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Biomedical subjects

D Wicks

Publications and source records attributed to D Wicks.

7 recordsLinked to original sources
PubMed1991

Major differences in the dynamics of primary and secondary progressive multiple sclerosis.

In patients with primary and secondary progressive multiple sclerosis (MS), major differences in the pattern and extent of abnormality on cerebral magnetic resonance imaging (MRI) between the two groups have recently been demonstrated. In the present study, 24 patients, matched for age, sex, duration of disease, and disability, had serial gadolinium diethylenetriaminepentaacetic acid-enhanced MRI over a 6-month period. The 12 patients in the secondary progressive group had a total of 109 new lesions over this time (18.2 lesions per patient per year) and 87% of these enhanced. Enhancement also occurred within and at the edge of preexisting lesions. In contrast, only 20 new lesions were seen in the primary progressive group (3.3 lesions per patient per year) and only one of these enhanced. There was no difference in the degree of clinical deterioration between the two groups over the 6-month period. These findings may indicate a difference in the dynamics of disease activity between the two forms of progressive MS, particularly in relation to the inflammatory component of the lesions, and have important implications for the selection of patients and the monitoring of disease activity in therapeutic trials.

Adult↗
PubMed1990

Implications of mainstream classrooms for adolescents with spina bifida.

This study examined the social and academic implications of mainstream, mainstream and special (combined) or special-class education for 31 adolescents with spina bifida, and for their primary caretakers. The Peabody Picture Vocabulary Test and the UCLA Loneliness Scale (adolescents) and the Personality Inventory for Children (caretakers) were administered. Adolescents in mainstream classes had the most normal scores for academic and social skills, those in combined classes had intermediate scores and those in special classes had the lowest scores. Paradoxically, adolescents in combined classes reported the least loneliness. This study suggests that even among students with relatively good social skills, mainstream placement is associated with greater subjective experience of loneliness than is combined placement.

Adolescent↗
PubMed1986

Volume flow measurement of pulsatile flow by digitised cine angiography.

The validation, by phantom experiments, of a method of measuring volumetric, pulsatile blood flow in vessels of about 4 mm calibre is described. 'Instantaneous' as well as integrated flow is obtained from cine angiograms by digitisation of the images and densitometric analysis in an advanced computer vision analysis system. From 48 frames per second cine, pulsatile flow at any moment between 0 and about 400 ml/min was calculated within about 10 per cent of the electromagnetic flow meter reading. Further improvement is expected. It is proposed to advance to 3D and have the methodology available for clinical use in due course.

Angiography, Digital Subtraction↗
PubMedDate not supplied

Using greyscale voxel databases for improved shading and segmentation.

Many different data representations are possible in computer graphics. Originally, in the medical field, simplified methods were used in order to reduce computation times on small computer systems. Currently a wider range of techniques is developing as costs of hardware continue to fall. In this paper we review a number of possible representations and explain the advantage of one that is greyscale, volumetric and random access. Different segmentation techniques can be used, as well as shading algorithms that give greatly improved appearances. A quantitative analysis of shading methods is derived in terms of the degree of sampling of the 'pseudo-normal' vectors that estimate the direction of the tangent to a surface. The application to a study of multiple sclerosis lesions in the brain using nuclear magnetic resonance data is shown.

Brain↗