Biomedical subjects

D Hellwig

Publications and source records attributed to D Hellwig.

64 records · Page 4Linked to original sources

PubMed1990

[Spinal angiomatous malformation: clinical course and limits of technical diagnosis].

The sensitivity of the diagnostic procedures in space occupying lesions of the spine have been markedly improved in the recent past, mainly due to the application of CT and MRI--technology and the introduction of superselective angiography. Despite these 'high-tech'-investigations, neurological examination still provides the sole in neurological diagnosis. To show the discrepancies between the techniques mentioned, we present a case of a vascular malformation of the spine with secondary myelopathy (so-called "Foix-Alajouanine-syndrome").

Adult↗

PubMed1989

The contraction fraction (CF) in myocardial studies with technetium-99m-isonitrile (MIBI)--correlations with radionuclide ventriculography and infarct size measured by SPECT.

Criteria for the detection of coronary artery disease in nuclear cardiology include visualization of perfusion defects and functional impairment of contraction. The purpose of this study is to combine both methods in one procedure with the new myocardial perfusion tracer, 99mTc-methoxy-isobutyl-isonitril (MIBI), reducing time and radiation burden to the patient. Following an uncomplicated recovery, ten patients with first myocardial infarction participated in this study. Radionuclide ventriculography (RNV) was performed at rest and during exercise. Within 2-3 days, 370 MBq 99mTc-MIBI were injected and SPECT acquisition commenced 1 h later. Data processing included a scar image in polar coordinates. Areas of significantly reduced tracer uptake were expressed as a percentage of the total myocardial area. Directly following SPECT, resting and maximum exercise gated planar LAO images were recorded and the contraction was quantified. The concept of the contraction fraction (CF) rested on the end systolic change in count distribution: their increase in density and their centripetal concentration. For comparison, geometrical inner edge detection techniques were also applied. All algorithms for describing an EF equivalent were verified by computer simulations, showing a perfect correlation over a wide range of preset EFs. When applied to the patient studies only the non geometric methods revealed a good correlation with the ejection fraction (EF) obtained by RNV, and with the infarct size measured by SPECT.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗

PubMed1989

Reliability of simple cytological methods in brain tumour biopsy diagnosis.

Stereotactic procedures in brain tumour diagnosis and therapy are used increasingly because small lesions are more frequently detected and methods of interstitial irradiation are gaining wide acceptance among neurosurgeons. The diagnosis of underlying pathological processes has to be performed from very small tissue samples. The method of smear and/or squash preparations therefore has long been used by neurosurgeons. Neuropathologists, formerly reluctant, are becoming more and more enthusiastic over this simple and elegant method. Since the diagnostic reliability in such small samples is questioned, we have undertaken to analyse 200 open tumour biopsies in a comparative investigation: the diagnosis from smear preparation on the one hand has been performed without knowledge of the lesion, and on the other hand the remaining material was submitted to the whole pattern of diagnostic methods including frozen sections, paraffin sections with special staining, immunohistochemistry, electron microscopy and tissue culture. Diagnostic reliability was estimated in a four step procedure: Is there tumour or not--is there neuroepithelial newgrowth or metastasis--what kind of tumour is it--has the degree of malignancy--according to the criteria of the WHO--been estimated correctly? The overall diagnostic reliability in our material is about 75%. This is less than the diagnostic reliability of other methods, mostly due to the lack of histologic "architecture" criteria in evaluating the cytological biopsies.

Adolescent↗

PubMed1988

The Schilling test cannot be replaced by an absorption test with unlabeled vitamin B12.

