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At least 1,243 records · Page 69Linked to original sources
PubMed2006

X-ray dose reduction in fluoroscopically guided electrophysiology procedures.

This study assessed the efficacy of a new dose reduction regime in fluoroscopically guided electrophysiology (EP) procedures, which included diagnostic electrophysiological investigations, radiofrequency ablation, and biventricular pacing. A modified dose regime for fluoroscopy was implemented in one of our cardiac electrophysiology laboratories. The x-ray system was programmed with a hierarchy of three fluoroscopy doses, and therefore image quality and settings. The default (lowest) dose mode was not expected to be suitable for all patient sizes or for the entirety of all procedures. Staff raised the dose level in a stepped manner as and when required to optimize the imaging requirements of the procedure. Phantom studies indicated that the low dose mode provided adequate image quality for visualizing EP catheters, while significantly lowering patient skin dose. In 52 clinical cases, questionnaires were used to assess the subjective clinical image quality. The mean image quality score for the low dose setting was rated between "adequate" and "good." The fluoroscopy dose level was raised from the lowest level for 6% of the total fluoroscopy time. Procedural Dose Area Product (DAP) meter readings were analyzed for patients prior to (n = 85) and after (n = 150) the implementation of the low dose regime and showed an overall reduction in DAP rate of 74%. The hierarchical dose regime proved to be acceptable in routine clinical practice for EP procedures, leading to significant reductions in patient doses.

Body Burden↗
PubMed2000

Nonfluoroscopic three-dimensional mapping for arrhythmia ablation: tool or toy?

INTRODUCTION: Conventional mapping and ablation rely on fluoroscopy, which can result in imprecise positioning of the ablation catheter and long fluoroscopic exposure times. We evaluated a nonfluoroscopic three-dimensional mapping system, termed CARTO, and compared the results of ablation using this technique with those of conventional mapping. METHODS AND RESULTS: We compared the results of 88 arrhythmia ablations (79 patients) using CARTO with 100 ablations (94 patients) using the conventional technique. The ablations were separated into four groups: (1) AV nodal reentrant tachycardia (AVNRT); (2) atrial tachycardia/flutter; (3) ventricular tachycardia (VT); and (4) bypass tract tachycardia. We compared the success rate, complications, and fluoroscopy and procedure times. The ablation outcomes were excellent and comparable in all four types of the arrhythmias between the two techniques. Major complications included one cardiac tamponade in each group and one second-degree AV block in the conventional group. Fluoroscopy time was shorter using the CARTO technique: 10+/-7 versus 27+/-15 minutes for AVNRT (P < 0.01), 18+/-17 versus 44+/-23 minutes for atrial tachycardia and flutter (P < 0.01), 15+/-12 versus 34+/-31 minutes for VT (P < 0.05), and 21+/-14 versus 53+/-32 minutes for bypass tract tachycardia (P < 0.01). Procedure times were similar except for the bypass tract patients, which was shorter in the CARTO group, 4+/-1.3 versus 5.5+/-2.5 hours (P < 0.01). CONCLUSION: The electroanatomic three-dimensional mapping technique reduced fluoroscopy time and resulted in excellent outcome without increasing the procedure time.

Atrial Flutter↗
PubMed1994

Nasojejunal feeding tube placement in children: four-year cumulative experience.

PURPOSE: Experience with fluoroscopically guided nasojejunal feeding tube placement in children was assessed regarding clinical diagnosis, fluoroscopy time, radiation dose, success rate, and placement failures. MATERIALS AND METHODS: From 1987 to 1991, 562 nasojejunal tubes were placed in 232 patients aged 1 week to 24 years (mean, 3 1/2 years) at the authors' institution. In every case, an 8-F feeding tube system was inserted. The fluoroscopy times and tube placement positions were evaluated in all cases. RESULTS: The mean fluoroscopy time was 5 minutes 30 seconds, which corresponded to an estimated mean midline fluoroscopy dose of 0.32 cGy. The tube was placed at or distal to the duodenojejunal junction in 543 attempts, for a success rate of 97%. The most common cause for unsuccessful tube placement was malrotation, with the fluoroscopic time and radiation dose significantly (P < .001) prolonged in these cases. CONCLUSION: Fluoroscopic guidance of placement of nasojejunal feeding tubes in children is successful, but the radiation exposure is not negligible and must be weighed against the need for nasojejunal feeding.

