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Biomedical subjects

M Skalej

Publications and source records attributed to M Skalej.

65 records · Page 4Linked to original sources
PubMed1988

[Optimized study technic in meniscopathies by NMR tomographic 3D imaging at 1.5 tesla].

Traumatic and degenerative changes in the meniscus can be demonstrated well by MRT, but the small size and complex anatomical structure of the menisci present practical problems. A correct understanding is only possible by images in several planes and good resolution, making the examination a lengthy procedure. A technique is therefore described using 3-D images and reconstruction of high-resolution films, which allows rapid examination of the menisci in optimal planes.

Cartilage Diseases↗
PubMed1988

[Technics of secondary reconstruction of planar images from magnetic resonance tomographic 3D data sets].

Description of a method to reconstruct planar images from MRT 3D data sets. These images can be of varying orientation. Reconstruction requires a computer and the control panel of a normal magnetic resonance tomography equipment. Calculation of reconstruction is done in a few minutes. Patients can be examined parallel to this without difficulty. The method yields in a much shorter time than before images with a definitely higher resolution than by the conventional technique.

Humans↗
PubMed1985

[T2-analysis of normal and pathological structures of the head].

Analyses of T2 values (spin-spin relaxation time constant) in magnetic resonance tomography were carried out in 29 patients with brain tumours. 21 of these had tumours of the glioma group (17 astrocytomas WHO I-III and oligoastrocytomas, 4 glioblastomas). Measurements were effected both pixel by pixel and according to relevant ROI (regions of interest). Although the measurements yielded a T2 value which was typical of the disease, it was individually difficult to effect proper grading on account of the scatter occurring from case to case. Markedly more relevant information was obtained by the introduction of profile measurements in T2 images. The relation between T2 profile and histology of the gliomas permits rough grading between more or less differentiated gliomas.

Adolescent↗
PubMedDate not supplied

Reliability and exactness of MRI-based volumetry: a phantom study.

This study investigated the influence of slice thickness, section orientation, contrast, shape, and sequence type on the exactness of MRI-based volumetry. Ni-doped agarose gel phantoms (4 to 46 ml) were scanned with a T1-weighted three-dimensional Fourier transform (FT) fast low-angle shot (FLASH) and a multiecho two-dimensional FT-Turbo spin-echo (SE) sequence. After segmentation with a three-dimensional region-growing algorithm, the geometric volume was measured considering the partial volume effect. The variability coefficient (Pearson) was .7%. The volumetric error increased with slice thickness, depending on the size and form of the object. Cross sections resulted in smaller error than longitudinal sections (finger-shaped phantoms, nonisotropic image data). Three-dimensional FT imaging. Results of slice thickness and section orientation experiments can be explained by the partial volume effect Higher errors in two-dimensional FT imaging were caused by object movements between two interleaved acquisitions. The study shows a considerable influence of the imaging parameters on the exactness, which depends on size and form of the structure of interest.

Algorithms↗
PubMedDate not supplied

Medical workstations for applied imaging and graphics research.

We present a medical workstation for the efficient implementation of research ideas related to image processing and computer graphics. Based on standard hardware platforms the software system encompasses two major components: A turnkey application system provides a functionally kernel for a broad community of clinical users working with digital imaging devices, including methods of noise suppression, interactive and automatic segmentation, 3D surface reconstruction and multi-modal registration. A development toolbox allows new algorithms and applications to be efficiently implemented and consistently integrated with the common framework of the turnkey system. The platform is based on an elaborate object class structure describing objects for image processing, computer graphics, study handling and user interface control. Thus expertise of computer scientists familiar with this application domain is brought into the hospital and can be readily used by clinical researchers.

Algorithms↗
PubMedDate not supplied

Patterns of age-related shrinkage in cerebellum and brainstem observed in vivo using three-dimensional MRI volumetry.

This study investigates the time course and regional differences in age-related volume loss in cerebellum and brainstem. Three-dimensional (3D) magnetic resonance imaging (MRI) volumetry was used to measure the volumes of 11 regions in the cerebellum and three regions in the brainstem in 48 healthy volunteers (age 19.8-73.1 years). Landmark-adjusted lattices were used to divide the cerebellum into three radial (lobules I-V = lingula/lobulus/culmen, lobules VI-VII = declive/folium/tuber, lobules VIII-X = pyramis/uvula/nodulus) and three transverse subdivisions (vermis, medial, lateral hemisphere). The radial sectors extended laterally throughout the vermis and the medial hemisphere. The brainstem was divided into midbrain, metencephalon (pons and tegmentum pontis) and medulla. Total cerebellar volume marginally declined with age using a linear regression model. An exponential model better described the age dependency of total cerebellar volume. The curve predicted that the volume remained stable until age 50 years and declined thereafter. Volume loss in the cerebellar vermis was striking. Shrinkage in the medial hemisphere was markedly less and only the inferior sector showed a trendwise negative association with age. The lateral hemisphere was not affected by age. No age effects were found for total brainstem volume, metencephalon and medulla. Only the mid-brain showed a trend for age-related shrinkage. The mediolateral gradient of decreasing age effects is similar to the histological pattern of alcoholic cerebellar atrophy (although our subjects were non-alcoholics according to DSM-IIIR criteria and laboratory data) suggesting that a common factor is involved in both processes. In search for a cause of the regional vulnerability, vascular, functional, structural and molecular/genetic factors may be considered.

Adult↗
PubMedDate not supplied

Semiautomatic evaluation procedures for quantitative CT of the lung.

Accuracy, reproducibility, and objectivity are important in quantitative assessment of lung density and structure by CT, and the measurement has to be carried out under tightly controlled conditions. We therefore employ respiratory gating at defined levels of inspiration for CT scanning. In the evaluation process, we found operator-induced errors of 2-6 HU standard deviation for the relatively simple task of global lung density estimates; in regional evaluations, they frequently exceeded 10 HU. We therefore developed semi-automated evaluation algorithms that isolate lung parenchyma by fast contour tracking and define subregions by shrinking, radial segmenting, and anteroposterior subdividing of the left and the right lung. Global and regional mean density values and histogram parameters were extracted. Based on our clinical studies, we estimate that an overall precision of better than 5% can be achieved in quantitative CT of the lung with cooperative patients.

Algorithms↗
PubMedDate not supplied

Subarachnoid hemorrhage due to septic embolic infarction in infective endocarditis.

During antibiotic therapy, a 56-year-old man with a Streptococcus bovis endocarditis developed an infarction of the right middle cerebral artery (MCA). Thirty hours after stroke onset, cranial computed tomography controls demonstrated a secondary subarachnoid hemorrhage, marked in the cistern of the right MCA. The latent period, cerebrospinal fluid analysis, angiographic and pathologic findings favor the assumption of a pyogenic arterial wall necrosis of the MCA due to a septic embolus. This pathomechanism of intracranial hemorrhage in infective endocarditis should be distinguished from a rupture of a mycotic aneurysm.

Cerebral Infarction↗
PubMedDate not supplied

A new endoscopic tool for the CRW Stereotactic System.

A new endoscopic tool designed and manufactured specifically for the CRW Stereotactic System (Radionics) has a high definition optical system, with a single optical and light cable long enough to leave the sterile operating area. The diameter of the scope is 4.5 mm, which is small enough to pass through the foramen of Monro in occlusive hydrocephalus. In addition, several multifunctional instruments are comparable with the endoscope.

Endoscopes↗