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CT fluoroscopy-guided abdominal interventions: techniques, results, and radiation exposure.

PURPOSE: To evaluate the benefits of computed tomographic (CT) fluoroscopy-guided interventions and assess radiation exposures incurred with CT fluoroscopy. MATERIALS AND METHODS: A 6-month period of use of CT fluoroscopy to guide abdominal biopsy procedures and catheter drainage was analyzed. Efficacy measures and needle placement and procedure room times were compared with those of the preceding 6 months during which conventional CT was used. CT fluoroscopic times and estimated radiation exposures were compared for two CT fluoroscopic methods. RESULTS: The sensitivity and negative predictive values for biopsy procedures and the success rate for needle aspiration or catheter drainages for CT fluoroscopy--98%, 86%, and 100%, respectively--were not significantly different from those for conventional CT--95%, 80%, and 97%, respectively. Room time was not reduced significantly, but mean needle placement time for CT fluoroscopy (29 minutes; n = 95) was significantly lower than that for conventional CT (36 minutes; n = 93; P < .005). The mean patient dose index was 74 cGy. Limiting CT fluoroscopy to scanning the needle tip rather than scanning the entire needle pass significantly reduced the dose to the patient and the operator. CONCLUSION: Although CT fluoroscopy is a useful targeting technique, significant radiation exposures may result. Therefore, radiologists need to be aware of different methods of CT fluoroscopic guidance and the factors that contribute to radiation exposure.

Abdomen↗

Comparison of sonographic and CT guidance techniques: does CT fluoroscopy decrease procedure time?

OBJECTIVE: Procedure times for percutaneous biopsies were compared for various guidance techniques including helical CT, CT fluoroscopy, sonography with an attached needle guide, and freehand sonography with computer guidance. MATERIALS AND METHODS: Three interventional radiologists experienced in CT- and sonographically guided procedures performed biopsies on a phantom model. The phantom simulated hepatic metastases of various sizes and depths with subcostal or intercostal locations. Lesion sizes were 7, 10, and 20 mm, at 3- and 7-cm depths. Using self-aspirating needles, two passes were performed in each lesion. Mean procedure time per biopsy pass was calculated. A two-tailed Student's t test was used to compare guidance techniques. RESULTS: Mean procedure time per biopsy pass for the four guidance techniques was sonography with a needle guide, 36+/-9 sec; sonography with computer guidance, 43+/-10 sec; helical CT, 146+/-42 sec; and CT fluoroscopy, 50+/-18 sec. CT fluoroscopy required 2.6+/-1.0 sec per biopsy. Helical CT required more procedure time than sonography with a needle guide, CT with computer guidance, and CT fluoroscopy (p < 0.0001). Sonography with a needle guide required less procedure time than sonography with computer guidance (p < 0.002) and CT fluoroscopy (p = 0.0003). Procedure times for CT fluoroscopy and sonography with computer guidance were not statistically different (p = 0.06). CT and sonographic guidance were equally effective regardless of lesion size, depth, or location. CONCLUSION: Traditional sonographic biopsy techniques are faster and more cost-effective than traditional CT techniques; however, CT fluoroscopy offers the localization advantages of CT with improved procedure times.

Abdomen↗

Transesophageal echocardiography or fluoroscopy during port-access surgery?

