Ziel: Die hochauflösende Darstellung der verschiedenen gastrointestinalen Wandschichten, um die Grundlage für ein auf morphologischen Kriterien basierendes Tumorstaging zu schaffen. Material und Methoden: 15 humane Gewebepräparate und 30 tierische Gewebepräparate vom Schwein aus unterschiedlichen Abschnitten des Gastrointestinaltraktes wurden über einen Zeitraum von 12 Monaten in einem 1,5 Tesla MR-Tomografen mittels endoluminaler MR-Empfangsspule untersucht. Verwendet wurden eine T 1-gewichtete Opposed-Phase-Sequenz, eine T 2-gewichtete Turbospinechosequenz mit Fettsuppression und eine schnelle T 2-gewichtete Inversion-Recovery-Sequenz. Die Anzahl der differenzierbaren Wandschichten, deren Breite und das jeweilige Signalverhalten wurden dokumentiert. Anschließend wurden die Ergebnisse mit den histologischen Präparaten verglichen, um die MR-morphologischen Wandschichten den anatomischen Wandschichten zuzuordnen. Mit einer Korrelationsanalyse nach Spearman wurde die Stärke des Zusammenhangs zwischen MRT und der entsprechenden Histologie ermittelt. Ergebnisse: In allen Sequenzen konnten sowohl beim Schwein als auch beim Menschen mindestens 3 Wandschichten, maximal 5 bzw. 6 (beim Schwein) gezählt werden. Es gelang die sichere Abgrenzung der Mukosa mit hyperintensem Signal, der Submukosa mit hypointensem Signal und der Muskularis mit intermediärem Signalverhalten. Die Subserosa/Adventitia war hypointens. Schlussfolgerung: Die hochauflösende MRT ermöglicht die differenzierte Erfassung der anatomischen Wandschichten des GI-Traktes vom Schwein und vom Menschen. Somit sind die Grundvoraussetzungen für ein auf morphologischen Kriterien basierendes Tumorstaging erfüllt.

Schwerpunkt Nierenetage: Die Behandlung der Nierenarterienstenose – Materialien, Methoden und Ergebnisse (Uder M)

Drug Prescribing for Patients with Chronic Kidney Disease in General Practice: a Cross-Sectional Study

Verbindung mit dem Platzieren von Kathetern im Gefäßmodell (PTA, Stent) eine – wie die Erfahrung beweist – sehr gute Kombination ist, sich mit den

Objectives:A standardized perfused ex vivo bovine liver model was used to evaluate the effect of organ perfusion on coagulation size and energy deposition during radiofrequency ablation (RFA) procedures. Materials and Methods:Bovine livers were perfused in a tank after rinsing the prepared liver vessels with anticoagulants. Tyrode's solution, oxygenated and heated to 36.5°C, was used as perfusion medium. A flow and pressure controlled pump regulated Portal vein circulation; a dialysis machine provided pulsatile arterial circulation. Impedance-guided radiofrequency ablations were performed with 4-cm LeVeen electrodes with and without underlying liver perfusion. Two-dimensional diameters (Dv, Dh) of each ablation area were measured after dissecting the livers. Results:In 4 bovine livers weighing 8.85 ± 0.83 kg per organ (min, 7.7 kg; max, 9.7 kg) altogether 40 RF ablations were performed. A total of 20 ablations were generated with underlying liver perfusion (group 1) and 20 ablations with no liver perfusion (group 2). In group 1, Dv was 28.4 ± 5.3 mm, Dh 38.6 ± 7.8 mm, and energy deposition 36.9 ± 18.0 kJ. The 20 ablation areas generated without liver perfusion displayed statistically significant differences, with Dv being 35.7 ± 6.5 mm (P = 0.001), Dh 49.5 ± 9.4 mm (P = 0.001), and energy deposition 25.5 ± 13.0 kJ (P = 0.018). Conclusion:The model reproduced the cooling effect of perfused tissue during RFA. The ablation areas produced under perfusion conditions had smaller diameters despite longer exposure times and higher energy deposition.

