Mechanical thrombectomy in hemodialysis access shunts using a 5F pigtail rotation catheter. In vitro and in vivo investigations.

RATIONALE AND OBJECTIVES: To evaluate the feasibility of mechanical thrombectomy in occluded hemodialysis access shunts by using a newly developed 5F pigtail rotation catheter. METHODS: Thrombosed hemodialysis access shunts were simulated by clotted bovine blood in silicone tubing (diameter 6 mm). After retrograde and antegrade sheath placement (6F), mechanical fragmentation was performed using a 5F rotatable pigtail device. Average tube length was 27 to 47 cm; average thrombus weight was 5 to 11.9 g (8.2 +/- 1.59). Clinical application involved six patients with fresh shunt occlusions (three Brescia-Cimino shunts, three Gore-Tex shunts). RESULTS: Using the in vitro setup, the device was able to restore a continuous lumen within 10 minutes with no remaining wall-adherent thrombi. The average amount of particles in the effluent was 3.0 g (2.0 to 3.9) for particles < or = 1.0 mm and 0.67 g (0.44 to 0.96) for particles > or = 0.2 mm wet weight; (compared with initial thrombus weight, 30.7% and 1.1%, respectively). Clinically, all six hemodialysis access shunts were successfully recanalized. Technical problems did not occur. There were no clinical symptoms indicating pulmonary embolism in any of the treated patients. CONCLUSIONS: In our experimental setup as well as under clinical conditions, effective treatment of occluded hemodialysis access sites was achieved. The pigtail rotation device is an easy-to-handle, inexpensive alternative to mechanical thrombus fragmentation in occluded hemodialysis access shunts. The rate of emboli in the effluent vein of approximately one third of the initial thrombus weight must be taken into consideration in frequent intraindividual use of this technique.

Comparative evaluation of digital radiography versus conventional radiography of fractured skulls.

OBJECTIVES: The authors assessed the relative efficacy of conventional and digital storage-phosphor radiographs for the detection of skull fractures. METHODS: Fifty conventional film-screen radiographs (FSR) and 50 digital storage-phosphor radiographs (DR) with 66 fractures were compared. Five radiologists evaluated image quality and fracture detectability. The results were analyzed by receiver operating characteristic (ROC) curve analysis. RESULTS: With a standard exposure, the ability to evaluate skull fractures was equally good with either technique (ROC area for DR, 0.8954; for FSR, 0.8870). Digital radiography was superior in evaluating nasal bone. For petrosal bone, the DR image simulates an underexposure. This disadvantage compared with FSR can be compensated by image postprocessing. CONCLUSION: In evaluation of skull fractures, radiologists performance with DR is equivalent to FSR.

Digital radiography versus conventional radiography for the detection of a skull fracture under varying exposure parameters.

RATIONALE AND OBJECTIVES: The effect of varying exposure parameters on the detectability of a fracture with digital and conventional radiography were examined. METHODS: A macerated fractured skull was imaged by film-screen radiography (FSR) and digital storage phosphor radiography (DR) with various exposure values. Five radiologists traced the course of a fracture line. The length of the fracture was reported and the results were analyzed by Student's t test for paired samples. RESULTS: At 35% of the conventional radiation dose, the standard DR screen displayed an average of 48% of the fracture length. The difference from the conventional image (45%) was not significant in this case. An increase of the dose to ten times the conventional dose (250 mAs) yielded no significant improvement in the detectability of the length of the fracture (51%). CONCLUSIONS: This experiment shows that with use of the DR with the standard screen, a dose reduction of approximately 35% appears to be possible without any resulting loss of image quality compared to FSR. Use of the high resolution screens should be avoided, since they require a higher incident image dose than standard screens without offering any diagnostic advantages. The image dose of digital radiographs can be roughly estimated based on the digital device sensitivity value. As a rule, the sensitivity value should range between 100 and 200.

Computed tomographic cholangiography using spiral scanning and 3D image processing.

Volumetric computed tomography (CT) scans ("spiral CT") were performed after intravenous (i.v.) cholangiography followed by additional 3D surface reconstructions of gallbladder and biliary ducts. 34 patients were investigated prior to cholecystectomy. No allergic adverse reactions were observed. The scan time was 24 s. Contrast enhancement in the extrahepatic bile duct and gallbladder were measured. All CT image series were reviewed independently by four experienced physicians (two radiologists, two surgeons) and compared for quality with conventional cholangiography on a three-point scale. The average rating for the demonstration of the biliary tract was significantly better for spiral CT than for conventional cholangiography (p < 0.01). In all cases sufficient contrast was found in the common bile duct (mean 315 HU). 3D imaging was considered to be helpful for intraoperative orientation during laparoscopic surgery.

