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At least 343 records · Page 19Linked to original sources
PubMed2000

A determination of ankle kinematics using fluoroscopy.

In vivo weight-bearing studies utilizing dynamic video fluoroscopy have been shown to offer an accurate and reproducible method for determining the kinematics of a joint. The purpose of this study was to evaluate translational and rotational motions of the distal tibia relative to the talus in the sagittal and frontal planes. Ten subjects, each having a normal ankle and a total ankle arthroplasty on the opposite side (Buechel-Pappas Total Ankle, Endotec, South Orange, NJ), were studied under in vivo, weight-bearing conditions using video fluoroscopy. All ten subjects were judged to have a successful arthroplasty without demonstrable pain or ligament instability. Under weight-bearing conditions, each subject performed successive motions moving from maximum dorsiflexion to plantarflexion. At maximum dorsiflexion, both the normal and implanted ankles had similar sagittal midline talar contact positions but with plantar flexion, implanted ankles had increased posterior talar contact. Contact points on the distal tibia revealed that the lateral surface contacted at the midline or posterior throughout range-of-motion with minimal translation. The medial distal tibia contacted the talus posterior on plantarflexion and often moved anteriorly with dorsiflexion. This translation described relative external rotation of the distal tibia on plantar flexion and internal rotation on dorsiflexion. The measured distances were larger for the implanted ankles with higher variability. The average range-of-motion was 37.4 degrees for normal ankles and 32.3 degrees for implanted ankles. This study defines the normal kinematic rotational and translational motions of the ankle joint by accurately describing the three dimensional joint orientations. The implanted ankles experienced rotational and translational motions but had contacts more posterior, possibly related to surgical technique or alterations of ligamentous tension.

Ankle Joint↗
PubMed1984

Digital fluoroscopy with a conventional fluoroscopic room and a nuclear medicine computer system.

The potential of a commercially-available nuclear medicine computer, with a digital video interface, supplied by its manufacturers, for digital fluoroscopy is described. In the absence of universally accepted standards against which the performance of digital fluoroscopy systems may be judged, the parameters included in the description of this system included linearity, uniformity, signal-to-noise ratio, matrix size at given frame rates and study sizes. In addition some examples of clinical studies involving subtraction are presented.

Cerebral Angiography↗
PubMed1995

Update on the recommended viewing protocol for FAXIL threshold contrast detail detectability test objects used in television fluoroscopy.

The significance of varying the viewing conditions that may affect the perceived threshold contrast of X-ray television fluoroscopy systems has been investigated. Factors investigated include the ambient room lighting and the viewing distance. The purpose of this study is to find the optimum viewing protocol with which to measure the threshold detection index. This is a particular problem when trying to compare the image quality of television fluoroscopy systems in different input field sizes. The results show that the viewing distance makes a significant difference to the perceived threshold contrast, whereas the ambient light conditions make no significant difference. Experienced observers were found to be capable of finding the optimum viewing distance for detecting details of each size, in effect using a flexible viewing distance. This allows the results from different field sizes to be normalized to account for both the magnification and the entrance air kerma rate differences, which in turn allow for a direct comparison of performance in different field sizes.

Clinical Protocols↗
PubMed2000

Thrombosis of mechanical heart valve prostheses: revisiting the role of fluoroscopy.

Prosthetic valve thrombosis is a rare but potentially fatal complication of heart valve replacement. Symptoms may be misleading, yet the condition may rapidly lead to death. A prompt diagnosis is therefore crucial. Ultrasound is the most often used technique for evaluating prosthesis dysfunction. We describe two cases of prosthesis thrombosis with negative Doppler results but with distinctly abnormal leaflet motion at fluoroscopy. A correct diagnosis would have been missed if the Doppler evaluation alone was relied on. Fluoroscopy should always form part of the diagnostic work-up in patients with artificial heart valves.

Coronary Thrombosis↗
PubMed2002

Mediastinal abscess successfully treated by percutaneous drainage using a unified CT and fluoroscopy system.

We report two patients with mediastinal abscess developing after surgery for oesophageal cancer who were treated by percutaneous drainage using a unified CT and angiography system, which allows both CT and fluoroscopy to be conducted with the patient on the same bed. Fine needle puncture is performed under CT guidance and this needle is used as a tandem for insertion of the drainage needle under fluoroscopic guidance, making safe puncture possible whilst confirming the position of the needle tip. Moreover, contrast medium can be injected from the drainage tube, allowing the extent of the abscess cavity to be determined by fluoroscopy and CT, thereby making accurate drainage possible.

