| 1. |
- Ahdida, C., et al.
(author)
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Track reconstruction and matching between emulsion and silicon pixel detectors for the SHiP-charm experiment
- 2022
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In: Journal of Instrumentation. - : IOP Publishing. - 1748-0221. ; 17:3
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Journal article (peer-reviewed)abstract
- In July 2018 an optimization run for the proposed charm cross section measurement for SHiP was performed at the CERN SPS. A heavy, moving target instrumented with nuclear emulsion films followed by a silicon pixel tracker was installed in front of the Goliath magnet at the H4 proton beam-line. Behind the magnet, scintillating-fibre, drift-tube and RPC detectors were placed. The purpose of this run was to validate the measurement's feasibility, to develop the required analysis tools and fine-tune the detector layout. In this paper, we present the track reconstruction in the pixel tracker and the track matching with the moving emulsion detector. The pixel detector performed as expected and it is shown that, after proper alignment, a vertex matching rate of 87% is achieved.
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| 2. |
- Ahdida, C., et al.
(author)
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Sensitivity of the SHiP experiment to light dark matter
- 2021
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In: Journal of High Energy Physics (JHEP). - : Springer Nature. - 1126-6708 .- 1029-8479. ; :4
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Journal article (peer-reviewed)abstract
- Dark matter is a well-established theoretical addition to the Standard Model supported by many observations in modern astrophysics and cosmology. In this context, the existence of weakly interacting massive particles represents an appealing solution to the observed thermal relic in the Universe. Indeed, a large experimental campaign is ongoing for the detection of such particles in the sub-GeV mass range. Adopting the benchmark scenario for light dark matter particles produced in the decay of a dark photon, with αD = 0.1 and mA′ = 3mχ, we study the potential of the SHiP experiment to detect such elusive particles through its Scattering and Neutrino detector (SND). In its 5-years run, corresponding to 2 · 1020 protons on target from the CERN SPS, we find that SHiP will improve the current limits in the mass range for the dark matter from about 1 MeV to 300 MeV. In particular, we show that SHiP will probe the thermal target for Majorana candidates in most of this mass window and even reach the Pseudo-Dirac thermal relic.
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| 3. |
- Ahdida, C., et al.
(author)
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Fast simulation of muons produced at the SHiP experiment using Generative Adversarial Networks
- 2019
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In: Journal of Instrumentation. - : IOP PUBLISHING LTD. - 1748-0221. ; 14
-
Journal article (peer-reviewed)abstract
- This paper presents a fast approach to simulating muons produced in interactions of the SPS proton beams with the target of the SHiP experiment. The SHIP experiment will be able to search for new long-lived particles produced in a 400 GeV/c SPS proton beam dump and which travel distances between fifty metres and tens of kilometers. The SHiP detector needs to operate under ultra-low background conditions and requires large simulated samples of muon induced background processes. Through the use of Generative Adversarial Networks it is possible to emulate the simulation of the interaction of 400 GeV/c proton beams with the SHiP target, an otherwise computationally intensive process. For the simulation requirements of the SHiP experiment, generative networks are capable of approximating the full simulation of the dense fixed target, offering a speed increase by a factor of O(10(6)). To evaluate the performance of such an approach, comparisons of the distributions of reconstructed muon momenta in SHiP's spectrometer between samples using the full simulation and samples produced through generative models are presented. The methods discussed in this paper can be generalised and applied to modelling any non-discrete multi-dimensional distribution.
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| 4. |
- Ahdida, C., et al.
(author)
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Measurement of the muon flux from 400 GeV/c protons interacting in a thick molybdenum/tungsten target
- 2020
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In: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 80:3
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Journal article (peer-reviewed)abstract
- The SHiP experiment is proposed to search for very weakly interacting particles beyond the Standard Model which are produced in a 400 GeV/c proton beam dump at the CERN SPS. About 1011muons per spill will be produced in the dump. To design the experiment such that the muon-induced background is minimized, a precise knowledge of the muon spectrum is required. To validate the muon flux generated by our Pythia and GEANT4 based Monte Carlo simulation (FairShip), we have measured the muon flux emanating from a SHiP-like target at the SPS. This target, consisting of 13 interaction lengths of slabs of molybdenum and tungsten, followed by a 2.4 m iron hadron absorber was placed in the H4 400 GeV/c proton beam line. To identify muons and to measure the momentum spectrum, a spectrometer instrumented with drift tubes and a muon tagger were used. During a 3-week period a dataset for analysis corresponding to (3.27 +/- 0.07)x1011protons on target was recorded. This amounts to approximatively 1% of a SHiP spill.
