Improved 3D MR Image Acquisition and Processing in Congenital Heart Disease

Congenital heart disease (CHD) is the most common type of birth defect, affecting about 1% of the population. MRI is an essential tool in the assessment of CHD, including diagnosis, intervention planning and follow-up. Three-dimensional MRI can provide particularly rich visualization and information. However, it is often complicated by long scan times, cardiorespiratory motion, injection of contrast agents, and complex and time-consuming postprocessing. This thesis comprises four pieces of work that attempt to respond to some of these challenges. The first piece of work aims to enable fast acquisition of 3D time-resolved cardiac imaging during free breathing. Rapid imaging was achieved using an efficient spiral sequence and a sparse parallel imaging reconstruction. The feasibility of this approach was demonstrated on a population of 10 patients with CHD, and areas of improvement were identified. The second piece of work is an integrated software tool designed to simplify and accelerate the development of machine learning (ML) applications in MRI research. It also exploits the strengths of recently developed ML libraries for efficient MR image reconstruction and processing. The third piece of work aims to reduce contrast dose in contrast-enhanced MR angiography (MRA). This would reduce risks and costs associated with contrast agents. A deep learning-based contrast enhancement technique was developed and shown to improve image quality in real low-dose MRA in a population of 40 children and adults with CHD. The fourth and final piece of work aims to simplify the creation of computational models for hemodynamic assessment of the great arteries. A deep learning technique for 3D segmentation of the aorta and the pulmonary arteries was developed and shown to enable accurate calculation of clinically relevant biomarkers in a population of 10 patients with CHD

A source modelling system and its use for uncertainty management

Human agents have to deal with a considerable amount of information from their environment and are also continuously faced with the need to take actions. As that information is largely of an uncertain nature, human agents have to decide whether, or how much, to believe individual pieces of information. To enable a reasoning system to deal in general with the demands of a real environment, and with information from human sources in particular, requires tools for uncertainty management and belief formation. This thesis presents a model for the management of uncertain information from human sources. Dealing, more specifically, with information which has been pre-processed by a natural language processor and transformed into an event-based representation, the model assesses information, forms beliefs and resolves conflicts between them in order to maintain a consistent world model. The approach is built on the fundamental principle that the uncertainty of information from people can, in the majority of situations, successfully be assessed through source models which record factors concerning the source's abilities and trustworthiness. These models are adjusted to reflect changes in the behaviour of the source. A mechanism is presented together with the underlying principles to reproduce such a behaviour. A high-level design is also given to make the proposed model reconstructible, and the successful operation of the model is demonstrated on two detailed examples

The commodification of health care in Kerala, South India: science, consumerism and markets

In India, alongside Information Technology, health care has become a leading sector in the country‘s development as a 'knowledge economy' (World Bank 2005). One of the major achievements and beacons of economic reform is the growth of some of the most technologically advanced hospitals in the world. This thesis examines the social processes shaping the expansion of the private health care system in the state of Kerala, South India, where large corporate hospitals and 'super-speciality' medicine have spread throughout urban and many rural areas. It explores the intersections between the local and the global, as the health system becomes the major driver of industrial development, unevenly linking the local health care system to the global marketplace for technologies, health care professionals and patients. It examines the three faces of the health care system in Kerala - as a knowledge industry and route to social mobility for the middle classes, in particular doctors and nurses; secondly, as a consumer economy, as people prioritise spending on health care and shop for treatment in the urban marketplace; and finally as a moral economy, as people develop high levels of dependency on doctors, hospitals and technologies in the hope of receiving good health care. The ethnography is set in Malabar, Northern Kerala, where the expansion of private health care has been financed by remittances from migration to the Arabian Gulf countries. The thesis examines the influence of migration and economic reforms on local ecologies of health and health care; the impact of the globalisation of trade in health services in the developing world; the relationship between the private health care system and the middle classes in South Asia; and the role of markets in the delivery of health services. Based on 18 months of participant observation across the urban and rural health care market with local communities of doctors and patients, it examines how doctors and patients adjust to a changing ecology and economy of health care

Illness representations, treatment beliefs and the relationship to self-care in heart failure

