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At least 199 records · Page 11Linked to original sources
PubMed1999

Portable mini-fluoroscopy improves operative efficiency in hand surgery.

A paired case cohort study was performed using retrospective review of operative times for defined hand surgical procedures in an attempt to quantify efficiency with and without the use of portable fluoroscopy. Patients included in the study underwent 1 of 4 defined surgical procedures controlled to ensure similar operative technique (total wrist fusion, in situ 4-corner fusion, closed reduction/internal fixation using K-wires of phalangeal shaft fractures, and metacarpophalangeal or interphalangeal joint fusions using K-wires). One group used intraoperative standard film radiographs and the other used portable mini-fluoroscopy to examine hardware placement. Both groups were paired by operative procedure to eliminate procedure bias on overall operating time. Analysis demonstrated a 38% reduction in total operative time in the group using portable mini-fluoroscopy compared with standard intraoperative radiographs.

Arthrodesis↗
PubMedDate not supplied

Prospective experience with a 20-gauge Tuohy needle for lumbar epidural steroid injections: Is confirmation with fluoroscopy necessary?

BACKGROUND AND OBJECTIVES: Small (20-gauge) Tuohy needles have been introduced for epidural steroid injection to optimize patient comfort and decrease the risk of spinal headache. These needles may be less reliable for indentification of the epidural space than standard 17- or 18-gauge needles because of their small size. We prospectively examined the success rate of lumbar epidural steroid placement with loss-of-resistance (LOR) technique compared with fluoroscopy confirmation. METHODS: One hundred patients without history of lumbar spine surgery were enrolled. A 20-gauge Tuohy needle was placed into the epidural space using LOR to saline. Confidence in epidural placement was recorded (Yes/No). Radiologic contrast was then injected and a fluoroscopic epidurogram interpreted by a blinded radiologist for correct placement, (Yes/No) separate from the clinical process. RESULTS: Reliability of LOR was less than our "gold standard" of fluoroscopy (P <.004). Sensitivity of LOR was 99% and specificity was 27%. Positive and negative predictive values were 92% and 75%. Increased patient age (>70 years) and male sex were associated with poor reliability of LOR (P <.05). CONCLUSIONS: In contrast to the reported 99% success rates for epidural placement of standard 17- or 18-gauge Tuohy needles, we observed a success rate of 92%. Small-gauge Tuohy needles are technically more difficult to use than larger needles and may require confirmation with fluoroscopy for correct epidural placement, especially in elderly male patients.

Aged↗
PubMed2001

Direct percutaneous endoscopic jejunostomy with small bowel enteroscopy and fluoroscopy.

BACKGROUND: Approaches to the creation of a percutaneous jejunostomy (PEJ) include enteroscopy with jejunal transillumination, fluoroscopy with small bowel distension and tract dilation, and jejunal enteral tube placement through a percutaneous endoscopic gastrostomy. Although all have been successful, the combination of enteroscopy and fluoroscopy may improve visualization and the success of PEJ placement. This is a description of such a technique and its successful use in 7 patients. METHODS: The procedure was performed with the patient under conscious sedation in a manner similar to standard PEG placement. The proximal jejunum was visualized and a standard snare was passed though the enteroscope and was opened. A needle and guidewire were directed percutaneously though the snare by using fluoroscopic guidance. Under direct endoscopic visualization the snare was closed around the guidewire. A standard 20F push-type "gastrostomy" tube was passed over the guidewire and through the mouth and the dome seated in the jejunum. A bumper was passed externally over the tube and tightened at the skin. RESULTS: PEJ placement was successful in all 7 patients. The average length of the procedure was 40 minutes (range 22-64 minutes). There were no major complications. Mean follow-up was 124 days (range 28-308 days). Feeding tubes remained functional until removal (2), death (1), or surgical removal for an unrelated reason (1). Three tubes are still in use. CONCLUSIONS: Percutaneous endoscopic jejunostomy tube placement can be performed successfully with enteroscopy and fluoroscopy. This technique is safe and efficient and provides distal enteral nutritional support for patients in whom PEG cannot be used.

Adult↗
PubMed2006

New needle holder facilitates percutaneous fluoroscopy-guided sacroiliac puncture.

