scholarly journals Improved CT-based estimate of pulmonary gas trapping accounting for scanner and lung-volume variations in a multicenter asthmatic study

2014 ◽  
Vol 117 (6) ◽  
pp. 593-603 ◽  
Author(s):  
Sanghun Choi ◽  
Eric A. Hoffman ◽  
Sally E. Wenzel ◽  
Mario Castro ◽  
Ching-Long Lin
Keyword(s):  
Volume Change ◽  
Healthy Subjects ◽  
Quantitative Computed Tomography ◽  
Therapeutic Interventions ◽  
Misclassification Rate ◽  
Breath Hold ◽  
Air Trapping ◽  
Imaging Protocol ◽  
Air Volume ◽  
Trapping Method

Lung air trapping is estimated via quantitative computed tomography (CT) using density threshold-based measures on an expiration scan. However, the effects of scanner differences and imaging protocol adherence on quantitative assessment are known to be problematic. This study investigates the effects of protocol differences, such as using different CT scanners and breath-hold coaches in a multicenter asthmatic study, and proposes new methods that can adjust intersite and intersubject variations. CT images of 50 healthy subjects and 42 nonsevere and 52 severe asthmatics at total lung capacity (TLC) and functional residual capacity (FRC) were acquired using three different scanners and two different coaching methods at three institutions. A fraction threshold-based approach based on the corrected Hounsfield unit of air with tracheal density was applied to quantify air trapping at FRC. The new air-trapping method was enhanced by adding a lung-shaped metric at TLC and the lobar ratio of air-volume change between TLC and FRC. The fraction-based air-trapping method is able to collapse air-trapping data of respective populations into distinct regression lines. Relative to a constant value-based clustering scheme, the slope-based clustering scheme shows the improved performance and reduced misclassification rate of healthy subjects. Furthermore, both lung shape and air-volume change are found to be discriminant variables for differentiating among three populations of healthy subjects and nonsevere and severe asthmatics. In conjunction with the lung shape and air-volume change, the fraction-based measure of air trapping enables differentiation of severe asthmatics from nonsevere asthmatics and nonsevere asthmatics from healthy subjects, critical for the development and evaluation of new therapeutic interventions.

scholarly journals Registration-based assessment of regional lung function via volumetric CT images of normal subjects vs. severe asthmatics

2013 ◽  
Vol 115 (5) ◽  
pp. 730-742 ◽  
Author(s):  
Sanghun Choi ◽  
Eric A. Hoffman ◽  
Sally E. Wenzel ◽  
Merryn H. Tawhai ◽  
Youbing Yin ◽  
...  
Keyword(s):  
Image Registration ◽  
Volume Change ◽  
Normal Subjects ◽  
Ct Images ◽  
Relative Increase ◽  
Lung Mechanics ◽  
Air Trapping ◽  
Computed Tomographic ◽  
Air Volume ◽  
Anisotropic Deformation

The purpose of this work was to explore the use of image registration-derived variables associated with computed tomographic (CT) imaging of the lung acquired at multiple volumes. As an evaluation of the utility of such an imaging approach, we explored two groups at the extremes of population ranging from normal subjects to severe asthmatics. A mass-preserving image registration technique was employed to match CT images at total lung capacity (TLC) and functional residual capacity (FRC) for assessment of regional air volume change and lung deformation between the two states. Fourteen normal subjects and thirty severe asthmatics were analyzed via image registration-derived metrics together with their pulmonary function test (PFT) and CT-based air-trapping. Relative to the normal group, the severely asthmatic group demonstrated reduced air volume change (consistent with air trapping) and more isotropic deformation in the basal lung regions while demonstrating increased air volume change associated with increased anisotropic deformation in the apical lung regions. These differences were found despite the fact that both PFT-derived TLC and FRC in the two groups were nearly 100% of predicted values. Data suggest that reduced basal-lung air volume change in severe asthmatics was compensated by increased apical-lung air volume change and that relative increase in apical-lung air volume change in severe asthmatics was accompanied by enhanced anisotropic deformation. These data suggest that CT-based deformation, assessed via inspiration vs. expiration scans, provides a tool for distinguishing differences in lung mechanics when applied to the extreme ends of a population range.

scholarly journals A Feasible Computational Fluid Dynamics Study for Relationships of Structural and Functional Alterations with Particle Depositions in Severe Asthmatic Lungs

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Sanghun Choi ◽  
Shinjiro Miyawaki ◽  
Ching-Long Lin
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Turbulent Flows ◽  
Severe Asthma ◽  
Volume Change ◽  
Healthy Subjects ◽  
Particle Deposition ◽  
Specific Flow ◽  
Cfd Models ◽  
Air Volume

