Biomedical subjects

D Delaere

Publications and source records attributed to D Delaere.

4 recordsLinked to original sources

PubMed2000

Theoretical study of the structure-property relationship in phosphole monomers

Use of the DFT method with the B3LYP functional offers an efficient way for determining geometries of phosphole structures. It also provides inversion barriers in good agreement with experiment. The molecular orbital MP2 method is better suited to calculate the relative stability of the considered isomers. Combination of geometric (Julg index) and magnetic (NICS) criteria leads to an interesting approach to analyze the pi-electron delocalization and/or aromaticity in conjugated heterocyclic systems and can be used for investigation of much larger oligomers. It thus allows us to confirm that planarizing the phosphorus atom in phosphole monomers leads to a greater conjugation over the butadienic pi-system and that substituents, characterized by a strongly pronounced pi-system, exhibit a large extent of conjugation with the pi-diene moiety of the heterocyclic system. In push-pull systems such as 2-BH2-5-NH2-1H-phosphole, the electron delocalization along the pi-diene system is even more pronounced than in phospholes with strongly pronounced pi-systems. The employed approach is also used to analyze the relationship between electron conjugation and the phosphorus inversion barrier. More relevant for chemical applications is the result that the computational study provides a method of fine-tuning of phosphole building blocks, which may enable us to obtain higher pi-conjugation along the polymer backbone.

Journal Article↗

PubMed1997

Evaluation of manual vs semi-automated delineation of liver lesions on CT images.

In this paper we compare a semi-automated delineation method with totally manual delineation for area quantification, with respect to efficiency, quality, and intra- and interobserver variability. Liver lesions on 28 CT images were delineated by three observers, twice using completely manual delineation and twice using a semi-automated method. Quantitative comparisons were performed with respect to delineated area and time required for the delineation tasks. Subjective comparisons were performed with respect to efficiency and perceived quality of the semi-automated method. The areas obtained using semi-automated delineation were significantly smaller (11 %) than those obtained using totally manual delineation. Intraobserver and interobserver variability with the semi-automated method were approximately three times lower than with manual delineation. Efficiency of the semi-automated method was subjectively rated favorable, although further improvements are possible. With respect to quality, the semi-automated method was ranked better than the manual method in 73 % of cases.

Humans↗

PubMed1995

Experimental teleradiology. Novel telematics services using image processing, hypermedia and remote cooperation to improve image-based medical decision making.

We illustrate the possible impact of information technology on digital radiology using two pilot projects. The first aimed to improve the transfer of radiological information and the interaction between radiologist and referring physician, using hypermedia documents and hypermedia electronic mail. During a 12-month evaluation period, approximately 100 hypermedia reports were generated and distributed to hepatologists and neurosurgeons. The second project aimed to improve planning of orthopaedic surgery, using an image processing service for three-dimensional visualization and a conferencing system to support active cooperation. Over two months, 12 routine cases were reconstructed in three dimensions and conferencing was carried out between surgeons and radiologists in hospitals 15 km apart. Initial results were encouraging. Telematics may be valuable in reconciling the growing need for multidisciplinary cooperation with the growing geographical and organizational separation of different experts. We conclude that to benefit from information technology, the focus should not be on a direct translation of traditional working methods, but rather on possibilities that were not available in the film-based environment.

Belgium↗

PubMed1991

Knowledge-based system for the three-dimensional reconstruction of blood vessels from two angiographic projections.

A knowledge-based system for the three-dimensional reconstruction of blood vessels from wide-angle coronary and stereoscopic cerebral angiographic projections is developed. For the reconstruction of the coronary vessels, the left coronary artery (LCA) is automatically labelled on standard RAO and LAO projections, using anatomical models of the LCA. The labelling system succeeds in giving the most important coronary arteries a correct anatomical label. These labelling results enable us to find corresponding segments in both images. In the case of the reconstruction of the cerebral vessels however, such an anatomical model is clearly unavailable. To find corresponding segments, small-angle projections must be relied on, resulting in very similar images. Owing to the small angular separation between both projections, the three-dimensional reconstruction will be less accurate. Once the corresponding segments in both projections are obtained, the three-dimensional artery trajectory is reconstructed with dynamic programming techniques. The three-dimensional reconstructed coronary vessels are also used for an automatic quantification of stenotic lesions.

Blood Vessels↗