Intraoperative CT Imaging Research Articles

A service for monitoring the quality of intraoperative cone beam CT images

Abstract In recent years, operating rooms (ORs) have transformed into integrated operating rooms, where devices are able to communicate, exchange data, or even steer and control each other. However, image data processing is commonly done by dedicated workstations for specific clinical use-cases. In this paper, we propose a concept for a dynamic service component for image data processing on the example of automatic image quality assessment (AQUA) of intraoperative cone beam computed tomography (CBCT) images. The service is build using the Open Surgical Communication Protocol (OSCP) and the standard for Digital Imaging and Communications in Medicine (DICOM). We have validated the proposed concept in an integrated demonstrator OR.

The intraoperative portable CT scanner-based spinal navigation: a viable option for instrumentation in the region of cervico-thoracic junction.

Innovative intraoperative imaging modalities open new horizons to more precise image acquisition and possibly to better results of spinal navigation. Planning of screw entry points and trajectories in this prospective study had been based on intraoperative imaging obtained by a portable 32-slice CT scanner. The authors evaluated accuracy and safety of this novel approach in the initial series of 18 instrumented surgeries in anatomically complex segment of cervico-thoracic junction. We report on the single-institution results of assessment of anatomical accuracy of C5-T3 pedicle screw insertion as well as its clinical safety. The evaluation of total radiation dose and of time demands was secondary endpoint of the study. Out of 129 pedicle screws inserted in the segment of C5-T3, only 5 screws (3.9%) did not meet the criteria for correct implant positioning. These screw misplacements had not been complicated by neural, vascular or visceral injury and surgeon was not forced to change the position intraoperatively or during the postoperative period. Quality of intraoperative CT imaging sufficient for navigation was obtained at all spinal segments regardless of patient´s habitus, positioning or comorbidity. A higher radiation exposition of the patient and 27min longer operative time are consequences of this technique. The intraoperative portable CT scanner-based spinal navigation is a reliable and safe method of pedicle screw insertion in cervico-thoracic junction.

Percutaneous pedicle screw placements: accuracy and rates of cranial facet joint violation using conventional fluoroscopy compared with intraoperative three-dimensional computed tomography computer navigation.

The goal of this study was to compare the accuracy and cranial facet joint violation rates between percutaneous pedicle screw placements using conventional fluoroscopy and intraoperative 3-D CT (O-arm) computer navigation. We reviewed 194 pedicle screw of 28 consecutive patients who underwent minimally invasive lumbar or thoracic spinal stabilization. The accuracy of screw placement was evaluated according to two criteria published by Neo et al. and Upendra et al. Facet joint violation was evaluated according to the classification described by Babu et al. Upon Neo grading, CFT group had 19.4% (14/72) pedicle breach rate and CT-IGN group had a 5.7% (7/122) pedicle breach rate (p<0.005). The same sets of screws were also assessed using the outcome-based classification established by Upendra. There were no screw caused neurovascular injuries (type 3=0) in both groups. The results showed that 87.5% (63/72) screws had acceptable placements (type I) and 12.5% (9/72) had unacceptable placements (type II) in CFT group. In contrast, 94.3% (115/122) screw had acceptable placements (type I) and only 5.7% (7/122) had unacceptable placements (type II) in CT-IGN group. Additionally, CFT group had a significantly higher facet joint violation rate of 30.5% (11/36) than CT-IGN group that had a 3.8% (3/79) violation rate (p<0.005). This study indicated the use of intraoperative CT imaging (O-arm) navigation in PPS placement have very beneficial implications for MIS.

Automatic localization of endoscope in intraoperative CT image: A simple approach to augmented reality guidance in laparoscopic surgery.

The use of augmented reality in minimally invasive surgery has been the subject of much research for more than a decade. The endoscopic view of the surgical scene is typically augmented with a 3D model extracted from a preoperative acquisition. However, the organs of interest often present major changes in shape and location because of the pneumoperitoneum and patient displacement. There have been numerous attempts to compensate for this distortion between the pre- and intraoperative states. Some have attempted to recover the visible surface of the organ through image analysis and register it to the preoperative data, but this has proven insufficiently robust and may be problematic with large organs. A second approach is to introduce an intraoperative 3D imaging system as a transition. Hybrid operating rooms are becoming more and more popular, so this seems to be a viable solution, but current techniques require yet another external and constraining piece of apparatus such as an optical tracking system to determine the relationship between the intraoperative images and the endoscopic view. In this article, we propose a new approach to automatically register the reconstruction from an intraoperative CT acquisition with the static endoscopic view, by locating the endoscope tip in the volume data. We first describe our method to localize the endoscope orientation in the intraoperative image using standard image processing algorithms. Secondly, we highlight that the axis of the endoscope needs a specific calibration process to ensure proper registration accuracy. In the last section, we present quantitative and qualitative results proving the feasibility and the clinical potential of our approach.

