Search PubMed⌕ Search

Biomedical subjects

R Knopp

Publications and source records attributed to R Knopp.

At least 73 records · Page 4Linked to original sources
PubMed1981

[Single-photon emission computed tomography (SPECT) of the liver with a rotating gamma camera system (author's transl)].

In a total of 202 patients conventional scintigraphy as well as emission computed tomography (SPECT) of the liver were performed. In 123 patients focal lesions could be excluded whereas in 30 cases the presence of liver tumors was verified. In 5 of the respective cases correct diagnosis was only possible by SPECT, in 9 further cases SPECT improved the diagnostic accuracy (topography, size and number of defects). In patients with normal findings of the liver, conventional scintigraphy yielded false-positive findings in 9 cases and SPECT in 7 cases. By combination of both methods the false-positive diagnoses could be reduced to 5. 48 patients had cirrhosis of the liver: in all of them conventional camera scintigraphy was superior to SPECT because of reduced activity accumulation in the liver (insufficient statistics).

Diagnosis, Differential↗
PubMed1980

Use of the tilt test in measuring acute blood loss.

We undertook to determine the accuracy of the tilt test in detecting acute blood loss. One hundred volunteers were phlebotomized a specific amount of blood (Group I, 450 cc; Group II, 1,000 cc in 500 cc increments). Orthostatic vital signs were recorded at timed intervals comparing the supine to sitting and supine to standing techniques. Using the criteria of pulse increase greater than or equal to 30/min or severe symptoms, the supine to standing test accurately distinguished 1,000 cc blood loss from no blood loss in our population. The major value of the tilt test is detecting blood loss of 1,000 cc or more.

Acute Disease↗
PubMed1980

Radionuclide venography as an outpatient screening test for deep venous thrombosis.

This study evaluated the use of radionuclide venography (RNV) as a screening test for patients with signs and symptoms of deep venous thrombosis (DVT). Seventy patients underwent RNV; 27 of the 70 patients also had contrast venography. The incidence of DVT was 19% (13 of 70). RNV had an observed sensitivity of 93% and an observed specificity of 100%. Follow-up at one month revealed no evidence of thromboembolic disease in patients with a negative scan. RNV is an accurate, practical screening test for DVT.

False Negative Reactions↗
PubMed1980

[Data acquisition techniques in functional heart scintigraphy. Advantages and disadvantages, Diagnostic significance (author's transl)].

Although equilibrium gated blood pool scintigraphy has become a topic of utmost interest during the last few years, there are still considerable variations in the sequential scintigraphic methods used by different groups. In view of the fact that there seems to be a lack of detailed knowledge of the various available techniques of data acquisition, the respective methods are collated in order to consider their advantages and disadvantages. From this, the most commendable technique for the scintigraphic evaluation of left ventricular function is derived.

Evaluation Studies as Topic↗
PubMed1979

[Quantitative gated nuclear cardiography for noninvasive evaluation of left ventricular function].

In 43 patients with angiographically proven coronary heart disease and in 24 patients without heart disease, gated blood pool scintigraphy was done under resting conditions with 15 mCi 99mTcHSA in LAO projection. Scintigraphic data were collected in list mode by means of a gamma camera connected to a computer system (Siemens 330). A cumulative scintigram sequence with a time resolution of 100 frames/s was constructed using several hundred heart cycles of equal duration. After background correction volume curves of the left ventricle were obtained and the following parameters were calculated: EF, dV/dt max,dV/dt min. In all patients with coronary heart disease, these parameters were reduced depending on the severity of the stenotic lesion. The changes of dV/dt min and to a greater extend of dV/dt max were more pronounced than those of the EF. These results are in keeping with invasively obtained data which show that a decrease of myocardial compliance is one of the earliest manifestations of CHD. Quantitative gated nuclear cardiography allows, therefore, noninvasive evaluation of left ventricular function even under resting conditions.

Coronary Disease↗
PubMed1979

[Data processing in clinical nuclear medicine (author's transl)].

