[Icterus--sometimes something is wrong: the rupture of an echinococcal cyst into the biliary tract].
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Adult↗
Biomedical subjects
A Bücker
Publications and source records attributed to A Bücker.
Hydrodynamic thrombectomy of haemodialysis grafts and fistulae: results of 51 procedures.
PURPOSE: To describe efficacy of hydrodynamic thrombectomy for occluded dialysis native and graft fistulae in 51 instances. MATERIALS AND METHODS: Fifty-one hydrodynamic thrombectomies of 34 native and graft a-v fistulae were performed. There were 32 thrombectomies in PTFE grafts and 19 procedures in native Brescia-Cimino fistulae. Multiple thrombectomies were performed in 11 of 34 fistulae. The estimated occlusion time was 36.4+/-22 h. The length of the occluded segment ranged from 2 to 50 cm (mean 28.8 cm). In all cases, a 7 F hydrodynamic thrombectomy catheter was used. Double-cannulation technique was used for graft fistulae, single-cannulation for native fistulae. Additionally, balloon dilatation was performed in all 51 cases, stenting in six, and aspiration thrombectomy in two cases. RESULTS: Arterialized flow was re-established by hydrodynamic thrombectomy and PTA in 43 of 51 cases (84%). By additional use of other techniques, technical success improved to 46 of 51 procedures (90%). Early re-thrombosis occurred in six cases within 24 h of thrombectomy (11%). Clinical success was achieved in 39 of 46 technically successful cases (85%). Cumulative patency was calculated at 63% after 1 week, 57% after 1 month, 48% after 3 months, 37% after 6 months, and 32% after 12 months. Patency of native fistulae after thrombectomy was better than patency of grafts. CONCLUSIONS: Hydrodynamic thrombectomy is an effective percutaneous technique for declotting haemodialysis fistulae and grafts recently thrombosed.
Adult↗
[The radiological-histological interpretation of artificial bone defects of the basal maxillary sinus cortical bone].
Twenty-one lateral maxilla specimens were taken from human autopsy specimens and after removing soft tissue 40 differing tooth roots of 23 molars and premolars were ground to create large artificial bone defects in the supporting cortical bone of the basal maxillary sinus. Conventional dental radiographs and axial CT scans were then compared with the macroscopic findings in relation to the identification of the artificial bone defects. Next the jaw segments were dissected analogous to the axial CT scan and corresponding histological microsections were prepared for a radiological-histological comparison. None of the artificial bone defects were identifiable on the dental radiographs. In comparison to this, however, cortical bone defects were identifiable on 25 tooth roots (62.5%) on the CT scans. The lateral demarcation of the antral defects on the CT scans depends on the setting of the tooth root, on the adjacent bone morphology, and on the visualization of the periodontal ligament space. If the periodontal space shows up on the CT images, it becomes possible to demarcate of a thin, 0.2 to 0.5 mm, cortical bone layer of the basal maxillary sinus.
Bicuspid↗
[Pseudotumorous heterotopic ossification of the hand].
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Adult↗
[The rheolytic thrombectomy of an iliac vein].
As an alternative to thrombolysis, a patient with recent rethrombosis of the right iliac vein was successfully recanalized by using a 5 F rheolytic catheter system. The patient had undergone bilateral stent recanalisation of the pelvic veins after iliocaval thrombosis due to retroperitoneal fibrosis three months earlier.
Aged↗
[Biliary cystadenocarcinoma of the liver].
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Aged↗
Assessment of alveolar bone loss with high resolution computed tomography.