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| 5. |
- Ahdida, C., et al.
(author)
-
Sensitivity of the SHiP experiment to dark photons decaying to a pair of charged particles
- 2021
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In: European Physical Journal C. - : Springer Nature. - 1434-6044 .- 1434-6052. ; 81:5
-
Journal article (peer-reviewed)abstract
- Dark photons are hypothetical massive vector particles that could mix with ordinary photons. The simplest theoretical model is fully characterised by only two parameters: the mass of the dark photon m(gamma)D and its mixing parameter with the photon, epsilon. The sensitivity of the SHiP detector is reviewed for dark photons in the mass range between 0.002 and 10 GeV. Different productionmechanisms are simulated, with the dark photons decaying to pairs of visible fermions, including both leptons and quarks. Exclusion contours are presented and compared with those of past experiments. The SHiP detector is expected to have a unique sensitivity for m. D ranging between 0.8 and 3.3(-0.5)(+0.2) GeV, and epsilon(2) ranging between 10(-11) and 10(-17).
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| 6. |
- Ahdida, C., et al.
(author)
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Sensitivity of the SHiP experiment to Heavy Neutral Leptons
- 2019
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In: Journal of High Energy Physics (JHEP). - 1126-6708 .- 1029-8479. ; :4
-
Journal article (peer-reviewed)abstract
- Heavy Neutral Leptons (HNLs) are hypothetical particles predicted by many extensions of the Standard Model. These particles can, among other things, explain the origin of neutrino masses, generate the observed matter-antimatter asymmetry in the Universe and provide a dark matter candidate. The SHiP experiment will be able to search for HNLs produced in decays of heavy mesons and travelling distances ranging between O(50 m) and tens of kilometers before decaying. We present the sensitivity of the SHiP experiment to a number of HNL's benchmark models and provide a way to calculate the SHiP's sensitivity to HNLs for arbitrary patterns of flavour mixings. The corresponding tools and data files are also made publicly available.
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| 7. |
- Ahdida, C., et al.
(author)
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The experimental facility for the Search for Hidden Particles at the CERN SPS
- 2019
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In: Journal of Instrumentation. - : Institute of Physics Publishing (IOPP). - 1748-0221. ; 14
-
Journal article (peer-reviewed)abstract
- The Search for Hidden Particles (SHiP) Collaboration has shown that the CERN SPS accelerator with its 400 GeV/c proton beam offers a unique opportunity to explore the Hidden Sector [1-3]. The proposed experiment is an intensity frontier experiment which is capable of searching for hidden particles through both visible decays and through scattering signatures from recoil of electrons or nuclei. The high-intensity experimental facility developed by the SHiP Collaboration is based on a number of key features and developments which provide the possibility of probing a large part of the parameter space for a wide range of models with light long-lived super-weakly interacting particles with masses up to O(10) GeV/c(2) in an environment of extremely clean background conditions. This paper describes the proposal for the experimental facility together with the most important feasibility studies. The paper focuses on the challenging new ideas behind the beam extraction and beam delivery, the proton beam dump, and the suppression of beam-induced background.
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| 8. |
- Ahdida, C., et al.
(author)
-
The magnet of the scattering and neutrino detector for the SHiP experiment at CERN
- 2020
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In: Journal of Instrumentation. - 1748-0221. ; 15:01
-
Journal article (peer-reviewed)abstract
- The Search for Hidden Particles (SHiP) experiment proposal at CERN demands a dedicated dipole magnet for its scattering and neutrino detector. This requires a very large volume to be uniformly magnetized at B > 1.2 T, with constraints regarding the inner instrumented volume as well as the external region, where no massive structures are allowed and only an extremely low stray field is admitted. In this paper we report the main technical challenges and the relevant design options providing a comprehensive design for the magnet of the SHiP Scattering and Neutrino Detector.
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| 9. |
- Ahdida, C., et al.