Aseptic spondylodiscitis: a complication of chemonucleolysis? A case report.

Discitis after intradiscal injection of chymodiactin is nearly always associated with an infection introduced by the needle tip. The authors report a patient with a postchemonucleolysis spondylodiscitis who recovered complete without surgery or antibiotics. The clinical findings and results of CRP and MRI suggested an aseptic spondylodiscitis due to chymodiactin.

[IHE (Integrating the Healthcare Enterprise): a new approach for the improvement of digital communication in healthcare]. / IHE (Integrating the Healthcare Enterprise): Ein neuer Ansatz zur Verbesserung der digitalen Kommunikation im Gesundheitswesen.

Parallel to the introduction of diagnosis related groups (DRGs) for the reimbursement of hospitals, a marked reduction of financial means within the healthcare system is taking place. Healthcare enterprise information systems will play an increasing role to accommodate the new working conditions by developing reliable and efficient workflow solutions. Interfacing the systems currently in use can meet considerable obstacles. By offering high connectivity, IHE (Integrating the Healthcare Enterprise), which was initiated by concerted actions of users and vendors, ensures improved health care delivery and, furthermore, assists in acquiring new information systems in the future. IHE is not a standard but makes extensive use of existing international standards, such as HL7 and DICOM. National IHE demonstrations confirmed the power of this approach and presented its mission to large groups of users and vendors. The concept continues to grow and for the first time provides groups of various interests cooperative solutions to the problems encountered in collecting and distributing information.

[Magnetic resonance tomography and sonography during articulation]. / Magnetresonanztomographie und Sonographie bei der Lautbildung.

The use of MRI for demonstrating the articulators during phonation by means of a snapshot-FLASH technique has been studied in ten healthy subjects. Unlike ultrasound, which can only demonstrate movement of the tongue during articulation, MRI with snapshot-flash technique provides significant information on all articulators during phonation.

[Embolization with gelatin-impregnated microspheres]. / Embolisation mit gelatine-imprägnierten Mikrosphären.

PURPOSE: This paper presents a new, easy to handle material for embolisation which comes up with sharply defined particle size and spherical shape, very suitable for peripheral embolisation in the small end arteries. METHODS: In 13 superselective embolisations with coaxial catheters the gelatine coated microspheres-sized 300-500, 500-700, 700-900 microns--were injected in the region of bronchial arteries (n = 7), vertebral bodies (n = 4) and pudendal arteries (n = 2). RESULTS: In all cases complete occlusion of the desired vessels was achieved. With the exception of one transient dysesthesia in the relevant dermatome during embolisation of the third lumbal vertebra, no adverse effects were noted. The microspheres were suspended in contrast medium and could be easily located by indirect methods, and hence the embolisation procedure was well controlled. DISCUSSION: Compared with other embolisation materials the ready-for-use gelatine coated microspheres due to their physical properties are an excellent alternative to superselective embolisation materials of end arteries.

[The renaissance of simultaneous tomography with the fluorescent-film storage system]. / Renaissance der Simultantomographie mit dem Speicherleuchtstoffoliensystem.

The handling, technical and exposure details of digital simultaneous tomography are explained, while particular emphasis is placed on image quality. Selected case reports demonstrate the application of this technique by using the digital storage fluorescent system (Fa. Siemens, Erlangen). Simultaneous tomography with storage fluorescent screens is particularly suitable to demonstrate or exclude osseous findings at the skull, the column and large joints.

[The potentials of digital image-intensifier radiography exemplified by digital spot imaging (DSI)]. / Möglichkeiten der digitalen Bildverstärkerradiographie am Beispiel des Digital Spot Imaging (DSI).

