Fluoroscopy-based Image Guidance Research Articles

Fluoroscopic Detection of Ventral Wall Violation during C2 Intralaminar Screw Insertion: A Descriptive Study

Introduction: The C2 (second cervical) laminar screws were considered for rigid fixation of the axis because the use of pars or pedicle screws posed a risk to the vertebral artery with C2. Though considered to be a relatively safe method, ventral spinal canal violations have been reported in laminar screws fixations. Fluoroscopy-based image guidance may increase the accuracy and safety of the technique. Aim: To report the use of fluoroscopy technique in the detection of ventral wall violation during C2 intralaminar screw insertion. Materials and Methods: This descriptive study reports seven dry axis vertebrae from the adult south Indian population for which fluoroscopic analysis was done from January 2013 to December 2013. True lateral views were taken before and after applying a vertical line of barium paint on the ventral surface of the lamina at two points: at the centre of the lamina and close to the facet joints at the face to-laminar junction. Results: In the total seven dry axis vertebrae analysed, the mean ratio of the distance from the spinolaminar junction to the barium line (drawn on the ventral surface of the lamina just next to face to laminar junction) to the distance between the spinolaminar junction and uppermost part of inferior articular facet of C2 vertebrae was 0.465±0.0389 mm. Conclusion: Even though considered a relatively safer technique, laminar cortical violations have been reported in C2 translaminar screw fixations. Fluoroscopy-based imaging guidance can improve the accuracy of C2 translaminar screw insertion, as this technology provides real-time imaging during the process of screw insertion and helps in accurate screw sizing.

Image-Guided Spinal Surgery and Robotics in MIS: Where Are We Now?

Use of pedicle screws is widespread in spinal surgery for degenerative, traumatic, and oncological diseases. The conventional technique is based on the recognition of anatomic landmarks, preparation and palpation of cortices of the pedicle under control of an intraoperative C-arm (iC-arm) fluoroscopy. With these conventional methods, the median pedicle screw accuracy ranges from 86.7% to 93.8%, even if perforation rates range from 21.1% to 39.8%.The development of novel intraoperative navigational techniques, commonly referred to as image-guided surgery (IGS), provide simultaneous and multiplanar views of spinal anatomy. IGS technology can increase the accuracy of spinal instrumentation procedures and improve patient safety. These systems, such as fluoroscopy-based image guidance ("virtual fluoroscopy") and computed tomography (CT)-based computer-guidance systems, have sensibly minimized risk of pedicle screw misplacement, with overall perforation rates ranging from between 14.3% and 9.3%, respectively."Virtual fluoroscopy" allows simultaneous two-dimensional (2D) guidance in multiple planes, but does not provide any axial images; quality of images is directly dependent on the resolution of the acquired fluoroscopic projections. Furthermore, computer-assisted surgical navigation systems decrease the reliance on intraoperative imaging, thus reducing the use of intraprocedure ionizing radiation. The major limitation of this technique is related to the variation of the position of the patient from the preoperative CT scan, usually obtained before surgery in a supine position, and the operative position (prone). The next technological evolution is the use of an intraoperative CT (iCT) scan, which would allow us to solve the position-dependent changes, granting a higher accuracy in the navigation system.

Augmented reality and cone beam CT guidance for transoral robotic surgery.

In transoral robotic surgery preoperative image data do not reflect large deformations of the operative workspace from perioperative setup. To address this challenge, in this study we explore image guidance with cone beam computed tomographic angiography to guide the dissection of critical vascular landmarks and resection of base-of-tongue neoplasms with adequate margins for transoral robotic surgery. We identify critical vascular landmarks from perioperative c-arm imaging to augment the stereoscopic view of a da Vinci si robot in addition to incorporating visual feedback from relative tool positions. Experiments resecting base-of-tongue mock tumors were conducted on a series of ex vivo and in vivo animal models comparing the proposed workflow for video augmentation to standard non-augmented practice and alternative, fluoroscopy-based image guidance. Accurate identification of registered augmented critical anatomy during controlled arterial dissection and en bloc mock tumor resection was possible with the augmented reality system. The proposed image-guided robotic system also achieved improved resection ratios of mock tumor margins (1.00) when compared to control scenarios (0.0) and alternative methods of image guidance (0.58). The experimental results show the feasibility of the proposed workflow and advantages of cone beam computed tomography image guidance through video augmentation of the primary stereo endoscopy as compared to control and alternative navigation methods.