In this in vitro study we compared high resolution computed tomography (HR-CT) with dental radiographs regarding the interpretation of horizontal and vertical alveolar bone loss. After removal of the soft tissue and metallic restorations of 20 dentate upper and lower jaw segments 40 infra-alveolar bony defects of different dimensions were experimentally produced. The specimens were examined radiographically with standardized dental radiographs and 1.0 mm thick contiguous axial CT-scans. On the specimens, radiographs and CT-scans the bone loss was measured between the cemento-enamel junction and the adjacent alveolar bone level of 472 mesial and distal tooth surfaces; the identification, classification and vertical depth of the infra-alveolar bony defects were also compared. An average underestimation of 0.6 mm of horizontal alveolar bone loss in the dental radiographs and an overestimation of 0.2 mm in CT-scanning was shown. No significant differences between the imaging accuracy of horizontal alveolar bone loss between dental radiographs and CT-scanning could be evaluated. In the dental radiographs 24 (60%) of the infra-alveolar bony defects could be identified and the vertical depth was underestimated by a mean of 2.2 mm. In comparison, all 40 (100%) infra-alveolar defects could be identified in the CT-scans and the vertical depth was underestimated by an average of 0.2 mm. The HR-CT-technique offers a three-dimensional interpretation of the alveolar morphology without overlying structures. This permits a high identification rate and classification of infra-alveolar bone loss according to the number of surrounding bone walls into one-, two or three-walled bony pockets.
Alveolar Bone Loss↗
Transbrachial fine-needle arteriography with special focus on haemodialysis shunt imaging.
Retrospective analysis of the complication rate of transbrachial fine-needle arteriography was made to determine whether the advantages of arterial angiograms over venous fistulograms outweigh the possible complications. We included 236 patients who had undergone 454 arterial fine-needle punctures with a 22-gauge cannula in the cubital fossa. Spasm as the only reliably detectable early complication of this retrospective study occurred with a frequency of 1.9% in dialysis patients. The only late and severe complication we found in reviewing 217 arterial follow-up angiograms was one aneurysm. We consider arterial angiogram, using the fine-needle puncture technique, as a safe method for angiographic control of haemodialysis shunts. We attribute the low complication rate of less than 0.5% to the introduction of this technique.
Angiography↗
Chronic venous occlusions in haemodialysis shunts: efficacy of percutaneous treatment.
PURPOSE: The efficacy of percutaneous treatment of chronic venous occlusions in haemodialysis fistulae was retrospectively analysed. MATERIALS AND METHOD: In 33 cases, percutaneous treatment of chronic venous occlusions was attempted. The type of shunt was an autologous arteriovenous fistula in 23 cases and a PTFE implant graft in 10 cases. The lesion involved forearm veins in six cases, an upper arm vein in 15 cases, and a central vein in 12 cases. The mean length of the occlusion was 7.4 +/- 5 cm with a range from 2 to 25 cm. Fresh thrombus material in addition to the chronic occlusion was present in five cases. The patients were referred for chronic shunt dysfunction in 29 cases and with acute shunt thrombosis with an underlying chronic venous occlusion in four cases. RESULTS: Mechanical recanalization succeeded in 27 of 33 occlusions (82%). In one further patient, direct recanalization failed but an alternative improved drainage was created by detouring the main venous outflow tract by the use of a stent. Immediate clinical success was therefore 85%. Simple balloon dilatation was used in 11 of 27 cases (41%). Additional stent implantation became necessary in 16 of 27 cases (59%). In 15 patients an event of reobstruction occurred during follow-up. Mean primary cumulative patency was 85% after treatment, 41% after 6 months, and 24% after 2 years. By use of reintervention shunt function was maintained at 74% up to 2 years. CONCLUSIONS: Percutaneous treatment of chronic venous occlusions is technically feasible with a success similar to treatment of stenotic lesions. Follow-up results do not show impaired follow-up data for that type of obstruction.
Aged↗
Visualization of MR-compatible catheters by electrically induced local field inhomogeneities: evaluation in vivo.
