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Biomedical subjects

K Lackner

Publications and source records attributed to K Lackner.

At least 55 records · Page 3Linked to original sources
PubMed1988

Calculation of flow velocities from the geometrical shape of contrast agent-induced time-density curves using DSA.

A method for the calculation of flow velocities in vessels is introduced. The method is validated by measurements with an artificial model. Measurements with the carrier fluids sodium chloride solution and human blood using various scattering objects, show good correlation (r greater than +0.9) of the calculated and volumetrically measured velocities. With a menu-oriented computer program, measurement of flow velocities on DSA series can be made following the routine clinical examination.

Angiography↗
PubMed1987

[Optimization of examining sequences in MR tomography using isosignal displays].

Contrast performance in MR tomography is influenced by the choice of technical parameters such as pulse repetition time (TR), echo time (TE) and inversion time (TI) in the same manner as by differences in the tissue parameters relaxation time and proton density. To optimise image contrast it is therefore suggested to preselect the imaging sequence. Such presselection is possible on the basis of isosignal visualisations S(T1, T2). In the inversion recovery sequence (IR) the isosignal images obtained with the parameters TE, TI, TR enable determination of relaxation time T1 by graphic representation, from the time of zero passage of the longitudinal tissue magnetisation.

Humans↗
PubMed1987

[Results and complications of percutaneous nephropyelostomy in 215 patients].

The results of 242 percutaneous nephropyelostomies in 215 patients were analysed retrospectively. No consideration was given to the experience of the individual operators. There was a total complication rate of 36.4% (mild complications 32.2%, serious complications 34.1%, fatality 0.4%). Rapid reduction in serum creatinine could be demonstrated following drainage in patients in whom renal function had been damaged by obstruction.

Creatinine↗
PubMed1987

[Cardiac MRT. Research technic and topographic anatomical imaging information].

ECG-triggered cardio-MRT, using T1-weighted SE sequences, provides images of the heart showing very high anatomical resolution. So far, however, it has not been possible to demonstrate the morphology of the valves and coronary vessels. By using multiplanar sections, it is possible to obtain cuts which are perpendicular to the portion of myocardium or valve under consideration. This provides optimal imaging for morphological diagnosis and for evaluating the ventricular myocardium and its function.

Coronary Vessels↗
PubMed1987

[Magnetic resonance tomography (MRT) of the orbit].

By using high field strengths and surface coils, MRT achieves a resolution comparable with CT in the orbita. The advantages of MRT are good contrast resolution and imaging in several planes. Twenty-six patients have been examined by MRT, which has shown high sensitivity and good detail for the demonstration of pathological changes. In spite of this, MRT at present is not a realistic alternative to ultrasound and CT, because it is unable to demonstrate bone and calcification; its specificity is low, but the time and cost of the examination is high. It is indicated only for problems involving the optic nerve and chiasma.

Adolescent↗
PubMed1987

[Diagnosis of muscle hematomas and pseudotumors in hemophilia].

Two hundred and twenty-six patients with haemophilia A and B were examined by CT. In 135 cases, some form of bleeding was demonstrated. CT permits exact anatomical localisation of the haematoma and its delineation from neighbouring structures. Measurements of the densities of the haematomas make it possible to determine their age from the change in absorption values. Computed tomography makes it easier for the clinician to choose between conservative or surgical treatment and to determine the duration of treatment during the regression of the haematoma.

Adolescent↗
PubMed1987

[Digital subtraction angiography and large-film angiography of the pelvic and leg arteries].

The diagnostic information and image quality of 1153 DSA studies of pelvic and lower limb arteries and of 104 conventional large film angiograms have been analysed. Using intra-arterial contrast, all large film angiograms and all DSA studies of the iliac, femoral, popliteal and upper calf arteries were satisfactory. For demonstrating the distal calf vessels and vessels in the foot, intra-arterial DSA was superior to large film angiography. Using intravenous DSA, 98% of the iliac, femoral and popliteal arteries were adequately demonstrated, although image quality was reduced.

Angiography↗
PubMed1987

[Magnetic resonance tomography (MRT) of the adrenals].

Thirty-eight MRT examinations were carried out in 35 patients who, between them, had 19 abnormalities in the adrenal glands. These included ten adenomas, three metastases, two carcinomas, two phaeochromocytomas, and two primary retroperitoneal tumours. MRT provides images of normal and abnormal adrenal glands which are equivalent to those of CT, with the exception that it cannot demonstrate calcification. Using a ratio of signal intensity from the adrenal tumours and the liver on T2-weighted images, it is usually possible to differentiate adenomas from metastases, carcinomas or phaeochromocytomas. The increased specificity of MRT is valuable in the investigation of patients with asymptomatic enlargement of the adrenal glands.

Adrenal Gland Neoplasms↗
PubMed1987

[Computed tomographic research on the viability of a free fat pedicle flap in the area of a laminectomy].

Nineteen patients were examined clinically and by CT three to five years after partial or total hemilaminectomy using a fat pedicle as cover. The results were compared with a control group of fourteen patients without fat pedicles. With CT it is possible to check the fat pedicles directly. Survival of the fat pedicle without peridural scarring was present in 68%. It was not possible to demonstrate any correlation between the extent of scarring and clinical abnormalities.

