Günter W. Kauffmann

Helical hydro-CT for diagnosis and staging of gastric carcinoma.

PURPOSE The purpose of this work was to define the accuracy of helical hydro-CT (HHCT) in the diagnosis and staging of gastric carcinoma. METHOD One hundred twelve patients with gastric carcinoma were preoperatively imaged by HHCT. Gastric distension was achieved by ingestion of up to 1,500 ml of water. Bolus tracking was performed, and peristalsis was minimized by intravenously administered spasmolytics. Contrast material was then injected, and helical scanning was performed at the time of peak enhancement of the liver. CT images were analyzed for tumor infiltration of the gastric wall, and TNM staging criteria were applied according to the International Union Against Cancer (UICC) classification. The results were correlated with histopathologic findings. RESULTS One hundred two of 115 (89%) gastric carcinomas were correctly diagnosed by HHCT. Small malignant ulcers (< or =2 cm) that corresponded to early gastric carcinoma were not visible on CT scans. T and N staging accuracies were 51% each; abdominal M staging was correct in 79% of all cases. The positive and negative predictive values of HHCT to foresee curative resection of gastric carcinoma were 75 and 84%, respectively. CONCLUSION Mural thickening as well as marked contrast enhancement of the gastric wall are firmly related to gastric carcinoma. The accuracy of HHCT is acceptable for M staging but inadequate for local staging of gastric carcinoma. Nonetheless, HHCT is a useful guide for choosing between tumor resection and nonoperative treatment of patients. We therefore recommend HHCT as the method of choice for preoperative imaging of gastric carcinoma.

Molecular cloning of genes differentially regulated by TNF-α in bovine aortic endothelial cells, fibroblasts and smooth muscle cells

OBJECTIVE Tumor necrosis factor-alpha (TNF-alpha) is a pleiotropic-cytokine binding to and thereby stimulating vascular cells. TNF-alpha mediated intermediate stimulation of vascular cells is believed to play a pivotal role in the development of arteriosclerosis. While extensive information has recently become available on gene induction by TNF-alpha, less is known about gene suppression by TNF-alpha in vascular cells. Endothelial cells are the first cell layer within the vessel wall interacting with circulating, cytokine releasing cells. Therefore, they were selected as target for these study. METHODS A differential screening approach has been used to isolate cDNAs whose abundance was suppressed by incubating bovine aortic endothelial cells (BAEC) for 6 h with 1 nM TNF-alpha. The gene expression of 6 isolated cDNAs after TNF-alpha was investigated by dot blots and nuclear run-on analysis in BAEC. The investigated genes were partially or completely sequenced. Differential expression after TNF-alpha stimulation of BAEC, bovine fibroblasts and vascular smooth muscle cells (SMC) was studied by Northern blots. RNA transcripts of the clone C7 in aortic aneurysms were examined by in situ hybridization. RESULTS 49 independent cDNAs were isolated by the differential screening approach and 6 clones were further analyzed. These genes were downregulated in a time and dose dependent manner in BAEC. Sequence analysis revealed that 3 cDNAs encoded previously unidentified genes (C1, C5, C7), while 3 encoded known genes: connective tissue growth factor (CTGF; A1), fibronectin (A8) and the mitochondrial genome (B1). A1 and B1 were suppressed in BAEC, fibroblasts and SMC, whereas A8, C1, C5 and C7 were not uniformly downregulated in the investigated cells. C7 RNA transcripts were exclusively induced in the endothelium of an uninflamed aortic aneurysm. The transcripts were undetectable in an inflamed aortic aneurysm and control vessels. CONCLUSIONS Gene suppression is a prominent feature of the intermediate effect of TNF-alpha on endothelial cells. Differences in the expression of the tested genes in endothelial cells, fibroblasts and vascular smooth muscle cells open possibilities for the study of cellular interactions in the vascular wall in disease situations with high local TNF-alpha concentrations.