Verbindung mit dem Platzieren von Kathetern im Gefäßmodell (PTA, Stent) eine – wie die Erfahrung beweist – sehr gute Kombination ist, sich mit den

Ziele: Um ein für experimentelle Untersuchungen mit der Radiofrequenzablation neu entwickeltes Rinderleberperfusionsmodell hinsichtlich seiner Perfusionseigenschaften zu validieren, wurde der Einfluss der Perfusion auf die Größe des Ablationsareals untersucht. Methode: In einem selbst entwickelten Leberperfusionsbecken erfolgte die Perfusion einer schlachtfrischen Rinderleber. Die arterielle und portalvenöse Perfusion wurde durch unterschiedliche, exakt regulierbare Pumpensysteme gewährleistet. Das venös abströmende Perfusionsmedium wurde über die V. cava dem Perfusionssystem wieder zur Verfügung gestellt. Das Perfusionsmedium war eine in Anlehnung an Lebertransplantatlösungen erstellte Tyrode-Lösung, welche durch einen Oxygenator mit Sauerstoff versorgt und durch eine Wärmepumpe auf 36–37 Grad Celsius aufgewärmt wurde. Mithilfe von am Leberperfusionsbecken angebrachten Schwenkarmen wurden die Radiofrequenzthermoläsionen mit standardisierter Punktionstiefe und Punktionswinkel zur Leberoberfläche reproduzierbar generiert. Die Radiofrequenzablation wurde mit einer 4cm LeVeen Elektrode und dem RF 3000 Radiofrequenzgenerator (Boston Scientific) durchgeführt. Die Größe des Ablationsareals, die Energieaufnahme, die Ablationsdauer und die Anfangsimpedanz wurden untersucht. Ergebnis: Insgesamt wurden 24 Thermoläsionen unter Perfusionsbedingungen generiert. Die mittlere Größe des Ablationsareals betrug 29mm, bei einer mittleren Energieaufnahme von 37 Kilojoule (kJ), einer mittleren Ablationsdauer von 395 Sekunden (s) und einer mittleren Anfangsimpedanz von 22.2 Ohm. In der Kontrollgruppe wurden insgesamt 24 Thermoläsionen ohne Leberperfusion generiert. Die mittlere Größe des Ablationsareals betrug hier 35mm, bei einer mittleren Energieaufnahme von 23 kJ, einer mittleren Ablationsdauer von 242s und einer mittleren Anfangsimpedanz von 25 Ohm. Die Unterschiede waren bis auf die Anfangsimpedanz statistisch signifikant (p<0.001). Schlussfolgerung: Das Rinderleberperfusionsmodell ist in der Lage, den Kühleffekt von perfundierten Organen zu reproduzieren. Die Größe des unter Perfusionsbedingungen generierten Ablationsareals ist signifikant kleiner, als das ohne Leberperfusion, trotz längerer Ablationsdauer und höherer Energieaufnahme. Moderne Impedanz-gesteuerte RF-Generatoren sind somit derzeit nicht in der Lage, eine konstante Größe des Ablationsareales bei unterschiedlichen Gewebeperfusionseigenschaften zu gewährleisten und die unterschiedliche Perfusion des Gewebes technisch auszugleichen.