INTRODUCTION: In Port-Access cardio-surgical procedures, both intraoperative transesophageal echocardiography (TEE) and fluoroscopy can be used for placement of the catheters and cannulae needed for cardiopulmonary bypass. Our study sought to clarify whether it is possible to rely exclusively on TEE for catheter placement without increasing the risk for the patient. MATERIALS AND METHODS: Forty patients underwent cardiac surgery with the Port-Access system. Fluoroscopy as well as TEE were used for placement of the transjugular and transfemoral catheters required for cardiopulmonary bypass. The time required for fluoroscopy was recorded, as were any complications during cannulation and cardiopulmonary bypass. RESULTS: The average fluoroscopy time was 10.7 +/- 12.1 min. Fluoroscopy time required for placement of the coronary sinus and pulmonary vent catheters could be reduced to zero early in the course of the study. Once we had gained enough experience with TEE, fluoroscopy for placement of the transfemoral catheters was also no longer necessary. During cannulation, 3 patients suffered complications requiring immediate surgical intervention. These complications were all diagnosed by TEE. CONCLUSION: Our data suggest that positioning of the coronary sinus and the pulmonary vent catheters is safe and practicable with TEE alone. Nonetheless, if TEE imaging is poor or fails, fluoroscopy has still a place in Port-Access surgery and should always be available intraoperatively.

Aged↗

CT-based and fluoroscopy-based navigation for cup implantation in total hip arthroplasty (THA).

The goal of using navigation systems in total hip arthroplasty (THA) is to minimise malpositioned components, increase range of motion, and decrease the risk of dislocation, which may result in long-term stability. The two systems used to navigate the acetabular component are CT-based and fluoroscopy-based. Between May 2001 and May 2002, surgery was performed on 153 patients using navigation systems for cup positioning. The CT-based system was used in 46 patients and fluoroscopy-based system in 107. The diagnoses were primary osteoarthritis in 120 of the patients, and secondary osteoarthritis following congenital and post-traumatic deformities in 33. The outcomes of the operations were investigated clinically and radiologically. Mean variation of the postoperative abduction angle to the preoperative planning was 2.7 (0-8) after CT-based navigation and 3.9 (0-9) after fluoroscopy-based navigation. After the first 30 surgeries with each system, the operating time was extended by 9 minutes using the CT-based system and by 13 minutes with the fluoroscopy-based system compared to hand implantation. Also, the preoperative planning using the CT-based system was more time-consuming. No additional planning was necessary with the fluoroscopy-based system was used. Both systems were accurate and provided an improved reproducible quality. The CT-based system provided a link between the preoperative planning and intraoperative placement of acetabular components. Only a minimal difference was noted when compared to the fluoroscopy-based procedure; however, the time-consuming set up remains a problem. The advantage in using the CT-based system is the three-dimensional feed back of anatomic landmarks, but a disadvantage is the time-consuming preoperative procedure (CT-scan, data transfer, planning). For this reason the CT-based method should be performed in cases of congenital and post-traumatic deformities. The fluoroscopy-based method is easier to handle in routine cases with normal anatomy or lesser deformities. Both systems present an excellent additional tool to improve reproducible quality in THA.

Adult↗

Balloon sizing and transcatheter closure of acute atrial septal defects guided by magnetic resonance fluoroscopy: assessment and validation in a large animal model.

PURPOSE: To quantitatively assess atrial septal defects (ASDs) with small shunts using MRI followed by transcatheter closure monitored by MR fluoroscopy. MATERIALS AND METHODS: Acute ASDs were created in 14 pigs under x-ray fluoroscopy. Six animals were studied in order to select MR-compatible delivery systems and imaging strategies. ASDs in eight animals were examined with balloon sizing under MR fluoroscopy, flow measurements, and contrast media injections, after which transcatheter closure was performed under MR fluoroscopy. The delivery system was assembled from commercially available materials. RESULTS: The ratio of pulmonary to systemic flow (Qp/Qs) was reduced from 1.23 +/- 0.15 before ASD closure to 1.07 +/- 0.11 after ASD closure (P < 0.001). In two out of eight animals Qp/Qs was close to 1.0 before closure despite the presence of defects >15 mm. The ASDs were measurable with MR balloon sizing in all of the animals. Balloon sizing was identical with MR (16.9 +/- 2.3 mm) and x-ray fluoroscopy (17.1 +/- 1.3 mm). The in-house-assembled delivery system allowed successful placement of closure devices under MR guidance. CONCLUSION: Assessment and closure of small shunts with MR fluoroscopy is feasible. A barrier to the rapid implementation of transcatheter closure in patients is uncertainty about the MR safety of guidewires and device delivery systems.

