| 1. |
- Alwin, Jenny, 1978-
(författare)
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Assessment of Support Interventions in Dementia : Methodological and Empirical Studies
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Dementia means a continuous deterioration of abilities and has a large impact on the persons affected as well as on family members and others close to the persons with dementia. Interventions aimed at this population in order to support and alleviate the often straining situation may be of great importance. There is a need to increase the knowledge and understanding of the impact and consequences of these interventions, both at an individual level and at a societal level. The demand for information concerning, e.g., economic and medical impact of technologies and interventions within health care is increasing. Assessment of technologies and interventions in dementia is related to certain methodological issues. The overall aim of this thesis is to contribute to the development of methodological knowledge concerning assessment studies and understanding of support interventions in dementia.This thesis work includes four studies that examine methodological aspects of assessment of support interventions in dementia and also report empirical research on the perception of support interventions from the perspectives of family caregivers of persons with dementia. In study I, an assessment model for assistive technology (AT) interventions in dementia was developed. In study II, part of the assessment model is applied, and a process evaluation of the AT intervention is presented. Study III examines family caregivers’ perception of the importance of different types of support and services. In the final study, study IV, a well‐acknowledged methodological challenge within the field of assessment in dementia is addressed: measuring health‐related quality of life (HRQoL). The studies are based on different data materials.An assessment model of AT interventions was developed that includes health economic evaluation from a societal perspective as well as evaluation of the intervention process. The perspectives of both persons with dementia and their relatives were incorporated in the model. The process evaluation was applied in study II in order to study the relatives’ perception of an AT intervention process. Assistive technology interventions in dementia may be of great significance for the relatives. By performing the process evaluation, several important aspects that need to be acknowledged in AT intervention processes in dementia were identified.Family caregivers of persons with dementia perceived different types of support/services within the comprehensive areas of counselling, relief and information as very important. Knowledge of the caregivers’ preferences is significant so that more directed support interventions may be provided.One specific methodological issue was addressed in study IV. The results of study IV showed that there were large differences in the results of cost‐effectiveness analyses depending on whether patient self‐ratings or proxy ratings (ratings of persons close to the patient) of patient HRQoL were used for the same analysis. These differences in the results could ultimately have an important impact on decision making and resource allocation.Support interventions aimed at persons with dementia and their relatives may be of great value. Conducting assessment studies of technologies and interventions within health care is important in order to increase the knowledge concerning, e.g., economic and medical impact. Assessment studies of support interventions dementia entails methodological issues that need to be addressed. There is a need for increased knowledge within this field and suggestions on methodology are made.
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| 2. |
- Andersson, Michael R., 1974-
(författare)
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Functional aspects of inorganic phosphate transport
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Inorganic phosphate is an essential nutrient for all organisms. It is required for many cellular components as nucleic acids and phospholipids, and as energy-carrying compounds such as ATP. Thus, a regulated uptake of this pivotal nutrient is of outermost importance. Depending of the availability of phosphate in the surroundings the yeast Saccharomyces cerevisiae make use of two different systems for transporting phosphate into the interior of the cell: a low-affinity system that is active during surplus phosphate conditions and a high-affinity system that is active when the availability becomes limited. This thesis focuses on the high-affinity system, which is comprised of the Pho84 and Pho89 transporters. Of the two transporters, Pho84 is the predominant one, responsible for almost all phosphate uptake during low phosphate conditions, and the contribution of Pho89 is of minor importance. Hence Pho84 is by far the most well characterized phosphate transporter. Even though much is known about phosphate transporters in yeast little in known about how phosphate is transported. The work in this thesis aims to broaden the knowledge about the transport mechanism by the means of site-directed mutagenesis and functional characterization. Also the similarity of Pho84 to glucose sensors and the potential role of conserved residues in phosphate signaling are investigated. By the use of a high-affinity system deletion strain (∆Pho84 ∆Pho89), we also managed to investigate the functional importance of well conserved residues in Pho89. In summary: the work presented in this thesis has contributed to increase the knowledge about transport mechanisms in phosphate transporters.
