224 research outputs found
Does Selling State Silver Generate Private Gold? Determinants and Impacts of State House Sales and Acquisitions in New Zealand
New Zealand experienced two natural experiments with respect to state-provided social housing after 1990. First, while continuing to acquire new state houses, the National Government substantially reduced the overall state house stock by selling a greater number of houses either to existing tenants (through the Home Buy scheme) or, if the house was vacant, to other purchasers (vacant sales). From 1999, the Labour-led government ended homebuys, greatly reduced vacant sales and increased acquisitions, resulting in a major increase in the state house stock. We examine determinants of the spatial distribution of homebuys, vacant sales and acquisitions over the period 1991–2006, focusing on levels of, and changes in, local deprivation status and house prices as determinants. Having modelled the determinants of each category, we test whether homebuys, vacant sales, and acquisitions in an area over one five-year period had an effect on changes in local deprivation and house prices in the succeeding five-year period, after controlling for initial levels of, and prior changes in, deprivation and house prices. We find that state house acquisitions in an area led to a subsequent rise in local deprivation, consistent with the policy aim of providing housing to those most in need. While vacant sales had no material effects, a greater number of homebuys in an area led to increased local real house price appreciation over the subsequent five year period. This finding, based on the results of a politically-driven natural experiment, is consistent with the hypothesis that a scheme that transforms existing tenants into homeowners (at the same location) improves community outcomes for the surrounding neighbourhood.state house sales, homeownership
Homeownership, Social Capital and Parental Voice in Schooling
We use New Zealand school board of trustees data to examine whether schools where parents have high rates of homeownership experience high parental voting turnout in elections. We also investigate whether homeownership influences the probability that a school board proceeds to election, indicating parental willingness to serve as a school trustee. Similarly, we examine whether state-owned social housing rates affect these outcomes. We compile results initially without controlling for other factors, and then controlling for a wide range of other characteristics, to test the robustness of simple observed associations between homeownership and state-ownership rates and outcome variables. Our findings show no discernible effect of homeownership on parental voting turnout in school elections after controls are added (contrary to the simple positive association), but a (robust) positive impact of both homeownership and state-ownership rates on the probability that a school holds an election.homeownership, school elections, parental voice, social capital
Cardiac Function Evaluation with Cine MRI of the Heart
This unit describes how to determine hemodynamic parameters of cardiac function such as ejection fraction (EF), end diastolic volume (EDV), end systolic volume (ESV), stroke volume (SV), and cardiac mass, based on experience using a Siemens 1.5 T Sonata scanner. Briefly, cine loops are acquired over several heartbeats, synchronized with the heart cycle by gating of the encoding steps with the patients electrocardiogram (ECG). Recently, it has become feasible to acquire cine loops in real time, although the temporal resolution is not optimal. Options discussed in this unit include breath hold versus free breathing, prospective triggering versus retrospective gating, and volumetric data sets versus biplanar approaches. Patient parameters such as heart rate or rhythm, degree of functional impairment, the presence of valvular disease, and the need to assess for jets from shunts or valve dysfunction are also treated.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/145342/1/cpmia1104.pd
Cardiac Function Evaluation with Cine MRI of the Heart
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/145199/1/cpmia1104.pd
Vessel Segmentation with Automatic Centerline Extraction Using Tubular Tree Segmentation
Presented at CI2BM09 - MICCAI Workshop on Cardiovascular Interventional Imaging and Biophysical Modelling, London, UK, September 20, 2009.The study of the coronary vessel structure is crucial to the diagnosis of atherosclerosis and other cardiovascular diseases, which together account for about 35% of all deaths in the United States per year. Vessel Segmentation from CTA data is challenging because of non-uniform image intensity along the vessel, and the branching and thinning geometry of the vessel tree. We present a novel method for vessel extraction that models the vasculature as a tubular tree and individual vessels as 3D tubes. We create an initial tube from a few seed points within the vessel tree, and then evolve this initial tube using a variational energy optimization approach to capture the vessel while automatically detecting branches in the vessel tree. A significant advantage of our proposed framework is that the center-line of the blood vessel tree, which is useful in defining cross sectional area of the vessel and evaluating stenoses, is detected automatically as the tubular tree evolves. Existing approaches on the other hand need an explicit step for skeletonization of the vessel volume after segmentation. Another benefit is that the parent-child relationships between branches are also automatically obtained, which is useful in fly-through visualization as well as clinical reporting
Evaluation of pericoronary adipose tissue attenuation on CT