It was the purpose of this study to evaluate the diagnostic usefulness of an oral absorption test using nonlabeled Vit B12 suggested by a commercial distributor as an alternative for the more expensive Schilling test (ST). Plasma levels of Vit B12 were measured with a commercial kit before and 4 h after oral administration of 1 mg Vit B12 in 32 normals, in 16 patients with normal ST, and in 14 patients with abnormal ST for determination of sensitivity and specificity with the ST as golden standard. In normals, a mean of 767 +/- 404 pg/ml before and 1096 +/- 776 pg/ml after oral Vit B12 with a mean increase of 331 +/- 453 pg/ml was measured. Because of the obvious large variation, no meaningful range for normal absorption could be established. In the two patient subsets, there was no Gaussian distribution of the results, with a meridian of Vit B12 increase after absorption of 142 pg/ml, range 27-2668 pg/ml, in the group with normal ST and a meridian of 244 pg/ml ranging from 40 to 2453 pg/ml in the group with abnormal ST. Statistical nonparametric analysis did not reveal any difference between the two groups. Assuming a minimum required increase of 100 pg/ml, as suggested by the kit distributor, a sensitivity of only 27% and a specificity of 75% was obtained.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1988

Radionuclide ventriculography (equilibrium gated blood pool scanning)--its present clinical position and recent developments.

Myocardial scanning (MS) and radionuclide ventriculography (RNV) are the foundation of nuclear cardiology. These procedures aim in two completely different directions: RNV tries to image heart motion, that is, mechanical (pump) function, and therefore belongs to the group of first-order functional imaging (FI, imaging mechanical function), whereas MS is based on myocardial metabolism, and therefore can be attributed to third-order functional imaging (metabolism). This statement is relevant for the assessment of the clinical position of RNV: Third-order (metabolism) functional imaging is the domain of nuclear medicine (NM), whereas first-order FI has to face the competition of alternative noninvasive procedures such as ultrasound (US), digital subtraction angiography (DSA), computer tomography (CT), and nuclear magnetic resonance (NMR). The domain of RNV includes stages two (acute infarction) and three (postinfarction period) of coronary arterial disease (CAD). The advantageous combination of quantitative data on global, left ventricular (LV) function and imaging of regional motion ensures the superiority of RNV over US. However, RNV is inferior to MS in physical examinations in the preinfarction stage of CAD, whereas US is clearly inferior to both NM procedures. Recent progress could be attained by gated SPECT (GASPECT). A proposal is presented for simplification of this time-consuming procedure. Technetium-labeled isonitriles offer the chance for the combination of "perfusion-motion" imaging of the myocardium. However, even standard RNV offers new possibilities. The multitude of parameters produced by quantitation has not yet been exploited completely. This can be done by discriminant analysis. The computer finds out an optimal subset from the whole set of parameters for the solution of a significant clinical problem. The software "learns" to find the "label" of a special pathognomonic entity. This computer work is supported by a relational data bank (Oracle) and an optical disk. Two examples for the effectiveness of the computer in problem solving are presented. It is concluded that RNV, even in the very competitive class of first-order functional imaging, enjoys a preferred position. The future indeed seems brighter because labeled isonitriles offer the chance for the combination of perfusion-motion imaging of the myocardium.

Coronary Disease↗

PubMed1988

Differentiation between infarction and cardiomyopathy in left bundle branch block by parametric radionuclide imaging.

In LBBB the diagnosis of the underlying disease, i.e. infarction (MI) or cardiomyopathy (CMP), is still a challenge. In this study, the usefulness of radionuclide ventriculography (RNV) for solving this problem noninvasively was tested. The hypothesis was that quantitation of the space-time sequence of left ventricular (LV) contraction by Fourier analysis may differentiate among MI, CMP, and LBBB-specific wall motion abnormalities (WMA). Forty-seven patients (pts) with LBBB were divided into 3 groups: 1) 20 pts with MI, 2) 7 pts with CMP, 3) 20 pts without MI or CMP. Regional parametric amplitude and phase data of eight LV sectors were calculated and expressed in standard deviation units (SDU) of normal. Out of the many regional data only the values of the mean amplitude and the standard deviation of the mean phase shift showed high discriminative power for separating the three groups, with an average squared canonic correlation of 0.5 and a Wilks lambda of 0.22, respectively. In other words, 17 of 20 pts in group 1, 6 of 7 pts in group 2, and 19 of 20 pts in group 3 were truly diagnosed by RNV alone. Such a separation also seems reasonable physiologically, since the mean amplitude reflects global left ventricular function and standard deviation of phase is a measure of time homogeneity of contraction. Furthermore, there was a significant septal phase delay of -4.92 +/- 5.3 SDU in 15 pts with septal MI compared to group 3 pts, who had a subtle premature septal motion of +0.75 +/- 2.64 SDU, whereas the septal amplitude was not different and slightly decreased in both.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1987