Adolescent↗
PubMed2002

Breath-by-breath measurement of the volume displaced by diaphragm motion.

To develop an accurate method to measure the volume displaced by diaphragm motion (DeltaVdi) breath by breath, we compared DeltaVdi measured by a previously evaluated biplanar radiographic method (Singh B, Eastwood PR, and Finucane KE. J Appl Physiol 91: 1913-1923, 2001) at several lung volumes during vital capacity inspirations in 10 healthy and nine hyperinflated subjects with 1) DeltaVdi measured from the same chest X-rays by two previously described uniplanar methods (Petroll WM, Knight H, and Rochester DF. J Appl Physiol 69: 2175-2182, 1990; Verschakelen JA, Deschepper K, and Demendts M. J Appl Physiol 72: 1536-1540, 1992) and a proposed method that considered actual cross-sectional shape of the rib cage and spinal volume (DeltaVdi(S)); and 2) DeltaVdi(S) measured by lateral fluoroscopy in the same 10 healthy subjects. Relative to biplanar DeltaVdi, DeltaVdi(S) values from lateral chest X-rays and fluoroscopy were not different, whereas DeltaVdi values of Petroll et al. and Verschakelen et al. were increased by (means +/- SD) 1.98 +/- 1.59 and 1.16 +/- 0.82 liters, respectively (both P < 0.001). During quiet breathing, DeltaVdi(S) by lateral fluoroscopy was 66 +/- 16% of tidal volume and similar to that between functional residual capacity and one-half inspiratory capacity by the biplanar radiographic method. We conclude that accurate breath-by-breath measurements of DeltaVdi can be made by using lateral fluoroscopy.

Adult↗
PubMed1998

Risk to patients from radiation associated with radiofrequency ablation for supraventricular tachycardia.

BACKGROUND: Radiofrequency ablation may be associated with prolonged fluoroscopy times. Previous studies have calculated radiation risks by measuring the radiation dose at a limited number (6) of body sites. This is an inherently inaccurate measure. Our study aimed to quantify more precisely patient-related radiation risks associated with radiofrequency ablation for supraventricular tachycardia. METHODS AND RESULTS: Nine female patients having radiofrequency ablation for supraventricular tachycardia were studied. The radiation dose was determined at 41 body sites in each patient with the use of thermoluminescent dosimeters and was correlated with that measured simultaneously with a Diamentor dose-area product meter. The estimated mean organ doses (mGy) per 60 minutes of fluoroscopy were: lungs 30.8; bone marrow 4.3; left breast 5.1; right breast 3. 5; and thyroid 2.4. From the average organ doses, the estimated mean total lifetime excess risk of a fatal malignancy was 294 per million cases (0.03%) per 60 minutes of fluoroscopy. The risk calculation from the Diamentor dose-area product and thermoluminescent dosimeters were similar, suggesting that radiation dose was measured accurately. The estimated risk of radiation-induced malignancy increased with increasing body mass index (P=0.03). CONCLUSIONS: Prolonged fluoroscopy during radiofrequency ablation may potentially cause a small increase in the lifetime risk of fatal malignancy, with lung malignancy being most likely. This risk is small only with the use of techniques and x-ray equipment optimized to keep radiation as low as possible. The risk is increased in obese patients.

Adult↗
PubMed2001

Accurate assessment of patient effective radiation dose and associated detriment risk from radiofrequency catheter ablation procedures.