PURPOSE:Experimental feasibility study of a new MR-Coil concept for enhanced visualization of the gastric wall.MATERIAL AND METHODS:The newly developed single-loop receiver coil for endoluminal imaging (Fraunhofer Institute, St. Ingbert, Germany) was evaluated in 4 explanted pig stomachs in a 1.5T MR unit (Siemens Symphony, Erlangen, Germany) with T1 w and T2 w MR sequences in three planes. The new coil consists of a foldable and self-expanding single loop coil (receiver coil) of a shape memory metal (nitinol). It was covered with a biocompatible material (silicone) to prevent direct contact of the wire with stomach tissue. The coil assumes a circular configuration with a diameter of 8 cm because of its memory metal properties. The flexible characteristics of the material used allow the passage through the instrument channel (13 mm diameter) of a specially designed MR-compatible endoscope. The purpose of our study was to assess feasibility of the coil design as a first step in developing a new endoluminal MRI-concept. Additionally the number and signal intensity of visible gastric wall layers were evaluated and findings were correlated with histopathological results of a pig stomach.RESULTS:The new coil concept was a feasible system in all 4 cases and showed good image quality for analysis. On T1 w images, 3 layers were visible in all cases, and on T2 w images 4 different gastric wall layers were seen in 2 cases. Due to histopathological correlation, the different gastric wall layers were identified as follows: mucosa, submucosa and muscularis propria if three layers were depicted; in cases of 4 visible wall layers, serosa and subserosa could be detected additionally. For each gastric wall layer, a distinct signal intensity was found.CONCLUSION:The new MR coil concept for endoluminal imaging proved to be a feasible technique. Good differentiation of gastric wall layers in the pig stomach could be demonstrated. We have shown that endoscopic MR-imaging with our new coil concept is a valuable technique for the visualization of gastric wall layers. Due to this fact, follow-up studies including assessing safety aspects are necessary to finally conduct an experimental-clinical study on in-vivo human gastric specimens to detect tumor growth and morphology within the gastric wall. Endoscopic MRI may have the potential in the future to overcome today's limitations of diagnostic imaging in gastric cancer.

Purpose: To evaluate the prevalence of latent and manifest hyperthyroidism in a non-selected group of patients admitted for contrast enhanced CT studies blood samples were tested for the levels of thyroid-stimulating hormone (TSH). Material and Methods: TSH blood levels were obtained in 548 consecutive patients who were scheduled for contrast-enhanced (Iopromide; 300 mg iodine/ml) CT scanning. In case of TSH levels < 0.4 mU/l, blood samples were also tested for triiodothyronine (T3) and tetraiodothyronine (T4) blood levels, and treatment with Irenat (R) (sodium perchlorate) was commenced before scanning. In case of TSH levels < 0.1 mU/l, CT scanning was not performed but further evaluation of the thyroid function was initiated. Results: TSH blood levels ranged from 0.4 to 7.5 mU/l in 512 patients, and 36 patients (6.6%) had TSH blood levels < 0.4 mU/l and 9 patients blood levels < 0.1 mU/l, with 32 of those patients (5.8%) having regular T3 and T4 blood levels consistent with latent hyperthyroidism. In 4 patients (0.8%), T3 or T4 blood levels were increased consistent with manifest hyperthyroidism. Conclusion: In South Germany, the prevalence of latent or manifest hyperthyroidism in a non-selected patient group is high. Therefore TSH blood levels should be obtained prior to contrast-enhanced CT studies.

PURPOSE:To evaluate the prevalence of latent and manifest hyperthyroidism in a non-selected group of patients admitted for contrast enhanced CT studies blood samples were tested for the levels of thyroid-stimulating hormone (TSH).MATERIAL AND METHODS:TSH blood levels were obtained in 548 consecutive patients who were scheduled for contrast-enhanced (Iopromide; 300 mg iodine/ml) CT scanning. In case of TSH levels < 0.4 mU/l, blood samples were also tested for triiodothyronine (T3) and tetraiodothyronine (T4) blood levels, and treatment with Irenat (sodium perchlorate) was commenced before scanning. In case of TSH levels < 0.1 mU/l, CT scanning was not performed but further evaluation of the thyroid function was initiated.RESULTS:TSH blood levels ranged from 0.4 to 7.5 mU/l in 512 patients, and 36 patients (6.6%) had TSH blood levels < 0.4 mU/l and 9 patients blood levels < 0.1 mU/l, with 32 of those patients (5.8%) having regular T3 and T4 blood levels consistent with latent hyperthyroidism. In 4 patients (0.8%), T3 or T4 blood levels were increased consistent with manifest hyperthyroidism.CONCLUSION:In South Germany, the prevalence of latent or manifest hyperthyroidism in a non-selected patient group is high. Therefore TSH blood levels should be obtained prior to contrast-enhanced CT studies.