Acute Disease↗

Effective dose of CT- and fluoroscopy-guided perineural/epidural injections of the lumbar spine: a comparative study.

The objective of this study was to compare the effective radiation dose of perineural and epidural injections of the lumbar spine under computed tomography (CT) or fluoroscopic guidance with respect to dose-reduced protocols. We assessed the radiation dose with an Alderson Rando phantom at the lumbar segment L4/5 using 29 thermoluminescence dosimeters. Based on our clinical experience, 4-10 CT scans and 1-min fluoroscopy are appropriate. Effective doses were calculated for CT for a routine lumbar spine protocol and for maximum dose reduction; as well as for fluoroscopy in a continuous and a pulsed mode (3-15 pulses/s). Effective doses under CT guidance were 1.51 mSv for 4 scans and 3.53 mSv for 10 scans using a standard protocol and 0.22 mSv and 0.43 mSv for the low-dose protocol. In continuous mode, the effective doses ranged from 0.43 to 1.25 mSv for 1-3 min of fluoroscopy. Using 1 min of pulsed fluoroscopy, the effective dose was less than 0.1 mSv for 3 pulses/s. A consequent low-dose CT protocol reduces the effective dose compared to a standard lumbar spine protocol by more than 85%. The latter dose might be expected when applying about 1 min of continuous fluoroscopy for guidance. A pulsed mode further reduces the effective dose of fluoroscopy by 80-90%.

Female↗

Intraoperative evaluation of bone decompression in anterior cervical spine surgery by three-dimensional fluoroscopy.

Sufficient bone decompression of osteophytes is essential for functional long-term outcome in surgery for spondylotic cervical myelopathy. Postoperative CT scans clearly show that decompression is sometimes insufficient. Intraoperative CT scanning has been used to monitor sufficient decompression. Instead of standard intraoperative fluoroscopy, we used an isocentered three-dimensional (3D) fluoroscopy with 3D image reconstruction to evaluate the extent of bone decompression. From October 2003 to April 2004, we have used intraoperative 3D fluoroscopy on seven patients with anterior cervical spine surgery due to cervical spondylotic myelopathy. Five patients were operated on in one level, two patients had surgery in two segments. If surgery was performed in two levels or preoperative cinetic MRT showed cervical instability, internal plate fixation was done additionally. All patients were positioned on a radiolucent operating table, made of carbon fibers. Three-dimensional fluoroscopy was always performed before wound closure to evaluate sufficient bone removal. The scanning time was 120 s and the whole procedure from scanning to evaluation is approximately 5 min. In all patients we were able to evaluate the extent of bone decompression. Additionally, placement of cage, plates and screws can be evaluated intraoperatively. In one patient, 3D fluoroscopy showed insufficient decompression, especially on the right side. Further bone removal was performed before the end of the procedure. Intraoperative 3D fluoroscopy is a valuable tool for imaging bone decompression and implant location in anterior cervical spine surgery. The technique is safe, reliable and should help us to avoid incomplete decompression or misplacement of implants and therefore improve long-term functional outcome in cervical spine surgery in the future.

Aged↗

Digital fluoroscopy to quantify lung tumor motion: potential for patient-specific planning target volumes.