Motion characterization of aortic wall and intimal flap by ECG-gated CT in patients with chronic B-dissection

RATIONALE AND OBJECTIVES To evaluate whether dynamic computed tomography (CT)-imaging can provide functional vessel information in patients with chronic aortic dissection type Stanford-B (ADB). MATERIALS AND METHODS In 32 patients, ECG-gated CT-angiography images were obtained. Cross-sectional area change and wall distensibility were investigated by semiautomatic vessel area segmentation at the end of aortic arch. Significance of distensibility differences was tested with regard to the aortic diameter, and the oscillation of the intimal flap was analyzed. RESULTS The aorta could be segmented successfully in all patients. These were separated into three subgroups: (A) 6 patients with an aortic diameter <4 cm and without a visible intimal flap, (B) 9 patients with an aortic diameter <4 cm, and (C) 17 individuals with an aortic diameter > or = 4 cm; (B) and (C) having a visible intimal flap. Differences in distensibility between the subgroups were not significant. Overall mean distensibility was D(tot)=(1.3+/-0.6) x 10(-5) Pa(-1). Analysis of intimal flap oscillation showed a pulsatile short axis diameter decrease of the true lumen of up to 29%. CONCLUSION Dynamic, ECG-gated CT-angiography can demonstrate pulsatile changes in aortic area and a highly variable motion of the intimal flap. Aortic distensibility appears independent of diameter or presence of a intimal flap. Follow-up studies may show correlation with possible complications.

In Vitro Comparison of Self-Expanding Versus Balloon-Expandable Stents in a Human Ex Vivo Model

The objective was to compare the radial strength and expansile precision of self-expanding stents and balloon-expandable stents in a human cadaver bifurcation model. Seven different self-expanding (LUMINEXX, JOSTENT SelfX, JOSTENT SelfX hrf, Sinus-Repo, Sinus SuperFlex, Easy Wallstent, SMART) and four different balloon-expandable stent models (Palmaz, Sinus Stent, SAXX Medium, JOSTENT peripheral), each type 10 stents (total n = 110 stents) were implanted into the common iliac arteries of human cadaver corpses. The maximum stent diameter was 10 mm for all models. After stent implantation, the specimens were filled with silicone caoutchouc. After 24 h, the vascular walls including the stents were removed from the hardened casts. Diameters were taken and the weight of the cast cylinders was measured in air and in purified water to calculate the volume of the bodies (according to Archimedes Law) as a relative but precise degree for the radial strength of the implanted stents. The cylindrical casts of the self-expanding stents showed lower mean diameters (8.2 ± 1.0 mm) and mean volumes (0.60 ± 0.14 ml/cm) than in the balloon-expandable stent group (10.1 ± 0.3 mm and 0.71 ± 0.04 ml/cm, respectively; p < 0.01). The nominal maximum diameter of 10 mm was not achieved in any of the self-expanding stents, but this was achieved in more than 70% (29/40) of the balloon-expandable stent specimens (p < 0.05). The variation between achieved volumes was significantly larger in self-expanding (range: 0.23–0.78 ml/cm) than in balloon-expandable stents (range: 0.66–0.81 ml/cm; p < 0.05). Self-expanding stents presented considerably lower radial expansion force and lower degree of precision than balloon-expandable stents.

MRI for staging of gastric carcinoma : First results of an experimental prospective study

PURPOSE Our goal was to define the accuracy of MRI in the staging of gastric carcinomas. METHOD Twenty consecutive surgical specimens were imaged immediately after gastrectomy for gastric carcinoma. Imaging was performed with a 1.0 T imaging system. T1-weighted, T2-weighted, and opposed phase images were acquired and analyzed for tumor infiltration of the gastric wall and the presence of perigastric lymph nodes. T and N stages were classified according to the International Union Against Cancer classification. Finally histopathologic staging of the specimens was compared with staging by MRI. RESULTS In gastric specimens, three to five layers of the gastric walls were visible. There were typical signal intensity patterns on T1-weighted, T2-weighted, and opposed phase images. Tumor diagnosis and lymph node detection were best achieved by opposed phase imaging. Nineteen of 20 (95%) carcinomas were localized by MRI; T staging accuracy was 65%. The sensitivity to detect metastatic lymph nodes was 87%, specificity 60%. N staging accuracy (nodes positive versus negative) was 80%. CONCLUSION High resolution MRI of gastric tumors is possible ex vivo. MRI enabled differentiation of up to five layers of the gastric wall, and therefore staging of gastric carcinomas is technically possible. However, to evaluate the exact role of MRI as a staging tool of gastric carcinomas, a correlation between MR morphology and the histologic structure of the gastric wall has to be achieved first.