Integration of fluoroscopy-based guidance in orthopaedic trauma surgery – A prospective cohort study

IntroductionComputer-assisted guidance systems are not used frequently for musculoskeletal injuries unless there are potential advantages. We investigated a novel fluoroscopy-based image guidance system in orthopaedic trauma surgery. Materials and methodsThe study was a prospective, not randomised, single-centre case series at a level I trauma centre. A total of 45 patients with 46 injuries (foot 12, shoulder 10, long bones seven, hand and wrist seven, ankle seven and spine and pelvis four) were included. Different surgical procedures were examined following the basic principles of the Arbeitsgemeinschaft für Osteosynthesefragen/Association for the Study of Internal Fixation (AO/ASIF). Main outcome measurements were the number of trials for implant placement, total surgery time, usability via user questionnaire and system failure rate. ResultsIn all cases, the trajectory function was used, inserting a total of 56 guided implants. The system failed when used in pelvic and spinal injuries, resulting in a total failure rate of 6.5% (n=3) of all included cases. The overall usability was rated as good, scoring 84.3%. ConclusionThe novel image-guidance system could be integrated into the surgical workflow and was used successfully in orthopaedic trauma surgery. Expected advantages should be explored in randomised studies.

Non-invasive, fluoroscopy-based, image-guided surgery reduces radiation exposure for vertebral compression fractures: A preliminary survey

Percutaneous vertebroplasty has gained widespread popularity to treat painful osteoporotic vertebral compression fractures (VCFs). Radiation exposure during these operations has become the major concern in recent years. Traditional percutaneous vertebroplasty for VCFs is associated with high operator radiation exposure. However, these procedures can be performed by fluoroscopy-based image guidance, which decreases the radiation exposure during vertebroplasty for VCFs. The study subjects were divided into two groups: one underwent traditional vertebroplasty and the other had the C-Arm fluoroscopy-based, image-guided procedure. Four patients in the first group underwent traditional vertebroplasty using repeated intermittent anteroposterior and lateral fluoroscopy to position the cannula used for the vertebroplasty. Six patients in the second group had C-Arm fluoroscopy-based, image-guided surgery. The dose area product values, obtained by thermoluminescent dosimeters, were measured in both groups. The accuracy of the non-invasive fluoroscopy-based image-guided surgery was high, with a maximum error of 2 mm. The mean dose area product values of the operator’s eyes, hands, neck and chest were 20.28 mGy, 20.34 mGy, 21.87 Gy and 18.27 mGy in the first group, and 3.51 mGy, 3.70 mGy, 3.02 mGy and 3.68 mGy in the second group, respectively, with fluoroscopy-based, image-guided surgery; the differences were statistically significant ( p < 0.05). The results of this preliminary study showed that noninvasive, fluoroscopy-based, image-guided surgery was accurate and was associated with reduced radiation exposure to medical personnel during percutaneous vertebroplasty procedures for VCFs.

Three‐dimensional image‐guided placement of percutaneous pedicle screws without the use of biplanar fluoroscopy or Kirschner wires: technical note

Percutaneous pedicle screws are commonly used in minimally invasive spinal procedures. Traditional techniques of percutaneous pedicle screw placement have employed the use of multiplanar fluoroscopy and Kirschner wires (K-wires). The use of multiplanar fluoroscopy for the placement of percutaneous pedicle screws likely increases radiation exposure to the surgeon when compared to open techniques. K-wires can break or become bent during the procedure, making it difficult to insert and remove instrumentation over them. Additionally, there is also a risk of visceral or vascular injury with the use of K-wires. The authors present a novel method of percutaneous pedicle screw placement utilizing three-dimensional (3D) fluoroscopy-based image guidance in which K-wires are not used and there is minimal to no radiation exposure to the surgeon and operating room staff. Thirty-six screws were placed in 15 patients using this technique. An independent radiologist graded screw placement using computed tomographic (CT) scans and the breach rate of the percutaneous pedicle screws was compared to the breach rate of 33 pedicle screws placed contralaterally using the mini-open technique. No bony breach was noted by any screw in either group and no complications occurred in this study as a result of screw placement. Percutaneous pedicle screws can be placed accurately and safely using 3D image guidance without the use of K-wires. Little to no radiation exposure to the surgeon or OR staff occurs with this technique. No complications occurred in this study as a result of screw placement or image guidance.