BACKGROUND: Radiofrequency (RF) cardiac catheter ablation procedures may require extended fluoroscopic exposure resulting in elevated radiation risk. The aim of the present study was to accurately establish RF ablation radiation risk levels and to provide means for accurate patient risk estimation from studies performed in any electrophysiology laboratory. METHODS AND RESULTS: Fluoroscopy required during cardiac ablation was classified into 4 types identified by beam orientation and irradiated tissue: (1) posteroanterior exposure during catheter advancing from the groin to the heart, (2) posteroanterior heart exposure, (3) left anterior oblique heart exposure, and (4) right anterior oblique heart exposure. The duration of each exposure was monitored in 24 patients undergoing RF cardiac ablation. Dose per minute of fluoroscopy was measured at 15 organs/tissues for each projection with the use of anthropomorphic phantom and thermoluminescence dosimetry. The effective dose rate was 219, 144, 136, and 112 mu/min for groin-to-heart posteroanterior, posteroanterior, left anterior oblique, and right anterior oblique exposure, respectively. A typical ablation procedure results in a total effective dose of 8.3 mSv per hour of fluoroscopy. The average excess of fatal cancers was estimated to be 650 and 480 per million patients undergoing RF ablation requiring 1 hour of fluoroscopy for US and UK populations, respectively. The average risk for genetic defects was determined to be 1 per million births. CONCLUSIONS: Radiation risk from RF cardiac ablation is moderate compared with other complications, but it may highly exceed radiation risk from common radiological procedures. Efforts should be made toward minimization of patient radiation risk from RF ablation procedures.

Adult↗
PubMed2002

The validity of using a video-based motion analysis system for measuring maximal area of fingertip motion and angular variation.

The aim of the study was to verify the application of a three-dimensional video motion analysis system to evaluate maximal fingertip motion area and angular variation of the hand by comparison and correlation with videofluoroscopic analysis. Eight normal subjects were recruited in this study. The maximal motion area of the fingertip and the angles of the metacarpal phalangeal (MP), proximal interphalangeal (PIP) and distal interphalangeal (DIP) joints in performing five sequential postures for functional evaluation of the hand were measured using a video motion analysis system and a fluoroscopy system respectively. The results indicated that the intraclass correlation coefficient (ICC) of the calculated maximal fingertip motion area between the two methods was 0.9597. The ICC for total active motion (TAM) measurements of three finger joints was 0.940 between the surface and bony landmarks by fluoroscopy, 0.952 between the surface landmarks from fluoroscopy and motion analysis, and 0.927 between the bony landmark from fluoroscopy and surface markers from motion analysis. The ICC for angular measurements between three different paired assessments was 0.9650, 0.8896 and 0.8799 for the MP, PIP and DIP joints respectively. The results indicate that motion analysis is a practical method for assessing impairment of the hand.

Adult↗
PubMed1994

Reduction of patient doses from barium meal and barium enema examinations through changes in equipment factors.

A study of patient doses for barium meal and barium enema examinations has been made for X-ray departments throughout Grampian Region. Dose-area products are substantially less than UK reference levels. Contributions from fluoroscopy and radiography varied significantly between different units, with fluoroscopy making up 35-92% of the mean doses for barium meals and 24-57% for barium enemas. Equipment related factors had a greater influence on patient doses than radiologists' techniques. The gain of the image intensifier and the exposure factors selected by the automatic exposure control (AEC) were the most important factors determining doses for fluoroscopy. Changes in kV/mA factors selected by the AEC have allowed reductions of 20-50% to be made in effective dose from fluoroscopy with some units. The method used for recording images was the major influence on radiographic doses. Digital spot images or fluorographic films taken from the intensifier gave only 10-20% of the dose with a film/screen system and are recommended where the image quality is satisfactory for the application. Changes in film/screen systems have given worthwhile reductions in radiographic doses. If all factors are optimized, mean doses for barium examinations could be reduced to 20% of current reference levels.

Barium Sulfate↗
PubMed2003

Patient dose values in a dedicated Greek cardiac centre.

