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Biomedical subjects

K Lackner

Publications and source records attributed to K Lackner.

At least 37 records · Page 2Linked to original sources
PubMed1991

[Experimental and clinical possibilities of MR spectroscopy of the heart].

MR-spectroscopy of the heart is a relatively new technique for the study of various aspects of cardiac metabolism. The majority of results has so far been obtained with the isolated perfused heart. Here, 31P-MR spectroscopy can be employed to measure high-energy phosphate metabolism and intracellular pH repeatedly and non-invasively. Using a technique called saturation transfer, velocities of enzymatic reactions, such as the creatine kinase reaction, can be measured. Intra- and extracellular Na+ and K+ concentrations can be registered with 23Na- and 39K-MR in conjunction with shift reagent. 13C-MR can be used to tackle carbohydrate metabolism. In-situ-R-spectroscopy allows determination of high-energy phosphates in intact large mammals. Clinical applications of MR-spectroscopy remain to be defined; preliminary results indicate high diagnostic and prognostic potential for patients with coronary artery disease and congestive heart failure.

Animals↗
PubMed1990

Collateral pathways in portal hypertension.

In a retrospective study angiographic image material of percutaneous direct portographies carried out in 43 patients was evaluated according to anatomic and radiologic criteria. These examinations were performed for therapeutic purposes (embolisation of vessels supplying varices). All the hepatofugally perfused veins were analyzed according to their localisation and course. Apart from the known portocaval collateral pathways a number of other collaterals not yet described could be documented by means of angiography.

Aged↗
PubMed1990

[Gadolinium-DTPA as an oral contrast medium for MR tomography of the abdomen].

150 MR examinations of the upper abdomen were carried out after the oral administration of 5 ml/kg body weight of a gadolinium DTPA formulation (1.0 mmol/l, 15 g/l mannitol), with reference to the delineation of the pancrease, the liver and intra-abdominal fat. For comparison, 100 MR examinations without oral opacification of the G.I. tract were evaluated. Contrast administration resulted in a signal-intensive demonstration of the G.I. tract for all measurement sequences. The intraluminal contrast improved the distinction between normal and abnormal structures. T1 and T2 sequences and the demonstration of fat on T2-weighted series. T1-weighted series showed the best diagnostic results. In 25% there was meteorism and diarrhoea within 24 hours of the administration of the oral contrast.

Abdomen↗
PubMed1990

[The value of color-coded duplex sonography of a dialysis shunt].

Two hundred and sixty-four shunt segments in 43 patients with 66 dialysis shunts were examined by colour-coded duplex sonography and the results compared with DSA. Sonography demonstrated shunt stenoses with an accuracy of 93.9% (sensitivity 90.6%, specificity 95.8%). Only central venous stenoses were shown better by DSA than by sonography. Sonography showed occlusions with a sensitivity of 83.3% and a specificity of 100%. All aneurysms demonstrated by DSA were correctly identified by sonography. In 18 patients PTA of the shunt was performed. The result of treatment could be quantified by measuring flow by means of sonography. The study confirmed the value of duplex sonography as a noninvasive diagnostic method for investigating insufficient dialysis shunts.

Adult↗
PubMed1990

[Dilatation and balloon-expandable stents for the treatment of central venous stenosis in dialysis patients].

On 10 dialysis patients we performed 12 balloon dilatations, 2 catheter lyses, 6 stent implants (Palmaz stent) and one atherectomy of central venous stenoses or occlusions (v. subclavia, v. brachiocephalica) at the shunt arm of the patient. The primary success rate was, in balloon PTA and lysis, 12/14 interventions, and in stent placement and atherectomy 7/7. The angiographical and clinical primary result after stent implantation was significantly better than after conventional dilatation. After 66% of the balloon dilatations recidivation occurred within the first year; this can be treated by means of repeated PTA. Whether long-term exclusion of recurrence can be achieved by stent implantation, must be established by means of follow-up studies that are at present in progress.