PURPOSE: To evaluate the success of a new guidance device for sacroiliac joint puncture. MATERIAL AND METHODS: The device was first tested on a human anatomical model and thereafter on two groups of patients. In the first group (n=8), the traditional hand-guided method was used, and in the second group (n=10) the needle-holder device. The parameters evaluated in each group were "the number of attempts", defined as the number of skin punctures, and "fluoroscopy-injection time", defined as the time from the beginning of the fluoroscopy to the end of the correct insertion of the needle into the joint. RESULTS: Sacroiliac injection with the new device required significantly fewer attempts (2.1 +/- 2 versus 4.3 +/- 3) and shorter fluoroscopy injection times (8.9 +/- 3 min versus 15 +/- 5 min; P<0.05). CONCLUSION: The new guidance device makes sacroiliac joint injection easier and prevents unnecessary exposure to radiation during the procedure.

Fluoroscopy↗
PubMed1997

Automatic system for measuring dose-area product (DAP) in ROI fluoroscopy.

A computerized system for monitoring dose-area product (DAP) has been developed for region of interest (ROI) fluoroscopy in which patient exposure is reduced using an x-ray attenuating filter with an aperture. The system includes an IBM compatible computer which is connected through an IEEE-488 interface to an electrometer which measures the charge from a DAP ionization chamber. A digital input/output board connects the computer to the filter placement device to determine whether the filter is in or out of the beam, and to the x-ray generator to determine when the exposure is due to spot filming. The computer logs the DAP from conventional fluoroscopy, ROI fluoroscopy and spot filming separately, applying the appropriate calibration factor for each. Measured DAPs, fluoroscopic DAP rates and exposure times are displayed in real-time. The system has been installed in a GI fluoroscopic room so that the dose-reduction potential of ROI imaging can be evaluated.

Automation↗
PubMed2004

Dose performance evaluation of a charge coupled device and a flat-panel digital fluoroscopy system recently installed in an interventional cardiology laboratory.

The purpose of the study was to evaluate the dose performance of a flat-panel (FP) and an image intensifier (II) charge coupled device (CCD) digital fluoroscopy X-ray systems newly installed in an Interventional Cardiology (IC) department. Filter entrance dose rate, detector dose rate (during fluoroscopy) and filter entrance dose per image were measured at 70 cm from the focus using 2 mm copper sheets to mimic normal size patient. Image quality was also evaluated. The patient dose survey included 277 patients, which had either a Coronary Angiography (CA) or a Percutaneous Transluminal Coronary Angioplasty (PTCA). Dose area product (DAP), fluoroscopy time (T) and total number of frames (F) values were also collected. The results showed that both systems performed within international recommendations with the exception of higher cine radiation doses, stressing the fact that neither specific protocols of measurement nor reference values for digital equipment were provided by the official bodies.

Cardiology↗
PubMed1997

Automatic filter placement device for region of interest (ROI) fluoroscopy.

In Region of Interest (ROI) Fluoroscopy, an ROI filter is inserted into the x-ray beam in order to decrease the patient exposure in the peripheral part of the field of view. A filter placement device has been designed and constructed for the practical implementation of ROI fluoroscopy. When unmodified spot films are required during fluoroscopic procedures, an electronic signal from the high voltage generator triggers the filter placement device to remove the ROI filter automatically from the field of view and to reinsert it after the conclusion of the spot film exposure. The filter placement device is easily fastened to existing tracks on undertable tube fluoroscopic collimators. A transmission ionization chamber may be placed above the filter assembly so that radiation to the patient may be monitored during ROI fluoroscopic procedures. The mechanical design is compact and involves only one miniature gear-head motor. The filter placement device allows rapid filter positioning in 200 ms so that there is no interference with spot filming. A simple electronic circuit provides 8 volts for rapid motion of the filter support arm and 4 volts for holding the filter in place. This device demonstrates that ROI fluoroscopy with its associated large reduction in patient integral dose can be practically implemented in standard fluoroscopic equipment.

Filtration↗
PubMed2003

Evaluation of patient and staff doses during various CT fluoroscopy guided interventions.