(author)
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The SHiP experiment at the proposed CERN SPS Beam Dump Facility
- 2022
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In: European Physical Journal C. - : Springer Nature. - 1434-6044 .- 1434-6052. ; 82:5
-
Journal article (peer-reviewed)abstract
- The Search for Hidden Particles (SHiP) Collaboration has proposed a general-purpose experimental facility operating in beam-dump mode at the CERN SPS accelerator to search for light, feebly interacting particles. In the baseline configuration, the SHiP experiment incorporates two complementary detectors. The upstream detector is designed for recoil signatures of light dark matter (LDM) scattering and for neutrino physics, in particular with tau neutrinos. It consists of a spectrometer magnet housing a layered detector system with high-density LDM/neutrino target plates, emulsion-film technology and electronic high-precision tracking. The total detector target mass amounts to about eight tonnes. The downstream detector system aims at measuring visible decays of feebly interacting particles to both fully reconstructed final states and to partially reconstructed final states with neutrinos, in a nearly background-free environment. The detector consists of a 50m\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\mathrm { \,m}$$\end{document} long decay volume under vacuum followed by a spectrometer and particle identification system with a rectangular acceptance of 5 m in width and 10 m in height. Using the high-intensity beam of 400GeV\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\,\mathrm {GeV}$$\end{document} protons, the experiment aims at profiting from the 4x1019\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$4\times 10<^>{19}$$\end{document} protons per year that are currently unexploited at the SPS, over a period of 5-10 years. This allows probing dark photons, dark scalars and pseudo-scalars, and heavy neutral leptons with GeV-scale masses in the direct searches at sensitivities that largely exceed those of existing and projected experiments. The sensitivity to light dark matter through scattering reaches well below the dark matter relic density limits in the range from a few MeV/c2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\mathrm {\,MeV\!/}c<^>2}$$\end{document} up to 100 MeV-scale masses, and it will be possible to study tau neutrino interactions with unprecedented statistics. This paper describes the SHiP experiment baseline setup and the detector systems, together with performance results from prototypes in test beams, as it was prepared for the 2020 Update of the European Strategy for Particle Physics. The expected detector performance from simulation is summarised at the end.
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| 10. |
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| 11. |
- Aartsen, M. G., et al.
(author)
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Search for steady point-like sources in the astrophysical muon neutrino flux with 8 years of IceCube data
- 2019
-
In: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 79:3
-
Journal article (peer-reviewed)abstract
- The IceCube Collaboration has observed a high-energy astrophysical neutrino flux and recently found evidence for neutrino emission from the blazar TXS 0506+056. These results open a new window into the high-energy universe. However, the source or sources of most of the observed flux of astrophysical neutrinos remains uncertain. Here, a search for steady point-like neutrino sources is performed using an unbinned likelihood analysis. The method searches for a spatial accumulation of muon-neutrino events using the very high-statistics sample of about 497,000 neutrinos recorded by IceCube between 2009 and 2017. The median angular resolution is approximate to 1 degrees at 1 TeV and improves to approximate to 0.3 degrees for neutrinos with an energy of 1 PeV. Compared to previous analyses, this search is optimized for point-like neutrino emission with the same flux-characteristics as the observed astrophysical muon-neutrino flux and introduces an improved event-reconstruction and parametrization of the background. The result is an improvement in sensitivity to the muon-neutrino flux compared to the previous analysis of approximate to 35% assuming an E-2 spectrum. The sensitivity on the muon-neutrino flux is at a level of E2dN/dE=310-13s-1. No new evidence for neutrino sources is found in a full sky scan and in an a priori candidate source list that is motivated by gamma-ray observations. Furthermore, no significant excesses above background are found from populations of sub-threshold sources. The implications of the non-observation for potential source classes are discussed.
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| 12. |
- Sakornsakolpat, Phuwanat, et al.