The purpose of this study was to collect information on the practice and patient doses in a major Greek cardiac centre, investigate differences between senior cardiologists of various levels of experience and compare results with the literature, in order to optimize angiographic and interventional cardiology procedures. Radiation doses from 292 patients have been studied, 195 of which had undergone coronary angiography and 97 percutaneous transluminal coronary angioplasty. All procedures were undertaken on a Siemens Angioscop X-ray equipment. The system performed under automatic exposure control using pulsed fluoroscopy of 12.5 pulses s(-1) and cine frame rate of 25 frames s(-1). Dose-area product values, fluoroscopy times, total number of cine frames as well as operator's name were collected for each patient. Only senior cardiologists have participated in the study. Median values for dose-area product were 39.1 Gy cm(2) for coronary angiography and 58.3 Gy cm(2) for percutaneous transluminal coronary angioplasty. Median fluoroscopy time was 5.0 min and 9.7 min and median number of frames was 1588 and 1823 for coronary angiography and percutaneous transluminal coronary angioplasty, respectively. Comparison showed that patient dose-area product values were lower than other studies and fluoroscopy time values were comparable. However, the total number of frames used was much higher than other published results. Differences between cardiologists with increased experience have been found. Analysis of the patient dose values obtained initiated a program of radiation protection optimization. The need for continuous training in radiation protection for interventionalists has been verified.

Adult↗
PubMed1988

Obstructive sleep apnea syndrome: preoperative radiologic evaluation.

The purpose of this study was to determine whether lateral radiographs of the pharynx and fluoroscopy of the lateral pharynx in the sleeping patient could be used as predictors of surgical success in patients undergoing soft-palate surgery for obstructive sleep apnea. A total of 12 patients had surgery after radiologic evaluation. There were six surgical successes and six failures. No successes occurred in patients with a soft-palate length of less than 46 mm, nor were there any successes among patients whose initial point of obstruction on fluoroscopy was inferior to the level of the soft palate. There was one surgical failure among patients in whom fluoroscopy showed upper airway obstruction beginning at the level of the soft palate during sleep. Results suggest that a patient is most likely to benefit from soft-palate resection if the soft palate is long--we conservatively suggest greater than 40 mm--and if sleep fluoroscopy of the lateral pharynx shows airway obstruction beginning at the level of the soft palate.

Fluoroscopy↗
PubMed2004

Does digital acquisition reduce patients' skin dose in cardiac interventional procedures? An experimental study.

OBJECTIVE: It is necessary to reduce the exposure doses from both fluoroscopy and angiocardiography. Pulsed fluoroscopy clearly reduces patients' exposure. By contrast, whether digital acquisition reduces patients' exposure is not clear. This study simulated the skin radiation doses of patients in cardiac catheterization laboratories with various radiography systems used in percutaneous transluminal coronary angioplasty to determine whether digital acquisition reduces patient exposure as compared with cine film recording. MATERIALS AND METHODS: The entrance surface doses with cineangiography and fluoroscopy of acrylic phantoms were compared for 11 radiography systems at seven facilities; each performs more than 100 cardiac intervention procedures per year. The entrance surface dose for an acrylic plate (20 cm thick) was measured using a skin-dose monitor. RESULTS: The maximum dose exceeded the minimum dose by 6.44 times for cineangiography and by 3.42 times for fluoroscopy. The entrance surface dose with acrylic plate was lower with digital-only acquisition (mean +/- SD, 3.07 +/- 0.84 mGy/sec) than with film recording (6.00 +/- 3.04 mGy/sec). By contrast, the entrance surface frame dose, after correction for the cine frame rate, tended to be higher with digital acquisition than with film recording (0.210 +/- 0.053 vs 0.179 +/- 0.058 mGy/frame, respectively). CONCLUSION. The entrance surface dose was approximately 50% less with digital-only acquisition than with film recording. However, after correcting the dose for cine frame rate, filmless acquisition did not in itself reduce the exposure. For the surface dose to be reduced for cardiac interventional radiography, even with digital filmless radiography systems, a low recording speed is necessary for angiocardiography.

Angioplasty, Balloon, Coronary↗
PubMed2004

C-arm-based mobile computed tomography: a comparison with established imaging on the basis of simulated treatments of talus neck fractures in a cadaveric study.