As CT scanners are more routinely used as a guidance tool for various types of interventional radiological procedures, concern has grown for high patient and staff doses. CT fluoroscopy provides the physician immediate feedback and can be a valuable tool to dynamically assist various types of percutaneous interventions. However, the fixed position of the scanning plane in combination with high exposure factors may lead to high cumulative patient skin doses that can reach deterministic threshold limits. The staff is also exposed to a considerable amount of scatter radiation while standing next to the patient during the procedures. Although some studies have been published dealing with this subject, data of patient skin doses determined by direct in vivo dosimetry remains scarce. The purpose of this study is to quantify and to evaluate both patient and staff doses by direct thermoluminescent dosimetry during various clinical CT fluoroscopy guided procedures. Patient doses were quantified by determining the entrance skin dose with direct thermoluminescent dosimetry and by estimating the effective dose (E). Staff doses were quantified by determining the entrance skin dose at the level of the eyes, thyroid, and both the hands with direct thermoluminescent dosimetry. For a group of 82 consecutive patients, the following median values were determined (data per procedure): patient E (19.7 mSv), patient entrance skin dose (374 mSv), staff entrance skin dose at eye level (0.21 mSv), thyroid (0.24 mSv), at the left hand (0.18 mSv), and at the right hand (0.76 mSv). The maximum recorded patient entrance skin dose stayed well below the deterministic threshold level of 2 Gy. Poor correlation between both patient/staff doses and integrated procedure mAs emphasizes the need for in vivo measurements. CT fluoroscopy doses are markedly higher than classic CT-scan doses and are comparable to doses from other interventional radiological procedures. They consequently require adequate radiation protection management. An important potential for dose reduction exists by limiting the fluoroscopic screening time and by reducing the tube current (mA) to a level sufficient to provide adequate image quality.

Adolescent↗
PubMed2002

Computed tomography-fluoroscopy guided drainage of pericardial effusions: experience in 11 cases.

RATIONALE AND OBJECTIVES: The purpose of the study was to evaluate feasibility and safety of CT-fluoroscopy in the drainage of pericardial effusion in cases not accessible by sonography. METHODS: Eleven drainages were performed in Seldinger-technique under CT-fluoroscopy on eight patients suffering from pericardial effusion. The inclusion criterion was a sonographically proved pericardial effusion not drainable under sonographic surveillance. In seven procedures the catheter was positioned using a medial, in four procedures a lateral approach from the apex was chosen. RESULTS: All catheters could be placed successfully (11/11) in the pericardial effusion and allowed for draining of the effusion in 10 of 11 cases. One epicardial laceration necessitated a surgical approach. The elapsed total procedure time for the drainage was on average 18:23 +/- 8:58 minutes. CONCLUSIONS: Visual surveillance by CT-fluoroscopy is a feasible method in the drainage of pericardial effusions even in cases not accessible by ultrasound.

Adult↗
PubMed1995

Clearing the cervical spine in obtunded patients: the use of dynamic fluoroscopy.

OBJECTIVE: Obtunded patients (Glasgow Coma Scale score of < 13) with normal cervical roentgenograms remain in collars until they can be clinically evaluated. Cervical collars provide incomplete immobilization and have complications. Our hypothesis was that cervical spines could be evaluated in obtunded patients with normal cervical roentgenograms using dynamic fluoroscopy. DESIGN: This study was a prospective clinical evaluation. METHODS: Obtunded trauma patients with normal cervical roentgenograms underwent fluoroscopic examination of the cervical spine through a full range of motion. RESULTS: Fluoroscopic evaluations were done in 116 patients. There were 113 true negative examinations. Two patients had facet fractures not diagnosed on cervical roentgenograms, and no instability on fluoroscopy. One patient had a positive exam, with 2 mm of subluxation. There were no neurologic complications. Decubiti were present in 44% and were more frequent when the collar was on > 5 days (p = 0.029). CONCLUSIONS: Dynamic fluoroscopy can safely and effectively clear the cervical spine in obtunded patients. Earlier removal of the collar decreases decubiti.

Adult↗
PubMed2001

Transpedicular screw placement: image-guided versus lateral-view fluoroscopy: in vitro simulation.