PURPOSE: To apply digital fluoroscopy integrated with CT simulation to measure lung tumor motion and aid in the quantification of individualized planning target volumes. METHODS AND MATERIALS: A flat panel digital fluoroscopy unit was modified and integrated with a CT simulator. The stored fluoroscopy images were overlaid with digitally reconstructed radiographs, allowing measurement of the observed lung tumor motion in relation to the corresponding contours on the static digitally reconstructed radiographs. CT simulation and digital fluoroscopy was performed on 10 patients with non-small-cell lung cancer. Actual tumor motion was measured in three dimensions using the overlaid images. RESULTS: Combining the dynamic data with digitally reconstructed radiographs allowed the tumor shadow from the fluoroscopy to be tracked in relation to the CT lung tumor contour. For all patients, the extent of tumor motion in three dimensions was unique. The motion was greatest in the superoinferior direction and minimal in the AP and lateral directions. CONCLUSION: We have developed a tool that allows CT simulation to be combined with digital fluoroscopy. Quantitative evaluation of the tumor motion in relation to the CT plan allows for customization of the planning target volume. The variability observed clearly demonstrates the need to generate patient-specific internal motion margins.

Adult↗

Guidance of percutaneous pulmonary biopsies with real-time CT fluoroscopy.

OBJECTIVE: Clinical evaluation of computed tomography (CT) fluoroscopy and comparison with conventional CT guidance for monitoring of percutaneous pulmonary biopsy procedures. METHODS: Twenty CT-guided pulmonary biopsy procedures were conducted. The interventions have prospectively been performed either with CT fluoroscopy or with conventional CT guidance. About 120 kV and 50 mA with a frame-rate of eight images per second were used for CT fluoroscopy. Number of pleural needle passages, procedure times, radiation doses and histologic results were analyzed separately for both methods. RESULTS: Compared with conventional CT guidance, CT fluoroscopy was associated with less pleural needle passages (1.8+/-0.6 vs. 1.1+/-0.3; P=0.003, t-test) and procedure times were shorter than for conventional CT guidance (12.7+/-2.2 min vs. 26.7+/-16.4 min; P=0.02). Analysis of estimated patient related radiation exposure and histologic outcome showed no significant difference between conventional and fluoroscopic CT-guided procedures (P>0.05). CONCLUSION: CT fluoroscopy facilitates guidance of percutaneous pulmonary biopsy procedures. Compared with conventional CT assistance, procedure times are decreased and less pleural needle passages are required. While patient-related radiation exposure is similar, operator-related radiation exposure remains a disadvantage associated with CT fluoroscopy.

Aged↗

Evaluation of diaphragmatic movement with MR fluoroscopy in chronic obstructive pulmonary disease.

The aim of this study was to show reduction of the diaphragmatic excursion with MR fluoroscopy in patients with chronic obstructive pulmonary disease (COPD) and to compare the results with pulmonary function test (PFT). The study included 13 men and 10 women (average age 56.2) with COPD, and 9 men and 6 women (average age 55.8) as a control group. MR fluoroscopy images with Spoiled Gradient-echo pulse sequence was obtained during deep inspiration and expiration. After examination, over cine-loop display, the highest and lowest positions of the diaphragm were identified and the distance of excursion was measured. Differences in the diaphragmatic excursion between patient and healthy subjects were compared. We have also compared MR fluoroscopy results with PFT. In each person of both groups, excursion of the diaphragm was demonstrated clearly in cine-loop display. Differences of excursion between deepest and highest point of diaphragm were on average 26 and 20 mm, respectively, in the right and left side in patients and 69 and 56 mm in healthy group. Significant correlation was found between expiratory volume in 1 s and MR fluoroscopy results. MR fluoroscopy study showed that there were significant statistical differences in diaphragmatic excursion between patients with COPD and healthy subjects. Expiratory volume in 1 s is closely associated with the diaphragmatic excursion. MR fluoroscopy would seem to be a useful method for showing diaphragmatic excursion.

Adult↗

Air enema for diagnosis and reduction of intussusception in children: clinical experience and fluoroscopy time correlation.