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| 3. |
- Brodtkorb, Thor-Henrik, 1976-
(författare)
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Cost-effectiveness analysis of health technologies when evidence is scarce
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Given the increasing pressures on health care budgets, economic evaluation is used in many countries to assist decision-making regarding the optimal use of competing health care technologies. Although the standard methods of estimating cost-effectiveness underpinning these decisions have gained widespread acceptance, concerns have been raised that many technologies would not be considered for funding, due to scarcity of evidence. However, as long as the amount and quality of evidence used for the analysis are properly characterized, scarce evidence per se should not be seen as a hindrance to perform cost-effectiveness analyses. Characterizing uncertainty appropriately, though, may pose a challenge even when there is a large body of evidence available, and even more so when evidence is scarce. The aims of this thesis are to apply a methodological framework of cost-effectiveness analysis and explore methods for characterising uncertainty when evidence is scarce. Three case studies associated with limited evidence provide economic evaluations on current decision problems, investigate the feasibility of using the framework, and explore methods for characterizing uncertainty when evidence is scarce.The results of the case studies showed that, given current information, providing transfemoral amputees with C-Leg and Airsonett Airshower to patients with perennial allergic asthma could be considered cost-effective whereas screening for hyperthrophic cardiomyopathy among young athletes is unlikely to be cost-effective. In the cases of C-Leg and Airsonett Airshower conducting further research is likely to be cost-effective. The case studies indicate that it is feasible to apply methods of cost-effectiveness in health care for technologies not commonly evaluated due to lack of evidence. The analysis showed that failing to account for individual experts’ might have a substantial effect on the interpretation of the results of cost-effectiveness analysis. Formal expert elicitation is a promising method of characterizing uncertainty when evidence is missing, and thus enable cost-effectiveness and value of further research to be appropriately estimated in such situations.In conclusion, this thesis shows that scarcity of evidence should not preclude the use of cost-effectiveness analysis. On the contrary, in such cases it is probably more important than ever to use a framework that enable us to define key parameters for a decision problem and identify available evidence in order to determine cost-effectiveness given current information and provide guidance on further data collection.
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| 4. |
- De Geer, Jakob, 1970-
(författare)
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On the use of computed tomography in cardiac imaging
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- BackgroundCardiac Computed Tomography Angiography (CCTA) is becoming increasingly useful in the work‐up of coronary artery disease (CAD). Several potential methods for increasing the diagnostic yield of cardiac CT are available.Purpose Study I: To investigate whether the use of a 2‐D, non‐linear adaptive noise reduction filter can improve CCTA image quality.Study II: To evaluate the variation in adenosine stress dynamic CT perfusion (CTP) blood flow as compared to stress 99mTc SPECT. Secondly, to compare the perfusion results from manual and automatic myocardial CTP segmentation.Study III: To evaluate the accuracy of non‐invasive, CCTA‐derived Fractional Flow Reserve (cFFR).Study IV: To evaluate the prognostic value of CCTA in terms of major adverse cardiac events (MACE).Materials and methodsStudy I: Single images from 36 consecutive CCTA exams performed with two different dose levels were used. Image quality in full dose, low‐dose and noise‐reduced low‐dose images was graded using visual grading analysis. Image noise was measured.Study II: CTP and SPECT were performed in 17 patients, and the variation in per AHA‐segment blood flow was evaluated and compared. CTP results from manual and automated image segmentation were compared.Study III: CCTA datasets from 21 patients were processed using cFFR software and the results compared to the corresponding invasively measured FFR (invFFR).Study IV: 1205 consecutive patients with chest pain of unknown origin underwent CCTA. Baseline data and data on subsequent MACE were retrieved from relevant registries. Survival, hazard ratios and the three‐year incidence of cardiac events and readmissions were calculated.Results Study I: There was significant improvement in perceived image quality for all criteria when the filter was applied, and a significant decrease in image noise.Study II: The correlation coefficients for CTP vs. SPECT were 0.38 and 0.41 (p<0.001, for manual and automated segmentation respectively. Mean per patient CTP blood flow in