(author)
-
Genetic landscape of chronic obstructive pulmonary disease identifies heterogeneous cell-type and phenotype associations
- 2019
-
In: Nature Genetics. - : Springer Science and Business Media LLC. - 1061-4036 .- 1546-1718. ; 51:3, s. 494-505
-
Journal article (peer-reviewed)abstract
- Chronic obstructive pulmonary disease (COPD) is the leading cause of respiratory mortality worldwide. Genetic risk loci provide new insights into disease pathogenesis. We performed a genome-wide association study in 35,735 cases and 222,076 controls from the UK Biobank and additional studies from the International COPD Genetics Consortium. We identified 82 loci associated with P < 5 x 10-8; 47 of these were previously described in association with either COPD or population-based measures of lung function. Of the remaining 35 new loci, 13 were associated with lung function in 79,055 individuals from the SpiroMeta consortium. Using gene expression and regulation data, we identified functional enrichment of COPD risk loci in lung tissue, smooth muscle, and several lung cell types. We found 14 COPD loci shared with either asthma or pulmonary fibrosis. COPD genetic risk loci clustered into groups based on associations with quantitative imaging features and comorbidities. Our analyses provide further support for the genetic susceptibility and heterogeneity of COPD.
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| 13. |
- Stolk, Jan, et al.
(author)
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Randomised controlled trial for emphysema with a selective agonist of the gamma-type retinoic acid receptor
- 2012
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In: European Respiratory Journal. - : European Respiratory Society (ERS). - 1399-3003 .- 0903-1936. ; 40:2, s. 306-312
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Journal article (peer-reviewed)abstract
- Palovarotene is an oral gamma-selective retinoid agonist. In animal emphysema models, palovarotene reduced inflammation, promoted structural repair and functional improvement. REPAIR (Retinoid treatment of Emphysema in Patients on the alpha(1)-antitrypsin International Registry), was an investigator-initiated, double-blind, placebo-controlled randomised study to assess the safety and efficacy of 5 mg.day(-1) palovarotene given for 1 year to 262 patients with severe alpha(1)-antitrypsin deficiency and emphysema confirmed by computed tomography. Change in volume-adjusted 15th percentile point lung density from baseline in 1 year was the primary endpoint; functional end-points were also regularly assessed. We randomly assigned 133 and 129 patients to placebo or palovarotene, respectively. Both groups were well matched for all baseline characteristics, including respiratory medications. 88% and 85% of patients completed 1 year of treatment with placebo and palovarotene, respectively. Palovarotene was generally well tolerated. In the study completers population, the placebo-corrected difference of lung density was -0.45 HU at week 28 (p=0.64) and -0.25 HU at week 52 (p=0.94). A nonsignificant treatment difference in most functional parameters of the lung in favour of the drug was observed over time suggesting potential pharmacological effects of palovarotene. Palovarotene 5 mg.day(-1) over 1 yr failed to show a significant benefit on lung density in moderate-to-severe emphysema secondary to severe alpha(1)-antitrypsin deficiency.
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| 14. |
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| 15. |
- Mostafavi, Behrouz, et al.
(author)
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Lung function and CT lung densitometry in 37-to 39-year-old individuals with alpha-1-antitrypsin deficiency
- 2018
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In: International Journal of COPD. - 1176-9106. ; 13, s. 3689-3698
-
Journal article (peer-reviewed)abstract
- Background: Alpha-1-antitrypsin (AAT) deficiency is a hereditary disorder that predisposes to emphysema. A cohort of severe (PiZZ) and moderate (PiSZ) AAT-deficient newborn infants was identified by the Swedish national neonatal AAT screening program in 1972–1974 and has been followed-up since birth. Our aim was to study whether the cohort has signs of emphysema in pulmonary function tests (PFTs) and computed tomography (CT) densitometry at 38 years of age in comparison with an age-matched control group, randomly selected from the population registry. Methods: Forty-one PiZZ, 18 PiSZ, and 61 control subjects (PiMM) underwent complete PFTs, measurement of resistance and reactance in the respiratory system by impulse oscillometry (IOS)/forced oscillation technique (FOT), and CT densitometry. The results were related to self-reported smoking habits. Results: The total lung capacity (TLC) % of the predicted value was significantly higher in the PiZZ ever-smokers than in the PiZZ never-smokers (P<0.05), PiSZ never-smokers (P=0.01) and the PiMM never-smokers (P=0.01). The residual volume (RV) % of the predicted value was significantly higher in the PiZZ ever-smokers compared to the PiMM never-smokers (P<0.01). The PiZZ ever-smokers had a significantly lower carbon monoxide transfer coefficient (Kco) than the PiSZ never-smokers (P<0.01) and PiMM never-smokers (P<0.01). Respiratory system resistance at 5 Hz (P<0.01), at 20 Hz (P<0.01), and the area of low reactance (Alx; P<0.05) were significantly lower and respiratory system reactance at 5 Hz (P<0.05) was significantly higher in PiZZ subjects compared to the PiMM subjects. No statistically significant differences in the CT densitometry parameters were found between the Pi subgroups. Conclusion: The physiological parameters in the PiZZ ever-smokers showed evidence of hyperinflation and emphysema before the age of 40 years.