Pericoronary adipose tissue (PCAT) is the fat deposit surrounding coronary arteries. Although PCAT is part of the larger epicardial adipose tissue (EAT) depot, it has different pathophysiological features and roles in the atherosclerosis process. While EAT evaluation has been studied for years, PCAT evaluation is a relatively new concept. PCAT, especially the mean attenuation derived from CT images may be used to evaluate the inflammatory status of coronary arteries non-invasively. The most commonly used measure, PCATMA, is the mean attenuation of adipose tissue of 3 mm thickness around the proximal right coronary artery with a length of 40 mm. PCATMA can be analyzed on a per-lesion, per-vessel or per-patient basis. Apart from PCATMA, other measures for PCAT have been studied, such as thickness, and volume. Studies have shown associations between PCATMA and anatomical and functional severity of coronary artery disease. PCATMA is associated with plaque components and high-risk plaque features, and can discriminate patients with flow obstructing stenosis and myocardial infarction. Whether PCATMA has value on an individual patient basis remains to be determined. Furthermore, CT imaging settings, such as kV levels and clinical factors such as age and sex affect PCATMA measurements, which complicate implementation in clinical practice. For PCATMA to be widely implemented, a standardized methodology is needed. This review gives an overview of reported PCAT methodologies used in current literature and the potential use cases in clinical practice.</p
Evaluation of pericoronary adipose tissue attenuation on CT
Pericoronary adipose tissue (PCAT) is the fat deposit surrounding coronary arteries. Although PCAT is part of the larger epicardial adipose tissue (EAT) depot, it has different pathophysiological features and roles in the atheroscle-rosis process. While EAT evaluation has been studied for years, PCAT evaluation is a relatively new concept. PCAT, especially the mean attenuation derived from CT images may be used to evaluate the inflammatory status of coronary arteries non-invasively. The most commonly used measure, PCATMA, is the mean attenuation of adipose tissue of 3 mm thickness around the proximal right coronary artery with a length of 40 mm. PCATMA can be analyzed on a per-lesion, per-vessel or per-patient basis. Apart from PCATMA, other measures for PCAT have been studied, such as thickness, and volume. Studies have shown associations between PCATMA and anatomical and functional severity of coronary artery disease. PCATMA is associated with plaque components and high -risk plaque features, and can discriminate patients with flow obstructing stenosis and myocardial infarction. Whether PCATMA has value on an individual patient basis remains to be determined. Furthermore, CT imaging settings, such as kV levels and clinical factors such as age and sex affect PCATMA measurements, which complicate implementation in clinical practice. For PCATMA to be widely implemented, a standardized methodology is needed. This review gives an overview of reported PCAT methodologies used in current literature and the potential use cases in clinical practice
Clinical Blood Flow Quantification with Segmented k-Space Magnetic Resonance Phase Velocity Mapping
To evaluate the accuracy of segmented k-space magnetic resonance phase velocity mapping (PVM) in quantifying aortic blood flow from through-plane velocity measurements.
Two segmented PVM schemes were evaluated, one with seven lines per segment (seg-7) and one with nine lines per segment (seg-9), in twenty patients with cardiovascular disease. A non-segmented (non-seg) PVM acquisition was also performed to provide the reference data.
There was agreement between the aortic flow curves acquired with segmented and non-segmented PVM. The calculated systolic and total flow volume per cycle from the seg-7 and the seg-9 scans correlated and agreed with the flow volumes from the non-seg scans (differences \u3c 5%). Sign tests showed that there were no statistically significant differences (P-values \u3c 0.05) between the segmented and the non-segmented PVM measurements. Seg-9, which was the fastest among the three sequences, provided adequate spatial and temporal resolution (\u3e 10 phases per cycle)
Relationships of pericoronary and epicardial fat measurements in male and female patients with and without coronary artery disease
INTRODUCTION: Although pericoronary adipose tissue (PCAT) is a component of the epicardial adipose tissue (EAT) depot, they may have different associations to coronary artery disease (CAD). We explored relationships between pericoronary adipose tissue mean attenuation (PCAT MA) and EAT measurements in coronary CT angiography (CCTA) in patients with and without CAD. MATERIAL AND METHODS: CCTA scans of 185 non-CAD and 81 CAD patients (86.4% >50% stenosis) were included and retrospectively analyzed. PCAT MA and EAT density/volume were measured and analyzed by sex, including associations with age, risk factors and tube voltage using linear regression models. RESULTS: In non-CAD and CAD, mean PCAT MA and EAT volume were higher in men than in women (non-CAD: -92.5 ± 10.6HU vs -96.2 ± 8.4HU, and 174.4 ± 69.1 cm 3 vs 124.1 ± 57.3 cm 3; CAD: -92.2 ± 9.0HU vs -97.4 ± 9.7HU, and 193.6 ± 62.5 cm 3 vs 148.5 ± 50.5 cm 3 (p < 0.05)). EAT density was slightly lower in men than women in non-CAD (-96.4 ± 6.3HU vs -94.4 ± 5.5HU (p < 0.05)), and similar in CAD (-98.2 ± 5.2HU vs 98.2 ± 6.4HU). There was strong correlation between PCAT MA and EAT density (non-CAD: r = 0.725, p < 0.001, CAD: r = 0.686, p < 0.001) but no correlation between PCAT MA and EAT volume (non-CAD: r = 0.018, p = 0.81, CAD: r = -0.055, p = 0.63). A weak inverse association was found between EAT density and EAT volume (non-CAD: r = -0.244, p < 0.001, CAD: r = -0.263, p = 0.02). In linear regression models, EAT density was significantly associated with PCAT MA in both non-CAD and CAD patients independent of risk factors and tube voltage. CONCLUSION: In CAD and non-CAD patients, EAT density, but not EAT volume, showed significant associations with PCAT MA. Compared to women, men had higher PCAT MA and EAT volume independently of disease status, but similar or slightly lower EAT density. Differences in trends and relations of PCAT MA and EAT by sex could indicate that personalized interpretation and thresholding is needed. </p
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