Abscess↗
PubMed2003

Do radiologists' radiation-related opinions predict their fluoroscopy doses?

The influence of radiologists' radiation-related opinions to fluoroscopy doses was studied. Dose-area products (DAP), screening times and the number of exposures per patient were recorded in 528 barium enema examinations performed by 23 residents (14 female, 9 male). The residents' scored opinions (on the general radiation risk in radiology, the importance of radiation protection in radiology and their estimate of their own dose level on which they operate when compared with their colleagues) were correlated with these radiation variables. Residents' opinion on the importance of radiation protection correlated positively with screening time (r=0.402, p=0.008) and with DAP (r=0.333, p=0.028). The female residents (score 8.3) considered radiation protection more important than the males (score 7.4, p=0.029). The stability of these opinions was suggested by finding them not to correlate with residents' age or radiological experience. Residents could not reliably estimate their true dose levels, which were compared with the estimated dose levels. Fluoroscopy behaviour and doses seem to be affected by psychological factors. Further psychologically oriented studies might assist in revealing such factors and in developing proper teaching methods for radiologists to control their doses.

Attitude of Health Personnel↗
PubMed2005

Dose implications of fluoroscopy-guided positioning (FGP) for lumbar spine examinations prior to acquiring plain film radiographs.

Fluoroscopy is increasingly being used as a positioning device prior to obtaining plain film radiographs. This is particularly true for those examinations where the type of projection and habitus of the patient present difficulties. An example is the examination of the lumbar spine; especially the L5/S1 projection. The purpose of this study was to determine the effect of fluoroscopy-guided positioning (FGP) on patient dose. The study assessed the difference in dose-area product (DAP) between conventional film-screen radiography (FSR) and a FGP assisted series of the lumbar spine. DAP values were monitored on 102 patients (50 FSR, 52 FGP) over 7 (4 FSR, 3 FGP) study sites. The median values for all FGP and FSR procedures were 8.3 Gy cm(2) and 12.5 Gy cm(2), respectively. The differences in doses were attributed to lower mAs and tighter collimation used in FGP assisted procedures. The study has demonstrated that it is possible to achieve lower DAP values using FGP. What now has to be asked is whether FGP should be acknowledged and further introduced into clinical practice. If so, there is a need for careful monitoring and reporting of dose so that strict protocols can be set in place to ensure the ALARA principle is enforced.

Adult↗
PubMed2003

Use of a quality index in threshold contrast detail detection measurements in television fluoroscopy.

The use of a single index to assist in quality control procedures of X-ray television fluoroscopy systems was investigated. A single quality index was devised incorporating a measure of threshold contrast detail detectability (TCDD) performance and taking into account image intensifier input kerma rate, field size, differences in radiation beam quality, and pulsed fluoroscopy. This was applied to a number of clinical systems to investigate changes in image quality index quantified over time. Accepted measurement protocols were used to obtain these measurements. The results show system performance for different systems and can establish the decline in performance parameters over time or assess non-optimal image quality with clinical systems in field measurements. The systems studied were assessed with a variety of performance parameters including TCDD results, low contrast sensitivity, limiting resolution, and image intensifier input kerma rate under clinical modes of operation. The TCDD quality index, and dose normalized quality index, were found to be useful image quality assessment parameters for serial testing of systems, which augment the use of graphical methods for the display of TCDD curves.

Fluoroscopy↗
PubMed1998

Detection of moving objects in pulsed-x-ray fluoroscopy.

We investigated the detectability of moving, low-contrast objects in white-noise image sequences. The computer-generated, cylindrical phantoms mimicked arteries, catheters, and guide wires in medical, x-ray fluoroscopy image sequences at 16 acquisitions/s (pulsed-16) or 32 acquisitions/s (pulsed-32). We measured detectability by using a reference-test, adaptive forced-choice method whereby reference and test presentations were alternated during an experimental session to minimize effects of subject attention and accuracy criteria. In the case of the largest cylinder (diameter 0.48 deg), the highest speed (5.86 deg/s) increased absolute detectability by approximately 42% compared with that in the stationary case. With the smallest cylinder (diameter 0.023 deg), this motion decreased detectability by approximately 51%. The dose savings of pulsed-16 was approximately 18% of that for pulsed-32, with relatively little effect of velocity or object size. In general, subjects took slightly longer to respond in the case of low-acquisition fluoroscopy. Detectability data were modeled with a nonprewhitening matched filter that included a physiological, spatiotemporal contrast sensitivity function and a suboptimal, spatiotemporal signal template with time-limited memory.

