Biomedical subjects

H Frey

Publications and source records attributed to H Frey.

203 records · Page 12Linked to original sources

PubMedDate not supplied

Toxicity of X-ray contrast media in cell cultures.

Monolayer cell culture techniques for neuronal and glial cells and fibroblasts were used for the investigation of the direct toxicity of x-ray contrast media. The effect of various concentrations of sodium diatrizoate, methylglucamine salts of diatrizoate, iothalamate, iodamide, metrizamide, iocarmate, ioserate, and ioglycamate were studied. The intravenous biliary contrast medium--ioglycamate--was most toxic to all cell types. All the contrast media studied were somewhat toxic to neurons in the concentration of 50 mmol/l and showed variable glial toxicity. In equiosmolar concentrations the contrast media studied showed toxicity on neurons in the following order: iothalamate, diatrizoate, iodamide, ioserate, iocarmate, ioglycamate. Fresh metrizamide solution in equimolar concentrations showed the least toxic effects on neurons but interfered considerably with the growth and survival of glial cells. Metrizamide solution proved to be highly toxic to neurons when refrigerated for two weeks. Methylgucamine iocarmate produced a peculiar swelling of fibroblasts.

Cell Survival↗

PubMedDate not supplied

3D real-time imaging of the fetal heart.

OBJECTIVE: The aim of this study was to evaluate the clinical utility of a novel 3D scanner system for real-time 3D fetal echocardiography. METHOD: In a prospective study, 13 single, healthy 20- to 24-week-old fetuses were examined with conventional 2D and real-time 3D echocardiography. The visualization rates and imaging quality of standard cardiac views were compared between both methods. RESULTS: The visualization rates of standard cardiac planes were found to be slightly increased and more easily obtainable in 3D imaging whereas the image quality showed better results with conventional 2D echocardiography. CONCLUSION: Our data show that real-time 3D fetal echocardiography can be considered a useful tool in the evaluation of the fetal heart with the necessity for further refinement of the resolution quality

Echocardiography↗

PubMedDate not supplied

Applicability of semi-automatic segmentation for volumetric analysis of brain lesions.

This project involves the development of a fast semi-automatic segmentation procedure to make an accurate volumetric estimation of brain lesions. This method has been applied in the segmentation of demyelination plaques in Multiple Sclerosis (MS) and right cerebral hemispheric infarctions in patients with neglect. The developed segmentation method includes several image processing techniques, such as image enhancement, amplitude segmentation, and region growing. The entire program operates on a PC-based computer and applies graphical user interfaces. Twenty three patients with MS and 43 patients with right cerebral hemisphere infarctions were studied on a 0.5 T MRI unit. The MS plaques and cerebral infarctions were thereafter segmented. The volumetric accuracy of the program was demonstrated by segmenting Magnetic Resonance (MR) images of fluid filled syringes. The relative error of the total volume measurement based on the MR images of syringes was 1.5%. Also the repeatability test was carried out as inter-and intra-observer study in which MS plaques of six randomly selected patients were segmented. These tests indicated 7% variability in the inter-observer study and 4% variability in the intra-observer study. Average time used to segment and calculate the total plaque volumes for one patient was 10 min. This simple segmentation method can be utilized in the quantitation of anatomical structures, such as air cells in the sinonasal and temporal bone area, as well as in different pathological conditions, such as brain tumours, intracerebral haematomas and bony destructions.

Brain↗

PubMedDate not supplied

Sleep Expert--an intelligent medical decision support system for sleep disorders.

A new type of associative knowledge-based decision support system (Sleep Expert) for the diagnosis and classification of sleep disorders is described. Sleep Expert is based on the International Classification of Sleep Disorders (1990). The programming system used was KnowledgePro (Windows), a high-level language that integrates object-oriented programming, hypertext and expert system technologies. Sleep Expert is an interactive program composed of 288 separate integrated submodules and 264 text files. The program includes eight reasoning questions about symptoms setting the limits for the diagnosis subset. The user obtains a list of possible diagnoses on the screen where he/she can examine their criteria. The program has been written in such a form that the user can freely associate and can move forwards and backwards. Detailed information is included in hypertext.

Diagnosis, Computer-Assisted↗

PubMedDate not supplied

Evaluation of Sleep Expert--a computer-aided decision support system for sleep disorders.

Sleep Expert--a medical decision support system--is a prototype program, with knowledge based on the International Classification of Sleep Disorders (1990). The goal of this project was to evaluate Sleep Expert. In the evaluation project the knowledge of the program was first validated. Three physicians, experts in sleep disorders, were asked to choose 10 typical patient cases with sleep disorders, and to write a description. They also made a diagnosis for each case. Next, each expert made a diagnosis of the cases supplied by the other experts. They were not given the original diagnosis. The 'right diagnosis' (so-called majority agreement) was determined from the three diagnoses. Then the diagnosis of each expert was compared with the 'right diagnosis'. Two physicians, not experts in sleep disorders, were asked to make a diagnosis by using Sleep Expert. Compared to the 'right diagnosis' the diagnoses of each user (non-expert physician) were correct to 63 and 70% of cases, which is quite a good result, although it does not reach the level of the expert physicians (> or = 87%). The functionality of Sleep Expert was studied by using a limited inquiry. On the basis of the user inquiry Sleep Expert provided a useful clinical tool for non-experts.

Diagnosis, Computer-Assisted↗