Accuracy and safety of targeting using intraoperative “O-arm” during placement of deep brain stimulation electrodes without electrophysiological recordings

The aim of our study was to investigate the accuracy of targeting using intraoperative “O-arm” during deep brain stimulation (DBS) surgery. Intraoperative O-arm (Medtronic, Minneapolis, MN, USA) images were obtained to confirm the accuracy of placement. The difference between intended and actual target coordinates was calculated based on intraoperative images and postoperative CT scan. Euclidian vector error was obtained to estimate the directional error. Correlation of targeting error with the pneumocephalus and the deviation from the planned trajectory was also estimated. Twenty eight DBS leads (globus pallidus internus [GPi], n=13; subthalamic nucleus [STN], n=9; ventralis intermedius nucleus [VIM], n=6) were implanted in 20 patients using the stereotactic Leksell frame (Elekta AB, Stockholm, Sweden) under general anesthesia over a period of 1year. The mean age was 63.6±standard error of the mean (SEM) 15.7years and 60% of patients were males. The mean absolute difference (+SEM) between intended and actual target in x, y and z coordinates based on intraoperative CT scan was 0.65±0.09 (p=0.84), 0.58±0.08 (p=0.98), 1.13±0.10 (p=0.08), respectively, and postoperative (1month) CT scan was 0.82±0.15 (p=0.89), 0.55±0.11 (p=0.97), and 1.58±0.29 (p=0.08), respectively. The Euclidean vector error was 1.59±0.10 and 2.16±0.26 based on intraoperative and postoperative images, respectively. There was no statistically significant targeting error based on fusion of intraoperative CT images to either preoperative CT scan or MRI as registration series, the presence of pneumocephalus, deviation from planned trajectory or the anatomical target (STN versus VIM versus GPi) (p>0.05). Superficial skin infection was encountered in a single patient in this study. The mean total operating room time was 193.5±74.6 minutes. None of the patients required revision in our study. DBS leads can be implanted safely and accurately using intraoperative O-arm with a frame based targeting system and can be used in selected patients.

24. Contemporary Outcomes For Autogenous Infrainguinal Bypass In the Endovascular Era

Objective: To report our initial experience of using intraoperative C-arm Cone beam CT (DynaCT ) image fusion guidance along with steerable robotic endovascular catheter navigation to facilitate visceral vessel cannulation procedures. Methods: Between October 2012 and August 2014, 11 patients underwent endovascular procedures using DynaCT image fusion technique along with HansenMagellan vascular robotic catheter. All patients had pre-operative contrast enhanced multi-slice CT imaging (MSCT). For case planning, relevant landmarks and centerlines were electronically marked and stored. At the beginning of each procedure, a non-contrast DynaCT was acquired in the hybrid operating room equipped with a flat-panel robotic C-arm angiographic system. Pre-operative images were co-registered to intra-operative DynaCT images using bony structures. Stored landmarks were overlaid on 2D fluoroscopic images as virtual markers. Vascular access and the robotic catheter were setup and performed per standard. Vessel cannulation was attempted based on virtual markers using robotic catheter. The impact of these virtual markers from image fusion on vessel cannulation was evaluated retrospectively. Results: All 14 vessels were cannulated successfully in 11 patients’ attempted using image fusion guidance. Median vessel diameter at origin was 5.1 mm (2.3 to 13mm), while 10/14 vessels had either calcified/stenosed origin from parent vessel, accounting for the range of vessel diameters. 8/14 vessels (57.1%) were cannulated without any contrast injection. Median number of angiograms required before cannulation was 0 (0 2). On qualitative assessment, 11/12 vessels (91.7%) had grade1⁄41 accuracy (guide-wire inside virtual ostial marker). 11/11 vessels had grade1⁄41 accuracy (virtual centerlines that matched with the actual vessel trajectory during cannulation). Conclusion: Our initial experience with using DynaCT image fusion guidance along with steerable endovascular robotic navigation indicates that such strategies enhance intra-operative 2D fluoroscopy and could play a role in reducing contrast agent use therebymaximizing the versatility of endovascular robotic technology.