Adipose Tissue↗
PubMed1987

[Results and complications of CT-guided puncture biopsies with a wide-lumen puncture needle].

The results obtained in 187 CT-guided biopsies using a wide lumen needle are described. Biopsies in the thorax, abdomen, retroperitoneum and in the pelvis have been evaluated. A retrospective analysis of the material has shown an accuracy of 97.8% and sensitivity of 95.8%. The total complication rate was 8%. Amongst 120 biopsies in the thorax, 6.6% developed a pneumothorax. Therapeutic drainage was carried out in fifteen patients.

Abdomen↗
PubMed1987

[Rapid MR tomography of the liver. Technic and initial results].

The fast-field-echo (FFE) sequence provides a new rapid imaging method for MR tomography. By using gradient echoes with shorter high frequency pulse repetitions than conventional sequences with 180 degrees echo pulses, it is possible to produce single cuts in 10 to 20 s with good signal-to-noise ratio. In this way the liver can be examined while respiratory movement artifacts are reduced. The possibility of obtaining T1- and T 2-weighted FFE images with good contrast resolution and the ability to determine relaxation times suggests a wide application of this rapid imaging procedure in the diagnosis of liver disease.

Carcinoma, Hepatocellular↗
PubMed1987

[Quantitative regional functional analysis of the left ventricle using ECG-directed cardiac computerized tomography].

ECG-gated cardio-CT using two different methods of subsequent calculation was performed in 152 patients to evaluate contractility of the anterior and posterior wall and apex of the left ventricle quantitatively. The results were compared with RAO laevo-cardiography. Apart from the localisation of abnormal contractility, CT diagnosis showed sensitivity, specificity and accuracy from 70% to 85%. ECG-gated CT was better at showing abnormal movements at the apex and of the anterior wall than of the posterior wall. Attempts to quantify abnormalities of the basis of laevo-cardiographic results.

Adult↗
PubMed1987

[Computed tomography of primary and secondary tumors of the eye and orbit].

Only computed tomography (CT) is able to demonstrate ocular, orbital and peri-orbital soft tissues, calcification and bony structures directly and without superimposition of other tissues. 165 patients with tumours of the eye or orbit have been examined by CT and in 143 the diagnosis has been confirmed. The value of CT lies in its ability to demonstrate tumours and to define their orbital and extra-orbital extension and their relationship to neighbouring structures. In 51% of the lesions there was bone destruction and in 6% intracranial extension. Density measurements before and after intravenous contrast medium only rarely provided a specific diagnosis.

Adolescent↗
PubMed1986

Identification of low density lipoprotein receptor binding domains of human apolipoprotein B-100: a proposed consensus LDL receptor binding sequence of apoB-100.

The human liver apoB-100 gene cloned in the lambda gt-11 expression vector expresses fusion proteins reacting with apoB antibodies. A fusion protein induced from a apoB-lambda gt-11 clone reacted with apoB-100 monoclonal antibodies known to block the binding of LDL to the LDL receptor. The fusion protein contains an amino acid sequence domain enriched in positively charged residues which is complementary to the negatively charged amino acids present in the consensus LDL receptor binding domain. This sequence of apoB-100 is proposed as a binding domain for the interaction with the LDL receptor. Comparison of derived amino acid sequences from the entire structure of apoB-100 molecule revealed several similar domains enriched in positively charged amino acids. A consensus sequence of the potential LDL binding domain was identified which contained positively charged amino acids at positions 1, 5 and 8 and a loop of 8-11 amino acids followed by two adjacent positively charged amino acids. These results are interpreted as indicating that there are several potential LDL receptor binding domains in apoB-100.

Amino Acid Sequence↗
PubMed1986

[Pathogenesis of bleeding esophageal varices].

Pressure in oesophageal varices was measured endoscopically in 52 patients, in 16 of them central portal-vein pressure additionally by percutaneously introduced transhepatic portal-vein catheter. Only in the region of the cardia occlusion segment was the portal-vein pressure the same as that in the oesophageal varices. The larger the varices the higher the average variceal pressure. Depending on the time interval since a meal there were marked pressure variations during the day in portal-vein pressure. Intra-abdominal pressure rise (e.g. on coughing, choking or vomiting) induces a sudden and marked pressure rise in the portal vein as well as the oesophageal varices. The larger the varices the greater the danger of rupture when these pressure rises occur. Gastro-oesophageal reflux plays no role in the pathogenesis of bleeding from oesophageal varices.

Adult↗
PubMed1986

[Indications for preventive sclerosing of esophageal varices].

In 72 patients with oesophageal varices the intravascular oesophageal variceal pressure was measured, in 31 of them the portal pressure as well. The portal pressure was identical with the variceal pressure only at the cardia. There was a positive relationship between the size of varices and the variceal pressure and between the size of varices and the occurrence of bleeding from varices. Prophylactic endoscopic sclerotherapy is indicated in grade II and III varices.

Adult↗
PubMed1986

[Digital subtraction angiography in traumatology].

The methods, indications and results of digital subtraction angiography in traumatology are presented, based on 56 examinations. The different use of intravenous or intraarterial DSA will be discussed with respect to expanding and localisation of traumatic vascular injury. DSA is recommended as the method of choice for follow-up after vascular reconstructive procedure.

Angiography↗