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A quantitative study of the plain X-ray in the acute abdomen, written from the point of view of the surgeon rather than the radiologist, is presented. Three questions are asked: 1. Which radiological signs are present in the plain X-ray in the acute abdomen and with what incidence? 2. Should plain X-rays be routinely performed in the acute abdomen? 3. Who should report the acute abdominal X-ray? All patients entered into the study were managed personally by the author. In the first part of the thesis, the plain abdominal X-rays of a series of patients (277 in all) suffering from each of the five most common acute abdominal diseases were reviewed for specific radiological features to assess the relative incidence and importance of each sign. In the second part of the thesis 249 consecutive patients admitted to hospital with an acute abdomen due to all types of disease were studied, and the plain abdominal X-rays of each assessed for their value in diagnosis. In the third part of the thesis, a questionnaire of 50 plain abdominal X-rays was answered by surgeons and radiologists of varying clinical experience and the scores of each group compared. The results of the study showed that: 1. Specific radiological features were found in not less than 4% of the X-rays of the five acute abdominal diseases studied in detail. 2. When performed routinely, 'positive' help was obtained from the acute abdominal X-rays of 42% of the 249 patients studied. An argument is presented for the inclusion of the plain X-ray as a routine in the acute abdomen. 3. The plain abdominal X-rays should be reported by a senior radiologist at the time of the investigation, if maximum benefit to both patient and surgeon is to be obtained.

Electrochemistry is a powerful technique that offers multiple possibilities and which is in constant evolution. Simple modifications of the electrode surface can result in an improvement of the selectivity and sensitivity of the method. However some situations require more complex modifications such as the incorporation of an external agent to the electrode surface, or within the actual electrode. This thesis describes the development and characterization of a range of novel electrochemical sensors for multiple applications covering agri-food, biomedical and environmental contexts. The foundations of the approach rest upon the development of carbon-loaded polycarbonate composite films. Their fabrication is described and the ease with which they can be modified and physically adapted is highlighted and critically evaluated. The response of the resulting sensors have been validated against conventional techniques. An overview of the technologies employing carbon electrodes is presented in Chapter 1 and serves to set the context of the subsequent research. The various methodologies employed are outlined in Chapter 2. Preliminary modifications of the analytical process has evolved from the ex situ functionalisation of the conventional carbon electrodes with copper (Chapter 3) through to the examination of the versatility and complexities of sample pre-treatment (Chapter 4). The pre-treatment of the sample using naphthoquinones as labeling agents has been developed and this work was extended to examine a wholly new derivatisation agent which could have analytical and clinical/veterinary diagnostic merit. A new direction was sought to overcome the limitations of the conventional analytical approach and composite systems were envisaged as providing an accessible yet flexible method of developing electrochemical sensors for discrete probe and flow systems. The basic procedure has been characterization and optimized for a range of analytes such as neurotransmitters (Chapter 5), anti-oxidants (Chapter 6), purine metabolites (Chapter 8) and phosphate (Chapter 9). Each chapter highlights a different aspect and applicability of the composite and go from simple physical surface modification (Chapter 5) to the incorporation of chemical agents (Chapter 6) and more complex systems such as enzymes (Chapters 8 and 9).

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This project has focussed on synthesising a range of bifunctional chelators (BFCs) for use in nuclear medicine, in particular positron emission tomography (PET). When such BFCs are complexed to a M(III) ion the overall charge on the complex varies between -1 and -3; this is expected to affect the renal clearance and biodistribution of these complexes.;A range of novel BFCs were produced; the synthesis of each requiring the use of new di-ester pendant arms. The BFCs were coupled to a range of moieties, including a patented biologically active peptide designed to locate at the site of angiogenesis, in order to allow the imaging of tumours to take place. The ultimate aim of the project was to couple the biologically active peptide to a tert-butyl deprotected BFC. This was achieved using various methodologies and reagents. The solution behaviour of the corresponding Eu(III) complex was studied. The hydration state of the peptide-coupled BFC was found to be q = 1, with 1 H NMR spectroscopy indicating a 4:1 mixture of square antiprismatic (SAP) : twisted square antiprismatic (TSAP) geometric isomers in solution.;Complexes of Ga(III), Eu(III), Y(III) and In(III) were synthesised with various benzylamine and N-Benzoyl-Gly-Lys coupled and tert-butyl protected BFCs. These were studied by 1H NMR and fluorescence spectroscopy where possible to provide an insight into their solution behaviour. Luminescent lifetime measurements indicated that the hydration state of all Eu(III) complexes was q = 1, indicating an 8-coordinate complex (with respect to ligand) with the ninth site occupied by a water. 1H NMR spectroscopy revealed the predominant geometric isomer in solution to be SAP, usually with a 4 : 1 ratio of SAP:TSAP. Selected benzylamine and N-Benzoly-Gly-Lys coupled BFCs were radiolabelled with 68Ga, using microwave heating for 1 min in order to illustrate their potential use in PET. This proved to be a superior method of radiolabelling on a small scale when compared to conventional heating.