Intraoperative CT verification of electrode localization in DBS surgery in Parkinson's disease

Precise and accurate placement of electrodes in DBS surgery is essential in achievement of proper therapeutical effect in movement disorders. Verification of their position in the target is necessary. It can be performed postoperatively. But more convenient for the patient is an intraoperative CT imaging in the operating room. We evaluated the results of DBS electrodes implantation in patients with Parkinson's disease by intraoperative CT. 21 patients with Parkinson's disease were operated in 2010–2012 in the Military Clinical Hospital in Bydgoszcz, Poland. Standard procedure of electrode implantation was verified by intraoperative CT in operating room. CT scans were fused with preoperative MRI plan of target (STN) and trajectory and accuracy were assessed. Mean differences between positions of tips of electrodes implanted and intended coordinates of targets were: 0.9 mm; 1.6 mm; and 0.8 mm in horizontal line, in vertical line, and in lateral line respectively and remain within the limits of the intraoperative CT resolution. In 1 case the accuracy was not satisfying and replacement of electrodes in one stage surgery was required. Intraoperative CT is a helpful tool in DBS procedures and enables comparison of preoperative plans with the final trajectory and localization of the tip of electrode visualized in CT in appropriate target. It eliminates necessity of post-op verification outside the operating room. All changes can be done during the procedure. It also allows to rule out the intracerebral haematoma caused by implantation.

Intraoperative portable CT-scanner based spinal navigation - a feasibility and safety study

Navigation based on an intraoperative CT scan is not a new approach to spinal instrumentation. Innovative intraoperative imaging technology, however, opens new horizons to more precise image acquisition as well as to further workflow. Planning of screw entry-points and trajectories in this study had been based on intraoperative imaging obtained by a portable 32-slice CT scanner. This prospective study evaluates feasibility, accuracy, and safety of this novel approach in an initial series of 85 surgeries. Medical records and radiological materials of 82 patients who underwent the first 85 consecutive stabilisations were analysed. Incorrect screw position, medical and technical complications as well as availability of this procedure in particular spinal levels were the subject of evaluation. Out of 571 implants inserted in all spinal levels, only five screws (0.87 %) did not meet the criteria for correct implant position. These screw misplacements had not been complicated by neural, vascular or visceral injury and the surgeon was not forced to change the position intraoperatively or during the postoperative period. The quality of intraoperative CT imaging sufficient for navigation was obtained at all spinal segments regardless of a patient's habitus or positioning or comorbidity. Intraoperative portable CT scanner-based navigation seems to be an effective way of doing spinal instrumentation guidance. High precision of implant insertion confirms the preconditions of navigation usage during more complex surgeries at any level of the spine.

Clinical and radiographic outcomes of minimally invasive percutaneous pedicle screw placement with intraoperative CT (O-arm) image guidance navigation

Intraoperative CT image-guided navigation (IGN) has been increasingly incorporated into minimally invasive spine surgery (MIS). The vast improvement in image resolution and virtual real-time images with CT-IGN has proven superiority over traditional fluoroscopic techniques. The authors describe their perioperative MIS technique using the O-arm with navigation, and they report their postoperative experience, accuracy results, and technical aspects. A retrospective review of 48 consecutive adult patients undergoing minimally invasive percutaneous posterior spinal fusion with intraoperative CT-IGN between July 2010 and August 2013 at Cedars-Sinai Medical Center was performed. Two surgeons assessed 290 screws in a blinded fashion on intraoperative O-arm images and postoperative CT scans for bony pedicle wall breach. Grade 1 breach was defined to be < 2 mm, Grade 2 breach to be between 2 and 4 mm, and a Grade 3 breach to be > 4 mm. Additionally, anterior vertebral body breach was recorded. Of 290 pedicle screws placed, 280 (96.6%) were in an acceptable position without cortical wall or anterior breach. Of the 10 breaches (3.4%) 5 were lateral (50%), 4 were medial, and 1 was anterior; 90% of breaches were Grade 1-2 and all medial breaches were Grade 1. The one Grade 3 breach was lateral. No vascular or neurological complications were observed intraoperatively, and no significant postoperative complications were noted. The mean clinical follow-up period was 18 months (range 3-39 months). The overall clinical outcomes, measured using the visual analog scale (back pain scores), were improved significantly postoperatively at 3 months compared with preoperatively (visual analog score 6.35 vs 3.57; p < 0.0001). No revision surgery was performed for screw misplacement or neurological deterioration. New CT-IGN with the mobile O-arm scanner has increased the accuracy of pedicle screw/instrumentation placement using MIS techniques. The authors' high (96.6%) accuracy rate in MIS compares favorably with historical published accuracy rates for fluoroscopy-based techniques. Additional advantages of CT-IGN over fluoroscopic imaging methods are lower occupational radiation exposure for the surgical team, reduced need for postoperative imaging, and decreased rates of revision surgery. For now, the authors simply conclude that use of intraoperative CT-IGN is safe and accurate.