OBJECTIVE: To analyse the image quality and diagnostic effectiveness of a new C-arm-based 3D imaging method (C-arm-CT) for intraoperative evaluation of screw osteosyntheses adjacent to a peripheral joint. MATERIALS AND METHODS: Insertion of screws into four cadaveric specimens simulated the surgical treatment of talus neck fractures. Ten orthopedic surgeons and 10 radiologists evaluated X-ray, C-arm fluoroscopy, C-arm-CT and CT images. RESULTS: The best image quality was obtained with X-rays (p < 0.001), followed by C-arm fluoroscopy (2D) and CT, with the C-arm-CT (3D) being rated lowest (p < 0.001). The most correct diagnoses were obtained with CT and C-arm-CT (with no statistical difference between them), while C-arm-fluoroscopy was inferior (p < 0.001) and X-rays were the worst (p < 0.05). CONCLUSIONS: Even if the image quality of C-arm-CT is definitely inferior to that of CT, screw misplacements can be reliably detected using C-arm-CT. As compared to the current standard procedures (intraoperative fluoroscopy and postoperative radiography), C-arm-CT performed better. C-arm-CT is ideally suited to the intraoperative diagnosis of high-contrast inquiries like bone fragments and OS material, especially at the extremities. Coupling of the new 3D imaging to existing navigation systems is possible. C-arm-CT will support the further development and implementation of open and minimally invasive surgical procedures.

Bone Screws↗
PubMed2002

Usefulness of three-dimensional non-fluoroscopic mapping in the ablation of typical atrial flutter.

BACKGROUND: Catheter ablation of the cavo-tricuspid isthmus is rapidly becoming the first line of treatment in the management of atrial flutter. The standard procedure is usually performed under fluoroscopy guidance and relays on multisite endocardial recordings to assess the completeness of the isthmus conduction block. Despite the high rate of success there is, at follow-up, a considerable number of recurrences which could reflect the limitations of conventional assessment of conduction block across the isthmus. This new non-fluoroscopic mapping system allowing high density mapping along the entire length of the ablation line, could provide a more accurate way of verifying complete conduction block. The aim of the present study was to describe our overall results and long-term follow-up using a three-dimensional mapping system to guide radiofrequency ablation of typical atrial flutter. METHODS: A multipoint three-dimensional map of the cavo-tricuspid isthmus, septal and lateral atrial wall was performed in 87 patients prior to and following ablation for typical atrial flutter. Evidence of persisting gaps in the line of block was identified by visual inspection of the color-coded activation maps and these sites were re-ablated. The conduction sequence was also assessed with conventional bidirectional pacing and recording. The assess the reduction in fluoroscopy time, two groups of patients were compared: group A (14 patients) in whom the entire mapping-ablation procedure was guided by the three-dimensional system (Carto, Biosense-Webster, Diamond Bar, CA, USA) and group B (32 patients) in whom the same protocol was used but the procedure was guided by standard fluoroscopic imaging. RESULTS: Acute success was achieved in every patient. During bilateral isthmus pacing, the mean local activation time increased from 20.3 +/- 13.3 ms pre-ablation to 148.3 +/- 53.2 ms (p < 0.01) post-ablation with a mean difference of 120 +/- 31 ms. In 11 patients (9.2%) there was evidence of persisting conduction across the line of block despite evidence of reverse activation of the cavo-tricuspid isthmus by conventional pacing. A gap in the ablation line was identified and re-ablated. At a mean follow-up of 16.3 +/- 2.2 months, there were 5 (4.2%) recurrences of atrial flutter and 12 (10%) recurrences of isolated atrial fibrillation. Four of the 5 recurrences occurred in patients in whom ablation was guided by conventional fluoroscopy (group B). The fluoroscopy time was 4.2 +/- 1.5 min in group A and 27.2 +/- 8.2 min in group B (p < 0.001). CONCLUSIONS: Multipoint mapping of the ablation line following radiofrequency ablation of typical atrial flutter performed using the Carto system allows a more accurate assessment of the isthmus conduction block. This has the potential to reduce the recurrence rate to the level observed for other supraventricular tachycardias.

Atrial Flutter↗
PubMed1984

Detection of early gastric cancer by panendoscopy.

