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Biomedical subjects

K Lackner

Publications and source records attributed to K Lackner.

At least 73 records · Page 4Linked to original sources
PubMed1996

Angiographic detection of gastrointestinal bleeding. An experimental comparison of conventional screen-film angiography and digital subtraction angiography.

RATIONALE AND OBJECTIVES: The authors experimentally assess and compare the detection limit of gastrointestinal bleeding in digital subtraction angiography (DSA) and conventional screen-film angiography. MATERIALS AND METHODS: Arterial blood flow was simulated using a tube model in which bleeding was imitated by exudation of liquid containing contrast material. Gut peristalsis was imitated using silicone tubes filled with air and liquid. Images were acquired by DSA and conventional screen-film angiography. The iodine concentration was increased in increments from 1 mg I/mL, with and without simulated peristalsis, and with both free and circumscribed extravasation of contrast material. RESULTS: The detection limit for free extravasation in DSA was 1 mg I/mL without peristalsis and 60 mg I/mL with peristalsis. The corresponding figures for circumscribed extravasation were 1 mg I/mL and 34 mg I/mL. The detection limit for free extravasation in screen-film angiography was 172 mg I/mL both with and without simulated peristalsis. Circumscribed extravasation was detected at 9 mg I/mL without peristalsis and 7 mg I/mL with peristalsis. CONCLUSION: Digital subtraction angiography is the more sensitive angiographic technique for detection of gastrointestinal bleeding and is superior to conventional screen-film angiography, provided that it is performed with adequate parasym-pathicolysis and suspended respiration. Only when these requirements cannot be achieved is screen-film angiography advantageous.

Angiography↗
PubMed1996

Recurrent bleeding of angiomyolipomas in tuberous sclerosis.

The diagnostic and therapeutic problems of renal hamartomas are illustrated by a case of recurrence of bleeding angiomyolipomas associated with tuberous sclerosis. Ultrasound and computed tomography provide clear evidence of lipomatous formation while, in rare instances, angiography can demonstrate the existence of multiple vascular tumor compartments. In view of the risk of bleeding, multiple or very large angiomyolipomas should be treated by interventional radiology in the form of superselective tumor embolization or by the most conservative surgery possible.

Adult↗
PubMed1996

Lipoprotein(a)-apheresis in the secondary prevention of coronary heart disease.

Lipoprotein(a) [Lp(a)] is one important cause of atherosclerosis. It consists of one molecule of low density lipoprotein and an additional molecule of apo(a) linked to apoB-100 by a disulfide bridge. Apo(a)s are partially homologous to plasminogen, with one kringle 5 and 10-40 repeats of kringle 4. As there is no drug therapy available, we treated three patients who had suffered from at least one myocardial infarction and had Lp(a) as the only risk factor for atherosclerosis. Since October 1992, 186 immunoadsorption treatments have been carried out weekly with Sepharose-coupled anti-Lp(a)-columns. To achieve a reduction in Lp(a) from 78-250 mg/dL before apheresis to below 25 mg/dL immediately after apheresis, patient plasma volume had to be treated two to three times. Treatments lasted 3-5 h. Immediately reversible side-effects such as flushing and tachycardia during the first treatment were seen in 9% of immunoadsorptions. Non-specific protein loss remained tolerable, if one takes into account that the patients received approximately 1 L of ACDB with heparin as anticoagulant and some of the column-rinsing buffer. One patient's clinical condition and exercise test improved dramatically as did coronary angiography after 2 years. Another patient had no change after 1 year, the third patient showed subjective improvement and has not yet had repeat angiography after 1 year of treatment. We conclude that Lp(a)-apheresis may retard progression of atherosclerosis in patients with selective Lp(a) elevation. Further studies to support this hypothesis are needed.

Adult↗
PubMed1996

[Asymptomatic endocarditis? Are consequent histological studies useful in valve surgery?].