Purpose: Experimental feasibility study of a new MR-Coil concept for enhanced visualization of the gastric wall. Material and Methods: The newly developed single-loop receiver coil for endoluminal imaging (Fraunhofer Institute, St. Ingbert, Germany) was evaluated in 4 explanted pig stomachs in a 1.5T MR unit (Siemens Symphony, Erlangen, Germany) with T1 w and T2 w MR sequences in three planes. The new coil consists of a foldable and self-expanding single loop coil (receiver coil) of a shape memory metal (nitinol). It was covered with a biocompatible material (silicone) to prevent direct contact of the wire with stomach tissue. The coil assumes a circular configuration with a diameter of 8 cm because of its memory metal properties. The flexible characteristics of the material used allow the passage through the instrument channel (13 mm diameter) of a specially designed MR-compatible endoscope. The purpose of our study was to assess feasibility of the coil design as a first step in developing a new endoluminal MRI-concept. Additionally the number and signal intensity of visible gastric wall layers were evaluated and findings were correlated with histopathological results of a pig stomach. Results: The new coil concept was a feasible system in all 4 cases and showed good image quality for analysis. On T1 w images, 3 layers were visible in all cases, and on T2w images 4 different gastric wall layers were seen in 2 cases. Due to histopathological correlation, the different gastric wall layers were identified as follows: mucosa, submucosa and muscularis propria if three layers were depicted; in cases of 4 visible wall layers, serosa and subserosa could be detected additionally. For each gastric wall layer, a distinct signal intensity was found. Conclusion: The new MR coil concept for endoluminal imaging proved to be a feasible technique. Good differentiation of gastric wall layers in the pig stomach could be demonstrated. We have shown that endoscopic MR-imaging with our new coil concept is a valuable technique for the visualization of gastric wall layers. Due to this fact, follow-up studies including assessing safety aspects are necessary to finally conduct an experimental-clinical study on in-vivo human gastric specimens to detect tumor growth and morphology within the gastric wall. Endoscopic MRI may have the potential in the future to overcome today's limitations of diagnostic imaging in gastric cancer.

Ziele: Ziel der Studie war es, den Einfluss der Gewebemodulation mit unterschiedlichen Flüssigkeiten auf die Größe der generierten Radiofrequenzthermoläsion zu untersuchen. Methode: In einem selbst entwickelten Leberperfusionsbecken erfolgte die Perfusion von schlachtfrischen Rinderlebern. Die arterielle und portalvenöse Perfusion wurde durch unterschiedliche, exakt regulierbare Pumpensysteme gewährleistet. Das venös abströmende Perfusionsmedium wurde über die V. cava dem Perfusionssystem wieder zur Verfügung gestellt. Das Perfusionsmedium war eine in Anlehnung an Lebertransplantatlösungen erstellte Tyrode-Lösung, welche durch einen Oxygenator mit Sauerstoff versorgt und durch eine Wärmepumpe auf 36–37 Grad Celsius aufgewärmt wurde. Mit Hilfe von am Leberperfusionsbecken angebrachten Schwenkarmen wurden die Radiofrequenzthermoläsionen mit standardisierter Punktionstiefe und Punktionswinkel zur Leberoberfläche reproduzierbar generiert. Die Radiofrequenzablation wurde mit einer 2cm LeVeen Elektrode und dem RF 3000 Radiofrequenzgenerator (Boston Scientific) durchgeführt. Die Gewebemodulation mit Kochsalz 0.9% und 10%, Alkohol (98%), Essigsäure (50%) und Lipiodol erfolgte durch zusätzlich angebrachte Punktionsnadeln. Die Größe der Thermoläsionen wurde makroskopisch evaluiert. Ergebnis: Insgesamt wurden 270 Thermoläsionen generiert. Die mittlere Größe betrug 3.9cm2 (nur RFA), 4.3cm2 (Kochsalz 0.9%), 4.7cm2 (Kochsalz 10%), 4.7cm2 (Alkohol), 5.4cm2 (Essigsäure) und 4.2cm2 (Lipiodol). Die Unterschiede waren statistisch nicht signifikant. (Friedmann test p=0.526). Schlussfolgerung: Die Gewebemodulation mit Essigsäure während der Radiofrequenzablation erzeugte zwar tendentiell die größten Thermoläsionen, es fand sich jedoch kein signifikanter Unterschied in der generierten Läsionsgröße zwischen den untersuchten Flüssigkeiten.