With the implementation of a small-caliber panendoscope which was made according to our suggestion, we gradually replaced the conventional barium meal as the first line of the upper gastrointestinal tract examination by panendoscopy after 1976. The efficacy of panendoscopy for the early detection of gastric cancer in our 8-yr experience was investigated. In 910 matched pairs of patients subjected to "screening" fluoroscopy or panendoscopy two and six cases of early gastric cancer were detected respectively. Panendoscopy was superior to fluoroscopy in its sensitivity for detection of gastric cancer (86.4% vs. 80.0%), in its specificity (99.5% vs. 97.0%) and in its low false-positive rate (17.4% vs. 69.2%). After 1976, the detection of early gastric cancer increased year by year. The frequency of early gastric cancer detected by panendoscopy was about three times that of early gastric cancer detected by fluoroscopy (61.5% vs. 21.7% of all cancer). Early cancer located in the proximal third of the stomach and superficial esophageal cancer were detected only by panendoscopy. All gastric cancers that were overlooked by panendoscopy were in the gastric body. How to prevent such overlooking is discussed. In 24,000 panendoscopies we have encountered six complications (0.03%). The cost of panendoscopy and fluoroscopy is 6,500 yen and 11,000 yen respectively.

Adult↗
PubMed1996

Esophageal dilation with polyvinyl (American) dilators over a marked guidewire: practice and safety at one center over a 5-yr period.

OBJECTIVE: Improvements in dilator technology over the past decade have revolutionized esophageal dilation. There remains, however, a number of controversies relating to several technical aspects of wire-guided dilation, including whether or not fluoroscopy is necessary. We describe our experience with wire-guided esophageal bougienage. METHODS: We retrospectively reviewed our experience with esophageal dilation using polyvinyl (American) dilators and marked guidewires over the period 1990-1994 to assess the practice habits of our endoscopists and the safety of the technique. We did 606 wire-guided dilations on 354 adult patients. Dilations were done by six different endoscopists. RESULTS: Fluoroscopy was used in only 32/606 dilations (5.3%) and then only to pass a guidewire when the scope could not be passed through the stricture. Fluoroscopy was not used to monitor dilator passage. Peptic strictures were dilated to their maximal target size (determined by the individual endoscopist) in one session in 195 of 253 instances (77.1%). Practice differences were seen between the individual endoscopists relating to how rapidly dilation was accomplished, the number of dilators passed per session, and the maximal dilator size passed. No perforations or other serious complications occurred in our series. CONCLUSIONS: Wire-guided esophageal bougienage is a very safe procedure when careful attention to technique is observed. No perforations were seen in our series of over 600 dilations. Fluoroscopy is needed only in those cases in which a scope cannot be passed through a stricture to assist with guidewire passage. In a majority of cases, peptic strictures can be dilated to a 45-to 51-Fr size in a single session.

Dilatation↗
PubMed1998

Duplex-directed vena caval filter placement: report of initial experience.

BACKGROUND: Fluoroscopy, cost, and patient transport contribute to difficulties occasionally associated with the placement of vena caval filters. Follow-up data in the literature document the use of duplex ultrasonography in visualizing the filter and determining caval patency. Filter placement at the bedside or in the vascular laboratory with duplex ultrasonography may simplify this common procedure. We have attempted to define the feasibility of this method. METHODS: Patients referred to the vascular surgery service for vena caval interruption were evaluated for ability to visualize the renal veins and inferior vena cava. Location of renal veins, maximum diameter of the vena cava, and presence or absence of thrombus were documented. If visualization was adequate, placement was performed at the bedside for patients in intensive care or in the vascular laboratory for nonmonitored patients. The initial 10 patients and subsequent patients in whom there was a question of adequate deployment underwent completion abdominal roentgenography. Patient follow-up was difficult. Duplex ultrasonography was used to assess migration, thrombus adherent to the filter, and vena caval patency. Patients in whom filter placement was prophylactic were given anticoagulants at the discretion of the primary physician. Inadequate visualization or vena caval size greater than 28 mm prompted fluoroscopic placement of the vena caval filter, because only Greenfield titanium filters were used in the study. RESULTS: Twenty-nine patients were referred for vena caval interruption. Inadequate visualization occurred in four obese patients, and filters were placed by fluoroscopy. There were no vena caval measurements greater than 24 mm. Twenty-five filters were placed without technical difficulty. One filter tilted into the right renal vein, requiring a suprarenal filter placed by fluoroscopy. Patient retrieval for follow-up has been difficult, but by ultrasonography there has been one vena caval thrombosis and no major filter migration. There have been no reported pulmonary emboli other than the one patient with initial tilt of the filter. CONCLUSIONS: Placement of vena caval filters is feasible with duplex ultrasonography. Visualization is the only limiting condition to placement and occurs rarely. Reducing the need for fluoroscopy, lowering costs, and not needing to transport the critically ill patient support the use of this system. Intravascular ultrasonography in selected patients may eliminate the need for fluoroscopic placement of vena caval filters.