Since the introduction of data processing into clinical nuclear medicine, significant advances could be achieved above all through the development of quantitative gamma camera scintigraphy, which is nowadays one of the most important fields of computer application. The technological properties of an adequate computer system for nuclear medicine use are dependent on a scale on the necessities of gamma camera sequential scintigraphy. If the computer capacity to carry out fast sequential scintigraphy is available, the system can be used for all modern scintigraphic procedures as well as for other tasks. If we look back on the experience gathered in more than ten years, the following areas can be named in which the use of computers appears worthwile and desirable: 1. scintigraphic diagnostics 2. functional diagnostics 3. medical record printout 4. operational management of the department, documentation and retrieval of the patients data 5. planning of therapy. Because of the importance of quantitative sequential scintigraphy, in many nuclear medicine departments two or more gamma camera computer systems are used. For reasons of costs, however, it will not be justifiable to connect each gamma camera with a separate effective data system. Therefore systems have been tested in which several gamma cameras are connected to a host computer via microprocessor-controlled buffer systems and by means of DMA interfaces. From practical experience, critera were worked out to draw up a computer concept for data processing in clinical nuclear medicine.

Computers↗
PubMed1979

[Application of harmonic analysis in quantitative heart scintigraphy (author's transl)].

Quantitative scintigraphy of the heart after equilibrium distribution of a radioactive tracer permits the measurement of time activity curves in the left ventricle during a representative heart cycle with great statistical accuracy. In the range of ventricular volumes which usually occur, the time activity curve corresponds with sufficient accuracy to the ventricular volume variation during one heart cycle. In cardiological terms, the parameters ejection fraction as well as maximum rates of ejection and filling have proved useful for evaluation of hemodynamic performance. By application of Fourier's analysis, criteria are to be attained in addition for evaluation of the volume curve as a whole. Thus the entire information contained in the volume curve is completely described in a Fourier spectrum. Because of the statistical noise, the volume curves drawn up from scintigraphic techniques require smoothing procedures, especially in determination of the differential quotients of ejection and filling rate. Smoothing by means of sliding average procedures causes a systematic deformation of the systolic dip and other similar regions of the curve, since the curve smoothened in this way does not converge towards the original curve at these points. Resynthesis after Fouier transformation seems to be an ideal method of smoothing because of its convergence in the minimum quadratic error for the type of function concerned.

Cardiac Volume↗
PubMed1979

[Time resolution of scintigraphically determined left ventricular volume curves (author's transl)].

In 25 patients with angiographically proven coronary heart disease and in 15 patients without heart disease, gated cardiac blood pool scintigraphy was done with 15 mCi 99mTc-HSA in LAO projection. Scintigraphic data were collected in list mode by means of a gamma camera connected to a computer system (Siemens 330). A cumulative scintigram scintigram sequence with a time resolution of 100, 50 and 25 frames/sec was constructed using several hundred heart cycles of equal duration. After background correction volume curves of the left ventricle with a time resolution of 25, 50 and 100 Hz were obtained and the following parameters of these curves were compaired: ejection fraction, maximum ejection rate and maximum filling rate. It could be demonstrated that smoothing by sliding average requires a time resolution of at least 50 Hz, whereas in volume curves smoothed by Fourier-Analysis a time resolution of only 25 Hz is necessary. However, using a time resolution of 25 Hz, the course of the volume curve can not always be clearly demonstrated, so that time resolution of 50 Hz combined with Fourier-Analysis for the gated cardiac blood pool scintigraphy is preferred.

Cardiac Volume↗
PubMed1979

[Bone scintigraphy with 99mTc-methylene diphosphonate in parodontopathy (author's transl)].

In a total of 20 patients (of these 8 without parodontopathy and 12 with parodontitis marginalis profunda), a quantitative scintigraphy of the jaw bones was carried out after application of 99mTc-methylene diphosphonate with a gamma camera computer system. In 8 patients without parodontopathies, approximately the same metabolic activity in the bone was found in the os occipitale as well as in the mandible and maxilla. The 12 patients with parodontitis marginalis profunda showed in contrast to this an appreciable raised bone metabolism in the region of the affected jaw bone. This finding was in agreement with corresponding alterations in the X-ray of the jaw. The use of bone scintigraphy in marginal parodontopathies thus provides in addition to the radiological finding information on processes of bone transformation and degradation which can be registered quantitatively. Digital analysis enables control of the course of therapie.