Adult↗
PubMed1990

[Color-coded duplex sonography before and after PTA of the arteries of the lower extremities].

The value of color-coded duplex sonography in the pelvic and lower limb arteries was studied prospectively in 52 patients and the findings were compared with intra-arterial DSA. There was high diagnostic accuracy (sensitivity 91.7%, specificity 98.9%) for the demonstration of vascular abnormalities. In 84.3% of cases a correct diagnosis could be obtained based entirely, or largely, on the color-coded signal. Both before and after PTA color-coded duplex sonography is a non-invasive method that is superior to conventional duplex sonography.

Angiography, Digital Subtraction↗
PubMed1990

[Magnetic resonance tomography (MRT) of the hand in chronic polyarthritis].

Forty hands of 39 patients with rheumatic joint disease were examined by MRT. The method differentiates between inflammatory exudative and proliferative processes in soft tissues and bone. T2-weighted images provided criteria for judging the activity of the disease. MRT provided better demonstration of the soft tissues than just conventional radiography. The methods were of equal value for showing bone lesions. MRT is suitable as a means of diagnosing rheumatoid changes in the hand.

Adult↗
PubMed1990

[Indications for cardio-MRT].

Cardio-MRT provides complex diagnostic information (morphology, function, biochemistry) with little stress for the patient and is therefore used increasingly for clinical diagnosis. There is great need for interdisciplinary studies concerning function, the use of contrast media and spectroscopy.

Animals↗
PubMed1989

[Imaging properties of digital image-intensifier radiography compared to the conventional x-ray technic for chest pictures].

Projection properties of a digital fluorographic system for chest examinations are examined using varying test phantoms. A maximal geometric distortion of +14% between the centre and the periphery of the image intensifier and a maximal spatial resolution of 2.6 LP/mm is found. Contrast detail diagrams are used to show the combination of spatial and contrast resolution of the system. Compared with diagrams for conventional radiographic systems there is a significant loss of resolution.

Adolescent↗
PubMed1989

[In vitro measurement of intravascular blood flow with color Doppler sonography].

The accuracy of colour Doppler sonography for measuring various aspects of intravascular flow (volume and velocity), under varying conditions, was studied experimentally. The effect of variable Doppler angles, different flow paths, frequency and vessel diameter on flow profiles was examined. At all levels of measurement (range 14 ml/min to 566 ml/min) there was a very close correlation between the actual and measured values (r greater than 0.99) and high accuracy. In the detection of very slow flow rates, the use of a specific high pass filter technique was able to quantify blood flow velocities of just under 1 cm./second. Multigated colour Doppler sonography is better for measuring flow volumes than a single channel duplex system.

Blood Flow Velocity↗
PubMed1989

[Computed tomographic volumetry of the orbit in endocrine orbitopathy].

The volumes of the four recti muscles and the orbital fat was measured by CT in 40 normal persons and in 60 patients with clinically confirmed Graves' disease. Compared with normal persons, 42 patients (70%) showed an increase in muscle volume and 28 patients (46.7%) an increase in the amount of fat. In nine patients (15%) muscle volume was normal, but the fat was increased. By using volumetric measurements, the amount of fat in the orbits in patients with Graves' disease could be determined.

Adipose Tissue↗
PubMed1979

[Demonstration of left-ventricular contraction anomalies with the two-dimensional sector-scanner (author's transl)].

Echocardiographic findings were compared with those obtained by cardiac catheterisation in 134 patients. Echocardiography was performed in the standard plane of the long and short axes, as well as from the cardiac apex. After dividing the left ventricle into several segments wall movement was measured in them and compared with those obtained by ventricular angiography in the right and left anterior oblique positions. It was found that in patients with left-ventricular aneurysm, proven by left ventricular angio, there was complete conformity with regard to localisation and extent of the aneurysm between the two methods of investigation. In this group 79% of the demonstrated segments could be adequately assessed and, in 91%, agreed with the radiological findings. In the group of patients without aneurysm only 68% of the segments could be adequately assessed, and 77% correctly assessed wall movement when compared with the laevocardiogram. Tracing recorded from the cardiac apex gave especially good results in demonstrating the ventricle and its segments.