Fluoroscopy↗
PubMed1998

[Clinical aspects of image quality and doses in gated pulsed imaging].

PURPOSE: The relations between image quality in last image hold images and dose in grid controlled fluoroscopy in comparison to the continuous mode need to be characterised and recommendations for the clinical application of this technique should be given. MATERIAL AND METHODS: Spatial resolution, signal-noise ratio and, contrast-detail visibility were evaluated by phantom measurements in grid controlled pulsed and continuous fluoroscopy. Dose was measured at the image intensifier entrance. Image quality of last image hold (LIH) images of clinical examinations was graded in relation to single shot exposures. RESULTS: Signal-noise ratio and contrast-detail visibility depend on the dose per puls. Spatial resolution and contrast-detail visibility in grid controlled fluoroscopy are superior than to in the continuous mode. Image quality of the LIH images from the grid controlled fluoroscopy was improved. Radiation exposure could be reduced to 10-46%. CONCLUSIONS: Combinations of puls-dose and -frequency are recommended for achieving extensive dose reduction and improved image quality of LIH images.

Diagnostic Imaging↗
PubMed1992

Magnum system for routine coronary angioplasty: a randomized study.

The Magnum system, initially designed for coronary angioplasty (PTCA) of chronic total occlusion, consists of a balloon catheter and a solid steel 0.021 inch (0.53 mm) steerable and removable wire with a soft and moldable distal portion, tipped with a 1 mm olive. To evaluate its performance in routine PTCA, 200 unselected consecutive patients were randomized to two equal groups, i.e., group Magnum (100 patients, 115 vessels) and group Standard (100 patients, 118 vessels) including 18 and 21 patients with chronic total occlusions, respectively. Randomization was performed by the sealed envelope system in the catheterization laboratory and crossover of system was imposed if it was not possible to place a balloon correctly within 20 min of fluoroscopy time. There were no significant differences between groups concerning clinical and angiographic baseline characteristics, size of initial balloons (3.0 +/- 0.3 mm in both groups), fluoroscopy time to cross the lesion with the wire (Magnum: 4 +/- 5, Standard: 5 +/- 6 min), total fluoroscopy time (Magnum: 11 +/- 9, Standard: 12 +/- 12 min), and need for crossover (Magnum: 10%, Standard: 16%). Success rates per lesion were comparable with 90% in group Magnum and 84% in group Standard, as were the complications with one inhospital death in group Standard, occurring three weeks after PTCA and stent implantation. There was no emergency operation. Six patients per group had myocardial infarction of whom two in group Magnum and one in group Standard developed a Q-wave. The following variables were significantly in favor of the Magnum system compared with the Standard system: success rate in nontotal lesions (97% versus 90%) crossover success in total occlusions (0 vs. 33%), fluoroscopy time to cross the lesion with the balloon once the wire was in place (1 +/- 2 vs. 2 +/- 4 min), and use of a single versus 1.2 +/- 0.5 wires per lesion. The only advantage of the Standard systems was the more common use of 7 French guiding catheters (Magnum: 40%, Standard: 53%, p = 0.09). The Magnum system compares favorably with standard systems for routine PTCA. The robust design of the Magnum wire does not impair ease of placement and safety but saves material and facilitates balloon advancement across the lesion.

Aged↗