Purpose: A retrospective analysis of long-term efficacy of combined transcatheter arterial chemoembolization (TACE) and percutaneous ethanol injection (PEI) and TACE monotherapy was conducted in patients with large, non-resectable hepatocellular carcinoma (HCC). Methods and Materials: Fifty patients with large, unresectable HCC lesions underwent selective TACE. Liver cirrhosis was present in 42 patients, due to alcohol abuse (n = 22) and viral infection (n = 17). In three patients, the underlying cause for liver cirrhosis remained unclear. Child A cirrhosis was found in 22 and Child B cirrhosis in 20 patients. Repeated and combined TACE and PEI were performed in 22 patients and repeated TACE monotherapy was performed in 28 patients. Survival and complication rates were determined and compared. Results: The 6-,12-, 24- and 36-month survival Fates were 61%, 21%, 4%, and 4% for TACE monotherapy and 77%, 55%, 39% and 22% for combined TACE and PEI (Kaplan-Meier method). The kind of treatment significantly affected the survival rate (p = 0.002 log-rank test). Severe side effects were present in two patients of the monotherapy group and in three patients of the combination therapy group. Conclusion: The combination of TACE and PEI is an effective and safe method in the palliative treatment of large HCC that has the potential of improving long term survival compared to TACE monotherapy.

Purpose: To evaluate multislice-CT versus MRI in the diagnosis and staging of pancreatic carcinoma in a prospective multi-reader analysis. Materials and Methods: Fifty patients with suspected pancreatic carcinoma underwent both multislice-CT (4-Row, "hydro-technique") and state-of-the-art MRI (two 1.5T units). In correlation with histopathologic findings or in case of a non-lesion diagnosis by follow-up (6-month interval), we evaluated MRI versus CT in a multi-reader analysis (2 reader pairs) for: 1. diagnostic quality; 2. examination time; 3. accuracy of potential resectability; 4. kappa analysis of observer variations; and 5. overall diagnostic reliability. Results: A total of 28 lesions (n = 22malignant, n = 6 benign) were present in the cohort group versus 22 patients without a focal lesion (n = 10 pancreatitis, n = 12 no tumor). For lesion detection, CT had a sensitivity of 100/89% (reader pair 1/2) and specificity of 77%, and MRI had a sensitivity of 75/89% and specificity of 77/73%. For the subgroup of adenocarcinomas of the pancreas (n = 17), we found a sensitivity of 100% and a specificity of 61% for CT versus a sensitivity of 82/94% and a specificity of 67/61% for MRI. The accuracy for determining the resectability was 91/82% for CT and 90/82% for MRI. The kappa analysis showed a good correlation for CT (0.71) and a moderate correlation of both groups for MRI (0.49). Conclusion: CT and MRI showed comparable results in the detection of pancreatic carcinomas as well as in the determination of resectability. Chronic pancreatitis as a "tumor-like-lesion" was the major factor of a missed diagnosis. The results of multi-reader analysis for both reading groups were almost identical with a moderate to good kappa correlation. There is no reason to prefer MRI (more expensive) over CT for patients with the presumptive diagnosis of pancreatic cancer.