STUDY DESIGN: In vitro evaluation of monitoring screw placement using an image-guided system compared with the routine use of an image intensifier. OBJECTIVES: To compare a new computer-guided method of monitoring pedicle screw placement with a well-known method of monitoring using an image intensifier, using measurements of screw placement time and accuracy. SUMMARY OF BACKGROUND DATA: Pedicle screw placement relies on the identification of anatomic landmarks for the point of entry of the pedicle. The direction and depth of screw penetration are guided by an intraoperative lateral-view image intensifier. The use of frameless stereotaxy for computer-aided pedicle screw placement may increase the accuracy and safety of the screw insertion. To the authors' knowledge, there are no published data comparing these systems on the basis of operative time and screw placement accuracy. METHOD: Eight human cadaveric sections of five vertebrae each were used for an in vitro simulation of pedicle screw placement. Four spine surgeons were chosen to simulate the transpedicular screw placement. Each surgeon placed one screw into each pedicle of two spine sections (10 vertebrae, 20 screws). The surgeon was assisted by the lateral-view image intensifier on one spine section and by the navigational system on the second one. The four surgeons placed 80 pedicle screws. Forty screw placements were monitored by fluoroscopy and 40 by the image-guided navigational system. The time spent to place one screw was recorded, as well as the remarks by each surgeons on each method. Spines were rescanned, and the positions of the screws were compared between the group on which the image intensifier has been used and the group on which the navigational system had been used. RESULTS: In the image-guided technique group, one thoracic screw disrupted the lateral cortex of the pedicle, the average distance to the anterior wall of the body was 5 mm, and the average time for the insertion of one screw was 13.5 minutes. In the other group, two screws disrupted the inner cortex of a thoracic pedicle, the average distance to the anterior wall was 10.7 mm, and the average time for the insertion of one screw was 4 minutes. CONCLUSIONS: In vitro computer-aided pedicle screw insertion is more accurate than lateral-view fluoroscopy in the thoracic spine. The main disadvantage is the time consumption compared with that required by lateral-view fluoroscopy. The total time of the surgical operation should be decreased with the future development of these techniques.

Bone Screws↗
PubMed2006

Reliability of two-dimensional echocardiography in the assessment of clinically significant abnormal hemidiaphragm motion in pediatric cardiothoracic patients: Comparison with fluoroscopy.

OBJECTIVE: To assess the utility and reliability of echocardiographic assessment of hemidiaphragm motion abnormalities in pediatric cardiothoracic patients. DESIGN: Retrospective observational study, with post hoc blinded assessment of echocardiographic and fluoroscopic results. SETTING: Tertiary care center. PATIENTS: Thirty-six consecutive pediatric cardiothoracic patients with suspected hemidiaphragm paralysis were identified and included in the study. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The results of both echocardiographic and fluoroscopic studies on all patients were included. In addition, blinded review of study results were performed. The sensitivity and specificity of fluoroscopy in identifying hemidiaphragms that needed plication were 100% and 74%, respectively. The positive predictive value was 55%; negative predictive value was 100%. Comparing reported diagnoses with blinded review of the studies showed poor agreement; reviewers agreed with 89% diagnosed as normal, 44% of paralyzed, and 76% of paradoxical hemidiaphragms. The sensitivity and specificity of echo in identifying hemidiaphragms that needed plication were 100% and 81%, respectively. The positive predictive value and negative predictive value were 66% and 100%. Comparing reported diagnoses with blinded review, reviewers agreed with 97% diagnosed as normal, 81% of paralyzed, and 100% of paradoxical hemidiaphragms. Echocardiography was less accurate in discriminating between paralyzed and paradoxical diaphragm motion. Echocardiography was specific for paradoxical motion, since both patients identified by echocardiography were confirmed by fluoroscopy, but it was not sensitive. In nine patients, echo showed paralyzed motion that was identified by fluoroscopy as paradoxical. CONCLUSIONS: This study supports the use of echocardiography in the assessment of diaphragm function. When the diaphragms are clearly visualized by echo, as they are in the majority of cases, the addition of an additional fluoroscopic study adds no clinical value. The differentiation between paralyzed and paradoxical motion is unreliable by both imaging modalities.

Adolescent↗
PubMedDate not supplied

Esophageal magnetic resonance fluoroscopy: optimization of the sequence.