PURPOSE: The objective of this study was to correlate the fluoroscopy time with radiologic outcome in the pneumoreduction of intussusception in children. METHODS: From September 1995 to December 1997, a prospective analysis of 181 cases of pediatric intussusception with pneumoreduction without sedation was done. A receiver operating characteristic curve of fluoroscopy time was drawn for correlation with radiologic outcome. RESULTS: The overall success and failure rates of pneumoreduction were 84% and 16%, respectively. Three patients (1.6%) experienced colon perforation. The mean fluoroscopy time was 2.8 +/- 1.7 minutes in successful procedure and 4.9 +/- 2.8 minutes in failed procedures (P < 0.001). Analysis of the receiver operating characteristic curve of fluoroscopy time indicates that 4 minutes fluoroscopy time was a good critical point in differentiating successful and failed cases. In those 18 patients who had successful reduction with fluoroscopy times of more than 4 minutes, 4 patients had clinical symptoms for more than 1 day and 14 patients less than 1 day. One of those 4 patients required operation 1 day later because of peritonitis caused by necrosis of terminal ileum. Two patients had high fever in the next 2 days and recovered after antibiotic treatment. CONCLUSIONS: Pneumoreduction is a good method in treatment of intussusception with high successful rate. Four minutes is the critical point of procedure. Reduction with greater than 4 minutes in those patients having illness more than 1 day might not benefit and have more complications.

Air↗

[Optimization of beam filtering, kv-ma regulation curve and image intensifier entrance exposure rate to reduce radiation exposure in angiographic fluoroscopy].

AIM OF STUDY: Evaluation of radiation exposure and image quality during fluoroscopy using a new vascular X-ray system. MATERIAL AND METHODS: The measurements were made on an Integris V 3000 X-ray system with MRC tube and SpectraBeam technology (Philips Medical Systems, Hamburg). Entrance dose rates were measured with phantoms for the three fluoroscopy levels (1-3) which differed with regard to beam filtering and image intensiver entrance exposure rate. We evaluated 132 diagnostic and interventional angiographic studies. The angiographic investigators were asked to start with level 1 and to change to the next fluoroscopy level only in the case of insufficient image quality. RESULTS: Entrance dose rate is reduced by approx. 74% at fluoroscopy level 1 and by approx. 46% at level 2 relative to level 3 which is comparable to angiographic X-ray systems without MRC tube and SpectraBeam technology. Because level 1 ensured a sufficient image quality in 92% of the diagnostic and 60% of the interventional angiographic procedures a change to higher fluoroscopy levels was not necessary. CONCLUSION: Reduction of the intensifier exposure rate and the optimization of beam filtering enabled us to reduce the radiation exposure considerably. The procedure was well accepted by the angiographic investigators due to the diagnostically sufficient image quality of the fluoroscopy level 1.

Angiography, Digital Subtraction↗

[CT-guided biopsies, drainage and and percutaneous gastrostomies: comparison of punctures with and without CT fluoroscopy].

PURPOSE: The purpose of this prospective and randomized study was to compare two CT guidance techniques (CT-fluoroscopy/conventional CT) on percutaneous biopsies, drainages and gastrostomies. MATERIAL AND METHODS: 78 CT-guided interventions (29 biopsies, 38 drainages, 8 gastrostomies) were recorded and the Mann-Whitney U-test was applied. In 3 cases both guidance techniques were used. Procedure times, yields and radiation doses were analyzed. RESULTS: All 38 drainages and all 8 gastrostomies were successfully applied. 13 biopsies with conventional CT guidance (n = 15) and 13 biopsies with CT-fluoroscopy (n = 14) showed a representative histopathologic result. The procedure times were not significantly different (drainages: p = 0.658, biopsies: p = 0.431, gastrostomies: p > 0.06). The radiation doses (CTID1) of the biopsies and drainages showed significantly higher values (drainages p < 0.001, biopsies p < 0.001) with CT-fluoroscopy than with conventional CT. There were no significant differences in gastrostomy procedures (p > 0.06). CONCLUSION: Procedure times and yields were not improved by using CT-fluoroscopy. Radiation doses showed significantly higher values with CT-fluoroscopy than with conventional CT guidance. CT-fluoroscopy was advantageous in non-compliant patients over conventional CT guidance.