The purpose of this study was to assess the feasibility of a newly developed field inhomogeneity catheter for interventional MRI in vivo. Different prototypes of a field inhomogeneity catheter (pigtail and multipurpose configuration, balloon catheters) were investigated in pigs. The catheters were introduced in Seldinger technique via the femoral vessels over a guidewire on an interventional MR system (Philips Gyroscan NT combined with a C-arm fluoroscopy unit [Philips BV 212]). Catheters were placed in veins and arteries. The catheter position was controlled by a fast gradient-echo sequence (turbo field echo [TFE]). Catheters were introduced over a guidewire without complications in all cases. Using the field inhomogeneity concept, catheters were easily visualized in the inferior vena cava and the aorta by the fast gradient-echo technique on MR in all cases. Although aortic branches were successful cannulated, the catheters were not well displayed by the TFE technique due to the complex and tortuous anatomy. All animals survived the experiments without complications. MR-guided visualization of a field inhomogeneity catheter is a simple concept that can be realized on each MR scanner and may allow intravascular MR-guided interventions in future.
Animals↗
Determination of stent stenosis: an in vivo experimental comparison of intravascular ultrasound and angiography with histology.
PURPOSE: To compare intravascular ultrasound (IVUS) and angiography with histology in determining the degree of stent stenosis in an in vivo experiment. METHODS: In 16 sheep, a total of 64 stents were implanted into the external iliac arteries. Two stents were inserted on either side. Patency was followed by angiography and IVUS. Four types of stent were used: two Dacron-covered (Cragg Endopro and heparinized Cragg Endopro) and two noncovered (Cragg and Memotherm stents). Eight animals were killed after 1 month, eight others after 6 months. Histological sections were prepared from the stented vessels. Measurements of the patent and total stent diameters determined by IVUS, angiography, and histology were compared. RESULTS: Correlation between IVUS and angiography was 0.75, between IVUS and histology 0.77, and between angiography and histology 0.85. A mean stent stenosis of 17 +/- 11% (range 0-51%) was found on angiography, of 10 +/- 11% (0-46%) on IVUS, and of 20 +/- 11% (4%-49%) on histology. In comparison with histology, IVUS underestimated the degree of stenosis by 10 +/- 8%, and angiography underestimated it by 3 +/- 6%. Resolution of IVUS was calculated to be about 0.35 mm and that of angiography to be about 0.15 mm. CONCLUSION: Under experimental conditions, IVUS was not superior to angiography in determining the degree of stent stenosis in long-segment stenoses of iliac artery stents, when measurements were correlated with histology. Angiography is sufficient for following the patency of iliac artery stents.
Angiography↗
Single and tandem stents in sheep iliac arteries: is there a difference in patency?
PURPOSE: To compare patency and neointima formation of single and tandem arterial stents. METHODS: In each of six sheep, two Memotherm nitinol stents (tandem stents) were inserted into the external iliac artery on one side and a single stent into the artery on the opposite side. The size of the iliac lumen was assessed in the proximal, middle, and distal segments of the stents by intravascular ultrasound (IVUS) before, immediately after, and 1 month after implantation when the sheep were killed. Neointimal thickness was determined in the proximal, middle, and distal segments of each stent by light microscopy. RESULTS: All stents remained patent. There was no significant difference in lumen and neointimal thickness between single and tandem stents. Cranial tandem stents showed a significantly wider lumen and smaller neointimal thickness than caudal tandem stents. In the proximal and distal segments, the lumen of the stents was significantly smaller and the neointimal thickness greater than in the middle segment; differences in neointimal thickness were significant only between the proximal and the middle segment. CONCLUSION: In an experimental setting, tandem stents did not interfere with one another with regard to patency and neointima formation when compared with a single contralateral stent. Neointimal thickening after stent insertion seems to be inversely related to the original arterial diameter.
Angiography↗
Interventional magnetic resonance: realistic prospect or wishful thinking?
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Humans↗
Magnetic resonance angiography of nonferromagnetic iliac artery stents and stent-grafts: A comparative study in sheep.