Adult↗
PubMed1979

[The normal liver-spleen scintigram with the gamma camera (author's transl)].

In 104 patients without liver disease, liver spleen scintigrams were analysed according to uniform criteria. The scintigrams were taken after application of 99mTc-sulfur colloid in at least six projections with the gamma camera and coupled data processing. As a significant difference compared to scanner scintigraphy, a non-homogeneous storage pattern is frequently also found in the healthy liver, especially in the ventral projection. Superimpositions or impressions caused by extra- or intrahepatic structures were also more frequent and more pronounced than with scanner scintigraphy. As expected, there were no appreciable differences with regard to the liver forms. The following quantitative parameters were determined (mean +/- SD): maximum vertical diameter of the liver: 199 +/- 20.0 mm, maximum horizontal diameter: 219 +/- 19.8 mm; liver area (ventral projection): 187 +/- 27.3 cm2; spleen area (dorsal projection): 55.3 +/- 15.9 cm2; index of liver size (liver area divided by the normal weight of the patient as determined from a given table): mean +/- SD = 2.69 +/- 0.58 (ventral projection); spleen area index (spleen area divded by body surface): mean = 3.03 +/- 0.81 (dorsal projection). The choice of projection did not have any appreciable effect on the area dimensions and indices, so that with super-imposition of organs these values can be determined with sufficient accuracy even from oblique projections.

Adult↗
PubMed1979

[Quantitative gated nuclear cardiography in coronary artery disease after administration of isosorbiddinitrate (author's transl)].

The change in left ventricular volume during a representative cardiac cycle was assessed in 19 patients with CAD and 8 control subjects before and after 10 mg isosorbiddinitrate sublingually. 15mCi99mTc-HSA were administered intravenously. After the tracer had equilibrated, the precordial changes of activity were measured with a gamma-camera connected to a computer. In order to determine the overall left-ventricular function from volume curves, the ejection fraction, the maximal systolic ejection rate and the maximal diastolic filling rate of the left ventricle were measured. For the assessment of regional wall motion abnormalities the volume changes were observed in a cinemode on a colour video display. In addition the relative changes of regional EF, regional stroke volume and the timing of endsystole were recorded as a functional scintigram. The results showed very clear differences between control subjects and patients with CAD. Furthermore differences existed between patients with hypokinesia and those with akinesia or aneurysm. The results emphasize that quantitative gated nuclear cardiography not only provides information concerning the left ventricular function but also allows the assessment of local wall motion as to reversible or irreversible asynergy.

Cardiac Output↗
PubMed1978

Near drowning.

Explore the source record for details and available documents.

Central Nervous System Diseases↗
PubMed1978

[Quantitative gated radionuclide cine cardiography. I Technical basis and methods (author's transl)].

Scintigraphic evaluation of the heart function is performed by means of sequential camera scintigraphy following i.v. injection of a 99mTc albumin bolus. The first tracer passage is registered during 30 seconds. About 10 minutes later--after equilibration of the tracer in the blood pool--volume curves of the left ventricle are recorded from a series of about 500 heart cycles. The principles of a computer program which has been developed for this method are described and discussed in detail.

Computers↗
PubMed1978

[Functional scintigraphy during contraction of the left ventricle. II. Evaluation of background correction (author's transl)].

During evaluation of cardiac function using 99mTc human serum albumen (functional scintigraphy during contraction of the left ventricle), it is necessary to take account of the background radiation which is derived from the lungs and great vessels overlying the heart. Only after correction of the background radiation is it possible to evaluate the severity of various types of cardiac insufficiency; this can be obtained by integrating the impulse during systole and subtracting this from the impulse rate over the left ventricle during a complete cardiac cycle. Apart from the background correction derived from the systolic-diastolic variation, it is necessary to obtain adequate resolution by examining 100 frames per second, an adequate picture matrix (4-K) in order to obtain adequate spacial resolution and accurate measurements of systole and diastole. The latter should be obtained not from the E.C.G., but directly from the volume curve of the left ventricle as determined by the isotope method.

Electrocardiography↗