PURPOSE: We performed a comparative study of digitally and conventionally acquired images in gastrointestinal examinations. MATERIAL AND METHODS: Radiation dose and spatial resolution were determined in a water phantom. In 676 examinations with either conventional or digital imaging (system: Diagnost 76, DSI) the number of images and the duration of the fluoroscopy time were compared. 101 examinations with digital as well as conventional documentation were evaluated by using 5 criteria describing the diagnostic performance. RESULTS: The entrance dose of the DSI is 12% to 36% of the film/screen system and the spatial resolution of the DSI may be better than that of a film/screen system with a speed of 200. The fluoroscopy time shows no significant difference between DSI and the film/screen technique. In 2 of 4 examination modes significantly more images were produced by the DSI. With exception of the criterion of edge sharpness, DSI yields a significantly inferior assessment compared with the film/screen technique. CONCLUSION: The DSI system was well integrated in the daily routine of gastrointestinal examinations. Low dose imaging, direct availability of images and dynamic studies with a frame rate up to 8 images per second are the advantages of the DSI. The lower spatial resolution in some cases is a diagnostic disadvantage that can reduce the diagnostic information.

[Protective pneumothorax in CT-guided mediastinal puncture]. / Protektiver Pneumothorax bei CT-gesteuerter Mediastinalpunktion.

PURPOSE: To achieve an extrapulmonary pathway for biopsy of mediastinal masses. METHODS: In 6 patients a protective, temporary pneumothorax was established before performing large-bore needle biopsies of mediastinal masses using a Verres-needle. RESULTS: Transpleural, extrapulmonary access was easy to achieve. One patient developed a tension pneumothorax after biopsy which was drained by percutaneous small chest tube. Another patient showed mediastinal tumor bleeding through the biopsy needle. As a prophylactic measure the bleeding was stopped by injection of tissue glue through the biopsy needle. CONCLUSION: The use of protective pneumothorax allows cutting needle biopsies of mediastinal masses where aspiration cytology yields no secure specific diagnosis.

[Fracture diagnosis with digital luminescence radiography]. / Frakturdiagnostik mit der digitalen Lumineszenzradiographie.

Conventional screen-film radiographs were compared with storage phosphorus images concerning diagnostic performance in traumatologic radiography. We used an image pool of 106 radiographs including 50 conventionally and 56 digitally recorded images. The images were reviewed by four experienced radiologists. Detectability of fractures was coded in a five-point scale of confidence and analysed by ROC statistics. Furthermore the image quality and the optical density was compared. Digital images are superior under difficult exposure conditions and offer advantages by additional image processing and documentation. For some indications (follow-up, functional examination), reduced x-ray exposure is tolerable. The detectability of subtle lesions, which is essential for the primary diagnosis of fractures was significantly better by conventional radiography.

[Preoperative spiral CT cholangiography with 3-dimensional surface reconstruction: the anatomical imaging potentials, limits and application strategies]. / Präoperative Spiral-CT-Cholangiographie mit dreidimensionaler Oberflächenrekonstruktion: anatomische Darstellungsmöglichkeiten, Grenzen und Einsatzstrategien.

PURPOSE: Evaluation of CT cholangiography compared to i.v. cholangiography concerning its diagnostic value before laparoscopic cholecystectomy and optimisation of CT cholangiography. METHOD: I.v. and CT cholangiographies of 54 patients were retrospectively evaluated by two radiologists. The time interval between contrast infusion and CT was correlated with the assessment of CT cholangiographies to detect the optimal timing for CT scanning. RESULTS: CT cholangiography was judged to be generally better than i.v. cholangiography. The optimal time interval for CT scanning is between 30 min and 60 min post contrast infusion. CONCLUSION: CT cholangiography should replace the conventional tomograms if i.v. cholangiography does not yield sufficient depiction of the biliary tree. It should be performed within 60 min post contrast infusion. Complete abolishment of i.v. cholangiography is not warranted. This is due to the fact that conventional cholangiography can sufficiently delineate the biliary tree and thereby reduce x-ray exposure and cost compared to initial performance of CT cholangiography.

[Functionally determined area changes in the oro-pharyngo-laryngeal vocal tract of singers as shown by magnetic resonance tomography]. / Funktionsbedingte Flächenänderungen des oro-pharyngo-laryngealen Vokaltraktes bei Sängern in der Magnetresonanztomographie.

The oro-pharyngeal-laryngeal resonating spaces were studied in 12 singers at varying stages of their training by means of medio-sagittal MRI images, and the results were compared. The singers were requested to sing /a/ /u/ and /i/ at various pitches and with increasing loudness. The total oro-pharyngo-laryngeal areas were integrated by means of the MRI sections. The relationship between the oro-pharyngeal and pharyngo-laryngeal areas was determined, as well as their ratio to total area. With increasing volume there was increase in the area of the oro-pharyngeal component with no change in the pharyngo-laryngeal component. The relationship of the partial areas depends on the extent of training of the singer.