normal segments varied between 94‐183 ml/100 ml tissue/min for manual segmentation, and 104‐196 ml/100 ml tissue/min for automated segmentation. The Spearman rank correlation coefficient for manual vs. automated segmentation CTP was ρ = 0.88 (p<0.001) and the Intraclass Correlation Coefficient (ICC) was 0.93 (p<0.001).Study III: The Spearman rank correlation coefficient for cFFR vs. invFFR was ρ = 0.77 (p<0.001) and the ICC was 0.73 (p<0.001). Sensitivity, specificity, positive predictive value and negative predictive value for significant stenosis (FFR<0.80, per vessel) were 0.83, 0.76, 0.56 and 0.93 respectively.Study IV: The hazard ratio for non‐obstructive CAD vs. normal coronary arteries was 5.13 (95% C.I 1.03‐25.43, p<0.05), and 151.40 (95% C.I 37.03‐619.08, p<0.001) for obstructive CAD vs. normal coronary arteries. The three‐year incidence of MACE was 1.1% for patients with normal vessels on CCTA, 2.5% for patients with non‐obstructive CAD and 42.7% for patients with obstructive CAD (p<0.001).Conclusions:Study I: Image quality and noise levels of low dose images were significantly improved with the filter, even though the improvement was small compared to the image quality of the corresponding diastolic full‐dose images.Study II: Correlation between dynamic CTP and SPECT was positive but weak. There were large variations in CTP blood flow in normal segments on SPECT, rendering the definition of an absolute cut‐off value for normal vs. ischemic myocardium difficult. Manual and automatic segmentation were equally useful.Study III: The correlation between cFFR and invFFR was good, indicating that noninvasively estimated cFFR performs on a similar level as invasively measure FFR. Study IV: The long‐term risk for MACE was very low in patients without obstructive CAD on CCTA, though there seemed to be a substantial increase in the risk for MACE even in patients with non‐obstructive CAD as compared to normal coronary arteries. In addition, even patients with normal coronary arteries or non‐obstructive CAD continued to have a substantial number of readmissions for chest pain or angina pectoris.
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| 5. |
- Furuhjelm, Jörgen, 1969-
(författare)
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Incorporating the end-of-life aspect into product development : analysis and a systematic approach
- 2000
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- It is evident that we face a major challenge to overcome the environmental problems associated with our consumption and production systems. The rate at which products flow through our society is steadily increasing and this leads to serious consequences in the form of accelerating depletion of the earth's resources and generation of enormous amounts of waste. This fact is being paid increasing attention and recent developments of legislation together with a growing market awareness have brought incentives to take the end-of-life aspect into account right from the product development stage. There is thus an industrial need to enhance knowledge on how cost-efficient and environmentally sound treatment of discarded product could be facilitated through design measures.This thesis provides an analysis and a systematic approach concerning how the end-of-life aspect could be incorporated during product development. The systematic approach has been created by the author and is mainly based on input from case studies at ABB Motors, Nokia and Ericsson. The approach functions in the thesis as a guiding structure for a comprehensive analysis of how an effective and efficient incorporation could be achieved, leading to products that facilitate cost-efficient recycling. In its normative character the approach aims at applicability in companies that want to improve their products' design from an environmental as well as a market perspective. In applying the approach as a normative tool the company is advised to follow a working structure made up of four steps; 1.) Analysing relevant areas, 2.) Deriving product demands for each area, 3.) Establishing a final list of product demands and 4.) Providing support for product development.The areas seen as relevant to pay attention to in Step 1 are the market demand related to the end-of-life phase, the take-back legislation currently being implemented and the products' end-of-life system. Applying the approach, the company should detern1ine how the product design could be improved leading to increased market potential, compliance with the legislative demands and cost-efficient end-of-life treatment. Effective design targets should then be established through a synthesis of the demands derived from each area. The fourth step of the approach deals with the actual integration of the end-of-life aspect in relevant product development activities. The thesis then analyses how, on the basis of the established product demands, the end-of-life aspects could be efficiently incorporated. For example, it is discussed how end-of-life-related demands could be included in the design specifications and the end-of-life aspect incorporated into the project management systems.