すりガラス状結節に対する胸腔鏡下肺切除術における術中可動型CT（O-arm）の使用経験―触知不能肺腫瘍に対する新たなアプローチ法―

O-arm Surgical Imaging Systemは，術中に2D及び3Dイメージングが可能なX線透視装置である．呼吸器外科領域でO-armを用いた手術の報告はされていない．我々は，すりガラス状結節（ground glass nodule；GGN）の症例に対しO-armが有用と考え手術を施行した．術中に腫瘍近傍と思われる臓側胸膜に糸付き針でマーキングし，両肺換気下にO-armを用いて術中computed tomography（CT）撮影を施行した．術中CT画像を参考に針マーキングと腫瘍の位置関係を把握し切除した．症例は80歳女性．術前CTで左上葉に10 mm大のGGNを認めた．O-armを用いた術中CTで病変が明確に描出され，病理学的に完全切除が可能だった．術中CT撮影は2回施行した．触知不能な肺病変に対する新たなアプローチ方法として，O-armは有用である可能性がある．

The surgical learning curve and accuracy of minimally invasive lumbar pedicle screw placement using CT based computer-assisted navigation plus continuous electromyography monitoring - a retrospective review of 627 screws in 150 patients.

ObjectiveThis study retrospectively assessed the accuracy of placement of lumbar pedicle screws placed by a single surgeon using a minimally-invasive, intra-operative CT-based computer navigated technique in combination with continuous electromyography (EMG) monitoring. The rates of incorrectly positioned screws were reviewed in the context of the surgeon's experience and learning curve.MethodsData was retrospectively reviewed from all consecutive minimally invasive lumbar fusions performed by the primary author over a period of over 4 years from April 2008 until October 2012. All cases that had utilized computer-assisted intra-operative CT-based image guidance and continuous EMG monitoring to guide percutaneous pedicle screw placement were analysed for the rates of malposition of the pedicle screws. Pedicle screw malposition was defined as having occurred if the screw trajectory was adjusted intraoperatively due to positive EMG responses, or due to breach of the pedicle cortex by more than 2mm on intraoperative CT imaging performed at the end of the instrumentation procedure. Further analysis of the data was undertaken to determine if the rates of malposition changed with the surgeon's experience with the technique.ResultsSix hundred and twenty-seven pedicle screws were placed in one hundred and fifty patients. The overall rate of intraoperative malposition and subsequent adjustment of pedicle screw placement was 3.8% (24 of 627 screws). Screw malposition was detected by intraoperative CT imaging. Warning of potential screw misplacement was provided by use of the EMG monitoring. With increased experience with the technique, rates of intraoperative pedicle screw malposition were found to decrease from 5.1% of screws in the first fifty patients, to 2.0% in the last 50 patients. Only one screw was suboptimally placed at the end of surgery, which did not result in a neurological deficit.ConclusionThe use of CT-based computer-assisted navigation in combination with continuous EMG monitoring during percutaneous transpedicular screw placement results in very low rates of malposition and neural injury that compare favourably with previously reported rates. Pedicle screw placement accuracy continues to improve as the surgeon becomes more experienced with the technique.

3D atlas-based registration can calculate malalignment of femoral shaft fractures in six degrees of freedom

Objective: This study presents and evaluates a semi-automated algorithm for quantifying malalignment in complex femoral shaft fractures from a single intraoperative cone-beam CT (CBCT) image of the fractured limb.Methods: CBCT images were acquired of complex comminuted diaphyseal fractures created in 9 cadaveric femora (27 cases). Scans were segmented using intensity-based thresholding, yielding image stacks of the proximal, distal and comminuted bone. Semi-deformable and rigid affine registrations to an intact femur atlas (synthetic or cadaveric-based) were performed to transform the distal fragment to its neutral alignment. Leg length was calculated from the volume of bone within the comminution fragment. The transformations were compared to the physical input malalignments.Results: Using the synthetic atlas, translations were within 1.71 ± 1.08 mm (medial/lateral) and 2.24 ± 2.11 mm (anterior/posterior). The varus/valgus, flexion/extension and periaxial rotation errors were 3.45 ± 2.6°, 1.86 ± 1.5° and 3.4 ± 2.0°, respectively. The cadaveric-based atlas yielded similar results in medial/lateral and anterior/posterior translation (1.73 ± 1.28 mm and 2.15 ± 2.13 mm, respectively). Varus/valgus, flexion/extension and periaxial rotation errors were 2.3 ± 1.3°, 2.0 ± 1.6° and 3.4 ± 2.0°, respectively. Leg length errors were 1.41 ± 1.01 mm (synthetic) and 1.26 ± 0.94 mm (cadaveric). The cadaveric model demonstrated a small improvement in flexion/extension and the synthetic atlas performed slightly faster (6 min 24 s ± 50 s versus 8 min 42 s ± 2 min 25 s).Conclusions: This atlas-based algorithm quantified malalignment in complex femoral shaft fractures within clinical tolerances from a single CBCT image of the fractured limb.

