The Experts below are selected from a list of 24525 Experts worldwide ranked by ideXlab platform
A Horsley - One of the best experts on this subject based on the ideXlab platform.
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lung clearance index in adults with non cystic fibrosis bronchiectasis
Respiratory Research, 2014Co-Authors: Sherif Gonem, Per E Gustafsson, Alys Scadding, Marcia Soares, Amisha Singapuri, Chandra M. Ohri, Simon Range, Christopher E. Brightling, Ian D. Pavord, A HorsleyAbstract:Lung clearance index (LCI) is a measure of abnormal Ventilation distribution derived from the multiple breath inert gas washout (MBW) technique. We aimed to determine the clinical utility of LCI in non-CF bronchiectasis, and to assess two novel MBW parameters that distinguish between increases in LCI due to Specific Ventilation inequality (LCIvent) and increased respiratory dead space (LCIds). Forty-three patients with non-CF bronchiectasis and 18 healthy control subjects underwent MBW using the sulphur hexafluoride wash-in technique, and data from 40 adults with CF were re-analysed. LCIvent and LCIds were calculated using a theoretical two-compartment lung model, and represent the proportional increase in LCI above its ideal value due to Specific Ventilation inequality and increased respiratory dead space, respectively. LCI was significantly raised in patients with non-CF bronchiectasis compared to healthy controls (9.99 versus 7.28, p 0.75), and correlated significantly with measures of spirometric airflow obstruction. LCI is repeatable, discriminatory, and is associated with spirometric airflow obstruction in patients with non-CF bronchiectasis. LCIvent and LCIds are a practical and repeatable alternative to phase III slope analysis and may allow a further level of mechanistic information to be extracted from the MBW test in patients with severe Ventilation heterogeneity.
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s45 Specific Ventilation inequality and dead space components of lung clearance index in patients with asthma and cystic fibrosis
Thorax, 2013Co-Authors: Sherif Gonem, Per E Gustafsson, A Horsley, Amisha Singapuri, Christopher E. Brightling, Sushiladevi Natarajan, Salman SiddiquiAbstract:Background Lung clearance index (LCI) is a widely reported marker of gas mixing inefficiency within the airways that is derived using the multiple breath inert gas washout (MBW) technique. We developed two novel parameters, LCI vent and LCI ds , to reflect the components of increased LCI due to (i) unequal convective Ventilation between relatively large lung units, and (ii) increased respiratory dead space, respectively. We hypothesised that these parameters would be repeatable, would effectively discriminate between healthy controls and patients with asthma and cystic fibrosis (CF), and would distinguish between different sub-phenotypes of these diseases. Methods Washout data from sixty-six healthy control subjects, seventy-four patients with asthma, and forty-one patients with CF were fitted to a two-compartment model of gas mixing, and the parameters LCI vent and LCI ds were calculated. Results LCI vent and LCI ds were markedly elevated in patients with CF, and mildly elevated in patients with asthma, compared to controls, as illustrated in Figure 1. LCI vent and LCI ds were weakly correlated in controls (R = 0.36, p ds was significantly raised in CF patients with chronic P. aeruginosa colonisation compared to those without chronic colonisation (1.49 vs 1.34, p = 0.004). LCI, LCI vent and LCI ds were significantly raised in CF patients with a severe genotype compared to those with a mild genotype. No significant differences were observed between any of the asthma sub-phenotypes (severe vs non-severe, poorly-controlled vs not poorly controlled, exacerbator vs non-exacerbator, and eosinophilic vs non-eosinophilic) with respect to any MBW parameter. The intraclass correlation coefficients of LCI vent and LCI ds exceeded 0.85 in the asthma and CF groups, and 0.60 in controls. Conclusion The novel parameters LCI vent and LCI ds are repeatable and effectively discriminate between sub-phenotypes of CF, although their utility in asthma is currently unproven. Further studies are required to determine their utility in other airway diseases such as chronic obstructive pulmonary disease, to investigate their role as outcome measures in clinical trials, and to delineate their structural correlates.
Sherif Gonem - One of the best experts on this subject based on the ideXlab platform.
