Analysis of first pass myocardial perfusion imaging with magnetic resonance

Early diagnosis and localisation of myocardial perfusion defects is an important step in the treatment of coronary artery disease. Thus far, coronary angiography is the conventional standard investigation for patients with known or suspected coronary artery disease and it provides information about the presence and location of coronary stenoses. In recent years, the development of myocardial perfusion CMR has extended the role of MR in the evaluation of ischaemic heart disease beyond the situations where there have already been gross myocardial changes such as acute infarction or scarring. The ability to non-invasively evaluate cardiac perfusion abnormalities before pathologic effects occur, or as follow-up to therapy, is important to the management of patients with coronary artery disease. Whilst limited multi-slice 2D CMR perfusion studies are gaining increased clinical usage for quantifying gross ischaemic burden, research is now directed towards complete 3D coverage of the myocardium for accurate localisation of the extent of possible defects. In 3D myocardial perfusion imaging, a complete volumetric data set has to be acquired for each cardiac cycle in order to study the first pass of the contrast bolus. This normally requires a relatively large acquisition window within each cardiac cycle to ensure a comprehensive coverage of the myocardium and reasonably high resolution of the images. With multi-slice imaging, long axis cardiac motion during this large acquisition window can cause the myocardium imaged in different cross- sections to be mis-registered, i.e., some part of the myocardium may be imaged more than twice whereas other parts may be missed out completely. This type of mis-registration is difficult to correct for by using post-processing techniques. The purpose of this thesis is to investigate techniques for tracking through plane motion during 3D myocardial perfusion imaging, and a novel technique for extracting intrinsic relationships between 3D cardiac deformation due to respiration and multiple ID real-time measurable surface intensity traces is developed. Despite the fact that these surface intensity traces can be strongly coupled with each other but poorly correlated with respiratory induced cardiac deformation, we demonstrate how they can be used to accurately predict cardiac motion through the extraction of latent variables of both the input and output of the model. The proposed method allows cross-modality reconstruction of patient specific models for dense motion field prediction, which after initial modelling can be use in real-time prospective motion tracking or correction. In CMR, new imaging sequences have significantly reduced the acquisition window whilst maintaining the desired spatial resolution. Further improvements in perfusion imaging will require the application of parallel imaging techniques or making full use of the information content of the ¿-space data. With this thesis, we have proposed RR-UNFOLD and RR-RIGR for significantly reducing the amount of data that is required to reconstruct the perfusion image series. The methods use prospective diaphragmatic navigator echoes to ensure UNFOLD and RIGR are carried out on a series of images that are spatially registered. An adaptive real-time re-binning algorithm is developed for the creation of static image sub-series related to different levels of respiratory motion. Issues concerning temporal smoothing of tracer kinetic signals and residual motion artefact are discussed, and we have provided a critical comparison of the relative merit and potential pitfalls of the two techniques. In addition to the technical and theoretical descriptions of the new methods developed, we have also provided in this thesis a detailed literature review of the current state-of-the-art in myocardial perfusion imaging and some of the key technical challenges involved. Issues concerning the basic background of myocardial ischaemia and its functional significance are discussed. Practical solutions to motion tracking during imaging, predictive motion modelling, tracer kinetic modelling, RR-UNFOLD and RR-RIGR are discussed, all with validation using patient and normal subject data to demonstrate both the strength and potential clinical value of the proposed techniques.Open acces