This study aims to investigate the effect of altered structures and functions in severe asthma on particle deposition by using computational fluid dynamics (CFD) models. Airway geometrical models of two healthy subjects and two severe asthmatics were reconstructed from computed tomography (CT) images. Subject-specific flow boundary conditions were obtained by image registration to account for regional functional alterations of severe asthmatics. A large eddy simulation (LES) model for transitional and turbulent flows was applied to simulate airflows, and particle transport simulations were then performed for 2.5, 5, and 10 μm particles using CFD-predicted flow fields. Compared to the healthy subjects, the severe asthmatics had a smaller air-volume change in the lower lobes and a larger air-volume change in the upper lobes. Both severe asthmatics had smaller airway circularity (Cr), but one of them had a significant reduction of hydraulic diameter (Dh). In severe asthmatics, the larger air-volume change in the upper lobes resulted in more particles in the upper lobes, especially for the small 2.5 μm particles. The structural alterations measured by Cr and Dh were associated with a higher particle deposition. Dh was found to be the most important metric which affects the specific location of particle deposition. This study demonstrates the relationship of CT-based structural and functional alterations in severe asthma with flow and particle dynamics.

scholarly journals Quantitative assessment of multiscale structural and functional alterations in asthmatic populations

2015 ◽  
Vol 118 (10) ◽  
pp. 1286-1298 ◽  
Author(s):  
Sanghun Choi ◽  
Eric A. Hoffman ◽  
Sally E. Wenzel ◽  
Mario Castro ◽  
Sean B. Fain ◽  
...  
Keyword(s):  
Pulmonary Function ◽  
Functional Residual Capacity ◽  
Volume Change ◽  
Healthy Subjects ◽  
Air Trapping ◽  
Bifurcation Angle ◽  
Computed Tomography Images ◽  
Severe Asthmatic ◽  
Structural Variables ◽  
Residual Capacity

Relationships between structural and functional variables in asthmatic lungs at local and global (or lobar) levels remain to be discovered. This study aims to investigate local alterations of structural variables [bifurcation angle, circularity, airway wall thickness (WT), and hydraulic diameter ( Dh)] in asthmatic subjects, and their correlations with other imaging and pulmonary function test-based global and lobar metrics, including lung shape, air-trapping, regional volume change, and more. Sixty-one healthy subjects, and 67 nonsevere and 67 severe asthmatic subjects were studied. The structural variables were derived from computed tomography images at total lung capacity (TLC). Air-trapping was measured at functional residual capacity, and regional volume change (derived from image registration) was measured between functional residual capacity and TLC. The tracheal diameter and WT predicted by 61 healthy subjects were used to normalize the Dh and WT. New normalization schemes allowed for the dissociation of luminal narrowing and wall thickening effects. In severe asthmatic subjects, the alteration of bifurcation angle was found to be correlated with a global lung shape at TLC, and circularity was significantly decreased in the right main bronchus. While normalized WT increased especially in the upper lobes of severe asthmatic subjects, normalized Dh decreased in the lower lobes. Among local structural variables, normalized Dh was the most representative variable, because it was significantly correlated with alterations of functional variables, including pulmonary function test's data. In conclusion, understanding multiscale phenomena may help to provide guidance in the search for potential imaging-based phenotypes for the development and outcomes assessment of therapeutic intervention.

Supine position decreases the ability of the nose to warm and humidify air

2001 ◽  
Vol 91 (6) ◽  
pp. 2459-2465 ◽  
Author(s):  
Paraya Assanasen ◽  
Fuad M. Baroody ◽  
Edward Naureckas ◽  
Julian Solway ◽  
Robert M. Naclerio
Keyword(s):  
Supine Position ◽  
Healthy Subjects ◽  
Air Conditioning ◽  
Upright Position ◽  
Nasal Mask ◽  
Total Water ◽  
Nasal Turbinate ◽  
Dry Air ◽  
Air Volume ◽  
Water Gradient

We tested the hypothesis that decreasing nasal air volume (i.e., increasing nasal turbinate blood volume) improves nasal air conditioning. We performed a randomized, two-way crossover study on the conditioning capacity of the nose in six healthy subjects in the supine and upright position. Cold, dry air (CDA) was delivered to the nose via a nasal mask, and the temperature and humidity of air were measured before it entered and after it exited the nasal cavity. The total water gradient (TWG) across the nose was calculated and represents the nasal conditioning capacity. Nasal volume decreased significantly from baseline without changing the mucosal temperature when subjects were placed in the supine position ( P < 0.01). TWG in supine position was significantly lower than that in upright position ( P < 0.001). In the supine position, nasal mucosal temperature after CDA exposure was significantly lower than that in upright position ( P < 0.01). Our data show that placing subjects in the supine position decreased the ability of the nose to condition CDA compared with the upright position, in contrast to our hypothesis.