Fluoroscopy↗
PubMed1999

Detection improvement in spatially filtered x-ray fluoroscopy image sequences.

The effect of spatial noise-reduction filtering on human observer detection of stationary cylinders mimicking arteries, catheters, and guide wires in x-ray fluoroscopy was investigated in both single image frames and image sequences. Ideal edge-preserving spatial filtering was simulated by filtering of the noise before addition of the target cylinder. This allowed us to separate the effect of edge blurring from those of noise reduction and spatial noise correlation. We used three different center-weighted averagers that reduced pixel noise variance by factors of 0.75, 0.50, and 0.25. As compared with no filtering, the effect of filtering on detection in single images was statistically insignificant. This indicated an adverse effect of spatial noise correlation on detection that countered the effect of noise reduction. By comparison, spatial filtering significantly improved detection in image sequences and yielded potential x-ray dose savings of 26-34%. Comparison of results with two observer models suggested that human observers have an improved detection efficiency in spatially filtered image sequences as compared with white-noise sequences. Pixel noise reduction, a measure commonly used to assess filter performance, overestimated the effect of filtering on detection and was not a good indicator of image quality. We conclude that edge-preserving spatial filtering is more effective in sequences than in single images and that such filtering can be used to improve image quality in noisy image sequences such as x-ray fluoroscopy.

Contrast Sensitivity↗
PubMed2002

Quantitative assessment of image quality enhancement due to unsharp-mask processing in x-ray fluoroscopy.

Spatial unsharp-mask processing and its variants are commonly used in x-ray radiography to enhance image contrast. We investigated the effect of three unsharp-masking filter kernels of different sizes on the detection of an advanced guidewire tip in simulated x-ray fluoroscopy image sequences. To isolate the effect of visual temporal processing, we repeated the experiments on single images. Filter gains were selected so that all three kernels increased the contrast of a 0.018-in. (0.457-mm) guidewire by a factor of 2 but had different effects on image noise and signal profiles. There was no statistically significant effect of unsharp masking on human-observer performance in single images. However, all three kernels significantly improved average performance in image sequences, and the guidewire contrast required for detection was reduced by 32%-40%. A prewhitening channelized observer model predicted the disparity between sequences and single images and fitted measurements at different kernel sizes well. A nonprewhitening observer model did not. We conclude that unsharp masking is a simple and effective method of improving guidewire visualization in fluoroscopically guided interventional procedures and that quantitative image quality studies are essential for evaluation of image-processing techniques in sequences such as x-ray fluoroscopy.

Adult↗
PubMed2004

CT fluoroscopy-guided bronchoscopic dye marking for resection of small peripheral pulmonary nodules.

STUDY OBJECTIVE: To determine the diagnostic reliability and safety of a new marking technique using transbronchoscopic dye injection under CT fluoroscopy for preoperative localization of a small pulmonary nodule. DESIGN: Prospective study. SETTING: Hyogo Medical Center for Adults and Shizuoka Cancer Center in Japan. PATIENTS: Seventeen patients who had a peripheral pulmonary nodule < 15 mm in size on CT scans that was suspected to be difficult to localize by visual inspection and manual palpation at our institutes between April 2000 and October 2002. INTERVENTIONS: After a bronchoscope was inserted orally under local anesthesia and was introduced into the related bronchus of the target nodule, a Teflon sheath catheter with metal tip was inserted transbronchoscopically and was advanced into the visceral pleura. By monitoring CT fluoroscopy, the catheter tip was positioned at the nearest pleural surface of the nodule, and 0.5 mL indigo carmine was injected under deep inspiratory breathhold. CT scans were obtained to confirm the relationship between the injected dye area and the nodule. MEASUREMENTS AND RESULTS: The dye injections were performed completely in all 17 patients, who subsequently underwent lung resection guided by the dye staining. There were no complications or harmful effects of the surgery. The area of injected dye was demonstrated as a hazy focal lesion about 10 mm beneath the pleura on the high-resolution CT scan, and was clearly visible as a patchy dark blue area about 20 mm in size on the visceral pleura at surgery. The mean distance between the nodule and the dye was 20 mm on the CT scan (distance range, 0 to 30 mm). The mean examination time with this technique was approximately 35 min (range, 25 to 45 min). The mean CT fluoroscopic time was 60 s (range, 30 to 120 s). CONCLUSIONS: Our transbronchial "tattooing" technique is safe and reliable. We think it is superior to previous marking methods.