Adult↗

[Radiation exposure during digital hysterosalpingography: how much is due to fluoroscopy?].

PURPOSE: To determine the proportion of radiation exposure from fluoroscopy during the performance of hysterosalpingography, using a digital image intensifier. MATERIAL AND METHOD: 20 women with primary or secondary sterility were examined. The total radiation dose was measured and the proportion due to fluoroscopy was determined. The use of a computer programme permitted accurate differentiation of the dose obtained by fluoroscopy and radiography. Total mean radiation dose was 256 cGy x cm2; fluoroscopy contributed 187 cGy x cm2. On average, fluoroscopy contributed 69% of total radiation dose. CONCLUSION: During hysterosalpingography with a digital image intensifier, fluoroscopy should be as brief as possible since it contributes most of the radiation dose.

Adult↗

Reduction of fluoroscopy duration in radiofrequency ablation obtained by the use of a non-fluoroscopic catheter navigation system.

AIMS: Radiofrequency (RF) ablation requires placement of several catheters at critical positions. The catheters are positioned with fluoroscopy, resulting in a significant radiation exposure. We have investigated to what degree an intracardiac navigation system reduces the fluoroscopy duration in different groups of routine RF ablations. METHODS AND RESULTS: The fluoroscopy time was evaluated in 365 consecutive routine RF ablations, performed between 2002 and 2005. An intracardiac navigation system (LocaLisa, Medtronic) was used from 2003. The data were prospectively entered into a database and subsequently retrieved, and the procedures classified as being performed with fluoroscopy only or with the aid of the LocaLisa system. After introduction of the LocaLisa system, the median fluoroscopy time decreased from 24 to 10 min in the 141 atrioventricular nodal re-entry tachycardia (AVNRT) ablations and from 43 to 28 min in the 71 atrial flutter (AFl) ablations (P<0.005 for both). In the 145 Wolff-Parkinson-White (WPW) ablations, a decrease from 27 to 23 min was observed (P=0.03). The decrease in AVNRT and AFl, but not in WPW was associated with the introduction of the LocaLisa system. CONCLUSION: The use of the LocaLisa system during RF ablations significantly reduced the fluoroscopy time in AVNRT and AFl ablations, by a median of 58% and 46%, respectively.

Catheter Ablation↗

Computed tomographic fluoroscopy-guided transthoracic needle biopsy for diagnosis of pulmonary nodules.

BACKGROUND: The purpose of this study was to evaluate the usefulness of computed tomographic (CT) fluoroscopy-guided transthoracic needle biopsy (TTNB) with an 18-gauge automatic biopsy gun for the diagnosis of pulmonary nodules. METHODS: Between March 1996 and January 1998, 50 patients in whom pulmonary lesions could not be diagnosed cytopathologically with fiberoptic bronchoscopy or were not clearly visualized with fluoroscopy underwent CT fluoroscopy-guided TTNB. RESULTS: Final pathological diagnoses were 23 lung carcinomas, five pulmonary metastases and 22 benign lesions. Sufficient tissue for analysis was obtained from 48 of the 50 lesions (96%). The overall diagnostic yield of CT fluoroscopy-guided TTNB was 90%. The sensitivity, specificity and accuracy for malignancy were 89%, 100% and 94%, respectively. In 20 of the 22 cases (91%) of benign lesions, histological analysis yielded correct and specific diagnoses. Complications occurred in 22 of the 50 cases (44%). The most common complication was pneumothorax, which occurred in 21 of the 50 cases (42%). Chest tube insertion was required in 6 (12%). CONCLUSIONS: Although CT fluoroscopy could not decrease the complication rate, CT fluoroscopy-guided TTNB with an automatic biopsy gun appears to be a promising technique for diagnosing pulmonary lesions, particularly benign lesions.

Adenocarcinoma↗

Routine evaluation of the cervical spine in head-injured patients with dynamic fluoroscopy: a reappraisal.