After aortic valve replacement for endocarditis, follow-up treatment with antibiotics is imperative. However, the question of how reliable preoperative and intraoperative diagnosis of endocarditis is in cases involving aortic defects is unclear. Of the 187 patients who underwent aortic valve replacement with or without coronary bypass surgery between June 1992 and June 1994, 150 exhibited no indications of endocarditis during preoperative and intraoperative examinations. In 17 cases (Group A) histological findings indicated acute florid endocarditis in 7 patients and chronic lymphocytic endocarditis in 10. Contrarily, histological examinations of 133 patients (Group B) revealed myxoid and/or sclerotic valve degeneration. WBC and LDH activity, examined one day preoperatively and on the first and second days postoperatively, exhibited no significant differences between the two groups, with the exception of LDH activity on the first postoperative day (Group A: 490 +/- 114, Group B: 403 +/- 132, p = 0.04). Of the clinically asymptomatic patients requiring aortic valve replacement, 11.3% exhibited acute florid endocarditis upon histologic examinations. This subgroup cannot be identified based upon routine preoperative or postoperative laboratory tests or intraoperative observation. Histological examination of the aortic valve is useful for identifying the high percentage of otherwise nonidentifiable endocarditis. Further study will be required to determine therapeutic recommendations based upon such diagnosis.

Adult↗
PubMed1996

[Local fibrinolytic therapy of arterial occlusions of the lower extremity: initial success and clinical outcome].

INDICATIONS: The efficiency of local fibrinolysis therapy in patients with chronic and acute peripheral arterial occlusions of the lower extremities has been investigated. PATIENTS AND METHODS: A total of 33 patients were examined following a local fibrinolysis therapy (in 14 cases with supplementary percutaneous transluminal angioplasty) for chronic or acute peripheral arterial occlusion of the lower extremities. The success of the intervention was first evaluated by angiography and then by subsequent controls by means of treadmill ergometry. RESULTS: A primary intervention success was achieved in 75.8% (25 of 33 patients) of the cases. In 18.2% (6 of 33 patients) a vascular surgical operation was required within 30 days of the intervention (5 therapy failures, 1 complication of the intervention). In two further patients, vascular surgery was necessary after five or six months. In 22 of the 25 successfully treated patients (92%), the Fontaine stage was reduced by at least one step after an average of 7.6 (range: 1 to 30) months. CONCLUSIONS: Local lysis with or without PTA represents an effective alternative therapy to vascular surgery for the treatment of peripheral arterial occlusions in not immediately endangered lower extremities. On the basis of our results and a survey of the literature, an aid for selecting therapeutic measures for patients with arterial occlusion of the extremities is presented.

Adult↗
PubMed1995

[Value of thoracic radiography in the assessment of cardiac size. A comparison with left ventricular cardiography].

PURPOSE: To determine the value of standard chest radiographs in the assessment of cardiac size. METHODS: In 193 patients cardiac size was compared between standard chest radiographs in the posteroanterior and lateral projection and left ventricular angiograms. The following parameters were determined: transverse diameter, lateral horizontal transverse diameter, cardiothoracic ratio and end-diastolic volume index (EDVI) and ejection fraction (EF). RESULTS: Subjective assessment of the left ventricular size resulted in a mean sensitivity/specificity/accuracy of 69.7%/87.4%/82.0% respectively, in comparison to EDVI. Estimation of global heart size yielded a mean sensitivity/specificity/accuracy of 48.8%/93.6%/77.8%, respectively, in comparison to EF. Cardiothoracic ratio for the detection of pathological EDVI or EF had a sensitivity of 77.3%/57.4% a specificity of 79.3%/80.8% and an accuracy of 78.9%/72.5%. CONCLUSIONS: Standard chest radiographs with the determination of cardiothoracic ratio remain a clinically relevant procedure for screening and follow-up of heart disease.

Adult↗
PubMed1995

[Value of computed tomography in the diagnosis of fistulas].