Real-time image guidance in laparoscopic liver surgery: first clinical experience with a guidance system based on intraoperative CT imaging

Laparoscopic liver surgery is particularly challenging owing to restricted access, risk of bleeding, and lack of haptic feedback. Navigation systems have the potential to improve information on the exact position of intrahepatic tumors, and thus facilitate oncological resection. This study aims to evaluate the feasibility of a commercially available augmented reality (AR) guidance system employing intraoperative robotic C-arm cone-beam computed tomography (CBCT) for laparoscopic liver surgery. A human liver-like phantom with 16 target fiducials was used to evaluate the Syngo iPilot(®) AR system. Subsequently, the system was used for the laparoscopic resection of a hepatocellular carcinoma in segment 7 of a 50-year-old male patient. In the phantom experiment, the AR system showed a mean target registration error of 0.96 ± 0.52 mm, with a maximum error of 2.49 mm. The patient successfully underwent the operation and showed no postoperative complications. The use of intraoperative CBCT and AR for laparoscopic liver resection is feasible and could be considered an option for future liver surgery in complex cases.

New generation intraoperative three-dimensional imaging (O-arm) in 100 spine surgeries: Does it change the surgical procedure?

The O-arm (Medtronic Sofamor Danek, Inc., Memphis, TN, USA), an intraoperative CT scan imaging system, may provide high-quality imaging information to the surgeon. To our knowledge, its impact on spine surgery has not been studied. We reviewed 100 consecutive spine surgical procedures which utilized the new generation mobile intraoperative CT imaging system (O-arm). The most common diagnoses were degenerative conditions (disk disease, spondylolisthesis, stenosis and acquired kyphosis), seen in 49 patients. The most common indication for imaging was spinal instrumentation in 81 patients (74 utilized pedicle screws). In 52 (70%) of these, the O-arm was used to assess screw position after placement; in 22 (30%), it was coupled with Stealth navigation (Medtronic Sofamor Danek, Inc.) to guide screw placement. Another indication was to assess adequacy of spinal decompression in 38 patients; in 19 (50%) of these, intrathecal contrast material was used to obtain an intraoperative CT myelogram. In 20 patients O-arm findings led to direct surgeon intervention in the form of screw removal/repositioning (n=13), further decompression (n=6), interbody spacer repositioning (n=1), and removal of kyphoplasty trocar (n=1). In 20% of spine surgeries, the procedure was changed based on O-arm imaging findings. We found the O-arm to be useful for assessment of instrumentation position, adequacy of spinal decompression, and confirmation of balloon containment and cement filling in kyphoplasty. When used with navigation for image-guided surgery, it obviated the need for registration.

Integration of Intraoperative Ultrasound Volume Into CT-Based Treatment Planning in Prostate HDR Brachytherapy: A Pilot Study

