Biomedical subjects

A Heinzel

Publications and source records attributed to A Heinzel.

3 recordsLinked to original sources

PubMed2001

Materials for fuel-cell technologies.

Fuel cells convert chemical energy directly into electrical energy with high efficiency and low emission of pollutants. However, before fuel-cell technology can gain a significant share of the electrical power market, important issues have to be addressed. These issues include optimal choice of fuel, and the development of alternative materials in the fuel-cell stack. Present fuel-cell prototypes often use materials selected more than 25 years ago. Commercialization aspects, including cost and durability, have revealed inadequacies in some of these materials. Here we summarize recent progress in the search and development of innovative alternative materials.

Journal Article↗

PubMed1999

Influence of patient position in myocardial SPECT on the diagnosis of CHD.

AIM: Of the study was to show that changing patient position from supine to prone results in improved specificity of myocardial SPECT (MS). METHODS: We examined the influence of patient position in MS on the diagnosis of coronary heart disease (CHD) in 151 patients. By using a Tc-99m-labeled compound (Tetrofosmin, Myoview, Nycomed, Amersham) examinations could be performed in supine and prone position within 35 minutes. Examinations were performed as a two-day stress-rest protocol with one gamma camera head and 180 degrees rotation without absorption correction. RESULTS: Semi-quantitative patient and heart phantom data show similar values for anterior and inferior wall in prone position in contrast to a lower count ratio of inferior to anterior wall in supine position. This demonstrates the importance of patient position with respect to artifacts specificity. Changing patient position from supine to prone mainly improves diagnostic specificity for CHD in the inferior wall in men (from 58% to 90%) and in the anterior wall in women (from 80% to 93%). Sensitivity is the same for both techniques. CONCLUSION: Changing patient position from supine to prone significantly improves diagnostic specificity while sensitivity remains unchanged.

Adipose Tissue↗

PubMed1976

[Liver metastases: diagnostic value of blood tests, scintiscanning, and laparoscopy (author's transl)].

In 90 patients with known extra-hepatic malignancy the liver was examined for metastases. The diagnostic value of clinical information, blood examinations, 99mTc scintiscan, and laparoscopy for the diagnosis of the liver metastases was evaluated. Clinical data (age, sex, time since onset of symptoms and localisation of primary tumor) are of no diagnostic value. The most reliable blood tests are alkaline phosphatase (AP) and GOT. The probability of liver metastastases rises with increasingly abnormal values of AP and GOT. However, the probability is not much greater in cases with highly abnormal values than in cases with only moderate elevation of AP and GOT. Diagnostic accuracy of AP is optimal by using a cutoff point of 76 U/l (sensitivity 79%, specificity 64%). Bilirubin, prothrombin time, haemoglobin and blood sedimentation rate are of very little value. Combinations of AP with these blood tests does not improve diagnostic accuracy. Therefore, it is not useful to determine more blood tests than AP alone. Informed reading of liver scans has a specificity of 75% and a sensitivity of 91%. Blind reading of scans has a sensitivity of 94% and a specificity of 95%. This diagnostic accuracy cannot be improved by additional blood tests. Laparscopy has a sensitivity of 85% and a specificity of 95%. Scanning and laparoscopy are complementary methods. When optimal diagnostic accuracy is required both methods should be used.

Adult↗