Painful Medial Branch Neuroma Treated with Minimally Invasive Medial Branch Neurectomy

Case report. To report an unusual complication following lumbar facet radiofrequency denervation and describe a successful, minimally invasive treatment of a presumed medial branch neuroma. Radiofrequency medial branch neurotomy is a common procedure for the treatment of mechanical back pain. Deafferentation injury and neuroma formation is well known and reported following chemical, surgical, and cryoablation neurolysis; however, it is thought to be rare with radiofrequency ablation. When this problem is encountered, treatment options appear to be limited. Further radiofrequency ablations may be ineffective and indeed may cause further injury. A 17-year-old male who sustained a traumatic fracture of the right L3-4 facet joint presented with increasing back pain after multiple radiofrequency ablations of the medial branches of the L2 and L3 dorsal rami. The description of the back pain, initially nociceptive in nature, had become progressively neuropathic with clear focal areas of allodynia and hyperesthesia. Further medial branch radiofrequency denervation was found to be ineffective. Diagnostic block of the right medial branch of the L2 dorsal ramus provided the patient with total relief of pain. This was followed by a minimally invasive open surgical ablation of the L2 medial branch neuroma using three-dimensional, fluoroscopy-based image guidance. At 7 months of follow-up, the patient reported complete resolution of pain, discontinuation of all pain medications, and return to all previous physical activities. Deafferentation injury is a rare but recognized complication of chemical, surgical, and thermal neuroablation. This case report presents a rare instance of presumed neuroma formation following multiple radiofrequency ablations for the treatment of facet-generated mechanical back pain. Open and minimally invasive medial branch neurectomy resulted in complete resolution of pain and return to baseline function.

Placement of C2 laminar screws using three-dimensional fluoroscopy-based image guidance by Eric W. Nottmeier and Andrew B. Foy

In their work colleagues Nottmeier and Foy present a retrospective series of eight patients treated with posterior C1–C2 fusion by laminar screws using three-dimensional fluoroscopy-based image guidance. They conclude from the results of their work that: “In this study, it has been shown that C2 laminar screws can be safely and accurately placed using 3D fluoroscopy-based image guidance. Advantages of this technology over traditional techniques include real-time 3D computerized feedback to the surgeon during placement, as well as the ability to size the screw to the patient’s anatomy using intraoperative computerized planning.” In the last decade, technology has advanced to the point where regular computer workstations are able to calculate in real-time the transformation matrices needed to determine the position of a camera-tracked object (in a surgical setting, typically a frame with fiducials) in relation to a camera-tracked reference base. By attaching the reference base to a patient and (surgical) instruments to camera-tracked objects, the workstation can calculate the respective positions/orientations and display their virtual interactions. When three-dimensional data sets representing the patient’s anatomy from modalities including CT/MRI/3D rotational X-ray imaging, are manipulated so that virtual and real reference bases are exactly aligned, surgical instruments and/or implants can be displayed on anatomical structures not visible for the surgeon intraoperatively. This is, in a nutshell, current “computer-assisted surgery” or “image-guided surgery”. Assuming that transformation matrix calculations are mathematical processes carried out with high fidelity and great reproducibility, imperfections in navigational accuracy must have other sources. Calibration errors in 3D fluoroscopy-based systems have, for example, been shown to account for approximately 1 mm accuracy in a phantom model [1]. In a more realistic cadaveric model, the accuracy of navigation deteriorated to approximately 2.5 mm, mainly due to bending of instruments and/or references during manipulation [2]. In clinical practice more inaccuracies can be introduced by occasional blocking of the camera field of view; inadvertently touching/hitting references and, especially, a nonrigid connection between the patient reference base and the actual surgical site. In the present study, the patient reference base was attached to a head clamp, which was, in turn, connected via pins to the patient’s skull while surgery was performed at the levels C1 and C2. This experimental setup represents quite a long chain of connections from the reference base to the surgical site with considerable opportunity for movement between the two extremes. This is without taking into account additional movements due to, for example, patient ventilation and direct manipulation of C1 and C2 by surgical instruments. Considering that the C0–C1–C2 complex is highly mobile, it came as a small surprise for this reviewer to find such accurate screw placement in the current study. As can be found in the article, the investigators did verify the image-guided technique (“After accuracy of navigation was confirmed by the surgeon ... ”). The interesting question that follows automatically is: “How?” Checking accuracy by probing the patient reference base with a navigated instrument and finding a perfectly matched position/orientation on the computer display does nothing for the flexibility/movement errors that may be present at the more distant surgical site. Most often, surgeons verify accuracy by a direct intraoperative view of the surgical site to see whether, for example, the proposed drill trajectory or planned screw length is in accordance to their own experience from conventional surgeries before moving on with navigation. This leads to the strange paradox that is really bugging contemporary image-guided procedures: the employment of a technique to enhance surgical accuracy requiring the surgeon’s intraoperative verification of its accuracy. The reluctance of surgeons to show complete faith in image guidance seems justified considering the errors demonstrated in accuracy studies. Using computer navigation without proper anatomical and surgical knowledge would be irresponsible. Armed with proper knowledge, however, navigation becomes largely superfluous since surgeons trust their surgical experience/skills and the direct intraoperative view over computer-generated images anytime, and adjust their actions accordingly. Which surgeon would happily volunteer when asked to perform a percutaneous procedure having to trust solely on information provided by any image-guided technique commercially available today? Until now, no large-scale long-term and properly controlled study has been published in the field of computer-assisted surgery that has convincingly showed any actual patient benefit when using image guidance. Lacking a control group and using a navigation technique susceptible to the aforementioned accuracy problems, the present study may, unfortunately, not be able to change this status.