A Diffused Air Volume Indicator for Unsaturated Soils

1975 ◽  
Vol 12 (4) ◽  
pp. 533-539 ◽  
Author(s):  
D. G. Fredlund
Keyword(s):  
Correction Factor ◽  
Volume Change ◽  
Unsaturated Soils ◽  
Effective Means ◽  
Computational Procedure ◽  
Technical Note ◽  
Water Volume ◽  
Volume Weight ◽  
Air Volume ◽  
Change Characteristics

The diffusion of air through saturated high air entry discs presents a serious problem in the testing of unsaturated soils. When determining either the strength (drained) or volume change characteristics of unsaturated soils, a technique must be available to measure the amount of diffused air in order for the appropriate corrections to be applied to the volume–weight relationships.The described diffused air volume indicator is a simple but effective means of measuring the quantity of diffused air. This technical note explains its construction and procedure of operation. Also outlined is the computational procedure for the correction factor that must be applied to the water volume change measurements. Numerous tests on the indicator show a reliability in the order of ±0.2 cc over a period of 2.5 weeks.

scholarly journals Radial-based acquisition strategies for pre-procedural non-contrast cardiovascular magnetic resonance angiography of the pulmonary veins

2020 ◽  
Vol 22 (1) ◽  
Author(s):  
Pascale Aouad ◽  
Ioannis Koktzoglou ◽  
Bastien Milani ◽  
Ali Serhal ◽  
Jose Nazari ◽  
...  
Keyword(s):  
Cardiovascular Magnetic Resonance ◽  
Image Quality ◽  
Healthy Subjects ◽  
Respiratory Gating ◽  
Free Breathing ◽  
Breath Hold ◽  
Thin Slab ◽  
Excellent Correlation ◽  
Acquisition Strategies ◽  
Stack Of Stars

Abstract Background Computed tomography angiography (CTA) or contrast-enhanced (CE) cardiovascular magnetic resonance angiography (CMRA) is often obtained in patients with atrial fibrillation undergoing evaluation prior to pulmonary vein (PV) isolation. Drawbacks of CTA include radiation exposure and potential risks from iodinated contrast agent administration. Free-breathing 3D balanced steady-state free precession (bSSFP) Non-contrast CMRA is a potential imaging option, but vascular detail can be suboptimal due to ghost artifacts and blurring that tend to occur with a Cartesian k-space trajectory or, in some cases, inconsistent respiratory gating. We therefore explored the potential utility of both breath-holding and free-breathing non-contrast CMRA, using radial k-space trajectories that are known to be less sensitive to flow and motion artifacts than Cartesian. Main body Free-breathing 3D Cartesian and radial stack-of-stars acquisitions were compared in 6 healthy subjects. In addition, 27 patients underwent CTA and non-contrast CMRA for PV mapping. Three radial CMR acquisition strategies were tested: (1) breath-hold (BH) 2D radial bSSFP (BH-2D); (2) breath-hold, multiple thin-slab 3D stack-of-stars bSSFP (BH-SOS); and (3) navigator-gated free-breathing (FB) 3D stack-of-star bSSFP using a spatially non-selective RF excitation (FB-NS-SOS). A non-rigid registration algorithm was used to compensate for variations in breath-hold depth. In healthy subjects, image quality and vessel sharpness using a free-breathing 3D SOS acquisition was significantly better than free-breathing (FB) Cartesian 3D. In patients, diagnostic image quality was obtained using all three radial CMRA techniques, with BH-SOS and FB-NS-SOS outperforming BH-2D. There was overall good correlation for PV maximal diameter between BH-2D and CTA (ICC = 0.87/0.83 for the two readers), excellent correlation between BH-SOS and CTA (ICC = 0.90/0.91), and good to excellent correlation between FB-NS-SOS and CTA (ICC = 0.87/0.94). For PV area, there was overall good correlation between BH-2D and CTA (ICC = 0.79/0.83), good to excellent correlation between BH-SOS and CTA (ICC = 0.88/0.91) and excellent correlation between FB-NS-SOS and CTA (ICC = 0.90/0.95). CNR was significantly higher with BH-SOS (mean = 11.04) by comparison to BH-2D (mean = 6.02; P = 0.007) and FB-NS-SOS (mean = 5.29; P = 0.002). Conclusion Our results suggest that a free-breathing stack-of-stars bSSFP technique is advantageous in providing accurate depiction of PV anatomy and ostial measurements without significant degradation from off-resonance artifacts, and with better image quality than Cartesian 3D. For patients in whom respiratory gating is unsuccessful, a breath-hold thin-slab stack-of-stars technique with retrospective motion correction may be a useful alternative.