Adult↗
PubMed1979

[Coronary calcification and luminal diameter in coronary disease (author's transl)].

Two hundred and thirty-six patients with coronary heart disease were examined by coronary angiography and laevo-cardiography. In 111 patients (47%) there was coronary artery calcification. Of these, 108 patients (97%) showed abnormal findings on the coronary angiogram; in 72 patients (67%) coronary stenosis was greater than or equal to 50% of the lumen. The severity of the stenoses increased with the amount of calcification. There were only three false positive findings and the presence of coronary calcification indicates coronary sclerosis with a high degree of probability. Fluoroscopy is the simplest and most sensitive method of examination and is of great value in the non-invasive investigation of coronary sclerosis.

Calcinosis↗
PubMed1979

[Computer tomography in the diagnosis of aortic aneurysms (author's transl)].

The paper describes the diagnosis of ten thoracic, 20 abdominal and three peripheral arterial aneurysms by computer tomography. This permits a definite diagnosis by a non-invasive method, it defines the extent of the aneurysm and the amount of thrombus in the aneurysm; it permits recognition of a leak and is painless and without risk and can be performed rapidly. Morever, computer tomography provides an accurate control of growth of the aneurysm. In some cases a dissection can be recognised. The use of adequate quantities of intravenous contrast medium prevents any possibility of an incorrect diagnosis. The extent and density of the aneurysms, their lumina, clot and wall thickness, as determined by computer tomography are described. The values are compared with the aortic diameters of patients with normal vessels. The advantages of the method, compared with other procedures, are discussed and its role in the diagnosis of aortic and peripheral arterial aneurysms is described.

Aged↗
PubMed1979

[Image characteristics of the computer tomograph (author's transl)].

In the present paper the images produced by spheres of varying diameter (d = 4,6,8,10 mm) embedded in a homogeneous substance of varying densities (H' = 3,48,93,137 Hounsfield units) as produced by computer tomography were studied. Measurements show that for each sphere diameter there is a minimum contrast between the substance of the sphere and its surroundings which must exist in order to show this sphere by computer tomography. It was also shown that the partial volume effect is of significance for the attenuation of the spheres. The effect of the position of the spheres within the slices to be imaged was studied. The results clearly indicate that in the investigation of small tissue changes in the body, the thickness of the slice and patient displacement should be kept as small as possible.

Absorptiometry, Photon↗
PubMed1979

[Computer-cardio-tomography in idiopathic hypertrophic subvalvular aortic stenosis--a new contribution to non-invasive diagnosis (author's transl)].

The use of computer tomography as a non-invasive procedure in the diagnosis of idiopathic hypertrophic subvalvular aortic stenosis is described. Seven patients were investigated in whom the diagnosis had been confirmed by echocardiography and laevocardiography with pressure measurements. Details of the method are discussed and computer tomography and echocardiography are compared. The features of greatest differential diagnostic importance relating to asymmetrical septum hypertrophy are discussed.

Cardiomegaly↗
PubMed1979

[Computer tomographic demonstration of lymph node metastases from malignant testicular tumours. A comparison of lymphography and computer tomography (author's transl)].

Lymphography and computer tomography was performed on 64 patients with malignant testicular tumours in order to demonstrate lymph node metastases. In 60 patients it was possible to confirm the findings by surgery. In 43 patients there was agreement between the findings of the computer tomogram and the lymphogram. In 39 of these patients lymph node metastases had been demonstrated, in three there was a false negative and in one a false positive. Amongst the patients in whom there was a descrepancy between the two types of examination, the CT findings were confirmed histologically in twelve, and the lymphographic findings in nine. In 12.5% CT added significant additional information. Accuracy of lymphography was 73% and of computer tomography 80%. Specificity for each examination was 79%.

Adult↗