Quantitative bone scintigraphy in patients with hyperparathyroidism.

Laboratory tests, including the determination of parathormone in serum, and x-ray examinations are often of limited value in diagnosing hyperparathyroidism (HPT). In this study, bone scintigraphy was carried out in 15 patients with proven HPT (primary and secondary in patients with chronic renal disease) and 25 normal subjects, to evaluate quantitatively increased bone metabolism. The count density ratios bone to soft tissue (D/S-index) were calculated. In normal, this D/S index averaged 3.66 +/- 0.94 and was significantly (p less than 0.001) different to that of HPT-patients averaging 6.37 +/- 1.64. The quantitative evaluation shows a sensitivity of 73%, a specificity of 100% and an accuracy of 90% for detecting HPT (based on the sample values). Discriminant analysis can be applied to calculate the probability of the presence of HPT (primary and secondary) as a function of the measured D/S index.

Bone Diseases, Metabolic↗

PubMed1986

Chemotherapy in intracerebrally transplanted tumors induced with transplacental administration of ethylnitrosourea in rats.

Four tumors of the spinal cord were induced with ethylnitrosourea in rats by transplacental administration and transplanted into the brains of animals of the same strain. One of these intracerebrally grafted tumor lines (G-XIII) was followed up over the first 10 passages and treated with CCNU and other alkylating drugs. The results were compared with findings in an earlier established line (G-XII) in passage 12 and 59, which in the first instance was sensitive to CCNU. The CCNU application prolonged survival in treated animals in various treatment schedules in the first 10 intracerebrally grafted generations of the tumor up to 59%. Induction times of tumors became increasingly shorter. The susceptibility of early passages was similar in both lines. Its loss in late passages went together with diffuse growth of the tumor and reticulin fiber production. In addition, glial fibrillary acid protein expression and formation of intermediate filaments in perivascular tumor cells was lost.

Animals↗

PubMed1981

[End-diastolic volumes of the left ventricle in computer tomography in comparison to heart catheter ventriculography].

In 47 patients the authors calculated the volume at the end of a diastole according to both the cardiac catheter ventriculogram and the CT ventriculogram, comparing the results obtained with each of these methods. A linear regression was found. The correlation coefficient was approximately r = 0,96; n = 47. Cardiological examination revealed that of the examined patients (including the cardiac catheter finding) 18 patients had coronary heart disease, whereas 9 had cardiomyopathy, 6 arterial hypertension, 9 had various cardiac abnormalities and 5 did not show any organically manifest heart disease. The article discusses CT determination of the volume at the end of the ventricular diastole, and discusses the results.

Cardiac Catheterization↗

PubMedDate not supplied

Effect of humidity on infection of turkeys with Alcaligenes faecalis.

Turkeys maintained at 75% to 80% relative humidity were more adversely affected by Alcaligenes faecalis infection than turkeys maintained at 20 to 35% relative humidity. Alcaligenes faecalis was reisolated earlier and more often from turkeys maintained at the higher humidity. Clinically, the turkeys maintained at high humidity exhibited both sinusitis and conjunctivitis earlier than the turkeys at low humidity. In both groups, antibody titers as determined by a microagglutination test developed by 2 weeks postinoculation and started to decline after the third week, lymphocytosis was demonstrated at 1 week postinoculation, and a lymphopenia developed at 5 weeks postinoculation.

Agglutination Tests↗