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lung clearance index in adults with non cystic fibrosis bronchiectasis
Respiratory Research, 2014Co-Authors: Sherif Gonem, Per E Gustafsson, Alys Scadding, Marcia Soares, Amisha Singapuri, Chandra M. Ohri, Simon Range, Christopher E. Brightling, Ian D. Pavord, A HorsleyAbstract:Lung clearance index (LCI) is a measure of abnormal Ventilation distribution derived from the multiple breath inert gas washout (MBW) technique. We aimed to determine the clinical utility of LCI in non-CF bronchiectasis, and to assess two novel MBW parameters that distinguish between increases in LCI due to Specific Ventilation inequality (LCIvent) and increased respiratory dead space (LCIds). Forty-three patients with non-CF bronchiectasis and 18 healthy control subjects underwent MBW using the sulphur hexafluoride wash-in technique, and data from 40 adults with CF were re-analysed. LCIvent and LCIds were calculated using a theoretical two-compartment lung model, and represent the proportional increase in LCI above its ideal value due to Specific Ventilation inequality and increased respiratory dead space, respectively. LCI was significantly raised in patients with non-CF bronchiectasis compared to healthy controls (9.99 versus 7.28, p 0.75), and correlated significantly with measures of spirometric airflow obstruction. LCI is repeatable, discriminatory, and is associated with spirometric airflow obstruction in patients with non-CF bronchiectasis. LCIvent and LCIds are a practical and repeatable alternative to phase III slope analysis and may allow a further level of mechanistic information to be extracted from the MBW test in patients with severe Ventilation heterogeneity.
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s45 Specific Ventilation inequality and dead space components of lung clearance index in patients with asthma and cystic fibrosis
Thorax, 2013Co-Authors: Sherif Gonem, Per E Gustafsson, A Horsley, Amisha Singapuri, Christopher E. Brightling, Sushiladevi Natarajan, Salman SiddiquiAbstract:Background Lung clearance index (LCI) is a widely reported marker of gas mixing inefficiency within the airways that is derived using the multiple breath inert gas washout (MBW) technique. We developed two novel parameters, LCI vent and LCI ds , to reflect the components of increased LCI due to (i) unequal convective Ventilation between relatively large lung units, and (ii) increased respiratory dead space, respectively. We hypothesised that these parameters would be repeatable, would effectively discriminate between healthy controls and patients with asthma and cystic fibrosis (CF), and would distinguish between different sub-phenotypes of these diseases. Methods Washout data from sixty-six healthy control subjects, seventy-four patients with asthma, and forty-one patients with CF were fitted to a two-compartment model of gas mixing, and the parameters LCI vent and LCI ds were calculated. Results LCI vent and LCI ds were markedly elevated in patients with CF, and mildly elevated in patients with asthma, compared to controls, as illustrated in Figure 1. LCI vent and LCI ds were weakly correlated in controls (R = 0.36, p ds was significantly raised in CF patients with chronic P. aeruginosa colonisation compared to those without chronic colonisation (1.49 vs 1.34, p = 0.004). LCI, LCI vent and LCI ds were significantly raised in CF patients with a severe genotype compared to those with a mild genotype. No significant differences were observed between any of the asthma sub-phenotypes (severe vs non-severe, poorly-controlled vs not poorly controlled, exacerbator vs non-exacerbator, and eosinophilic vs non-eosinophilic) with respect to any MBW parameter. The intraclass correlation coefficients of LCI vent and LCI ds exceeded 0.85 in the asthma and CF groups, and 0.60 in controls. Conclusion The novel parameters LCI vent and LCI ds are repeatable and effectively discriminate between sub-phenotypes of CF, although their utility in asthma is currently unproven. Further studies are required to determine their utility in other airway diseases such as chronic obstructive pulmonary disease, to investigate their role as outcome measures in clinical trials, and to delineate their structural correlates.
Joseph M Reinhardt - One of the best experts on this subject based on the ideXlab platform.
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registration based regional lung mechanical analysis retrospectively reconstructed dynamic imaging versus static breath hold image acquisition
Proceedings of SPIE, 2009Co-Authors: Kai Ding, Kunlin Cao, Gary E Christensen, Eric A Hoffman, Joseph M ReinhardtAbstract:The lungs undergo expansion and contraction during the respiratory cycle. Since many disease or injury conditions are associated with the biomechanical or material property changes that can alter lung function, there is a great interest in measuring regional lung Ventilation and regional mechanical changes. We describe a technique that uses multiple respiratory-gated CT images and non-rigid 3D image registration to make local estimates of lung tissue expansion. The degree of regional lung expansion is measured using the Jacobian (a function of local partial derivatives) of the registration displacement field. We compare the ventral-dorsal patterns of lung expansion estimated in both retrospectively reconstructed dynamic scans and static breath-hold scans to a xenon CT based measure of Specific Ventilation and a semi-automatic reference standard in four anesthetized sheep studied in the supine orientation. The regional lung expansion estimated by 3D image registration of images acquired at 50% and 75% phase points of the inspiratory portion of the respiratory cycle and 20 cm H2O and 25 cm H2O airway pressures gave the best match between the average Jacobian and the xenon CT Specific Ventilation respectively (linear regression, average r 2 =0 .85 and r 2 =0 .84). The registration accuracy assessed by 200 semi-automatically matched landmarks in both the dynamic and static scans show landmark error on the order of 2 mm.