Purpose The purpose of this study was to explore the beliefs people with heart failure hold about their illness and its treatment and to determine any relationships between these beliefs and self-care using the Common Sense Model (CSM) of illness cognitions and behaviour as the theoretical framework (Leventhal et al, 1980). Methods Using a mixed methodology (Creswell and Plano Clark, 2007), findings from patient interviews were used to adapt the Revised Illness Perception Questionnaire (IPQ-R) (Moss-Morris et al, 2002) and the Beliefs about Medicines Questionnaire (BMQ) (Horne et al, 1999) in order to make them illness-specific. A questionnaire assessing self-care was developed based on the European Heart Failure Self-care Behaviour Scale (EHFScBS) (Jaarsma et al, 2003), the interview findings and a nominal group technique with specialist heart failure nurses. These questionnaires were used to determine beliefs and the relationship to behaviour in a cross-sectional survey of 169 patients with heart failure. Results A number of statistically significant correlations were found between beliefs and self-care. Most notably, perceived medication knowledge (r = 0.51, p ≤ 0.01), beliefs about the necessity of medication (r = 0.45, p ≤ 0.01) and illness coherence (r = 0.39, p ≤ 0.01). Multiple regression analysis revealed that 46% of the variance in self-care could be explained by illness representations and treatment beliefs (Adj. R2 = 0.46, F = 9.93, p = 0.00). Three factors were significant predictors of self-care - medication knowledge (β = 0.319, p = 0.003), a belief in the illness having serious consequences (β = 0.258, p = 0.008) and the impact of medication use on lifestyle (β = -0.231, p = 0.03). Discussion The exploration of illness representations revealed a realistic picture of heart failure with a cluster of beliefs around a chronic illness with serious consequences and a high number of symptoms. There was a strong belief in the necessity of medication but for some, medication use had a negative impact on daily life. Patients were confident in their knowledge of medication but this was reduced when family members took control of medication management. A number of beliefs were predictive of self-care, suggesting that interventions designed to maximise these beliefs and correct any misconceptions may enhance self-care and potentially improve clinical outcomes in this population

Non-Cardiac Chest Pain: the Role of Physical, Psychosocial, and Service-Related Factors in the Persistence of Pain and Health Service Use

Chest pain is one of the most frequent complaints in medical settings, yet more than half of cases have no detectable cause. Once a cardiac cause has been excluded, patients are typically discharged with a label of non-cardiac chest pain (NCCP). Patients with NCCP have been shown to have poor outcomes in terms of continued symptoms, distress, and continuing concern about heart disease. In addition, NCCP represents a significant burden to health services. The aetiology and management of NCCP is under-researched and poorly understood. This study sought to examine the predictors of persistent pain and health service use for patients in whom a cardiac diagnosis had been excluded. It also sought to explore how patients interpreted their symptoms in the context of normal test results, and the impact of their experiences with health services on these interpretations. A mixed-methods design was adopted. A prospective cohort study was initially conducted with 145 participants with chest pain who attended exercise stress testing and had normal test results. At one-year follow-up, 69% reported continued pain. In addition, nearly half of participants had returned to their general practitioner and one in ten had attended the emergency department for the investigation of chest pain. In logistic regression analyses, the variables heartburn, pain precipitated by movement, cardiac anxiety, illness perceptions, and lack of communication about test results were predictive of persistent chest pain. When participants with continued chest pain were categorised into persistent healthcare users and non-persistent healthcare users, these variables were predominantly associated with participants with persistent health service use for chest pain. In addition, a number of psychological variables including anxiety and depression distinguished the persistent service users. Employment appeared to be a protective factor against persistent pain and related service use. A small sample of participants from this cohort was interviewed in a qualitative study informed by the principles of Interpretative Phenomenological Analysis (IPA). Analysis revealed three predominant themes: 1) the disempowerment of normal test results; 2) limbo - the inner struggle of negating and relating to potential causes; and 3) the inadequacy of healthcare to validate and care for symptoms. The dynamic, complex process of interpreting symptoms and deciding whether to seek healthcare was illuminated. The results indicate that interventions targeting the assessment of a potential gastro-oesophageal or musculoskeletal cause and the reduction of cardiac anxiety are likely to improve outcomes in these patients. Improved communication with patients is also indicated. Psychological factors appear to drive persistent service use and interventions targeting these are likely to reduce medical costs. Patients with NCCP are not a homogenous patient group and an individualised, stepped-care approach to management appears to be warranted