Relationships between people with dementia and their carers

This thesis consists of three papers, a literature review, an empirical paper and a reflective paper. The literature review covers two distinct but interlinked areas of research: the impact of dementia on the quality of relationships, and the impact of relationship quality on the experience of living with dementia. The literature review clarifies the interactions between these factors by using a model to demonstrate the influence of relationship factors on the experience of living with dementia. Methodological issues and suggestions for future research are discussed, and the findings are summarized with particular reference to clinical implications. The empirical paper reports on a study of the awareness of carer distress in people with dementia. Ratings of carer psychological health were elicited from people with dementia and from the carers themselves as a pair. Comparison of the ratings showed that people with dementia are aware of their carers' psychological health. A control group of people with arthritis also participated in the study. The level of awareness shown by the participants with dementia was comparable to the level of awareness of carer psychological health shown by the control group. The level of awareness of carer psychological health in the participants with dementia was not related to their level of awareness of their own memory difficulties. The thesis concludes with a reflective paper which focuses on observations made whilst conducting research interviews and recruiting participants through support groups. Reflections and learning drawn from these observations are discussed

Studies of appetite variation in juvenile Atlantic cod (Gadus morhua L.) using demand feeding systems

This thesis covers two studies based on the feeding of juvenile Atlantic cod (Gadus morhua). The first study was carried out using an AQl interactive feedback feeding system and investigated their feeding patterns, both seasonal (chapter 2) and daily (chapter 3). The second study involved designing an on-demand feeding system for juvenile cod, then examining the process of the fish learning to use the feeder, focusing on the roles of individual fish. The first trial was carried out in two sections, the first from March until August 2004 and the second form November 2004 until February 2005. Five 124 litre tanks were stocked with cod of 5 grams. The tanks were equipped with an AQl feeding system with infra red sensors at the outlet of each tank. The system added test feeds every 30 minutes and the feed input each minute was recorded to an attached computer. The sensors were affected by suspended solids in the water, causing false readings of waste pellets, causing under feeding. The data set was therefore cleaned up by removing affected days. Chapter 2 focuses on the seasonal changes in feed consumption of the cod. The mean daily feed input (as a percentage of bodyweight per day, BWD) varied between 0 and 10%, with the mean being around 5%. The feed input (%BWD dropped to its lowest levels around early summer, the opposite result to that expected. The effects of temperature and photoperiod on feed input were also opposite to the expected outcome, when the day length was longer, and when the temperature was high, the feed intake dropped. There was a significant pattern of autocorrelation in feed input, leading to the conclusion that juvenile cod appetite is affected by a medium term internal rhythm. Chapter 3 focuses on the daily feeding patterns of the juvenile cod. The main pattern found during the first part of the trial was a significant dawn peak when up to 40% of the days feed was consumed. The remaining part of the day was spent browsing. In the second part of the trial, there were a lot less definite patterns; there was a trend towards browsing over a full 24 hour day with heavier feeding nocturnally and short phases of crepuscular feeding, again with continuous light browsing at other times. The reasons for the differences in feeding pattern are discussed and the peak feeding hour and percentage nocturnal consumption are investigated. Chapter 4 concentrates on the process of juvenile cod learning to use a demand feeder. Every group of fish learnt to use the demand feeder, though only one fish from each group was responsible for activating the trigger. That fish was also found to be the boldest when tested in a novel object test and its growth was significantly higher than the other fish in the group, it was named the trigger fish. Another group emerged at the other end of the scale; they did not interact with the sensor at all, nor approached the novel object. They were significantly smaller than all the other individuals and gained the least weight, in some cases, the fish lost weight

