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Title: Quantitative measurement of intracranial deformation by magnetic resonance imaging
Author: Dai, Dongyong
Awarding Body: University of Glasgow
Current Institution: University of Glasgow
Date of Award: 1993
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A new quantitative framework for the objective assessment of the severity of intracranial deformation caused by brain tumours and how they respond to treatment is developed using shape analysis and feature extraction techniques. Conventional criteria for assessing the effects of a brain tumour by medical images are inaccurate and unsatisfactory because of problems defining tumour boundaries. Clinical response is relevant but is influenced by many factors and assessment is very subjective. In order to provide an objective and accurate assessment of the effects of brain tumours, a new and reliable method is introduced which quantifies the distortions and displacements of intracranial structures caused by brain tumours. The deformations of the hemispheres, the lateral ventricles and the falx cerebri are analysed in terms of size, position and shape in both individual sectional images and three dimensional MRI image data sets. 28 invariant attributes (size, rotation and position invariant), such as compactness, elongation, and central moments, are used to characterise the deformation of the hemispheres. The shape of the lateral ventricles is specified by Fourier descriptors, the method being used to match ventricular shapes even through they have different sizes and orientations. Using the Fourier descriptors, the shape of the lateral ventricles can be characterised by 6 invariant attributes. A new technique to describe deformation in the intracranial surfaces is presented. The technique is used specifically to analyse the deformation of the falx cerebri. The deformation of the falx cerebri is described by measuring the Gaussian curvature and the mean curvature. 28 attributes are obtained to quantify changes in the surface of the falx cerebri. Based on the measurements of the hemispheres, the lateral ventricles and the falx cerebri from 15 volunteers and 28 patients with intracranial deformation and combining all the 62 invariant attributes using data reduction techniques (the Karhunen-Loeve transform), three criteria (the decision rules) are established to classify the normal and abnormal intracranial structures. A scale for assessing the severity of intracranial deformation and a scale for assessing the effects of therapy also are established. The criteria and scales are applied in a blinded prospective manner to a further group of patients. The results reveal some important relationships between an intracranial deformation and its effects. For example, all studied patients who initially had a larger severity scale (SSID >5), with one exception, died within 8 months no matter how great the decrease of the deformation following treatment. The quantitative assessments are compared with clinical assessments for the same group of patients, and results show that the quantitative approach is more objective and accurate. The quantitative framework provides an objective and accurate index of intracranial deformation and may provide a sensitive and relevant basis for clinical decision making.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available