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| 16. |
- Stockley, Robert A., et al.
(author)
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Therapeutic efficacy of alpha-1 antitrypsin augmentation therapy on the loss of lung tissue: an integrated analysis of 2 randomised clinical trials using computed tomography densitometry
- 2010
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In: Respiratory Research. - : Springer Science and Business Media LLC. - 1465-9921 .- 1465-993X. ; 11
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Journal article (peer-reviewed)abstract
- Background: Two randomised, double-blind, placebo-controlled trials have investigated the efficacy of IV alpha-1 antitrypsin (AAT) augmentation therapy on emphysema progression using CT densitometry. Methods: Data from these similar trials, a 2-center Danish-Dutch study (n = 54) and the 3-center EXAcerbations and CT scan as Lung Endpoints (EXACTLE) study (n = 65), were pooled to increase the statistical power. The change in 15(th) percentile of lung density (PD15) measured by CT scan was obtained from both trials. All subjects had 1 CT scan at baseline and at least 1 CT scan after treatment. Densitometric data from 119 patients (AAT [Alfalastin (R) or Prolastin (R)], n = 60; placebo, n = 59) were analysed by a statistical/endpoint analysis method. To adjust for lung volume, volume correction was made by including the change in log-transformed total lung volume as a covariate in the statistical model. Results: Mean follow-up was approximately 2.5 years. The mean change in lung density from baseline to last CT scan was -4.082 g/L for AAT and -6.379 g/L for placebo with a treatment difference of 2.297 (95% CI, 0.669 to 3.926; p = 0.006). The corresponding annual declines were -1.73 and -2.74 g/L/yr, respectively. Conclusions: The overall results of the combined analysis of 2 separate trials of comparable design, and the only 2 controlled clinical trials completed to date, has confirmed that IV AAT augmentation therapy significantly reduces the decline in lung density and may therefore reduce the future risk of mortality in patients with AAT deficiency-related emphysema.
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| 17. |
- Stoel, Berend C., et al.
(author)
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Eureka?
- 2011
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In: Radiology. - : Radiological Society of North America (RSNA). - 1527-1315 .- 0033-8419. ; 259:2, s. 610-611
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Journal article (peer-reviewed)
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| 18. |
- Stolk, Jan, et al.
(author)
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Progression parameters for emphysema: A clinical investigation
- 2007
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In: Respiratory Medicine. - : Elsevier BV. - 1532-3064 .- 0954-6111. ; 101:9, s. 1924-1930
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Journal article (peer-reviewed)abstract
- In patients with airflow limitation caused by cigarette smoking, lung density measured by computed tomography is strongly correlated with quantitative pathology scores of emphysema, but the ability of lung densitometry to detect progression of emphysema is disputed. We assessed the sensitivity of lung densitometry as a parameter of disease progression of emphysema in comparison to FEV1 and gas transfer. At study baseline and after 30 months we measured computed tomography (CT)-derived lung density, spirometry and carbon monoxide diffusion coefficient in 144 patients with chronic obstructive pulmonary disease (COPD) in five different centers. Annual change in lung density was 1.31 g/L/year (CI 95%: -2.12 to -0.50 HU, p = 0.0015, 39.5 mL/year (CI 95%: -100.0-21.0 mL, p = 0.2) for FEV1, (-39.5 mL) and 24.3 mu mol/min/kPa/L/year for gas transfer (CI 95%: -61.0-12.5 mu mol/min/kPa/L/year, p = 0.2). Signal-to-noise ratio (mean change divided by standard error of the change) for the detection of annual change was 3.2 for lung densitometry, but 1.3 for both FEV1 and gas diffusion. We conclude that detection of progression of emphysema was found to be 2.5-fold more sensitive using lung densitometry than by using currently recommended lung function parameters. Our results support CT scan as an efficacious test for novel drugs for emphysema. (c) 2007 Published by Elsevier Ltd.
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| 19. |
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