scholarly journals Short-term Physiologic Consequences of Regional Pulmonary Vascular Occlusion in Pigs

2019 ◽  
Vol 131 (2) ◽  
pp. 336-343 ◽  
Author(s):  
Thomas Langer ◽  
Valentina Castagna ◽  
Serena Brusatori ◽  
Alessandro Santini ◽  
Tommaso Mauri ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Pulmonary Artery ◽  
Dead Space ◽  
Quantitative Computed Tomography ◽  
Vascular Occlusion ◽  
Lung Density ◽  
Air Volume ◽  
Lung Area ◽  
Perfused Lung ◽  
Lung Densitometry

Abstract Editor’s Perspective What We Already Know about This Topic What This Article Tells Us That Is New Background Acute unilateral pulmonary arterial occlusion causes ventilation–perfusion mismatch of the affected lung area. A diversion of ventilation from nonperfused to perfused lung areas, limiting the increase in dead space, has been described. The hypothesis was that the occlusion of a distal branch of the pulmonary artery would cause local redistribution of ventilation and changes in regional lung densitometry as assessed with quantitative computed tomography. Methods In eight healthy, anesthetized pigs (18.5 ± 3.8 kg) ventilated with constant ventilatory settings, respiratory mechanics, arterial blood gases, and quantitative computed tomography scans were recorded at baseline and 30 min after the inflation of the balloon of a pulmonary artery catheter. Regional (left vs. right lung and perfused vs. nonperfused area) quantitative computed tomography was performed. Results The balloon always occluded a branch of the left pulmonary artery perfusing approximately 30% of lung tissue. Physiologic dead space increased (0.37 ± 0.17 vs. 0.43 ± 0.17, P = 0.005), causing an increase in Paco2 (39.8 [35.2 to 43.0] vs. 41.8 [37.5 to 47.1] mmHg, P = 0.008) and reduction in pH (7.46 [7.42 to 7.50] vs. 7.42 [7.38 to 7.47], P = 0.008). Respiratory system compliance was reduced (24.4 ± 4.2 vs. 22.8 ± 4.8 ml · cm H2O−1, P = 0.028), and the reduction was more pronounced in the left hemithorax. Quantitative analysis of the nonperfused lung area revealed a significant reduction in lung density (−436 [−490 to −401] vs. −478 [−543 to −474] Hounsfield units, P = 0.016), due to a reduction in lung tissue (90 ± 23 vs. 81 ± 22 g, P &lt; 0.001) and an increase in air volume (70 ± 22 vs. 82 ± 26 ml, P = 0.022). Conclusions Regional pulmonary vascular occlusion is associated with a diversion of ventilation from nonperfused to perfused lung areas. This compensatory mechanism effectively limits ventilation perfusion mismatch. Quantitative computed tomography documented acute changes in lung densitometry after pulmonary vascular occlusion. In particular, the nonperfused lung area showed an increase in air volume and reduction in tissue mass, resulting in a decreased lung density.

scholarly journals BOLD differences normally attributed to inhibitory control predict symptoms, not task-directed inhibitory control in ADHD

2019 ◽  
Author(s):  
Andre Chevrier ◽  
Russell J. Schachar
Keyword(s):  
Inhibitory Control ◽  
Error Detection ◽  
Healthy Subjects ◽  
Stop Signal ◽  
Therapeutic Interventions ◽  
Stop Signal Task ◽  
Neural Processing ◽  
Significant Group ◽  
Significant Group Difference ◽  
Symptomatic Behavior