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| 6. |
- Hallert, Eva, 1947-
(författare)
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Disease activity, function and costs in early rheumatoid arthritis
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Rheumatoid arthritis (RA) is a major cause of progressive joint damage and disability, and is associated with decline in quality of life, reduced ability to work and increased health care utilisation. The economic consequences of the disease are substantial for the individuals and their families and for the society as a whole. This thesis describes a 5-year follow up of 320 patients with early RA, enrolled between January 1996 and April 1998 in the Swedish multi-centre inception cohort TIRA (early interventions in rheumatoid arthritis). Health status, function and costs were investigated. Predictors of high costs were calculated, and an algorithm was constructed to predict future need for TNFinhibitor treatment in patients not responding to traditional disease-modifying antirheumatic drugs (DMARDs). Clinical and laboratory data, measures of functional capacity and self-reported assessments were collected regularly. In addition, patients completed biannual/annual questionnaires concerning all health care utilisation and days lost from work due to the disease. Within 3 months, improvements were seen regarding all variables assessing disease activity and functional ability, but 15% of the patients had sustained high or moderate disease activity throughout the study period. The scores of ‘health assessment questionnaire’ (HAQ) were similar for men and women at baseline, but had a less favourable course in women, who also had DMARDs more frequently prescribed.Ambulatory care accounted for 76% of the direct costs during the first year. Women had more ambulatory care visits and higher usage of complementary medicine compared to men. Men ≥65 years had low costs compared to younger men and compared to women of all ages. In multiple logistic regression tests, HAQ, high levels of IgM-class rheumatoid factor (RF), and poor hand function increased the odds of incurring high direct costs. Poor hand function and pain increased the odds of incurring high indirect costs.Indirect costs exceeded direct costs all three years. The average direct costs were €3,704 (US$ 3,297) year 1 and €2,652 (US$ 2,360) year 3. All costs decreased over the years, except those for medication and surgery. The indirect costs were €8,871 (US$ 7,895) year 1 and remained essentially unchanged, similarly for both sexes. More than 50% were on sick leave or early retirement at inclusion. Sick leave decreased but was offset by increase in early retirement. 14 patients (5%) were prescribed TNF-inhibitors at the 3- year follow up, thus increasing drug costs substantially. However, they incurred higher costs even before prescription of anti-TNF therapy.At the 5-year follow-up (2001-2003), 31 patients (12%) were prescribed TNFinhibitors. Baseline values of erythrocyte sedimentation rate, C-reactive protein, anti-CCP antibodies and morning stiffness were significantly higher in this group. These patients were also to a larger extent RF-positive and carriers of the ‘shared epitope’ (SE). Anti-TNF treated patients were significantly younger and more often women. For men, a predictive model was constructed using baseline data including SE+ and IgA-RF >100 U/L and anti-CCP >240 U/L yielding a specificity of 98% and a sensitivity of 71%. For women, disease activity score (DAS28) at the 3-month follow-up proved to be a better predictor, and the final model comprised SE+ and 3-month DAS28>5.2, giving a specificity of 95% and a sensitivity of 59%.
