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Background: High-resolution computed tomography (HRCT) scans can help identify subsets of asthma patients who show rapid decline in lung function. Purpose: To evaluate high-resolution computed tomography (HRCT) findings in adult patients with asthma, obtain quantitative measurements of air trapping on expiratory scans, and correlate the findings with pulmonary function tests (PFTs). Material and Methods: Thirty adults with asthma with persistent-mild, persistent-moderate, and persistent-severe categories as per standard clinical guidelines were evaluated with inspiratory and expiratory HRCT for various imaging features of bronchial asthma. Expiratory HRCT scan were used to quantify degree of air-trapping, and their values quantified as "pixel index," using a special "density' mask" software. Complete spirometry and body plethysmography were performed on each patient within 0–2 days of HRCT scans. HRCT findings were correlated with the clinical severity groups and the CT pixel indices (PI) were correlated with the PFT results using correlation coefficients and linear regression analysis. Results: The inspiratory CT findings did not correlate with increase in disease severity. Expiratory scans accurately quantified areas of air trapping. CT-PI correlated well with PFT values indicative of airway obstruction and airflow limitation, which helped differentiate patients with asthma with increasing severity from those with milder forms of the disease. Conclusion: Expiratory thin-section CT is a useful objective method to quantify air-trapping in people with asthma. The air-trapping score measured in "pixel indices" correlates well with PFT results and can successfully identify patients with severe asthma. Further studies are needed to confirm if this parameter can serve as a potential marker for airway remodeling and declining lung function. [ABSTRACT FROM AUTHOR]

Background: Obesity is known to diminish lung volumes and worsen asthma. However, mechanistic understanding is lacking, especially as concerns small‐airway responsiveness. The objective of this study was therefore to compare small‐airway responsiveness, as represented by the change in expiratory:inspiratory mean lung density ratios (MLDe/i, as determined by computed tomography [CT]) throughout methacholine testing in obese versus non‐obese women with asthma. Methods: Thoracic CT was performed during methacholine bronchoconstriction challenges to produce standardized response curves (SRC: response parameter versus ln[1 + % PD20], where PD20 is the cumulative methacholine dose) for 31 asthma patients (n = 18 non‐obese and n = 13 obese patients). Mixed models evaluated obesity effects and interactions on SRCs while adjusting for age and bronchial morphology. Small airway responsiveness as represented by SRC slope was calculated for each third of the MLDe/i response and compared between groups. Results: Obesity‐associated effects observed during experimental bronchoconstriction included: (i) a significant baseline effect for forced expiratory volume in 1 second with lower values for the obese (73.11 ± 13.44) versus non‐obese (82.19 ± 8.78; p = 0.002) groups prior to methacholine testing and (ii) significantly higher responsiveness in small airways as estimated via differences in MLDe/i slopes (group×ln(1 + % PD20 interaction; p = 0.023). The latter were pinpointed to higher slopes in the obese group at the beginning 2/3 of SRCs (p = 0.004 and p = 0.021). Significant obesity effects (p = 0.035 and p = 0.008) indicating lower forced vital capacity and greater % change in MLDe/I (respectively) throughout methacholine testing, were also observed. Conclusion: In addition to baseline differences, small‐airway responsiveness (as represented by the change in MLDe/i) during methacholine challenge is greater in obese women with asthma as compared to the non‐obese. [ABSTRACT FROM AUTHOR]