Accomplishing public work: encounters with park rangers

The aim of this ethnographic study is to advance the understanding of the situated contingencies and implications of working in public view. It does so by tracing the quotidian work practices and face-to-face interactions of the Urban Park Rangers in Cardiff, UK as they routinely go about their rounds, maintaining and managing urban park space. Their maintenance and management work is inevitably public, and a central organisational aspect of it is the regularity and ordinariness of their encounters with members of the public. As legitimate ‘approachables’ and ‘auditables’, it is a practical requirement of their job to regularly account for their practice, and such characteristics as ‘professionalism’, ‘strategy’, and ‘system’ are displayed as in-built features of their work activities. Analyses pay close attention to the participants’ observations and category work, and show how the categorial device of ‘public worker’–‘member of the public’ is omnirelevant in the relational organisation and mutual elaboration of their practice and the space. The parks themselves are collaboratively, ordinarily, and emergently assembled through practical action and interaction. Not only must they account for their practice, but as ‘stocked characters’ (Goffman, 1971) the Park Rangers are also approached about troubles outside of their technical remit: burst river banks, what time the boat hire opens, what the rugby score was, and so on. Their public availability and visibility produce them as constituent features of the urban fabric to the point that they become practically responsible for myriad public troubles, and must ‘pick up the slack’ of other practitioners and organisations. It is therefore proposed that ‘stocked characters’ are vital to the accomplishment of public space as public space. The experience of ‘being in public’ is ordinarily contingent on the assumption of the express availability of some public worker to ask for help, information, assistance, or who you can go to with some trouble and whose category-boundness to the space obliges them to help to the best of their ability. Public work, then, is shown to be radically constitutive of public space

The measurement of the underwater radiated noise from a marine piling operation

Assessment of the underwater acoustic radiated noise during a marine piling operation was carried out in UK coastal waters in April 2006. A 2 m diameter, 65 m long test pile was driven into a "hard chalk‟ sediment. The pile was placed in an area of average water depth of 10-15 m approximately 3 km offshore

Temporal and spectral characteristics of a marine piling operation in shallow water

Analysis of the underwater radiate acoustic characteristics for marine piling operations for two pile diameters, 2m and 4.74m, in a relatively shallow water site are presented. Measurements of the entire piling sequence for several piles were conducted at ranges from 10m to 22km for piles in 10-20 m water depth. Variations in the temporal and spectral characteristics of radiated energy are analysed in context of pile size, range from source, hammer energy used and pile penetration depth. Analysis of hammer energy used shows a strong interdependence between mechanical strike ‘hammer’ energy and underwater radiated acoustic energy. This process appears ‘coarsely’ linear for individual piling operations although considerable variation in overall gradient were observed between operations. For individual hammer energy step increases often the largest increases in radiated energy were observed at the initial hammer energy increase, with subsequent strikes at the same hammer energy resulting in a gradual reduction in radiated energy to a level 1-2 dB lower. These effects are potentially due to sediment compacting / relaxation effects relating to the time and number of strikes and penetration. Temporal and spectral variations in radiated energy due to pile penetration are also examined for fixed hammer energy and range. Simultaneous recordings of radiated energy made at increasing distances from the pile showed evidence of temporal and spectral dispersion effects consistent with relatively shallow water propagation. Correlation of received levels at various ranges in differing seabed topographies were made suggesting complex shallow water modal propagation dependant on both the source and environment characteristics including seabed topography, sediment type and water column acoustic properties

A methodology for the measurement of radiated noise from marine piling

This paper describes a methodology that has been developed for measuring marine piling noise, which is designed to record the temporal, spatial and spectral characteristics of the radiated sound field. Results are presented for measurements of two pile diameters, 2m and 4.74m, in a shallow water site off the east coast of the UK. Measurements of the entire piling sequence for several piles were conducted at ranges from 10 m to 22 km for piles in 10-20 m water depth. To assess variations in the temporal, spatial and spectral characteristics, a number of recording systems were simultaneously deployed at various ranges and depths, allowing the full piling sequence to be measured. This allowed assessment of source level variation at fixed locations, and the effect of propagation within the water column

Serious Organised Crime Early Intervention Service Evaluation

The Serious Organised Crime Early Intervention Service (SOCEIS) is an innovative intervention for young people aged 11 to 18 years. It is aimed at identifying young people involved in, or at risk of involvement in serious organised crime, addressing the vulnerabilities that led to their involvement and diverting them towards more positive pathways. Following its success in Glasgow, Action for Children were awarded funding from the National Lottery Community to implement SOCEIS in four new areas: Cardiff, Dundee, Edinburgh and Newcastle. To examine the wider feasibility and applicability of SOCEIS, this process evaluation was commissioned by Action for Children in 2020