Adult↗
PubMed2004

Ultrathin bronchoscopic barium marking with virtual bronchoscopic navigation for fluoroscopy-assisted thoracoscopic surgery.

STUDY OBJECTIVES: To facilitate marking and to reduce its complications, we performed barium marking using an ultrathin bronchoscope with virtual bronchoscopic (VB) navigation before thoracoscopic surgery for small pulmonary peripheral lesions. We then evaluated the feasibility, safety, and efficacy of this technique. DESIGN: A pilot study. SETTING: A tertiary teaching hospital. PATIENTS: The subjects were consecutive patients with small pulmonary peripheral lesions (ie, </= 10 mm) showing a CT scan-confirmed pure ground-glass opacity pattern between December 2001 and August 2003. INTERVENTIONS: VB images to the planned marking sites near each lesion were produced from helical CT scan data. Based on these images, an ultrathin bronchoscope was advanced to the target bronchus under direct vision. Under CT scan and radiographic fluoroscopy, a catheter was inserted to the planned site via the bronchoscope, and barium sulfate suspension was instilled for marking. RESULTS: The subjects were 23 patients (8 men and 15 women) who had a total of 31 lesions. The bronchial branching patterns seen in VB images were highly consistent with those confirmed using the ultrathin bronchoscope. Therefore, the ultrathin bronchoscope could be guided under direct vision to a median of the sixth generation bronchi (range, fourth to ninth generation bronchi) toward the planned marking sites. Marking was achieved without causing complications in any of the patients. The median marking time was 23.5 min, and the median shortest distance between the barium marker and the lesion was 4 mm (within 10 mm in 27 lesions). In patients undergoing thoracoscopic surgery, all barium-marked sites were identified by intraoperative radiographic fluoroscopy, and all lesions were resected. A pathologic examination demonstrated primary lung cancer in 17 lesions (bronchioloalveolar carcinoma, 15; adenocarcinoma, 2), atypical adenomatous hyperplasia in 12 lesions, and pneumonia in 2 lesions. CONCLUSIONS: This method can be readily performed without complications and is a useful marking method before thoracoscopic surgery for small pulmonary peripheral lesions.

Aged↗
PubMed2005

Electromagnetic catheter navigation during bronchoscopy: validation of a novel method by conventional fluoroscopy.

BACKGROUND: Electromagnetic navigation in bronchoscopy is a novel method for assisting in the localization of peripheral lung lesions. STUDY OBJECTIVE: To assess the usability, accuracy, and safety of electromagnetic navigation during flexible bronchoscopy in a clinical setting. DESIGN: Prospective evaluation. PATIENTS: Consecutive patients referred to the bronchoscopy unit for the diagnosis of peripheral infiltrates or solitary pulmonary nodules (SPNs). METHODS: Navigation was performed using an electromagnetic tracking system with a position sensor encapsulated in the tip of a flexible catheter that was pushed through the working channel of the bronchoscope. Real-time, multiplanar reconstruction of a previously acquired CT data set provided three-dimensional views for localization of the catheter. To match the position of the sensor with the CT scan, four anatomic landmarks were used for registration. The sensor position generated in the navigation system was controlled by fluoroscopy, and the corresponding error distances were measured. This was performed with all SPNs and at two different peripheral locations of the right upper lobe (RUL). RESULTS: Sixteen patients (10 men and 6 women; mean age, 63.7 years) were studied. Navigation prolonged bronchoscopy by 3.9 +/- 1.3 min (mean +/- SD). The navigation system identified all lesions. The position sensor achieved a direct hit in three of five SPNs. Fluoroscopy failed to recognize three SPNs (60%) and three infiltrates (38%). The mean error distances between sensor tip position and fluoroscopically verified RUL reference position were 10.4 mm (lateral position) and 12.5 mm (apical position) respectively. The mean error distances between the sensor tip and two endobronchial registration points at the end of the procedure were 4.2 mm and 5.1 mm, respectively. CONCLUSION: Electromagnetic navigation is useful, accurate, and safe in the localization of peripheral lung lesions and may help to improve the yield of diagnostic bronchoscopic procedures.

Adult↗
PubMed1985

Bronchial and transbronchial lung biopsy without fluoroscopy in sarcoidosis.