AbstractBackgroundAltered brain activity that has been observed in attention deficit hyperactivity disorder (ADHD) while performing cognitive control tasks like the stop signal task (SST), has generally been interpreted as reflecting either weak (under-active) or compensatory (over-active) versions of the same functions as in healthy controls. If so, then regional activities that correlate with the efficiency of inhibitory control (i.e. stop signal reaction time, SSRT) in healthy subjects should also correlate with SSRT in ADHD. Here we test the alternate hypothesis that BOLD differences might instead reflect the redirection of neural processing resources normally used for task-directed inhibitory control, toward actively managing symptomatic behavior. If so, then activities that correlate with SSRT in TD should instead correlate with inattentive and hyperactive symptoms in ADHD.MethodsWe used fMRI in 14 typically developing (TD) and 14 ADHD adolescents performing the SST, and in a replication sample of 14 healthy adults. First we identified significant group BOLD differences during all phases of activity in the SST (i.e. warning, response, reactive inhibition, error detection and post-error slowing). Next, we correlated these phases of activity with SSRT in TD, and with SSRT, inattentive and hyperactive symptom scores in ADHD. We then identified whole brain significant correlations in regions of significant group difference in activity.ResultsOnly three regions of significant group difference were correlated with SSRT in TD and replication groups (left and right inferior frontal gyri (IFG) during error detection, and hypothalamus during post-error slowing). Consistent with regions of altered activity managing symptomatic behavior instead of task-directed behavior, left IFG correlated with greater inattentive score, right IFG correlated with lower hyperactive score, and hypothalamus correlated with greater inattentive score and oppositely correlated with SSRT compared to TD.ConclusionsResults are consistent with stimuli that elicit task-directed integration of neural processing in healthy subjects, instead directing integrated function towards managing symptomatic behavior in ADHD. The ability of the current approach to determine whether altered neural activities reflect comparable functions in ADHD and control groups has broad implications for the development and monitoring of therapeutic interventions.

scholarly journals 509 A biochemical approach to atrial fibrillation in older patients

2021 ◽  
Vol 23 (Supplement_G) ◽  
Author(s):  
Giulia Ricciardi ◽  
Giuseppe Pieraccini ◽  
Claudia Di Serio ◽  
Giancarlo La Marca ◽  
Stefano Fumagalli
Keyword(s):  
Atrial Fibrillation ◽  
Amino Acids ◽  
Healthy Subjects ◽  
Older Patients ◽  
Metabolic Diseases ◽  
The Elderly ◽  
Therapeutic Interventions ◽  
Untargeted Metabolomics ◽  
Clinical Approach ◽  
Laboratory Activity

Abstract Aims Atrial fibrillation (AF) is the most common arrhythmia among the elderly. It is characterized by a disordered electrical activity of the atria and is associated with increased morbidity and mortality. The pathogenesis of AF is not completely understood as it depends on a multifactorial combination of electrical and structural remodelling and inflammation. Metabolomics is the study of the small molecules present in a given biological sample and it has been widely used to determine the metabolic signatures of certain diseases. Untargeted metabolomics consists of a comprehensive screening of all measurable metabolites to identify patterns related to a certain disease, while targeted metabolomics aims at analysing a defined group of metabolites belonging to a specific metabolic pathway or class of compounds. Mass spectrometry (MS), coupled with gas chromatography (GC) and liquid chromatography (LC) offers the possibility of performing quantitative analyses with high selectivity and sensitivity. Aims of this project were to understand the biomolecular mechanisms underlying the onset of AF. Methods We compared plasma samples of older patients with AF with those of healthy subjects. We started from untargeted metabolomics to explore the whole metabolome; then we focused on the lipidomic profile, and, finally, we measured the plasma concentration of acylcarnitines and some amino acids, known to be diagnostic markers of certain metabolic diseases. Fifty patients (age: 76 ± 6 years) and 26 healthy subjects (age: 65 ±19 years) were recruited for the study. A blood sample was drawn by each patient. Samples for metabolomics and lipidomics were processed, respectively, with a GC-MS platform and with high-resolution LC-MS. Results Differences in diseased and healthy metabolomic and lipidomic profiles were not detected, while the concentration of some acylcarnitines and amino acids resulted to be significantly different in the two groups. In particular, two long-chain acylcarnitines (LCACs), C14 and C18:1, were more abundant in the plasma of AF patients, while glycine, which has scavenger properties, had a lower concentration. High levels of circulating LCACs have been associated with cardiovascular diseases and they are known to alter the heart electrophysiology, thus representing a possible marker of the development of arrhythmias. We can hypothesize that the different concentrations we found possibly reflect a higher oxidative and metabolic stress induced by the arrhythmia. Conclusions The alterations of the LCACs we found in AF patients could represent the basis to guide specific therapeutic interventions aimed at reducing the incidence of the hemodynamic and embolic complications of the arrhythmia. In particular, recent guidelines for the management of AF patients introduced the acronym ABC, which means ‘Avoid stroke’—A, ‘Better symptoms management’—B, and ‘Cardiovascular risk and comorbidity management’—C. In this sense, the present research represents an attempt to join and enrich the traditional clinical approach with data derived from laboratory activity, to improve the outcome of the oldest segment of cardiac patients, often presenting rhythm alterations.

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