PURPOSE: To compare nonferromagnetic iliac artery prostheses in their suitability for patency monitoring with magnetic resonance angiography (MRA) using conventional angiography as a reference. METHODS: In experiment 1, three Memotherm stents were inserted into the iliac arteries of each of six sheep: two "tandem" stents on one side and a single stent on the other side. In experiment 2, four prostheses (normal and low-porosity Corvita stent-grafts, Memotherm, ZA-stent) were inserted in each of 11 sheep. Patency was monitored before and 1, 3, and 6 months after insertion with 3D phase-contrast and two 2D time-of-flight sequences (TOF-1: TR/TE = 18/6.9, TOF-2: 13/2.5) with and without contrast at 1.5 T. On 206 coronal MIP images (72 pre-, 134 post-stenting), three readers analyzed 824 iliac segments (206 x 4) for patency and artifacts. RESULTS: There was no difference in the number of artifacts between tandem and single iliac Memotherm stents. The ZA-stent induced significantly fewer artifacts than the other prostheses (p < 0.00001). With MRA, patency of the ZA-stent was correctly diagnosed in 88% of cases, which was almost comparable to nonstented iliac segments (95%), patency of the Memotherm stent in 59%, and of the Corvita stent-grafts in 57% and 55%. The TOF-2 sequence with contrast yielded the best images. CONCLUSION: MRA compatibility of nonferromagnetic prostheses depends strongly on the design of the device. MRA may be used to monitor the patency of iliac ZA-stents, whereas iliac Memotherm stents and Corvita stent-grafts appear to be less suited for follow-up with MRA.
Animals↗
Comparative in vitro study of two percutaneous hydrodynamic thrombectomy systems.
PURPOSE: To test the efficacy of clot removal in small- and large-caliber vessels and determine the extent of procedure-related particle embolization for two rheolytic thrombectomy devices, the Hydrolyser and Angiojet. MATERIALS AND METHODS: Both systems were applied with and without guiding catheters in an arterial (7-mm tube diameter, wall-adherent thrombus [mean, 5.3 g], flow of 500 mL/min)and a venous (20-mm tube diameter, free-floating thrombus [mean, 12 g], flow of 1,500 mL/min) flow model. RESULTS: Particle embolization was significantly lower for the Angiojet device (mean, 1.8% +/- 2.9 [standard deviation] vs mean 4.8% +/- 6.1 for particles > 1,000 microns). When the devices were used without guiding catheters, mean clot removal rates were 65% +/- 12 with the Hydrolyser and 49% +/- 9.2 with the Angiojet in the arterial flow model and 88% +/- 15.5 with the Hydrolyser and 85% +/- 17.8 with the Angiojet in the venous flow model. Significant improvements in clot removal rates were achieved with use of guiding catheters: 81% +/- 5.4 with the Hydrolyser and 89% +/- 3.9 with the Angiojet in the arterial flow model and 95% +/- 1.4 with the Hydrolyser and 97% +/- 0.84 with the Angiojet in the venous flow model. CONCLUSION: Use of guiding catheters improved the performance of both systems significantly. Both rheolytic catheters remove sufficient amounts of soft thrombus from a large-caliber vessel, especially when applied with a guiding catheter. However, firmer thrombus is difficult to remove. The particle embolization rate is low for both systems.
Animals↗
MR imaging-guided percutaneous nephrostomy and use of MR-compatible catheters in the nondilated porcine urinary tract.