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| 7. |
- Hamodi, Hussan
(författare)
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Reliability and Life Cycle Cost Modelling of Mining Drilling Rigs
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In the context of mining, drilling is the process of making holes in the face and walls of underground mine rooms, to prepare those rooms for the subsequent operation, which is the charging process. Due to the nature of the task, drilling incurs a high number of drilling rig failures. Through a combination of a harsh environment (characterised by dust, high humidity, etc.), the operating context, and reliability and maintainability issues, drilling rigs are identified as a major contributor to unplanned downtime.The purpose of the research performed for this thesis has been to develop methods that can be used to identify the problems affecting drilling rig downtime and to identify the economic lifetime of drilling rigs. New models have been developed for calculating the optimum replacement time of drilling rigs. These models can also be used for other machines which have repairable or replaceable components. Based on an analysis performed in a case study, a life cycle cost (LCC) optimization model has been developed, taking the most important factors affecting the economic replacement time of drilling rigs into consideration. To this end, research literature studies, case studies, and simulation studies have been performed, interviews have been held, observations have been made and data have been collected. For the data analysis, theories and methodologies within reliability, maintainability, ergonomics and optimization have been combined with the best practices from the related industries.Firstly, this thesis analyses the downtime of the studied drilling rigs, with the precision and uncertainty of the estimation at a given confidence level, along with the factors influencing the failures. Secondly, the thesis identifies components that significantly contribute to the downtime and the reason for that downtime (maintainability and/or reliability problems). Based on the failure analysis, some minor suggestions have been made as to how to improve the critical components of the drilling rig. Thirdly, a new method is proposed that can help decision makers to identify the replacement time of reparable equipment from an economic point of view. Finally, the thesis proposes a method using the artificial neural network (ANN) for predicting the economic lifetime of drilling rigs through a series of basic weights and response functions. This ANN-based method can be made available to engineers without the use of complicated software.Most of the results are related to specific industrial and scientific challenges, such as planning for cost-effectiveness. The results of the case study are promising for the possibility of making a significant reduction in the LCC by optimizing the lifetime. The results have been verified through interaction with experienced practitioners from both the manufacturer and the mining company using the drilling rig in question.
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| 8. |
- Hedlund-Åström, Anna, 1957-
(författare)
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Model for End of Life Treatment of Polymer Composite Materials
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Because of increasing environmental demands, especially on dealing with products end of life phase, product manufacturers and designers must consider the future disposal of their products. For conventional materials like steel and aluminium well-functioning recycling methods exists. This is not the case for structures of polymer composites, which are used more extensively, especially for structures like vehicles and vessels. Several techniques do exist but they are not yet commercially available. The current disposal methods of polymer composites are landfill and incineration. Polymer composites are materials, which consist of several materials like fibre, matrix, and additives. In the form of sandwich constructions also foam core material is added. This circumstance complicates the waste treatment of composite materials. In this thesis a model for assessing possible future waste treatment techniques for polymer composites including sandwich structures is presented. The model is meant to be used as an aid for preparing future disposal for end of life products for planning waste treatment and for facilitating communication in contacts with waste receivers. Recommendations for waste treatment have been formed for a number of polymer composites. These recommendations are based on the analysis of costs and environmental effects and they compare different scenarios for mechanical material recycling and energy recovery by waste incineration. The result of this study points out material recycling as the preferable method for the main part of the studied materials. But this recommendation is strongly dependent on type of virgin material replaced by the recycled material. Energy recovery can also be considered if the polymer composite waste replaces coal, which is non renewable. Though incineration will always result in a cost for the waste producer. In the recommendations mentioned above no information concerning implementation of the different waste disposal techniques is included. Therefore, in this study a model for assessing possible waste disposal techniques for polymer composites is presented. The model is based on internal factors, which are related to the waste and to the processes. To implement the model relevant waste properties must be identified in order to fulfil the conditions set by the required processes involved. A case study was carried out using the proposed model for assessing different waste disposal techniques for the hull of the Visby Class Corvette in the Royal Swedish Navy. Six different techniques were studied for the hull structure. Since almost all the important waste properties were known and the waste was assessed to be treatable all the included techniques except one are shown to be usable in the future. Many investigations have pointed out material recycling as the best alternative considering environmental effects. This is also valid for polymer composite materials. Since recycling polymer composites is a complicated process, especially recycling thermoset composite it is important to aquire comprehensive information about the constituents of these materials.