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registration based estimates of local lung tissue expansion compared to xenon ct measures of Specific Ventilation
Medical Image Analysis, 2008Co-Authors: Joseph M Reinhardt, Kai Ding, Kunlin Cao, Gary E Christensen, Eric A Hoffman, Shalmali V BodasAbstract:Abstract The main function of the respiratory system is gas exchange. Since many disease or injury conditions can cause biomechanical or material property changes that can alter lung function, there is a great interest in measuring regional lung Ventilation and regional Specific volume change. We describe a registration-based technique for estimating local lung expansion from multiple respiratory-gated CT images of the thorax. The degree of regional lung expansion is measured using the Jacobian (a function of local partial derivatives) of the registration displacement field, which we show is directly related to Specific volume change. We compare the ventral–dorsal patterns of lung expansion estimated across five pressure changes to a xenon CT based measure of Specific Ventilation in five anesthetized sheep studied in the supine orientation. Using 3D image registration to match images acquired at 10 cm H 2 O and 15 cm H 2 O airway pressures gave the best match between the average Jacobian and the xenon CT Specific Ventilation (linear regression, average r 2 = 0.73 ).
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registration derived estimates of local lung expansion as surrogates for regional Ventilation
Information Processing in Medical Imaging, 2007Co-Authors: Joseph M Reinhardt, Kai Ding, Gary E Christensen, Eric A Hoffman, Kunlin CaoAbstract:The main function of the respiratory system is gas exchange. Since many disease or injury conditions can cause biomechanical or material property changes that can alter lung function, there is a great interest in measuring regional lung Ventilation. We describe a registration-based technique for estimating local lung expansion from multiple respiratory-gated CT images of the thorax. The degree of regional lung expansion is measured using the Jacobian of the registration displacement field. We compare lung expansion estimated across five pressure changes to a xenon CT based measure of Specific Ventilation, and have shown good agreement (linear regression, r2 = 0.89 during gas wash-in) in one animal.
Mitchell S Albert - One of the best experts on this subject based on the ideXlab platform.
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marked pericardial inhomogeneity of Specific Ventilation at total lung capacity and beyond
Respiratory Physiology & Neurobiology, 2009Co-Authors: James P Butler, Peter Lindholm, Jessica Gereige, Massimo Ferrigno, Mitchell S Albert, Ronn P. Walvick, Stephen H. LoringAbstract:We measured regional Ventilation at 1 liter above functional residual capacity (FRC+1L) and total lung capacity (TLC) in three normal subjects and four elite breath-hold divers, and above TLC after glossopharyngeal insufflation (TLC+GI) in the divers. Hyperpolarized 3He MRI was used to map the local Ventilation per unit volume over the entire lung. At TLC and above, there was markedly increased regional Ventilation of the lungs in the pericardial region compared with the relatively uniform Ventilation throughout the rest of the lung. The distribution of fractional Ventilation regionally was relatively uniform at FRC+1L, with a small non-gravitational cephalocaudal gradient of Specific Ventilation in the supine posture. Our observations at high lung volumes are consistent with the effect of high pleural tension in the concave pericardial region, which promotes expansion of the subjacent lung, leading to a higher local effective compliance and a higher Specific Ventilation.
Shalmali V Bodas - One of the best experts on this subject based on the ideXlab platform.
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registration based estimates of local lung tissue expansion compared to xenon ct measures of Specific Ventilation
Medical Image Analysis, 2008Co-Authors: Joseph M Reinhardt, Kai Ding, Kunlin Cao, Gary E Christensen, Eric A Hoffman, Shalmali V BodasAbstract:Abstract The main function of the respiratory system is gas exchange. Since many disease or injury conditions can cause biomechanical or material property changes that can alter lung function, there is a great interest in measuring regional lung Ventilation and regional Specific volume change. We describe a registration-based technique for estimating local lung expansion from multiple respiratory-gated CT images of the thorax. The degree of regional lung expansion is measured using the Jacobian (a function of local partial derivatives) of the registration displacement field, which we show is directly related to Specific volume change. We compare the ventral–dorsal patterns of lung expansion estimated across five pressure changes to a xenon CT based measure of Specific Ventilation in five anesthetized sheep studied in the supine orientation. Using 3D image registration to match images acquired at 10 cm H 2 O and 15 cm H 2 O airway pressures gave the best match between the average Jacobian and the xenon CT Specific Ventilation (linear regression, average r 2 = 0.73 ).