PURPOSE: The purpose of the study was to determine the value of computed tomography (CT) in demonstrating fistulae in comparison with conventional radiographic methods. METHODS: In a prospective study 25 patients were evaluated by conventional radiographic methods and CT. RESULTS: The identification of the fistulous tract was possible with CT in 27 of 29 cases, whereas 2 fistulae could only be detected by indirect signs. Furthermore, CT showed a larger extent of the fistulous tract in 5 patients and revealed complications such as inflammatory mass, abscess or osteomyelitis in 11 cases. CONCLUSION: CT seems to be superior in demonstrating the extent of a fistulous tract and provides valuable information on the surrounding structures.

Adult↗
PubMed1995

Metabolic changes in acute and subacute cerebral infarctions: findings at proton MR spectroscopic imaging.

PURPOSE: To analyze the advantages of proton magnetic resonance (MR) spectroscopic imaging in the evaluation of acute and subacute cerebral infarcts. MATERIALS AND METHODS: Metabolite maps of choline-containing compounds, total creatine consisting of creatine and phosphocreatine, N-acetyl aspartate (NAA), and lactate were obtained in 23 patients with acute and subacute cerebral infarctions 1-35 days after onset of symptoms. Maps were obtained with a 1.5-T MR system with 32 x 32 phase-encoding steps. RESULTS: Distinct abnormal metabolite distributions could be detected in all lesions larger than 1 cm in diameter. In the center of infarcts with a diameter larger than the section thickness of 2 cm, NAA values decreased to 20% +/- 8 compared with contralateral brain as early as 1 day after onset of symptoms (P < .0001). Choline was reduced to 67% +/- 30 (not significant) and creatine to 51% +/- 22 (P = .0025). Large amounts of lactate were detected in all acute infarcts. Choline, creatine, and lactate values declined during the first 5 weeks after stroke. CONCLUSION: MR spectroscopic imaging allows visualization of metabolic changes in stroke with a reasonable spatial resolution.

Acute Disease↗
PubMed1995

[Spectroscopic imaging of the brain. Examination technique and clinical applications].

PURPOSE: MR spectroscopy allows the acquisition of a two-dimensional array of spatially resolved proton spectra of the human brain, known as MR spectroscopic imaging. Here the examination protocol and clinical applications in focal brain lesions are presented. METHOD: An array of data is acquired from a tissue slice positioned in the brain. These data can be presented as a set of spectra, in which each spectrum is allocated to a specific position in the sample, or as a set of images or "metabolite maps". RESULTS: The NAA signal typical for neuronal tissue is decreased in the centre of brain tumours as well as in brain infarcts. The intensity of the choline signal is increased in solid tumour tissue, whereas it is reduced in infarcts. CONCLUSION: Spectroscopic imaging reveals metabolite alterations in and around focal lesions. The spatial resolution of spectroscopic imaging enables matching with other macro-morphological or functional imaging methods like positron emission tomography.

Adult↗
PubMed1994

[Intra- and extrahepatic shunts in liver cirrhosis--evaluation by means of combined invasive nuclear medicine methods].

The use of combined invasive nuclear medicine procedures allows the estimation of intra- and extrahepatic shunt volumes in patients with liver cirrhosis. The investigations were carried out after transhepatic portography and injection of 99mTc-MAA into the peripheral portal vein (hilum of the spleen) as well as into the central portal vein (hilum of the liver). A subtraction technique allowed the evaluation of shunt volumes (percentage). In 32 out of 36 patients an extra-hepatic shunt volume of 29.2% (0%-84%) and an intra-hepatic shunt volume of 23.6% (0%-81%) was found. This technique may contribute to improving the results of shunt surgery.

Humans↗
PubMed1994

[CT and MRT in progressive multifocal leukoencephalopathy (PML)].