Purpose/Objective(s): The main challenge for CT-based prostate HDR treatment planning is to accurately define target (prostate) volume in CT images due to the poor soft-tissue contrast. To overcome this limitation, we propose a novel approach that integrates an intra-operative ultrasound (US)-based prostate volume into treatment planning through US-CT coregistration based on the catheters (needle tracks). Materials/Methods: In CT-based prostate HDR brachytherapy, needle placement is commonly performed under the guidance of intra-operative transrectal ultrasound, while treatment planning is based on post-operative prostate CT images. However, prostate delineation using CT images is difficult. We have developed a technology that integrates an intraoperative US-based prostate volume into HDR treatment planning. Our approach requires an additional 3D US images acquired in the operating room right after the catheters are inserted, which takes less than 5 minutes. These US images are then used to create prostate contours. The catheters are reconstructed on intra-operative US and post-operative CT images, and subsequently used as landmarks for the US-CT image registration using a fuzzy-to-deterministic algorithm. The intra-operative US-based prostate volume is then deformed using B-splines to the CT image to obtain the accurate CT prostate volume, which is used for treatment planning. Three fiducial (gold) markers are implanted into the prostate and the displacements between their positions on the postregistration US and CT images are used to evaluate the accuracy of our technique. This technique was first tested using a prostate phantom, and further investigated in a prospective study of 10 consecutive patients (age: 59 10) who had received HDR monotherapy or boost brachytherapy for prostate cancer. Results: For the prostate phantom study, 14 catheters and 3 gold markers were implanted. The mean displacement of the 3 gold markers between the post-registration US and CT images was 0.41 0.11 mm, which demonstrated the precision of our intra-operative US-based prostate volume approach. In the pilot study of 10 patients, 14-18 catheters were implanted and 9 out of 10 patients had 3 gold markers implanted. US-CT registration was successfully performed for all 10 patients. The mean displacement of 27 gold markers of the 9 patients was 1.09 0.25 mm. This further demonstrated the feasibility and accuracy of our approach. Conclusions:We have introduced a novel approach that integrates intraoperative ultrasound-based prostate volume into CT-based prostate HDR treatment planning, and demonstrated it clinical feasibility. This technique will improve prostate delineation, enable accurate dose planning and delivery, and potentially enhance prostate HDR treatment outcome. Author Disclosure: X. Yang: None. P. Rossi: None. T. Ogunleye: None. W.J. Curran: None. T. Liu: None.

Percutaneous pedicle screw placement with computer-navigated mapping in place of Kirschner wires

Percutaneous pedicle screw insertion techniques are commonly used to treat a variety of spinal disorders. Typically, Kirschner (K)-wires are used to guide the insertion of taps and screws during placement since the normal anatomical landmarks are not visualized. The use of K-wires adds risks, such as vascular and nerve injuries as well as increased radiation exposure given the use of fluoroscopy. The authors describe a series of patients who had percutaneous pedicle screws placed using a new computer-assisted navigation technique without the need for K-wires. Minimally invasive percutaneous pedicle screw placement in the thoracic and lumbar spine was performed in a consecutive series of 15 patients for a variety of spinal pathologies. Intraoperative 3D CT images were obtained and used with a computer-assisted navigation system to insert an awl-tap into each pedicle. The tap location in the pedicle was marked with the navigation software, and the awl-tap was then removed. The navigation system was used to identify each landmark to insert the pedicle screw. Connecting rods were then inserted percutaneously under fluoroscopic guidance. Postoperative CT scans were obtained in each patient to evaluate screw placement. On postprocedure scanning, only 1 screw had a minor lateral and superior breach that was asymptomatic. To date, there have been no hardware failures. Percutaneous pedicle screws can be placed effectively and safely without the use of K-wires.

Accuracy of deep brain stimulation electrode placement using intraoperative computed tomography without microelectrode recording

In this prospective study the authors' objective was to evaluate the accuracy of deep brain stimulation (DBS) electrode placement using image guidance for direct anatomical targeting with intraoperative CT. Preoperative 3-T MR images were merged with intraoperative CT images for planning. Electrode targets were anatomical, based on the MR images. A skull-mounted NexFrame system was used for electrode placement, and all procedures were performed under general anesthesia. After electrode placement, intraoperative CT images were merged with trajectory planning images to calculate accuracy. Accuracy was assessed by both vector error and deviation off the planned trajectory. Sixty patients (33 with Parkinson disease, 26 with essential tremor, and 1 with dystonia) underwent the procedure. Patient's mean age was 64 ± 9.5 years. Over an 18-month period, 119 electrodes were placed (all bilateral, except one). Electrode implant locations were the ventral intermediate nucleus (VIM), globus pallidus internus (GPI), and subthalamic nucleus (STN) in 25, 23, and 12 patients, respectively. Target accuracy measurements were as follows: mean vector error 1.59 ± 1.11 mm and mean deviation off trajectory 1.24 ± 0.87 mm. There was no statistically significant difference between the accuracy of left and right brain electrodes. There was a statistically significant (negative) correlation between the distance of the closest approach of the electrode trajectory to the ventricular wall of the lateral ventricle and vector error (r(2) = -0.339, p < 0.05, n = 76), and the deviation from the planned trajectory (r(2) = -0.325, p < 0.05, n = 77). Furthermore, when the distance from the electrode trajectory and the ventricular wall was < 4 mm, the correlation of the ventricular distance to the deviation from the planned trajectory was stronger (r(2) = -0.419, p = 0.05, n = 19). Electrodes placed in the GPI were significantly more accurate than those placed in the VIM (p < 0.05). Only 1 of 119 electrodes required intraoperative replacement due to a vector error > 3 mm. In this series there was one infection and no intraparenchymal hemorrhages. Placement of DBS electrodes using an intraoperative CT scanner and the NexFrame achieves an accuracy that is at least comparable to other methods.

