Biomedical subjects

K Wentz

Publications and source records attributed to K Wentz.

6 recordsLinked to original sources

PubMed1996

MRI-guided endoscopy in the brain: a feasability study.

For neuronavigation in neuroendoscopy conventional navigation systems cannot exclude tissue movements caused by loss of cerebrospinal fluid (CSF). Open MRI can serve as a real-time navigation system if special conditions of endoscopic instruments and equipment are followed. We adapted an endoscopic system to the MRI and installed a miniaturized laser guidance system to project the central transaxial and coronal planes onto the phantom. A human cadaveric model was examined with a flexible microendoscope marked with a titanium wire inside the open magnet. The procedures were guided by gradient echo sequences refreshing the image every 4.5 seconds to control position of the endoscope. Endoscopic and corresponding MRI-findings are presented. Results and technical conditions are discussed.

Artifacts↗

PubMed1995

Use of ultrafast computed tomography in dental surgery: a case report.

A case of a transdental fixation planned on the basis of ultrafast computed tomography is reported. This method allows to gain an insight in the osseous structures required for the operative procedure. Ultrafast computed tomography is superior to the conventional radiographs in obtaining accurate information about the vertical bone supply and the extension of the facial osseous sinus wall. A set of axial CT-images with an extension of 3 mm was acquired in the region of the alveolar bone. By means of frontal reconstructions and data processing methods the thickness of the bone layer in transverse direction was accurately determined. The calculated bone thickness allowed to anchor a transdental self-tapping titanium screw.

Adult↗

PubMed1993

[Magnetic resonance tomography in data collection in biomechanics].

Invasive measurement of internal loads is either not possible at all, or is extremely difficult. A non-invasive method for use in the clinical setting might be the computer-aided simulation of a mechanical model. All the geometrical data required can be obtained, at a level of accuracy not previously attainable, with the aid of magnetic resonance imaging.

Biomechanical Phenomena↗

PubMed1991

[Multilocular angiosarcoma with involvement of the heart].

A thyroid tumour, initially diagnosed as an anaplastic carcinoma of the thyroid, was removed in a 66-year-old woman. Further examination, other than ultrasonography of the abdomen (normal), were refused, 26 months later a painful swelling was noted in the right buttock: a fist-sized haematoma, without evidence of malignancy was removed at another hospital. Computed tomography revealed a cystic tumour in the left upper abdomen, about 8 x 11 cm, not clearly related to any organ. Echocardiography, performed because of atrial fibrillation, demonstrated a space-occupying lesion, 42 x 38 mm, in the left atrium with central necroses and originating broad-based from the interatrial septum and the aortic root. The retroperitoneal upper-abdominal tumour encircling the root of the aorta and a gluteal tumour in the area of the previous haematoma could not be completely removed. Histologically they and the previously removed (and again examined) thyroid tumour were angiosarcomas. Removal of the atrial tumour was not attempted. Six months later it had penetrated the entire atrial septum and grown into the right atrium. The patient had lost 25 kg and three months later died of respiratory failure. Autopsy was refused. The findings suggest a left-atrial angiosarcoma which may well have been the primary tumour site. In case of angiosarcomatous tumours echocardiography should be performed as a staging examination.

Aged↗

PubMed1989

Ten-year study of pediatric drownings and near-drownings in King County, Washington: lessons in injury prevention.

The factors associated with submersion events among less than 20-year-old persons that occurred in King County from 1974 to 1983 were studied to focus prevention efforts. Near-drowning (n = 103) and drowning (n = 96) victims were identified from medical examiners' reports, paramedics' reports, and hospital discharge registers. Annual incidence was 5.5; the mortality rate was 2.6 per 100,000 children. Although preschool-aged children had the largest incidence (12.8), followed by older adolescents (4.9), adolescents had the largest case fatality rate, 77%. Lake and river victims had the largest incidence, mortality, and case fatality rate; swimming pools, the smallest case fatality rate (25%). A total of 89% of all victims had absent or no supervision; victims supervised by lifeguards had a 42% case fatality rate. Prior seizures were part of the history of 7.5% of all victims; 25% of fatal submersions by adolescents were associated with alcohol. Bathtub submersions were associated with child abuse in three of 16 preschool-aged children and epilepsy in four of five older children. Certain age groups and sites combined had the greatest incidence: preschool-aged children in swimming pools, infants in bathtubs, teenagers in lakes and rivers. Incidence decreased in public and semipublic pools coincident with fencing regulations. These findings suggest prevention strategies: extending fencing requirements to private pools, discouraging alcohol consumption during water sports, changing bathing practices of epileptics, and improving lifeguard efficacy.

Adolescent↗

PubMed1981

Experimental studies on microcirculation under normobaric hyperoxia using the microspheres method.

The perfusion of the heart, kidneys, adrenals, stomach, intestines, brain and musculature under normobaric hyperoxia was studied in anaesthetized mini pigs using radioactively labelled microspheres. After a 2-hour control period using room air, the influence of normobaric hyperoxia on the perfusion of the organs was measured at 2-hour intervals. A significant increase in the perfusion of tissue was found in the kidneys, adrenals, gastro-intestinal tract and brain after 4-6 hours of exposure. No change in perfusion could be demonstrated for the myocardium. Values for the skeletal musculature (diaphragm and musculus psoas) were widely scattered, but an increase could be suspected. The increase in tissue perfusion at constant blood pressure and pulse rate must be interpreted as an expression of vasodilation. These results are contrary to the majority of statements in the literature, which mainly report vasoconstriction under normobaric hyperoxia.

Adrenal Glands↗