PubMed Health⌕ Search

Biomedical subjects

R Krasny

Publications and source records attributed to R Krasny.

13 recordsLinked to original sources
PubMed1993

A new holder and surface MRI coil for the examination of the newborn infant hip.

A special holder was developed for examination of the infant hip joint using MRI. This holder allows the infant hip joint to be examined both in a neutral position and in various defined functional positions. A special integrated surface coil, also developed for this purpose, provides the high spatial resolution required for assessment of the fine joint structures. Thirty infants were examined and the new device has proved useful in advanced hip dysplasia, therapy-resistant subluxation and luxation, and for operative therapy planning (reconstruction of the acetabular roof, redirectional osteotomies). Interpretation errors due to misprojection can be eliminated to a large extent since the holder allows standardized and reproducible positioning.

Child, Preschool↗
PubMed1992

[Stereolithographic model construction based on 3-dimensional reconstructed CT sectional image sequences].

Techniques for 3D reconstruction of medical objects and production of models by CAM have been markedly improved. Milling tools have limited abilities to reproduce complex anatomical structures. Even if 5-axis milling systems are used, the problem of collisions between tool and object is not yet under control. An alternative is offered here by stereolithography. We performed a computed tomography (Somatom DRH, Siemens/Erlangen) of a child with extensive maxillary bone defect after surgical treatment of a congenital tumour. The bone defect was covered by an alloplastic implant. 3D reconstructions were performed by the aid of a conventional personal computer. Generated 3D volume data sets were transferred to a stereolithography system (3D Systems GmbH, Darmstadt/FRG). The produced model revealed high accuracy of the anatomical structures. Intraoperatively, the alloplastic prosthesis was removed and the shape of the new implant could be designed using the stereolithographic model.

Child↗
PubMed1991

MR-anatomy of infants hip: comparison to anatomical preparations.

The correlation between anatomical preparations and MRI images of the most important structures of newborn hips in coronal and axial orientation was performed in 18 post mortem babies. T1-weighted images present a good differentiation between cartilage, bone, ligaments and surrounding soft tissues. Coronal images give the best opportunity to study the clinically important structures of the roof of acetabulum including the labrum and the ground of the acetabulum. The latter is shown in a more detailed way by MRI than by sonography. Axial images allow additional examinations of the ventral and dorsal parts of the joint. By using both coronal and axial images the exact determination of the centering of the femur head in the hip joint is possible.

Acetabulum↗
PubMed1991

[CO2 angiography: studies of gas filling of vessels and assessing the factors of influence on the injection process with a cardiovascular model].

Following the advent of digital subtraction angiography (DSA), carbon dioxide gas has become a useful contrast agent for arterial angiography. Former manual injection methods had precluded accurate dosing and reproducibility. An original gas injector was therefore developed and tested in a circulatory system model. This permitted an accurate evaluation of vascular gas-filling. it also proved possible to measure the injection parameters taking different influencing factors into account. It was shown that vessels up to 10 mm in diameter are virtually completely filled with gas. In vessels larger than 10 mm in diameter, a residual fluid level remains, which in turn reduces the possibility for complete vessel imaging. The injection flow is dependent primarily on the vascular circulation rate, vessel diameter and the inclination of the vessel. With respect to other factors examined, neither catheter size, number of holes nor the direction of the injection have any relevant influence.

Angiography, Digital Subtraction↗
PubMed1990

[Arterial DSA using CO2 as a contrast medium: improvement of picture quality using a novel gas injector in an animal experiment].

The use of CO2 as contrast medium for DSA requires accurate and reproducible doses of the gas. This cannot be achieved by manual injection or by using injectors designed for liquid contrast media. For this reason a new gas injector has been developed which meets these requirements despite the compressibility of gas. The suitability and ease of use of the injector has been confirmed in experiments on 15 dogs. At the same time optimal volumes for different vessels with varying diameters have been determined. It has been shown that the injection parameters (gas speed and volume) in small vessels up 10 mm. diameter are not critical. With increasing vessel diameter accurate gas dose becomes important in order to perform optimal angiograms safely.

Angiography, Digital Subtraction↗
PubMed1990

[CO2 angiography: development and trial of an animal experimental gas dosage device].

Gas have long been used in radiological examinations, in particular for the diagnostic evaluation of gastrointestinal diseases. However, not until the introduction of digital subtraction angiography was carbon dioxide also used with success for angiography of arteries. In order to advice exact and reproducible dosage of the gas with freely selectable injection parameters, a carbon dioxide gas metering device was developed. The principle of gas metering is based on the measurement of the pressure gradient of the gas across a defined pneumatic resistance. The gas metering devices was tested in 15 animal experiments to produce survey and selective angiograms.

Angiography, Digital Subtraction↗
PubMed1988

[Hyaline articular cartilage in MR tomography of the knee joint at 1.5 T].

MRI is a new method for imaging the knee joint. There is still some uncertainty regarding the extent and the signal from hyaline articular cartilage. MRI images were therefore compared with anatomical and histological preparations of the knee joint and the difference between MRI and the anatomical sections have been determined. It was shown that demonstration of hyaline cartilage was obscured by an artifact. Further investigations are required to determine the cause of this artifact and to achieve accurate imaging of hyaline cartilage by MRI.

Cadaver↗
PubMed1988

[Paget's disease of bone: MR characteristics at 1.5 T].

Thirteen patients with confirmed Paget's disease were examined using a 1.5 T MR tomograph. Five patients had polyostotic and eight patients monostotic forms of the disease. The results of these MR examinations were compared with the results of MR examinations performed on patients with osseous changes of different origin (metastases of breast cancer and prostate cancer, osteomyelitis, bone marrow infiltration due to acute lymphatic leukaemia and plasmocytoma). MR tomography permits evaluation of bone marrow space, osseous changes, and the surrounding soft tissue. Areas of sclerotic bone, thickened corticalis and bands of connective tissue in the marrow space were recognised as structures with no signal in T1- and T2-weighted images. The red and yellow marrows showed normal signal intensity patterns, although they were often reduced in size.

Aged↗
PubMed1987

[Initial experiences with CO2 as a gaseous contrast medium in digital subtraction angiography].

Electronic contrast enhancement allows the use of CO2 as a contrast material for studying the vascular system with DSA. Its use, safety and the information provided were studied in 40 patients and in 5 animal experiments and the results were compared with iodine-containing contrast media. The available results indicate that CO2 is a safe negative contrast medium for peripheral arteriography and that it provides angiograms with a picture quality comparable to those of iodinated contrast media in the extremities. The method can therefore be used to advantage in patients with allergies to the iodinated contrast media and in patients with renal failure.

Angiography↗
PubMedDate not supplied

Biomechanics of valvular plane displacement of the heart.

There has been no consensus concerning the particular movement of the valvular plane of the heart (VPM). As shown in this study involving a mathematical model based upon the momentum equation and experiments on a specially designed artificial heart pump, the VPM not only results from the shortening of the heart, but also from blood flow within the heart and large blood vessels, from the forces caused by the muscle movements, and from the elastic properties of the heart's suspension. The results of the calculations and the experiments confirm the effect of the so-called valve mechanism and its influence on the economic beating action of the heart.

Aortic Valve↗