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| 9. |
- Kentson, Magnus
(författare)
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Fatigue and Peripheral Muscle Dysfunction: Studies on Vitamin D Status, Muscle Metabolism and Systemic Inflammation in Patients with COPD : Aspects of COPD severity beyond FEV1 and exacerbations
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- BackgroundThe severity of Chronic Obstructive Pulmonary Disease (COPD) is usually described in terms of forced expiratory volume in one second (FEV1) and number of exacerbations. However, COPD is a complex disease with different ways of expression, involving pulmonary symptoms, extra pulmonal manifestations and comorbidities, which altogether affect the patient by contributing to reduced functional capacity, increased shortness of breath, reduced health-related quality of life and increased mortality. Systemic inflammation is common in COPD and can potentially constitute a link between the lungs and other organs. The aim of this thesis was to broaden the aspects of COPD severity beyond FEV1 and exacerbations by studying fatigue, the role of vitamin D, nutritional factors, systemic inflammation and peripheral muscle function in patients with COPD. Methods and ResultsIn paper I, we included 101 patients with COPD, and 34 control subjects. Assessment of experience of fatigue, functional limitation due to fatigue, and the relationships to physiological, psychological and situational variables and quality of life (QoL) were evaluated. We found that experience of fatigue was highly prevalent (72% versus 56% in control subjects) and a troublesome symptom in COPD. Patients with COPD and fatigue had lower lung function, shorter walking distance, more dyspnoea, anxiety and depressive symptoms and poorer health status compared to patients without fatigue (all p < 0.01). Several contributing factors were identified to experience of fatigue and functional limitations of fatigue with dyspnoea, depressive symptoms and insomnia as the most prominent factors. No clear association with systemic inflammation was found. Paper II evaluated vitamin D status in 66 patients with advanced COPD (28 with long-term oxygen therapy (LTOT)) and 47 control subjects. 25-hydroxyvitamin 25(OH)D were deter-mined in early fall in a short period of seven weeks. Questionnaires about COPD symptoms, general health, lifestyle, dietary habits and QoL were answered. Lung function tests and blood sampling including systemic inflammatory markers, carotenoids and protein carbonylation (PC) were assessed. The peak annual 25(OH)D of COPD patients was significantly lower than in the control subjects, but there was no significant difference between COPD patients with and without LTOT. Among vitamin D-deficient COPD patients, 25(OH)D correlated positively with lung function, blood oxygenation, food portion size, Mediterranean Diet Score and Ultra-violet Score and negatively with dyspnoea and DOSE-index, a composite index for COPD se-verity. Ongoing vitamin D supplementation was the single most important intervention to maintain 25(OH)D levels <50 nmol/L. In paper III, we evaluated in the same cohort as paper II oxidative damage and levels of carotenoids. Patients with COPD (±LTOT) did not demonstrate increased oxidative damage. Com-pared with the control group, levels of several carotenoids were significantly lower in COPD, and the diet contained significantly less fruit and vegetables. Lycopene correlated positively with saturation and lutein correlated positively with some inflammatory markers but negatively with IL-6, an important marker for systemic inflammation. The study highlights the importance of dietary factors in COPD. In paper IV, 32 patients with COPD answered questionnaires, and were subjected to lung function tests and blood analysis including systemic inflammatory markers. Magnetic resonance imaging (MRI) for analysis of whole-body and thigh muscle composition was performed. Bioenergetics in the resting thigh muscle, (PCr/Pi ratio), were analysed using 31phosphorus magnetic resonance spectroscopy (31P-MRS). We found that adverse muscle composition was common in the COPD group. Clinical characteristics reflecting COPD severity were all associated with a raise of the PCr/Pi ratio in the thigh muscle. Increased MFIa correlated positively to systemic inflammatory markers, negative to physical activity and PCr/Pi ratio. We compared the COPD group with a virtual control group from UK Biobank (n= 3200). ConclusionsSevere COPD is much more than airway obstruction and exacerbations. The presence of fatigue is associated, as well as vitamin D status and nutritional factors, with important clinical out-comes reflecting COPD severity. Adverse muscle composition is common in COPD and there seems to be a link between systemic inflammation, muscle fat infiltration and bioenergetics.