PURPOSE: To investigate technique and practicability of MR-guided percutaneous nephrostomy (MRPCN) and to test magnetic resonance (MR)-compatible catheters inside the urinary tract. MATERIALS AND METHODS: In 10 healthy pigs, a percutaneous nephrostomy tube was placed into the nonobstructed pelvicaliceal system with use of exclusive MR guidance with a standard 1.5-T magnet. The urinary tract was visualized by intravenous injection of Gd-DTPA in combination with low-dose furosemide. The procedure was controlled with use of a T1-weighted turbo gradient-echo sequence in two orthogonal planes. The equipment for MRPCN included an 18-gauge MR-compatible puncture needle, a nitinol guide wire, and different 5-F MR catheters. RESULTS: In all 10 animals, the puncture needle was safely directed into the nondilated target calix. Slight deviations of the needle were detected on both MR image planes, which enabled immediate correction. This technique achieved a "first attempt" puncture of the targeted calix in each animal. MR images accurately demonstrated the dysprosium labelled tip of the different inserted catheters. It proved essential to inject a gadolinium-insaline solution via these catheters to preserve the endoluminal contrast enhancement as long as necessary. Balloon catheters were directed and inflated inside the ureter under exclusive MR guidance. Complications such as perforation and leakage were visualized by MR imaging. CONCLUSIONS: MRPCN is a promising technique for puncturing the pelvicaliceal system. The ability to successfully enter the urinary tract, even when it is nondilated, underscores the accuracy achievable with multiplanar MR imaging.
Animals↗
[Treatment of osteoid osteoma: percutaneous procedure in comparison with open surgery].
AIM: In recent years osteoid osteomas have been treated more frequently by means of percutaneous procedures. Several percutaneous techniques have been established. Our study presents the results which were obtained using a percutaneous drill system. In addition, a comparison between the results of the percutaneous procedure and the open surgical therapy is performed. METHOD: The retrospective study included patients with an osteoid osteoma who underwent percutaneous therapy or open surgery between 1992 and 2000. The following variables were addressed: age, gender, duration of complaints, localisation of the tumour, duration of hospital stay, size of the nidus, histology and recurrences. RESULTS: Of the total of 22 patients with an osteoid osteoma, 10 (45 %) were treated percutaneously and 12 (55 %) surgically. With regard to age, gender, and duration of complaints, the two groups were similar. Six (60 %) of the percutaneously treated patients sustained at least one recurrence. On the other hand, only one patient (8 %) of the surgically treated group experienced a recurrence. CONCLUSIONS: In comparison with recent studies presenting success rates in percutaneous treatment of osteoid osteomas between 77 and 100 percent, our own results are worse. One explanation for the low success rate might be the small drill size used.
Adolescent↗
[Portable NMR-MOUSE: a new method and its evaluation of the Achilles tendon].
AIM: The increased demands placed on the Achilles tendon in recreational and professional sports have led to a rise in pathological changes in this anatomic region. Magnetic resonance evaluations of the tendon have proven to be a valid but expensive and stationary diagnostic tool. In this study, a new mobile NMR sensor was to be tested in the evaluation of the Achilles tendon. METHOD: The technical development of the so-called NMR-MOUSE ( Mobile Universal Surface Explorer) represents a novelty with an open and portable sensor. To appraise its diagnostic efficacy, healthy athletes (professional soccer players, track and field, as well as aquatic athletes), healthy controls and patients with Achilles tendon lesions were evaluated. As an accessible, sensitive and reproducible parameter for the study the transverse relaxation time T2 with its angular dependency was chosen. As part of the examination, the relaxation times of the skin, the tendon and the surrounding soft tissue were determined. RESULTS: During the evaluation with the NMR-MOUSE, the skin and peritendineous tissue exhibited relatively long T2 relaxation times, while the tendon itself had significantly shorter T2 times, allowing for a clear differentiation of the structures. The T2 relaxation time of the Achilles tendon in the control group averaged 5.8 ms. The MRI-MOUSE was able to demonstrate an increase in the T2 relaxation times in patients with pathological lesions of the tendon due to the increased water retention of the tissue. CONCLUSION: The novel NMR-MOUSE represents a cost efficient and portable sensor, which allows for a reliable evaluation of surface structures, such as the Achilles tendon. The anisotropic structure of the tendon and the surrounding soft tissue can be reliably differentiated with the help of the NMR-MOUSE.
Achilles Tendon↗