Biomedical subjects

S Duda

Publications and source records attributed to S Duda.

At least 19 recordsLinked to original sources

PubMed1992

[Magnetic resonance tomography: value and limits in gastroenterologic diagnosis].

At present, the value and limitations of magnetic resonance imaging (MRI) as a diagnostic modality in gastroenterology cannot be conclusively determined. MRI has a high sensitivity in the detection of focal liver lesions. The signal intensity of focal liver lesions on plain and contrast-enhanced T1-weighted images and on plain T2-weighted scans narrows the differential diagnosis in many cases. Imaging of the gallbladder and pancreas presently is no indication for MRI. The high sensitivity of MRI in the detection of fistulae and abscesses in Crohn's disease and the differentiation from fibrosis represents an advantage over other modalities in imaging of inflammatory bowel disease. MRI is superior to CT in differentiating recurrent rectal cancer from fibrosis. Further development of MRI and the use of contrast media for both oral and intravenous administration may offer new perspectives of MRI in the diagnosis of diseases in gastroenterology.

Digestive System Diseases↗

PubMed1991

Potential use of holmium lasers for angioplasty: evaluation of a new solid-state laser for ablation of atherosclerotic plaque.

Tissue effects of the mid-IR Holmium laser (emitting at a wave-length of 2130 nm) were evaluated. This wavelength is attractive because it combines high water absorption and easy transmission through standard optical fibres. The laser was pulsed with pulse durations in the range of 100 microseconds and repetition rates between 2 and 6 Hertz. For all experiments a repetition rate of 2 Hertz was used. The laser beam was coupled into waterfree quartz fibers with core diameters of 200 and 800 microns with an efficiency of 70 and 80%, respectively. Ablation of atherosclerotic plaque has been performed at an ablation threshold of 10J/cm2 for the 800 microns and 40J/cm2 for the 200 microns fibre. Removal of calcified plaque was possible. Ablation efficiency increased in a non-linear fashion with increasing pulse energies. The ablation rate per pulse was approximately 2 mm at energy fluences of 1000J/cm2 for the 200 microns fibre and 1.25 mm at energy fluences of 70J/cm2 for the 800 microns fibre; a further increase in energy densities did not result in higher ablation rates. On macroscopic examination only very limited thermal injury was found in crater adjacent tissue structures. Crater edges were even and did not reveal signs of crater charring or debris in the crater lumen. However, the histologic specimens revealed zones of thermal damage extending 100 up to 1000 microns lateral into adjacent tissue. Thermal damage increased with increasing radiant exposures and depended on the medium used.

Angioplasty, Laser↗

PubMed1990

[Experimental intracoronary Excimer laser angioplasty].

To determine the feasibility of intracoronary application of pulsed ultraviolet laser light 38 coronary arteries of 18 in situ hearts were treated with the bare fiber technique and a specially constructed catheter device. Eight hearts had no coronary artery disease, in 10 hearts coronary artery disease of one or more vessels could be documented angiographically. Total time of laser irradiation varied from 30-490 seconds. Radiation was performed until vessel wall perforation was documented. In all cases a reduction of the stenotic area was realized using the bare fiber technique. Due to a lack in the flexibility of the bare fiber only proximal lesions could be treated and the time of perforation could not be precisely predicted. Dissections were observed in six coronary arteries. The handling of the catheter device was comparable to the conventionally used balloon technique. Ablative treatment of distal vessel lesions was possible. Perforations did not occur. The histologic specimens documented smooth lumen margins not revealing thermal damage. It can be expected that the innovative catheter device will enhance the intracoronary use of pulsed laser light.

Angioplasty, Balloon, Coronary↗

PubMed1989

Percutaneous coronary excimer laser angioplasty: initial clinical results.

A novel 1.3 mm diameter laser catheter, consisting of 20 concentric 100 microns quartz fibres around a central lumen for a 0.35 mm flexible guide wire, was used to ablate atherosclerotic tissue in thirty patients with coronary artery disease. The laser catheter was coupled to an excimer laser delivering energy at a wavelength of 308 nm and a pulsewidth of 60 ns. The primary success rate was 90% (27 of 30 lesions). The mean (SD) percentage stenosis fell from 85 (15)% to 41 (19)% after laser ablation. In ten patients the lumen diameter after laser angioplasty was considered sufficient, but subsequent balloon angioplasty was carried out for the other twenty patients. Failure to pass the lesion was caused by vessel kinking in two patients and a total occlusion in one patient. No complications directly attributable to laser ablation, such as vessel wall perforation, occurred; one dissection occurred but had no clinical sequelae. There was one early reocclusion and death in a patient with triple vessel disease and unstable angina, probably as a result of plaque rupture after balloon angioplasty. These results are encouraging and justify further clinical investigations.

Angioplasty, Balloon↗

PubMed1989

[Percutaneous transluminal excimer laser coronary angioplasty].

Percutaneous transluminal laser coronary angioplasty (PTLCA) was undertaken in five patients (four men and one woman, aged 44-72 years) with coronary artery stenosis. The vessel diameter was increased in all patients after PTLCA; complete ablation of the atheromatous plaque succeeded in three. In the other two the catheter could not be advanced across the entire stenotic region. After PTLCA the stenoses were 40-50% of normal lumen. Balloon dilatation was additionally done in all five patients. In three this caused dissection of the vessel wall distal to the stenosis and possible intracoronary thrombus formation: this would suggest that balloon dilatation after laser angioplasty is not recommendable. PTLCA widens the spectrum of invasive methods for treating coronary artery stenosis.

Adult↗

PubMed1989

[Imaging diagnosis of aggressive fibromatosis and the MRT-pathological correlation].

Aggressive fibromatoses (desmoid tumours) tend to grow in an infiltrative and destructive manner without metastases. Computed tomography of aggressive fibromatoses yields no uniform attenuation pattern. The tumours are typically isodense when no contrast medium is used and enhance clearly to hyperdense during infusion of contrast medium. In magnetic resonance tomography (MRT) a high signal (long T2) on T2-weighted pulse sequences as well as an accumulation of i.v. Gd-DTPA seems to be the characteristic appearance of aggressive fibromatoses, although different signal intensities can be seen. The MRT histopathologic correlation shows increasing signal intensities on T2-weighted sequences dependent on an increment in cellular content of the tumours. Only histopathological methods can provide a definite diagnosis.

Adolescent↗

PubMed1989

[Diagnostic strategies in liver and pancreatic tumors using imaging procedures--nuclear medicine].

The different biokinetic behaviour of radioactive tracers which can be monitored by nuclear medicine procedures may be helpful in the diagnosis or differential diagnosis of tumours or tumour-like lesions of the liver or pancreas: autologous red blood cells in the detection of haemangiomas; iminodiacetates in delineation of focal nodular hyperplasia, resp. liver adenomas versus other tumours; colloidal albumin in differentiating focal fatty infiltration from diffuse infiltration by metastases; monoclonal antibodies in revealing liver metastases or abscesses, resp. pancreas neoplasms. In general the clinical suspected diagnosis and the result of morphologic imaging modalities determine the use of the appropriate radioactive tracers.

Adenoma↗

PubMed1984

[Experimental evaluation of vascular two-sided velour prostheses].

Prototypes of Polish knitted vascular grafts with velours on two sides were implanted into abdominal aorta of 6 dogs. Suturing was easy, permeation was small and it stopped after 2.5 min. The grafts healed in well, and were covered with the even layer of lining. Recapitulating it can be concluded that Polish knitted vascular grafts with velours on two sides promise good results when applied in reconstructive vascular surgery.

Animals↗

PubMed1977