TNM staging of gastrointestinal tumors by hydrosonography: results of a histopathologically controlled study in 60 patients

Abstract.Background: The study is a prospective evaluation of preoperative TNM staging of gastrointestinal tumors by hydrosonography (HUS). Methods: Sixty patients with suspected gastric or colorectal cancer underwent HUS for TNM staging. All patients were operated on and the tumors completely removed when possible. HUS findings were correlated with histopathologic staging. Results: HUS correctly localized tumors in 75% of patients. T stage accuracy was low for gastric cancers (41%). N staging of gastric cancers was accurate in 68% of all cases and was highly specific (100%). Staging was more accurate for colorectal tumors (70%), especially with respect to infiltration of other structures (sensitivity 100%, specificity 95%). N staging, however, was not reliable, mostly owing to impaired examination conditions. Conclusion: HUS easily misses tumors of the gastric cardia and distal part of the rectum. T staging of colorectal tumors with HUS is highly accurate, reaching 92% if the tumor is localized. T1 cancers of the stomach tend to be overstaged, and serosal infiltration by gastric cancers is often misjudged. With the exception of cardial gastric and distal rectal cancers, HUS comes close to endosonography for staging gastrointestinal tumors. HUS does not require intraluminal access.

MRI of pouch-related fistulas in ulcerative colitis after restorative proctocolectomy.

PURPOSE Our purpose was to determine the value of MRI in diagnosing pouch-related fistulas in patients with ulcerative colitis and to compare pulse sequences with and without contrast enhancement in their performance of visualization. METHOD Forty-four patients with pelvic symptoms after restorative proctocolectomy underwent MRI. All 26 patients with pouch-related fistulas were treated surgically; 18 patients with pouchitis were treated conservatively. MRI was performed at 1.0 T with T1-weighted FLASH sequences before and after administration of Gd-DTPA, T2-weighted and proton density-weighted turbo SE sequences, and a T2-weighted fat saturation sequence. Images were analyzed for the presence of fistula; pulse sequences were additionally compared for best visualization on a four point scale of diagnostic confidence. RESULTS MRI detected 23 of 26 cases of fistulas; there were no false-positive diagnoses. Surgery revealed fistulas in three cases in which no pathology was found on MRI. Two patients had a short sinus tract at the pouch-anal anastomosis, and a third patient had a pouch-vaginal fistula. The Gd-enhanced FLASH sequence obtained the highest score, and second best was the T2-weighted fat saturation technique. CONCLUSION MRI is a valuable technique for diagnosing pouch-related fistulas, However, there are limitations in detection of short sinus tracts and pouch-vaginal fistulas. Highest diagnostic confidence is obtained with a Gd-enhanced FLASH sequence, which might be helpful after pelvic surgery or if the fact saturation technique is equivocal.

Sonographisch gesteuerte Punktion der Pfortader beim transjugulären intrahepatischen portosystemischen Stentshunt (TIPSS)

ZusammenfassungDie Anlage eines transjugulären intrahepatischen portosystemischen Stentshunts (TIPSS) setzt die Kenntnis der individuellen Lebergefäßanatomie voraus. Das bei dieser Patientengruppe erhöhte Risiko eines kontrastmittelinduzierten Nierenversagens limitiert die Möglichkeiten einer angiographischen Komplettdiagnostik während des Eingriffs. Das ebenfalls erhöhte Blutungsrisiko bei intraabdominellen Fehlpunktionen verlangt aber eine möglichst genaue Steuerung der Punktionsnadel. Wir haben durch Einsatz der transkutanen sonographischen Steuerung bei TIPSS die Eingriffszeiten und Komplikationsraten senken können. Steuerungsverfahren anderer Arbeitsgruppen werden im Vergleich vorgestellt.SummarySuccessful completion of a transjugular intrahepatic portosystemic stentshunt (TIPSS) relies on knowledge of the individual hepatic vascular anatomy. The patients referred for TIPSS have an increased risk of contrast-medium-induced renal failure, and therefore the potential for a complete angiographic work-up during the procedure is limited. The same patient population also carries an increased risk of bleeding, which necessitates a rather accurate guiding technique for portal punctures. We have established transcutaneous sonographic guidance as a standard technique for transjugular portal puncture, reducing complication rates and intervention time. Competing imaging modalities for guidance are discussed.

Experimental functional analysis of self-expanding stents using a new developed ex vivo model.