OBJECTIVE: The purpose of this study was to try to delineate the esophageal passage under dynamic conditions and to determine optimum settings for esophageal magnetic resonance (MR) imaging. METHODS: Ten healthy volunteers underwent MR fluoroscopy with two T1-weighted sequences: turbo field echo (TFE) and T1-weighted fast field echo (T1-FFE). These sequences were compared for signal-to-noise ratios (SNRs) and image quality. To determine the optimum slice thickness, an additional 10 healthy volunteers underwent MR fluoroscopy. Results obtained for slice thicknesses of 25, 35, 45, and 55 mm were compared for delineated length of the esophagus and image quality. RESULTS: The T1-FFE sequences provided higher SNRs and better image quality than the TFE sequences (T1-FFE: 89.4 +/- 28.0, TFE: 52.4 +/- 16.7; P < 0.001). Artifacts were less prominent and delineation of the esophageal wall was better on the T1-FFE images. The delineation of the esophageal wall was best with a 35-mm slice thickness, although delineated length was the longest with a 55-mm slice thickness. CONCLUSION: This study showed T1-FFE to be a more suitable sequence than TFE and that the 35-mm slice thickness was the optimum slice thickness for esophageal MR fluoroscopy.

Adult↗
PubMed2006

CT fluoroscopy shielding: decreases in scattered radiation for the patient and operator.

PURPOSE: High-radiation exposure occurs during computed tomographic (CT) fluoroscopy. Patient and operator doses during thoracic and abdominal interventional procedures were studied in the present experiment, and a novel shielding device to reduce exposure to the patient and operator was evaluated. MATERIALS AND METHODS: With a 16-slice CT scanner in CT fluoroscopy mode (120 kVp, 30 mA), surface dosimetry was performed on adult and pediatric phantoms. The shielding was composed of tungsten antimony in the form of a lightweight polymer sheet. Doses to the patient were measured with and without shielding for thoracic and abdominal procedures. Doses to the operator were recorded with and without phantom, gantry, and table shielding in place. Double-layer lead-free gloves were used by the operator during the procedures. RESULTS: Tungsten antimony shielding adjacent to the scan plane resulted in a maximum dose reduction of 92.3% to the patient. Maximum 85.6%, 93.3%, and 85.1% dose reductions were observed for the operator's torso, gonads, and hands, respectively. The use of double-layer lead-free gloves resulted in a maximum radiation dose reduction of 97%. CONCLUSIONS: Methods to reduce exposure during CT fluoroscopy are effective and should be searched for. Significant reduction in radiation doses to the patient and operator can be accomplished with tungsten antimony shielding.

Antimony↗
PubMed1999

Perception of temporally filtered X-ray fluoroscopy images.

For noisy X-ray fluoroscopy image sequences we quantitatively evaluated image quality after digital temporal filtering to reduce noise. Using an experimental paradigm called a reference/test adaptive forced-choice method we compared detectability of stationary low-contrast disks in filtered and unfiltered, computer-generated image sequences. In the first experiment, a low-pass first-order recursive filter used in X-ray fluoroscopy was found to be much less effective at enhancing detectability than predicted from the reduction of display noise variance, a common measurement of filter effectiveness. Detectability was reasonably predicted by a nonprewhitening human-observer model (NPW-HVS) that included an independently determined human temporal-contrast-sensitivity function. In another experiment, designed to test models over a range of temporal frequencies, we used paired high-pass and low-pass temporal filters that both reduced noise variance by 25%. The high-pass filter was artificially applied to the noise only and greatly improved detectability, while the low-pass filter had little effect. The human-observer model quantitatively described the measurements, but classical prewhitening and nonprewhitening signal detectors did not. As compared to the nonprewhitening, spatio-temporal matched filter, human-observer efficiency was low and variable at 2.1%, 2.9%, and 0.06% for 60 frames of unfiltered low-pass and high-pass noise, respectively. As compared to this detector, humans were not very effective at combining information across frames. On the other hand, signal to noise ratios (SNR's) from the human-observer model were comparable to human performance, and efficiencies were reasonably constant at 40%, 52%, and 32%, respectively. We conclude that it is imperative to include human-observer models and experiments in the analysis of noise-reduction filtering of noisy image sequences, such as X-ray fluoroscopy.