Radiological findings and course of progressive multifocal leukoencephalopathy in 14 patients (1 woman, 13 men; 13 HIV seropositive, 1 chronic lymphatic leukaemia) were analysed retrospectively and correlated with clinical symptoms. A total of 21 CT and 16 MRI studies were evaluated. CT scans and MR images of 9 patients, which had been obtained in less than two weeks, could be compared to each other. MRI was superior to CT: 6 lesions with a diameter of 1 cm and below were not detected on CT scans, in 5 patients the extent of lesions was underestimated. Cortical involvement, mass effect or signs of atrophy were missing. Only 1 of 67 lesions showed a tiny enhancement after Gd injection. Due to the pattern and spread of lesions, which showed a close correlation to the neurologic symptoms, three different types of PML are suggested: 1. initial precentral demyelinisation with contralateral hemiparesis (n = 8); 2. lesions in temporo-occipital locations with visual disturbances (n = 2); 3. predominantly bilateral lesions of cerebellar white matter with ataxia (n = 4).

Adult↗
PubMed1993

[The computed tomographic differentiation of endobronchial tumors and tumor-caused bronchial compression].

The efficiency of computed tomography in differentiating between a bronchial compression due to tumour formation and an endobronchial tumour was tested in comparison to bronchoscopy results. 624 bronchial segments were evaluated in 65 patients with masses in the pulmonary hilus area. Computed tomographical identification of pathological lesions (n = 71) was achieved with a sensitivity of 83% and a specificity of 96%. Out of 52 bronchial segments with endobronchial tumour, 90% showed pathological lesions and 85% were classified correctly. When the morphology of the bronchial lesions (endoluminal mass, smooth or irregularly demarcated bronchostenosis or bronchial displacement) was assessed with CT, only the CT identification of an endoluminal mass could distinguish endobronchial tumour growth with a probability of 91% from bronchial narrowing due to external causes and normal bronchi.

Adult↗
PubMed1993

[31P-cardio-MR-spectroscopy in myocardial insufficiency].

The relative linear relationships of creatine phosphate/gamma-adenosine triphosphate (PCr/ATP) and of phosphodiester (PDE)/ATP were measured in 38 normals and 27 patients with cardiac insufficiency using cardiac 31P-MR-spectroscopy. There was no significant difference between normals and those with dilated cardiomyopathy (19 cases) and severe aortic valve lesions (8 cases), irrespective of the clinical stage of the cardiac abnormality. Within subgroups of insufficiency there was a correlation between PCr/ATP and the severity of the disease with significant differences between mild and severe cardiac insufficiency. In 6 patients a significant rise in PCr/ATP could be demonstrated following clinical improvement under drug therapy. There was no correlation between the relative linear relationship and the left ventricular ejection fraction.

Adult↗
PubMed1992

Direct measurement of spin-lattice relaxation times of phosphorus metabolites in human myocardium.

T1 values of phosphorus metabolites visible in human cardiac 31P-MR spectra were determined in 12 volunteers at 1.5 T. Consecutive spectra were acquired with varying pulse repetition time (TR) from 1.6 to 24 s; volume selection was achieved with ISIS. T1's of creatine phosphate (CP), [gamma-P], [alpha-P], and [beta-P]ATP, 2-3 diphosphoglycerate, and phosphodiesters were 6.1 +/- 0.5, 5.4 +/- 0.5, 5.5 +/- 0.5, 5.8 +/- 1.0, 7.6 +/- 1.0, and 5.0 +/- 1.0 s, respectively. CP/ATP ratios showed little change with varying TR; linear regression of CP/ATP vs TR was of borderline significance (r = 0.28, P = 0.06). T1's for CP and ATP were also determined in standard solution (20 mM CP, 10 mM ATP) yielding T1CP of 8.7 +/- 0.2 and T1[gamma-P]-ATP of 9.9 +/- 0.7 s. Thus, T1's for CP and ATP were similar at 1.5 T in both human heart and standard solution. In human cardiac 31P-MR spectra, CP/ATP ratios may need little correction for partial saturation.

2,3-Diphosphoglycerate↗