Integrated Intraoperative Flat-Panel CT, Vascular Imaging, and Navigation in Skull Base Surgery: An Initial Experience in the Geneva Hybrid Operating Suite

Introduction: Although the advantages of intraoperative imaging in intra-axial tumors are well documented, their role in skull base surgery is not clarified yet. Here, we used an integrated hybrid operating room equipped with a flat panel arm for intraoperative angiography, interventional procedures, and CT acquisition for skull base tumor procedures and describe our initial experience with 19 procedures. Methods: A flat panel system, integrating a pivoting C-arc intraoperative CT (Philips Allura FD20), a surgical microscope (Zeiss Pentero), and infrared-based neuronavigation (Brainlab VectorVision II) was used. Intraoperative 3D angiography and same-session interventional procedures were also possible. Acquisition of images was performed pre-, peri-, or postoperatively. Results: Nineteen surgeries were performed on 15 patients from February 2008 to September 2012: 7 meningiomas (2 foramen magnum, 1 pontocerebellar, 1 sellar, 1 petrosigmoid, 1 jugular foramen, 1 petroclival), 9 chordomas and chondrosarcomas (6 of the clivus, 2 petrous, 1 petroclival), 1 foramen jugular schwannoma, 1 suprasellar teratoma, and 1 petrous breast cancer metastasis. Neuronavigation was used in 12 surgeries. An intraoperative CT was done and correlated to navigation in 5 patients (1 meningioma and 4 chordomas/chondrosarcomas) for resection control in 7 cases, and anatomical orientation in 2 cases. Intraoperative CT imaging was categorized as useful in all patients who had intraoperative CT (9/19, 47%) by helping surgical decisions (change or confirmation of surgical plan). Associated interventional procedures (one immediate preoperative tumor embolization and one endovascular obliteration of an associated dural arteriovenous fistula) were done in two patients. Conclusion: Perioperative CT imaging and navigation can be successfully integrated in skull base procedures without significantly disrupting the surgical workflow. The main advantages of this setting are real-time anatomic orientation and resection control when needed. Moreover, the possibility of one-session pre- or postoperative CT imaging, vascular imaging, or associated interventional procedures can further optimize surgical workflow. Overall, we judge that an integrated interventional suite and perioperative CT imaging increase the comfort of the surgeon in many procedures, although intraoperative CT was not always judged necessary. Whether integrated perioperative imaging increases resection rates or avoids complications needs to be assessed in further studies with more patients.