Placement of C2 laminar screws using three-dimensional fluoroscopy-based image guidance

The use of C2 laminar screws in posterior cervical fusion is a relatively new technique that provides rigid fixation of the axis with minimal risk to the vertebral artery. The techniques of C2 laminar screw placement described in the literature rely solely on anatomical landmarks to guide screw insertion. The authors report on their experience with placement of C2 laminar screws using three-dimensional (3D) fluoroscopy-based image-guidance in eight patients undergoing posterior cervical fusion. Overall, fifteen C2 laminar screws were placed. There were no complications in any of the patients. Average follow-up was 10 months (range 3-14 months). Postoperative computed tomographic (CT) scanning was available for seven patients allowing evaluation of placement of thirteen C2 laminar screws, all of which were in good position with no spinal canal violation. The intraoperative planning function of the image-guided system allowed for 4-mm diameter screws to be placed in all cases. Using modified Odom's criteria, excellent or good relief of preoperative symptoms was noted in all patients at final follow-up.

Computer-assisted Spinal Navigation Versus Serial Radiography and Operative Time for Posterior Spinal Fusion at L5-S1

To review the operative time differences between computer-assisted spinal navigation versus serial radiography. There have been multiple studies describing the use of computer-assisted image guided surgery (IGS) in the application of spinal instrumentation. Techniques have evolved to allow attainment of multilevel visualization intraoperatively both successfully and safely. These have proven to result in low screw misplacement rates, low incidence of radiation exposure and excellent operative field viewing. As a result, image guidance has become an increasingly accepted and practiced form of intraoperative spinal navigation. However, potential limitations to IGS have been described including longer operating times. Many studies have looked at the success of beneficial outcomes; however, none to our knowledge have reviewed such described operative time increments with IGS. The authors performed a retrospective database analysis of 105 patients undergoing posterior L5-S1 spine fusion with pedicle screw instrumentation for isthmic spondylolisthesis with and without the use of fluoroscopy-based image guidance. This was followed by a chart review of anesthesia operative time documentation. Subsequent time calculations and statistical analysis were performed for comparison. Computer-assisted image-guided spine surgery has overall demonstrated shorter mean operative times when compared with intraoperative serial radiography technique; an average of 40 minutes less per case (P<0.001). There is also less variation in operative times using image guidance, with 13 of 43 (30%) cases using serial x-ray lasting more than 3.75 hours compared with none of the 57 done via image guidance (P<0.001). The operative duration for both procedures trended downward over time. For both procedural cohorts operating room time continued to decrease as of the most recent year being performed. Lastly, in an attempt to minimize such a confounding factor as a learning curve, the last 20 cases in each group were compared. There was an average difference of about 22 minutes less for the image guidance group but missed being statistically significant (P=0.0503). Image-guided spinal surgery did not cause an increase in operative time. In the best scenario, image navigation saved a statistically significant (P<0.001) amount of time in the operating room. At its worst, fluoroscopy-based image-guided navigation is not significantly different from standard serial radiography.