[The computed tomographic morphology of Crohn's disease and ulcerative colitis]. / Computertomographische Morphologie von Morbus Crohn und Colitis ulcerosa.

PURPOSE: To assess the value of computed tomography for the diagnosis of Crohn's disease and ulcerative colitis. METHOD: We analysed the CT examinations of 109 patients with 197 involved bowel locations. 81 patients suffered from Crohn's disease, 28 from ulcerative colitis. Diagnosis was based on the combination of clinical, endoscopic and histopathologic findings. Three radiologists evaluated the CT series concerning the presence of morphologic changes analogous to conventional radiographic findings. RESULTS: In Crohn's disease, we found irregular outer contours in 26% of cases. The bowel wall was thickened in 82%. In acute phases, the bowel wall was thickened in 100%. Abscess and fistula as complications of inflammatory disease were present in 26 and 14% respectively. In ulcerative colitis, a target sign of the bowel wall was present in 40%, whereas in Crohn's disease a homogeneous wall density was present in all but two cases. Reduced attenuation due to submucosal fat deposits was found in 16% and mucosal tunneling in 27% of cases with ulcerative colitis. Even if severe mucosal destructions were found, the outer contour of the gut was smooth and regular in 95% of the ulcerative colitis cases. CONCLUSION: CT can provide additional information on acuity, extent and complications in inflammatory bowel disease. In combination with conventional radiographic findings a three-step classification for Crohn's disease and ulcerative colitis (early changes, acute and chronic phase) can be proposed.

Multi-slice CT for visualization of pulmonary embolism using perfusion weighted color maps.

PURPOSE: The purpose of our preliminary study was to evaluate the feasibility of a new technique for the perfusion weighted color display of the density of lung parenchyma derived from multi-slice CT (MSCT) data sets of clinical routine examinations for visualization of pulmonary embolism (PE). MATERIALS AND METHODS: Imaging of patients with suspected PE was performed on a commercially available MSCT (Somatom Volume Zoom; Siemens, Forchheim, Germany) after intravenous application of 120 cc of contrast-medium using a power injector. Scan parameters were 140 kV and 100 mAs, using a thin collimation of 4 x 1 mm and a table speed of 7 mm (pitch: 1.75). Derived from thin collimation axial slices (slice thicknesseff. 1.25 mm, reconstruction increment 0.8 mm), a new image processing technique was deployed. Based on these source images, an automated 3D-segmentation of the lungs was performed followed by threshold based extraction of major airways and vascular structures. The filtered volume data were color encoded and finally overlayed onto the original CT images. This color encoded display of parenchymal density distribution of the lungs was shown in axial, coronal and sagittal plane orientation. In four patients with excluded PE as well as in two patients with proven PE this new technique was performed. RESULTS: In the four patients that were considered negative regarding PE on MSCT, lung densitometry showed a homogeneous distribution of color encoded densities without circumscribed decreased or increased areas, beside the usually present gravity-dependent gradient in ventro-dorsal direction. In the two patients with proven PE, low density values on perfusion weighted color maps were found distally to the occluded pulmonary arteries. CONCLUSIONS: Our initial experience indicates that lung densitometry with an optimized display of the density distribution within the lung parenchyma may provide additional information in patients with suspected or proven PE. However, a comparison with ventilation/perfusion scintigraphy and a larger number of patients are necessary for the full clinical evaluation of this new functional imaging methodology.

[Automated image analysis of lateral roentgen images of the spine using anatomic models]. / Automatisierte Bilderkennung lateraler Röntgenaufnahmen der Wirbelsäule mit Form Modellen.

PURPOSE: Development of a software for fully automated image analysis of lateral lumbar spine X-rays. MATERIAL AND METHOD: Using the concept of active shape models, we developed a software that produces a form model of the lumbar spine from lateral lumbar spine radiographs and runs an automated image segmentation. This model is able to detect lumbar vertebrae automatically after the filtering of digitized X-ray images. The model was trained with 20 lateral lumbar spine radiographs with no pathological findings before we evaluated the software with 30 further X-ray images which were sorted by image quality ranging from one (best) to three (worst). There were 10 images for each quality. RESULTS: Image recognition strongly depended on image quality. In group one 52 and in group two 51 out of 60 vertebral bodies including the sacrum were recognized, but in group three only 18 vertebral bodies were properly identified. CONCLUSION: Fully automated and reliable recognition of vertebral bodies from lateral spine radiographs using the concept of active shape models is possible. The precision of this technique is limited by the superposition of different structures. Further improvements are necessary. Therefore standardized image quality and enlargement of the training data set are required.