BACKGROUND: The mechanism for clearing the cervical spine in patients with altered mental status remains controversial. Recommendations have ranged from removal of the cervical collar after 24 hours in patients with normal radiographs, to indefinite immobilization in a cervical collar, and recently cervical flexion-extension examinations using dynamic fluoroscopy. The purpose of this study was to evaluate the efficacy and safety of dynamic fluoroscopy flexion-extension examinations in identifying ligamentous cervical spine injury and clearing the cervical spine in patients with altered mental status after trauma. METHODS: Patients with a Glasgow Coma Scale score < 13 for greater than 48 hours after admission and normal cervical spine radiographs were candidates for fluoroscopic evaluation. The protocol required visualization of the entire cervical spine, through T1, through full extension and flexion under the direct supervision of a radiologist. Oblique fluoroscopic views were obtained, as necessary, to visualize the cervicothoracic junction. Demographic data, fluoroscopy time, total time per study, true and false positives and negatives, and complications were recorded. RESULTS: From July 1992 through December 1999, fluoroscopic examinations were performed on 301 patients. There were 297 true-negative examinations, 2 true-positive examinations (stable injuries), 1 false-negative examination, and 1 false-positive examination. The incidence of ligamentous injury identified by fluoroscopy in this study was 2 of 301 (0.7%). Unstable cervical spine ligamentous injuries were identified in only 0.02% of all trauma patients. One patient developed quadriplegia when fluoroscopic evaluation was performed after two protocol violations. CONCLUSION: Unstable cervical spine ligamentous injury without fracture is a rare occurrence. The cervical spine may be cleared after a normal cervical spine series (plain radiograph and computed tomographic scan) as recommended in the 1998 Eastern Association for the Surgery of Trauma guidelines. If dynamic fluoroscopy is to be used, adherence to the protocol, including review of the cervical spine radiographs before fluoroscopy and visualization of the entire cervical spine, C1-T1, is mandatory to ensure patient safety.

Adult↗

Virtual fluoroscopy: computer-assisted fluoroscopic navigation.

STUDY DESIGN: In vitro accuracy assessment of a novel virtual fluoroscopy system. OBJECTIVES: To investigate a new technology combining image-guided surgery with C-arm fluoroscopy. SUMMARY OF BACKGROUND DATA: Fluoroscopy is a useful and familiar technology to all musculoskeletal surgeons. Its limitations include radiation exposure to the patient and operating team and the need to reposition the fluoroscope repeatedly to obtain surgical guidance in multiple planes. METHODS: Fluoroscopic images of the lumbar spine of an intact, unembalmed cadaver were obtained, calibrated, and saved to an ). A was used for the sequential insertion of a light-emitting diode-fitted probe into the pedicles of L1-S1 bilaterally. The trajectory of a "virtual tool" corresponding to the tracked tool was overlaid onto the saved fluoroscopic views in real time. Live fluoroscopic images of the inserted pedicle probe were then obtained. Distances between the tips of the virtual and fluoroscopically displayed probes were quantified using the image-guided computer's measurement tool. Trajectory angle differences were measured using a standard goniometer and printed copies of the workstation computer display. The surgeon's radiation exposure was measured using thermolucent dosimeter rings. RESULTS: Excellent correlation between the virtual fluoroscopic images and live fluoroscopy was observed. Mean probe tip error was 0.97 +/- 0.40 mm. Mean trajectory angle difference between the virtual and fluoroscopically displayed probes was 2.7 degrees +/- 0.6 degrees. The thermolucent dosimeter rings measured no detectable radiation exposure for the surgeon. CONCLUSIONS: Virtual fluoroscopy offers several advantages over conventional fluoroscopy while providing acceptable targeting accuracy. It enables a single C-arm to provide real-time, multiplanar procedural guidance. It also dramatically reduces radiation exposure to the patient and surgical team by eliminating the need for repetitive fluoroscopic imaging for tool placement.

Fluoroscopy↗