Co-registration methods for 2D ultrasound and nuclear magnetic resonance images

Event Abstract Back to Event Co-registration methods for 2D ultrasound and nuclear magnetic resonance images Santos R. Yusniel1*, Javier Figueredo2, Joe Michel López Inguanzo1, Marlis Ontivero1, Daylin Gongora1, Jorge Iglesias Fuster1 and Maria Bobes1 1 Cuban Center for Neuroscience (CNEURO), Department of Cognitive Neuroscience, Cuba 2 Center of Medical and Surgical Research (CIMEQ), Cuba Intra-operative MRI and CT images provide information about patient's brain several times during surgery. However, they have serious drawbacks concerning the relatively long image acquisition procedures, high investment and operating costs, a spatially limited workspace and need for special (MR- or CT-compatible) surgical equipment. The optimal solution for neurosurgeons includes a navigation system with high quality images combined with real-time processing and three-dimensional imaging capabilities. Many of these capabilities are available in the ultrasound systems used in neurosurgery for several years. These systems have drawbacks associated with a limited viewing angle, the mixing of study and image data and variable dimensions. However, recent advances has improved the image quality up to a level comparable with intra-operative MRI. Thus, by sorting these limitations, the integration of ultrasound with high resolution MRI represents an efficient and inexpensive procedure for pre-operative surgical planning and intra-operative imaging. Our work combines intra-operative 2D ultrasound images and pre-operative MRI, as well includes fusion with fMRI and DTI images. We present data obtained from surgical procedures in patients with brain tumors. In all cases this procedure allowed the evaluation of 2D ultrasound images combined with MR structural images, fMRI and DTI data, allowing a more efficient surgical planning with successful outcomes. Keywords: brain tumors, ultrasound, neuro-navigation, surgical planning, co-registration Conference: Neuroinformatics 2013, Stockholm, Sweden, 27 Aug - 29 Aug, 2013. Presentation Type: Poster Topic: Neuroimaging Citation: Yusniel SR, Figueredo J, López Inguanzo J, Ontivero M, Gongora D, Iglesias Fuster J and Bobes M (2013). Co-registration methods for 2D ultrasound and nuclear magnetic resonance images. Front. Neuroinform. Conference Abstract: Neuroinformatics 2013. doi: 10.3389/conf.fninf.2013.09.00121 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 23 Jul 2013; Published Online: 23 Jul 2013. * Correspondence: Mr. Santos R Yusniel, Cuban Center for Neuroscience (CNEURO), Department of Cognitive Neuroscience, Havana, Cuba, santos@cneuro.edu.cu Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Santos R Yusniel Javier Figueredo Joe Michel López Inguanzo Marlis Ontivero Daylin Gongora Jorge Iglesias Fuster Maria Bobes Google Santos R Yusniel Javier Figueredo Joe Michel López Inguanzo Marlis Ontivero Daylin Gongora Jorge Iglesias Fuster Maria Bobes Google Scholar Santos R Yusniel Javier Figueredo Joe Michel López Inguanzo Marlis Ontivero Daylin Gongora Jorge Iglesias Fuster Maria Bobes PubMed Santos R Yusniel Javier Figueredo Joe Michel López Inguanzo Marlis Ontivero Daylin Gongora Jorge Iglesias Fuster Maria Bobes Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Deformable registration of the inflated and deflated lung in cone‐beam CT‐guided thoracic surgery: Initial investigation of a combined model‐ and image‐driven approach

Surgical resection is the preferred modality for curative treatment of early stage lung cancer, but localization of small tumors (<10 mm diameter) during surgery presents a major challenge that is likely to increase as more early-stage disease is detected incidentally and in low-dose CT screening. To overcome the difficulty of manual localization (fingers inserted through intercostal ports) and the cost, logistics, and morbidity of preoperative tagging (coil or dye placement under CT-fluoroscopy), the authors propose the use of intraoperative cone-beam CT (CBCT) and deformable image registration to guide targeting of small tumors in video-assisted thoracic surgery (VATS). A novel algorithm is reported for registration of the lung from its inflated state (prior to pleural breach) to the deflated state (during resection) to localize surgical targets and adjacent critical anatomy. The registration approach geometrically resolves images of the inflated and deflated lung using a coarse model-driven stage followed by a finer image-driven stage. The model-driven stage uses image features derived from the lung surfaces and airways: triangular surface meshes are morphed to capture bulk motion; concurrently, the airways generate graph structures from which corresponding nodes are identified. Interpolation of the sparse motion fields computed from the bounding surface and interior airways provides a 3D motion field that coarsely registers the lung and initializes the subsequent image-driven stage. The image-driven stage employs an intensity-corrected, symmetric form of the Demons method. The algorithm was validated over 12 datasets, obtained from porcine specimen experiments emulating CBCT-guided VATS. Geometric accuracy was quantified in terms of target registration error (TRE) in anatomical targets throughout the lung, and normalized cross-correlation. Variations of the algorithm were investigated to study the behavior of the model- and image-driven stages by modifying individual algorithmic steps and examining the effect in comparison to the nominal process. The combined model- and image-driven registration process demonstrated accuracy consistent with the requirements of minimally invasive VATS in both target localization (∼3-5 mm within the target wedge) and critical structure avoidance (∼1-2 mm). The model-driven stage initialized the registration to within a median TRE of 1.9 mm (95% confidence interval (CI) maximum = 5.0 mm), while the subsequent image-driven stage yielded higher accuracy localization with 0.6 mm median TRE (95% CI maximum = 4.1 mm). The variations assessing the individual algorithmic steps elucidated the role of each step and in some cases identified opportunities for further simplification and improvement in computational speed. The initial studies show the proposed registration method to successfully register CBCT images of the inflated and deflated lung. Accuracy appears sufficient to localize the target and adjacent critical anatomy within ∼1-2 mm and guide localization under conditions in which the target cannot be discerned directly in CBCT (e.g., subtle, nonsolid tumors). The ability to directly localize tumors in the operating room could provide a valuable addition to the VATS arsenal, obviate the cost, logistics, and morbidity of preoperative tagging, and improve patient safety. Future work includes in vivo testing, optimization of workflow, and integration with a CBCT image guidance system.