Sixty-eight patients with a clinical diagnosis of sarcoidosis underwent flexible fiberoptic bronchial and transbronchial lung biopsies without the aid of fluoroscopy. Close observation of the normal respiratory excursions of the distal tracheobronchial tree and tactile sensations were found to be helpful in preventing pleural rupture. Sarcoidosis was histologically confirmed in bronchial or transbronchial tissue (or both) by this technique in 51 (76 percent) of 67 patients. Only a single pneumothorax and no significant bleeding resulted from this procedure. In the hands of experienced physicians, peripheral bronchial biopsies and transbronchoscopic lung biopsies are safe and accurate procedures even when performed in institutions where fluoroscopy is not immediately available.

Adolescent↗
PubMed2004

Importance of access to fixed-imaging fluoroscopy: practice implications for the vascular surgeon.

PURPOSE: To examine the impact of unfettered access to high quality fixed-imaging fluoroscopy in a vascular surgery practice. METHODS: The case mix of 2 vascular surgeons was retrospectively examined for a 12-month period before (period A) and after (period B) routine access to fixed-imaging equipment was established. Operative and endovascular cases were identified by their CPT codes. Trends in procedure frequency and gross charges were assessed. RESULTS: Endovascular code usage increased 174% (p<0.001) following routine access to fixed imaging equipment. There was an overall 2.3-fold increase in angioplasty across all vascular beds (p<0.001), as well as a 2.1-fold increase in stent utilization (p<0.001). More complex diagnostic and interventional procedures were performed, as evidenced by a large increase in third-order catheterizations (p<0.001). Open surgical therapy decreased overall by 11.4% (p=0.051) in period B. Reductions in open surgery for peripheral arterial occlusive disease were most pronounced, decreasing 35.6% (p<0.001). Overall gross charges increased 6% in group B. Endovascular procedures accounted for 36.6% of gross charges in period B, doubling its contributions from period A (17.1%, p=0.01). Open major vascular case contributions to gross charges fell from 54.4% to 36.2%. CONCLUSIONS: A significant shift in case mix was observed after routine access to fixed imaging equipment was established, with a dramatic increase seen in percutaneous endovascular case volume and complexity. Corresponding contributions to gross charges for endovascular procedures became equivalent to that of all open major vascular cases combined. Routine access to fixed imaging fluoroscopy appeared to be the chronological fulcrum on which the balance of endovascular and open vascular cases has shifted, allowing the development of a fully integrated vascular and endovascular practice.

Angioplasty↗
PubMed2003

Percutaneous sclerotherapy for venous malformations using polidocanol under fluoroscopy.

This retrospective study evaluated the safety and efficacy of using polidocanol with X-ray fluoroscopy for percutaneous sclerotherapy of venous malformations of the limbs, head, and neck. The subjects were 16 of 18 patients who presented to our department with venous malformations. Two patients were excluded because they were unlikely to benefit from the treatment. Of the 16 included in the study, 1 could not be treated because of inaccessibility, and another was lost to follow-up. Among the 14 cases that we were able to follow-up, 11 cases had had pain as their primary symptom. Following treatment, this symptom remained unchanged in 1 patient, was improved in 4, and had disappeared in 6; however, there was a recurrence of pain for 3 of these patients. Two patients had sought treatment for cosmetic purposes; following treatment, the lesion disappeared in one and showed a significant reduction in the other. The remaining patient presented with a primary symptom of mouth bleeding, which disappeared following treatment. There were no critical complications. Percutaneous sclerotherapy of venous malformations using polidocanol is safe and effective, and permits repeat treatments. The efficacy is especially good for resolving pain, and complications are minor. It is desirable to use fluoroscopy for these procedures

Administration, Cutaneous↗
PubMed1980

Computerized fluoroscopy: digital subtraction for intravenous angiocardiography and arteriography.

Computerized fluoroscopy is a system comprising on-line digital time and energy subtraction algorithms designed to isolate and enhance the iodine signal from image intensified fluoroscopy. The apparatus is described and its use for time subtraction intravenous arteriography of the carotid, abdominal, extremely arteries, as well as the heart, is illustrated. Vascular diseases such as stenoses, obstruction, emboli, ulcerative plaques, and aneurysms are readily demonstrated. The technique has a potential for evaluating cardiac motion and the patency of coronary artery bypass grafts. The method appears to be a safe and less expensive alternative to catheter arteriography and angiocardiography in certain instances.

Adult↗