Transmitral diastolic blood flow velocities were recorded in 54 healthy volunteers. The effect of respiration and physiological variables on measurements derived from these transmitral recordings were assessed. The effects of respiration on transmitral flow were found to be highly significant. The inherent variability of transmitral flow velocity spectra over time was investigated in 50 unselected patients and the effects of operator and interpretative variation in the recording and analysis of transmitral spectra investigated. Clinically acceptable observer variability for recording and measurement of transmitral flow was observed. Small inherent variation of certain pulsed Doppler parameters was established. The relationship between left ventricular relaxation measured by M-mode echocardiography and pulsed Doppler transmitral flow parameters was examined in 35 healthy subjects. Close correlation was found to exist between early diastolic events measured by the Doppler techniques and rate of diastolic ventricular expansion. Simultaneous recordings of left ventricular diastolic pressure and transmitral diastolic flow were performed in 50 patients undergoing clinical assessment of ischaemic heart disease. While significant correlation was observed between direct pressure measurements and several pulsed Doppler parameters of diastolic flow, reliable clinical prediction of diastolic ventricular pressure using pulsed Doppler velocimetry was not found to be possible.

The aim of this thesis is to combine experimental and theoretical investigations of the sources of error in flow measurement techniques which use the Doppler principle and to look for possible ways to improve the accuracy. Computer models were developed in this thesis to simulate the Doppler spectrum. Results from the computer models were carefully compared with the experimental data. The effect of factors including geometrical spectral broadening, type and size of the transducer, focusing, depth of the vessel, beam-vessel angle misalignment of the beam and vessel, reflection and refraction at vessel wall were analysed using these models. Experiments showed that the errors in the diameter measurement were significant. Non-linear propagation has no significant effect on the Doppler measurement. It was confirmed experimentally that the mean velocity of pulsatile flow could be estimated by half of the maximum velocity averaged over an integral number of cardiac cycles. It was suggested that the geometrical spectral broadening and transit time spectral broadening were not the same effect as generally believed and should be treated separately. A detailed study of the flow phantom was also made prior to the investigation of the factors resulting in errors. Possible improvements of the accuracy of volumetric flow measurement were sought during these studies. It was found that a half pulse length correction in the diameter measurement can significantly improve the accuracy of the cross-sectional area estimation.

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No description available.

Magnetic resonance imaging (MRI) offers the unique ability to examine the heart in three dimensions and to provide tissue characterisation. This thesis aims to investigate two areas of particular interest, namely the quantification of cor pulmonale and acute myocardial infarction. The methods currently available for assessing right ventricular hypertrophy and dilatation are discussed, with particular reference to patients with chronic obstructive pulmonary disease. The results of pulmonary haemodynamic and blood gas data are compared with the results from cardiac gated MRI. A good correlation is obtained between the mean and systolic pulmonary artery pressures, the pulmonary vascular resistance and the right ventricular wall volume measured by MRI. This technique is subsequently used in a small group of patients, to determine the response to long term oxygen therapy. The various techniques employed to assess the size of myocardial infarcts are discussed, and the previous literature on the ability of MRI to detect infarction is reviewed. A new technique, which is supported by phantom experiments, is described to measure the volume of infarcted myocardium using saturation recovery - inversion recovery and spin-echo images. The T1 images are compared with radionuclide pyrophosphate scanning and serum creatine kinase-MB release and a satisfactory agreement obtained. Myocardial infarct size measured by both pulse sequences is compared directly. The spin-echo technique is used to assess alterations in myocardial infarct size with time and the response to various therapeutic options is compared. In conclusion the limitations of both techniques are discussed and future developments proposed.