation. However, it should be prescribed only after weighing the cost of radiation exposure with the benefit of the diagnostic information that can be obtained from the scan. MethodsThe purpose of this article is to discuss the application and advantages of intraoperative CBCT in endodontics, while reducing radiation exposure during complex endodontic procedures. ResultsIn cases of increased difficulty or intraoperative complications such as complex anatomy, dystrophic calcifications, root resorptions, perforations, and root fractures, it is prudent to consider the use of CBCT with its inherent diagnostic value and limited radiation exposure. ConclusionsThe benefits of the added diagnostic information provided by intraoperative CBCT images in select cases justify the risk associated with the limited level of radiation exposure.

Volume rendering of three-dimensional fluoroscopic images for percutaneous scaphoid fixation: An in vitro study

Percutaneous fixation of scaphoid fractures offers potential advantages to cast treatment but can be difficult to perform with conventional two-dimensional imaging. This study aimed to evaluate the use of a novel navigation technique using volume-rendered images derived from intraoperative cone-beam computed tomography imaging, without the need for typical patient-based registration. Randomized in vitro trials in which a guidewire was inserted into a scaphoid model were conducted to compare volumetric navigation to conventional fluoroscopic C-arm (n = 24). Central wire placement, surface breach, procedure time, drilling attempts, and radiation exposure were compared between groups. Compared to conventional percutaneous insertion, navigation achieved equal or significantly better placement of the guidewire with fewer drilling attempts and less radiation exposure. On average, navigation took 74 s longer to perform than the conventional method, which was statistically significant but clinically irrelevant. This evaluation suggests that the technology is promising and may have many clinical benefits including improved fixation placement, fewer complications, and less radiation exposure. The intraoperative workflow is more efficient and eliminates the need for preoperative computed tomography, image segmentation, and patient-based registration typical of traditional navigated procedures.

Volume CT with a flat‐panel detector on a mobile, isocentric C‐arm: Pre‐clinical investigation in guidance of minimally invasive surgery

A mobile isocentric C-arm (Siemens PowerMobil) has been modified in our laboratory to include a large area flat-panel detector (in place of the x-ray image intensifier), providing multi-mode fluoroscopy and cone-beam computed tomography (CT) imaging capability. This platform represents a promising technology for minimally invasive, image-guided surgical procedures where precision in the placement of interventional tools with respect to bony and soft-tissue structures is critical. The image quality and performance in surgical guidance was investigated in pre-clinical evaluation in image-guided spinal surgery. The control, acquisition, and reconstruction system are described. The reproducibility of geometric calibration, essential to achieving high three-dimensional (3D) image quality, is tested over extended time scales (7 months) and across a broad range in C-arm angulation (up to 45 degrees), quantifying the effect of improper calibration on spatial resolution, soft-tissue visibility, and image artifacts. Phantom studies were performed to investigate the precision of 3D localization (viz., fiber optic probes within a vertebral body) and effect of lateral projection truncation (limited field of view) on soft-tissue detectability in image reconstructions. Pre-clinical investigation was undertaken in a specific spinal procedure (photodynamic therapy of spinal metastases) in five animal subjects (pigs). In each procedure, placement of fiber optic catheters in two vertebrae (L1 and L2) was guided by fluoroscopy and cone-beam CT. Experience across five procedures is reported, focusing on 3D image quality, the effects of respiratory motion, limited field of view, reconstruction filter, and imaging dose. Overall, the intraoperative cone-beam CT images were sufficient for guidance of needles and catheters with respect to bony anatomy and improved surgical performance and confidence through 3D visualization and verification of transpedicular trajectories and tool placement. Future investigation includes improvement in image quality, particularly regarding x-ray scatter, motion artifacts and field of view, and integration with optical tracking and navigation systems.