Use of intraoperative isocentric C-arm 3D fluoroscopy for sextant percutaneous pedicle screw placement: case report and review of the literature

Background context Three-dimensional (3D) fluoroscopy-based image guidance system using an isocentric C-arm (Iso-C) fluoroscope was shown to be as effective as computed tomography–based systems in guiding the accurate percutaneous placement of lumbar pedicle screws in cadavers. To date, however, no description is available of the intraoperative use of 3D fluoroscopy to guide lumbar pedicle screw placement in an actual spinal fusion procedure. Purpose We report a case in which isocentric 3D fluoroscopic images, along with image-guidance software, were used to guide the placement of percutaneous pedicle screws for fusion in a patient with degenerative spondylolisthesis. Study design/setting Operating room of a large academic medical center during the placement of percutaneous pedicle screws in a patient with degenerative spondylolisthesis. Methods A percutaneous dynamic reference array was attached to the L3 spinous process. A satisfactory image set was obtained and automatically registered. The L4 and L5 pedicles were localized, and pedicle holes were then cannulated, drilled and tapped. A screw was then inserted using the Sextant system for percutaneous pedicle screws. In this manner, bilateral pedicle screws were inserted into the L4–L5 pedicles. All steps of pedicle cannulation were performed under Iso-C 3D image guidance. Results A postoperative computed tomography scan showed accurate placement of all pedicle screws. The patient experienced an improvement in leg pain with no new neurologic deficits. Conclusions The present case is the first case to demonstrate the intraoperative use of a 3D fluoroscopy-based image-guidance system for accurate navigation during lumbar pedicle screw placement.

Accuracy of thoracic vertebral body screw placement using standard fluoroscopy, fluoroscopic image guidance, and computed tomographic image guidance: a cadaver study.

A surgical simulation study in human cadaver spine specimens was conducted to evaluate the accuracy of thoracic vertebral body screw placement using four different intraoperative imaging techniques. To compare standard fluoroscopy, fluoroscopy-based image guidance with two different referencing methods, and computed tomography-based image guidance by the measuring the time required for screw placement, the radiation exposure to specimen and surgeon, and the accuracy of screw position in the thoracic spine. Image guidance provides additional anatomic information to the surgeon and may improve safety of technically difficult surgical procedures. The placement of screws in the thoracic spine is a technically demanding procedure in which inaccurate screw positioning places the spinal cord, nerve roots, and paraspinal structures such as the aorta and pleural space at risk for injury. Image-guided surgery may improve the accuracy of thoracic screw placement. Using four different intraoperative imaging methods, two experienced surgeons placed 337 vertebral body screws through the pedicles of thoracic vertebrae in 20 human cadaver thoracic spine specimens. The specimens then were examined with radiographs, computed tomography, and anatomic dissection to determine screw position. Measurements included procedure setup and screw insertion time, radiation exposure to the specimen, the surgeon's hand, the surgeon's body, frequency, direction, and magnitude of screw perforation through the cortical margins of thoracic vertebrae. As compared with surgery using standard fluoroscopy, fluoroscopy-based image guidance that uses multiple reference marks and computed tomography-based image guidance improves the accuracy of thoracic vertebral body screws, but increases the time required for screw placement and the specimen radiation exposure. Exposure to radiation is minimal at the surgeon's body level and dependent on surgical technique at the surgeon's hand level. Screw perforation occurs most frequently in the lateral direction. Fluoroscopy-based image guidance that uses only a single reference marker for the entire thoracic spine is highly inaccurate and unsafe. Systems with registration based on the instrumented vertebrae provide more accurate placement of thoracic vertebral body screws than standard fluoroscopy, but expose the patient to more radiation and require more time for screw insertion.