Adult↗
PubMed1997

Voxel-based 2-D/3-D registration of fluoroscopy images and CT scans for image-guided surgery.

Registration of intraoperative fluoroscopy images with preoperative three-dimensional (3-D) CT images can be used for several purposes in image-guided surgery. On the one hand, it can be used to display the position of surgical instruments, which are being tracked by a localizer, in the preoperative CT scan. On the other hand, the registration result can be used to project preoperative planning information or important anatomical structures visible in the CT image onto the fluoroscopy image. For this registration task, a novel voxel-based method in combination with a new similarity measure (pattern intensity) has been developed. The basic concept of the method is explained at the example of two-dimensional (2-D)/3-D registration of a vertebra in an X-ray fluoroscopy image with a 3-D CT image. The registration method is described, and the results for a spine phantom are presented and discussed. Registration has been carried out repeatedly with different starting estimates to study the capture range. Information about registration accuracy has been obtained by comparing the registration results with a highly accurate "ground-truth" registration, which has been derived from fiducial markers attached to the phantom prior to imaging. In addition, registration results for different vertebrae have been compared. The results show that the rotation parameters and the shifts parallel to the projection plane can accurately be determined from a single projection. Because of the projection geometry, the accuracy of the height above the projection plane is significantly lower.

Fluoroscopy↗
PubMed2004

Improvement of depth position in 2-D/3-D registration of knee implants using single-plane fluoroscopy.

Two-dimensional (2-D)/three-dimensional (3-D) registration techniques using single-plane fluoroscopy are highly important for analyzing 3-D kinematics in applications such as total knee arthroplasty (TKA) implants. The accuracy of single-plane fluoroscopy-based techniques in the determination of translation perpendicular to the image plane (depth position), however, is relatively poor because a change in the depth position causes only small changes in the 2-D silhouette. Accuracies achieved in depth position using conventional 2-D/3-D registration techniques are insufficient for clinical applications. Therefore, we propose a technique for improving the accuracy of depth position determination in order to develop a system for analyzing knee kinematics over the full six degrees of freedom (6 DOF) using single-plane fluoroscopy. In preliminary experiments, the behaviors of errors for each free variable were quantified as evaluation curves by examining changes in cost function with variations in the free variable. The evaluation curve for depth position was more jagged, and the curve peak less pointy, compared to the evaluation curves of the other five variables, and the curve was found to behave differently. Depth position is therefore optimized independently of the other variables, using an approximate evaluation curve of depth position prepared after initial registration. Accuracy of the proposed technique was evaluated by computer simulation and in vitro tests, with validation of absolute position and orientation performed for each knee component. In computer simulation tests, root-mean-square error (RMSE) in depth position was improved from 2.6 mm (conventional) to 0.9 mm (proposed), whereas for in vitro tests, RMSE improved from 3.2 mm to 1.4 mm. Accuracy of the estimation of the remaining two translational and three rotational variables was found to be almost the same as that obtained by conventional techniques. Results of in vivo tests are also described in which the possibility of full 6 DOF kinematic analysis of TKA implants is shown.

Algorithms↗
PubMed2000

Diagnostic catheterization and balloon sizing of atrial septal defects by echocardiographic guidance without fluoroscopy.

To avoid x-ray exposure prior to interventional closure of atrial septal defects (ASDs), we recently developed a technique for diagnostic catheterization and balloon sizing of the defect by echocardiographic guidance without fluoroscopy. We report on our first experiences with this technique. Fourteen patients with atrial septal perforations (mean age, 23 years; range, 1-66 years) underwent diagnostic catheterization and balloon sizing prior to possible interventional defect closure. Mean size of the defects was 16 mm (7-29 mm). Mean left-to-right shunt was Qp/Qs = 2.0 (range, 1.0-4.0). Without fluoroscopy, the procedures were performed in two children by transthoracic echocardiography (TTE) and in 12 patients by both TTE and transesophageal echocardiography (TEE). Mean procedure time was 59 minutes (range, 35-90 minutes). We conclude that oxymetry, pressure recordings, and the estimation of the balloon-stretched size of atrial septal perforations can be performed safely by echocardiographic guidance without fluoroscopy. The x-ray exposure for patient selection prior to a transcatheter closure of an ASD can be avoided with this technique.

Adolescent↗