Biomedical subjects

W Jaschke

Publications and source records attributed to W Jaschke.

131 records · Page 8Linked to original sources

PubMedDate not supplied

Therapy for biliary stenoses and occlusions with use of three different metallic stents: single-center experience.

PURPOSE: The authors report their experience with three different metallic stents for the treatment of biliary obstructions during a 6.5-year period (between February 1989 and June 1995). MATERIALS AND METHODS: In an uncontrolled, nonrandomized, and prospective study, 168 patients with obstructive jaundice underwent transhepatic placement of metallic stents. Patients were excluded if they were deemed too ill for intervention or had incorrectable coagulopathy. Those patients undergoing external and/or intraluminal radiation therapy, and patients in whom an internal-external catheter was kept in place after insertion of a stent were not included. Inoperable malignant disease was diagnosed in 157 patients (93.5%). Eleven patients presented with a benign biliary stricture that could not be managed by means of angioplasty. One hundred fifty-five Wallstents were placed in 122 patients, 65 tantalum Strecker stents were placed in 30 patients, and 18 Memotherm stents were placed in 16 patients. The patients were followed until September 1996 or until death. RESULTS: Regarding malignant obstruction, the 30-day mortality rate was 10.7% without any procedure-related death, and overall survival rates after 100 and 200 days were 63% and 22%, respectively. Regarding benign stricture, eight of 11 patients were alive after a median follow-up of 50.6 months without any 30-day mortality. Major complications occurred in 16 patients (10.2%) who had malignancy, and in two patients (18.2%) with benign biliary disease. The cumulative patency rate in malignant obstructions was significantly higher for the Wallstent than for the Memotherm stent (P < .05) and nonsignificantly higher for the Wallstent than for the tantalum Strecker stent (P > .05). Reintervention due to recurrent obstructive jaundice was necessary in 28 patients (17.8%) with malignancy, and in six patients (54.5%) with benign stricture. CONCLUSIONS: The Wallstent is the most effective in achieving long-term palliation in patients with malignant obstructive jaundice. The treatment of benign biliary strictures with metallic stents is associated with a low long-term patency rate.

Adult↗

PubMedDate not supplied

Quantitation of intracardiac shunts by cine-CT.

Quantitation of intracardiac shunts is important in the evaluation of congenital heart disease and ventricular septal defects postmyocardial infarction. Shunt detection and quantitation is currently performed by either oximetry or radionuclide angiography. Oximetry is an invasive technique and radionuclide angiography, although noninvasive, does not have sufficient spatial resolution to provide detailed anatomic information. The present study evaluated a new technique for quantitating right-to-left shunts by analysis of indicator dilution curves acquired noninvasively using cine-CT. This technique was evaluated in a phantom and in postoperative dogs with a surgically created variable shunt. The phantom model demonstrated the accuracy and reproducibility of the curve analysis algorithm, and the canine model permitted the comparison of oximetry with cine-CT for shunt quantitation. Cine-CT accurately estimated right-to-left shunt fraction when compared with oximetry (r = 0.91) and is more sensitive than oximetry in detecting small shunts. The results of this study suggest that contrast enhanced cine-CT provides a precise noninvasive technique for measuring shunt lesions in congenital and acquired heart diseases.

Animals↗

PubMedDate not supplied

Flow measurements with a high-speed computed tomography scanner.

A high-speed computed tomography (CT) scanner with a scan time of 50 ms was used to measure flow in a phantom constructed to simulate both tissue and vessels. After a bolus injection of iodinated contrast medium, the phantom was scanned at a rate of up to 2 images/s. A gamma-variate curve was fit to the time-density data obtained from the inlet and outlet, as well as from the tissue-equivalent part of the phantom. Flow was then calculated using different curves and curve parameters according to the Stewart-Hamilton equation, the mean transit time, and a modification of the Sapirstein principle. Actual flow rates were assessed by timed sampling. The results demonstrated that high-speed CT can measure flow accurately by all these methods. Application of high-speed CT for flow measurements in experimental animals and patients is, therefore, promising. The limitations of each technique for clinical application are discussed.

Blood Flow Velocity↗

PubMedDate not supplied

Attenuation changes of the normal and ischemic canine kidney. Dynamic CT scanning after intravenous contrast medium bolus.

The potential of CT scanning to explore total and regional renal blood flow was evaluated in a dog model with unilateral renal artery stenosis (n = 7, reduction of renal blood flow: 32-75% of base line flow). Attenuation versus time curves were generated for the renal cortex and medulla, as well as for the aorta and renal vein. A fast CT scanner was used which allowed for up to 24 scans/minute at the same level (slice thickness: 10 mm). A total of 10 ml contrast medium was injected into a peripheral vein for each scan series taken. During baseline conditions, the curve of the renal cortex and medulla demonstrated 2 peaks. The first peak was mainly related to early vascular enhancement, whereas the second peak corresponded mainly to the appearance of contrast medium in the distal convolutes and collecting ducts. Ischemia of the kidney resulted in a reduction of the first peak and a flattening of the leading edge slope. Transport of contrast medium through the extravascular compartments of the kidney was delayed during ischemia. Relative renal blood flow was obtained from the CT data by dividing peak enhancement by rise-time as assessed from the cortical curve. All measurements were related to baseline flow and validated by flow measurements using radioactive labeled microspheres (n = 5). Correlation was found to be r = 0.97.

Animals↗

PubMedDate not supplied

Control of hepatic tumor hemorrhage by transcatheter embolization with Ethibloc.

Two patients with abdominal hemorrhage from a hepatic tumor underwent transcatheter embolization using Ethibloc. The hemorrhage ceased rapidly in both patients. No complications related to the embolization procedure were observed. One patient is doing well after 4 years. The second patient died of extensive metastatic disease eleven weeks after embolization. Control angiography after 14 months and 2 weeks, respectively, demonstrated persistent occlusion of the embolized hepatic arteries. Ethibloc offers the advantage of permanent vascular occlusion and appears to be a safe and effective embolization material for partial occlusion of the hepatic arteries.

Adult↗