Objective:To modify an ex vivo test procedure for balloon expandable stents as a means to evaluate the mechanical properties of self-expanding stents. Methods:Ten stents each of 7 different stent models measuring 10 mm in diameter (LUMINEXX Vascular Stent/Memotherm-FLEXX Vascular Stent [identical to Bard], Jostent SelfX, Jostent SelfX high radial force [Jomed], sinus-Repo stent, sinus-SuperFlex stent [Optimed], S.M.A.R.T. stent [Cordis], and Easy Wallstent [Boston Scientific]) were implanted in common iliac arteries taken from cadavers (n = 35). They were randomized to either the right or left bifurcation. The vessels were then maintained at 37°C for 24 hours in a special solution that inhibited autolysis, making it possible for the stents to expand. Afterward, they were filled with silicone caoutchouc. After another 24 hours, the vessel walls and stents were removed from the hardened casts. By means of fine analytic measurements, we demonstrated that the volume of a hardened cast formed in the stent cylinder is an indirect but precise measure of the radial force of a stent. Furthermore, using correlation analysis, we examined the relationship between radial force and vessel diameter as well as that between radial force and the degree of arteriosclerosis. Results:The differences between the actually measured volumes, ie, radial strength, (1 cm stent length) of the various stent models (LUMINEXX/Memotherm-FLEXX: 0.6198 mL ± 0.1537 mL; Jostent SelfX: 0.6756 mL ± 0.1298 mL; Jostent SelfX high radial force: 0.6321 mL ± 0.1817 mL; sinus-Repo stent: 0.5508 mL ± 0.1485 mL; sinus-SuperFlex stent: 0.6174 mL ± 0.0953 mL; S.M.A.R.T. stent: 0.5627 mL ± 0.1270 mL; and Easy Wallstent: 0.5613 mL ± 0.1019 mL) were not statistically significant (P > 0.05), but the differences to the theoretically possible volumes that we had previously calculated were highly significant (P < 0.05). Correlation and regression analyses demonstrated a significantly stronger relationship between stent volume and vessel diameter than between stent volume and degree of arteriosclerosis. Conclusion:The modification of our ex vivo model of balloon-expandable stents now makes it possible for researchers to obtain comparable and realistic values for both the radial force and the expansion of self-expanding stents under realistic conditions. Our methods should therefore be employed as an additional procedure to optimize the preclinical evaluation of new stent during certification.

TIPSS-Kontrolle mit Farbduplexsonographie unter Anwendung eines Ultraschallverstärkungsmittels erste Ergebnisse

ZusammenfassungIn einer Studie wurde die farbduplexsonographische Darstellung des transjugulären intrahepatischen portosystemischen Stent Shunt (TIPSS) und die Erkennung von Stenosen unter Anwendung eines kapillargängigen Ultraschallverstärkungsmittels untersucht. 37 Farbduplexsonographien wurden bei 37 Patienten nativ und nach i.v. Gabe des Ultraschallverstärkerungsmittels „Levovist®” (Schering AG, Berlin) durchgeführt. Die Darstellung von Farb- und Flußsignalen in der Pfortader und im TIPSS-Trakt wurde mit einer 4-Punkte-Skala bewertet. Weiterhin wurde die Detektion von Stenosen im TIPSS-Trakt untersucht. Am gleichen Tag durchgeführte transjuguläre Portographien dienten als Vergleich. Mit Levovist® zeigte sich eine signifikante Verbesserung der Farb- und Flußsignale bezogen auf die Pfortader und den pfortadernahen Shunt bei nur 9 von 37 Untersuchungen, bezogen auf den lebervenenseitigen Ausflußtrakt bei 35 von 37 Sonographien. 11 von 13 angiographisch interventionsbedürftigen Stenosen wurden mit Levovist® korrekt erkannt. 11 von 13 Stenosen lagen am lebervenenseitigen Ausflußtrakt. Mit Ultraschallverstärkungsmittel kann die sonomorphologische Darstellbarkeit des TIPSS-Traktes in der Farbduplexsonographie signifikant verbessert werden, insbesondere die Darstellung des Ausflußtraktes. Stenosen, die häufig im Ausflußtrakt lokalisiert sind, können so besser dargestellt werden.SummaryA study was performed to determine the visualization of the transjugular intrahepatic portosystemic stent shunt (TIPSS) and the detection of stenosis by the use of a capillary transversing signal enhancer. In 37 patients 37 colour-coded duplex sonographies were performed before and after intravenous injection of the ultrasound signal enhancer Levovist® (Schering, Berlin). The examinations were evaluated using a four-category score. Special attention was paid to the detection of stenoses in the TIPSS. Transjugular portal venograms of the same day were used as gold standard. The use of Levovist® provided better colour and flow signals for the portal vein end of the shunt in only 9 of 37 sonograms and for the hepatic vein end of the shunt in 37 of 39 sonograms. Eleven of 13 stenoses requiring reintervention in portal venography could be correctly identified with signal enhancer. Eleven of these 13 stenoses were located in the hepatic vein end of the shunt. Ultrasound signal enhancer can significantly improve the sonomorphological visualization especially of the hepatic vein end of TIPSS in colour-coded duplex sonography. Stenoses which usually occur in the hepatic vein end of the shunt may be better detected.