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| 10. |
- Kihlberg, Johan, 1970-
(författare)
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Magnetic Resonance Imaging of Myocardial Deformation and Scarring in Coronary Artery Disease.
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Although improved treatments have reduced the rates of acute complications from myocardial infarction, sequelae such as heart failure and sudden death threaten the future wellbeing of those patients. Secondary prevention after myocardial infarction is related to cardiovascular risk factors and the effect of the infarct on left ventricular function. Cardiovascular magnetic resonance imaging (CMR) is necessary to determine the size of the infarct scar and can with great precision determine left ventricular volumes, left ventricular ejection fraction, and deformation (strain and torsion). The purpose of this thesis was to improve on CMR methods to facilitate image acquisition and post processing in patients with high risk of coronary artery disease (CAD).In Paper 1, a three-dimensional phase-sensitive inversion-recovery (3D PSIR) sequence was modified to measure T1 during a single breath hold. The measured T1 values were used to extrapolate a map of T1 relaxation, which avoided the time-consuming manual determination of the inversion time. The data collection consisted of phantom experiments, Monte Carlo simulations of the effect of various heart rates, and clinical investigation of 18 patients with myocardial infarction. Scar images created with the modified sequence were compared to those created with the standard sequence. The 3D PSIR sequence was able to measure T1 relaxation with a high accuracy up to 800 ms, which is in the suitable range for scar imaging. Simulated arrhythmias showed that the method was robust and able to tolerate some variation in heart rate. The modified sequence provides measurements of inversion time that can be used to facilitate standard scar imaging or to reconstruct synthetic scar images. Images of infarct scar obtained with the 3D PSIR sequence bore striking similarity to images obtained with the standard sequence.In Paper 2, 125 patients with high risk of CAD were investigated using the displacement encoding with stimulated echoes (DENSE) sequence. Image segments with infarct scar area >50% (transmurality) could be identified with a sensitivity of 95% and a specificity of 80% based on circumferential strain calculated from the DENSE measurements. The DENSE sequence was also applied in other directions, but its sensitivity and specificity to detect scar was lower than when used for circumferential strain.In Paper 3, 90 patients with high risk of CAD were examined by DENSE, tagging with harmonic phase (HARP) imaging and cine imaging with feature tracking (FT), to detect cardiac abnormalities as manifested in end-systolic circumferential strain. Circumferential strain calculated with DENSE had higher sensitivity and specificity than the competing methods to detect infarction with transmurality >50%. Global circumferential strain measured by DENSE correlated better with global parameters such as left ventricular ejection fraction, myocardial wall mass, left ventricular end-diastolic and end-systolic volume; than strain measured by FT or HARP.In Paper 4, myocardial torsion was investigated using DENSE, HARP, and FT in 48 patients with high risk of CAD. Torsion measured by each of the three methods was correlated with other global measures such as left ventricular ejection fraction, left ventricular mass, and left ventricular end-diastolic and end-systolic volumes. The torsion measurements obtained with DENSE had a stronger relationship with left ventricular ejection fraction, left ventricular mass, and volumes than those obtained with HARP or FT.DENSE was superior to the other methods for strain and torsion measurement and can be used to describe myocardial deformation quantitatively and objectively.
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