[Local lysis with alteplase for the treatment of acute embolic leg ischemia following the use of the duett closure device: preliminary results]. / Lokale Alteplase-Lyse zur Therapie der akuten embolischen Beinischämie nach Einsatz des Duett-Verschluss-Systems: vorläufige Ergebnisse.

PURPOSE: To analyze retrospectively the result of the alteplase lysis therapy of embolic complications following the use of the Duett closure device. METHODS AND MATERIALS: For 3.5 years, the Duett closure device was used in 1,398 angiographies to close the femoral puncture site. The Duett device consists of a balloon and a liquid procoagulant containing collagen and thrombin, which is injected into the puncture tract under endovascular balloon protection of the arterial puncture site. In 9 patients (0.64 %), the procoagulant was incidentally injected into the femoral artery causing acute leg ischemia. Eight patients received local lysis therapy with alteplase via a contralateral femoral access. One patient underwent surgery. On average, 21 mg alteplase (4 - 35 mg) were administered within 14 h (4 - 21 h). The course of the lysis was followed angiographically and clinically. All patients were interviewed by telephone 23 months (4 - 35 months) later. RESULTS: In 3 patients, lysis was complete. In 5 patients, only little thrombotic material remained. In all patients, symptoms of ischemia resolved completely within the first hours after initiation of lysis. In 5 cases, bleeding occurred at the puncture site closed with the Duett device during lysis, including development of a false aneurysm in 2 cases. Complications led to premature termination (n = 2) or interruption of the lysis (n = 3). All complications were treated conservatively. Clinically, long-term sequelae were paresthesia and hypoesthesia in the lower leg and foot in 2 patients treated with lysis, and in the patient who underwent surgery. CONCLUSION: Very rarely occurring embolic complications after use of the Duett closure device can be effectively treated with alteplase lysis. A high rate of complications is to be expected at the puncture site closed with the Duett device.

[Initial experiences with a new optical target system (SimpliCT) for CT-guided punctures]. / Erste Erfahrungen mit einem neuen optischen Zielsystem (SimpliCT) für CT-gesteuerte Punktionen.

PURPOSE: To evaluate the prototype of a new optical target device for CT-guided punctures and interventions. METHODS: An optical target device for CT-guided punctures was applied in 24 interventions. The system consists of a laser target device mounted on a stand. The biopsy needle is adjusted according the course of a laser beam. The target angle has to be adjusted on the laser unit. The laser carrier can be moved along an 90 degrees-angled rail, allowing punctures from any angle in plane. Furthermore, angulation in the z-plane is possible, supporting interventions with gantry tilt. Size and depth of the target lesions, the planned and the actual angle of the inserted needle, the numbers of corrections of the needle position, and the time required for the puncture were evaluated. The user rated the benefit of the system and the ease of the application. RESULTS: All 24 interventions were carried out successfully. The mean difference between the planned and the actual angle of the needle was 1.3 degrees (SD: 0.7 degree). The system was considered as easy to handle and as a valuable aid. CONCLUSIONS: The laser target device is a simple navigation system which allows accurate positioning of a needle. Requiring an acceptable low preparation time, it easily can be integrated into the procedure.

[Virtual organization in the digital age of radiology - principle and solution for radiologic research?]. / Virtuelle Organisation im digitalen Zeitalter der Radiologie - Prinzip und Lösung für die radiologische Forschung?

The research project "VICORA - Virtual Institute for Computer-Assisted Radiology", funded by the German Federal Ministry of Education and Research, was initiated in the year 2000. Its virtual organization brings together physical science, engineering, information technology, clinical radiology and the medical technology industry. In the German radiology research domain VICORA serves as a model for interdisciplinary collaboration for the changing radiology paradigm illustrated by a "radiologycube". The project does not only aim at scientific goals but also considers the infrastructure, components and human resource management within a virtual organization. The common rapid prototyping platform ILAB 4 ensures user-friendly and time-efficient software that assists with the routine radiology work-flow including full DICOM functionality. By offering a new work environment and collaborative culture based on telematics and knowledge exchange in radiology research, VICORA overcomes limitations of traditional research organization.