Objectives: The study reports our experience with paired inspiration/expiration thin-section computed tomographic (CT) scans in the follow-up of COVID-19 patients with persistent respiratory symptoms. Methods: From August 13, 2020, to May 31, 2021, 48 long-COVID patients with respiratory symptoms (27 men and 21 women; median age, 62.0 years; interquartile range: 54.0–69.0 years) underwent follow-up paired inspiration-expiration thin-section CT scans. Patient demographics, length of hospital stay, intensive care unit admission rate, and clinical and laboratory features of acute infection were also included. The scans were obtained on a median of 72.5 days after onset of symptoms (interquartile range: 58.5–86.5) and at least 30 days after hospital discharge. Thin-section CT findings included ground-glass opacity, mosaic attenuation pattern, consolidation, traction bronchiectasis, reticulation, parenchymal bands, bronchial wall thickening, and air trapping. We used a quantitative score to determine the degree of air trapping in the expiratory scans. Results: Parenchymal abnormality was found in 50% (24/48) of patients and included air trapping (37/48, 77%), ground-glass opacities (19/48, 40%), reticulation (18/48, 38%), parenchymal bands (15/48, 31%), traction bronchiectasis (9/48, 19%), mosaic attenuation pattern (9/48, 19%), bronchial wall thickening (6/48, 13%), and consolidation (2/48, 4%). The absence of air trapping was observed in 11/48 (23%), mild air trapping in 20/48 (42%), moderate in 13/48 (27%), and severe in 4/48 (8%). Independent predictors of air trapping were, in decreasing order of importance, gender (p = 0.0085), and age (p = 0.0182). Conclusions: Our results, in a limited number of patients, suggest that follow-up with paired inspiratory/expiratory CT in long-COVID patients with persistent respiratory symptoms commonly displays air trapping. Key Points: • Our experience indicates that paired inspiratory/expiratory CT in long-COVID patients with persistent respiratory symptoms commonly displays air trapping. • Iterative reconstruction and dose-reduction options are recommended for demonstrating air trapping in long-COVID patients. [ABSTRACT FROM AUTHOR]

In contrast to studies of adults with emphysema, application of fixed thresholds to determine low- and high-attenuation areas (air-trapping and parenchymal lung disease) in pediatric quantitative chest CT is problematic. We aimed to assess age effects on: (i) mean lung attenuation (full inspiration); and (ii) low and high attenuation thresholds (LAT and HAT) defined as mean attenuation and 1 SD below and above mean, respectively. Chest CTs from children aged 6–17 years without abnormalities were retrieved, and histograms of attenuation coefficients were analyzed. Eighty examinations were included. Inverse functions described relationships between age and mean lung attenuation, LAT or HAT (p < 0.0001). Predicted value for LAT decreased from −846 HU in 6-year-old to −950 HU in 13- to 17-year-old subjects (cut-off value for assessing emphysema in adults). %TLCCT with low attenuation correlated with age (rs = −0.31; p = 0.005) and was <5% for 9–17-year-old subjects. Inverse associations were demonstrated between: (i) %TLCCT with high attenuation and age (r² = 0.49; p < 0.0001); (ii) %TLCCT with low attenuation and TLCCT (r² = 0.47; p < 0.0001); (iii) %TLCCT with high attenuation and TLCCT (r² = 0.76; p < 0.0001). In conclusion, quantitative analysis of chest CTs from children without lung disease can be used to define age-specific LAT and HAT for evaluation of pediatric lung disease severity. [ABSTRACT FROM AUTHOR]

Air-trapping affects clinical outcomes in patients with chronic obstructive pulmonary disease (COPD) and may be detected by reactance at 5 Hz (X5) on respiratory oscillometry because X5 sensitively reflects the elasticity of the chest wall, airway and lung. However, the longitudinal association between X5 and air-trapping remains to be explored. This study aimed to test whether longitudinal changes in X5 could be associated with air-trapping progression, exacerbations, and mortality in patients with COPD. In this prospective COPD observational study, the follow-up period consisted of the first 4 years to obtain longitudinal changes in X5 and residual volume (RV) and number of exacerbations and the remaining years (year 4 to 10) to test mortality. Patients were divided into large, middle, and small X5 decline groups based on the tertiles of longitudinal change in X5, and mortality after 4 years was compared between the groups. Patients with COPD (n = 114) were enrolled. The large X5 decline group (n = 38) showed a greater longitudinal change in RV and more exacerbations compared with the small X5 decline group (n = 39) in multivariable models adjusted for age, sex, body mass index, and smoking history. Long-term mortality after the 4-year follow-up was higher in the large X5 decline group than in the small X5 decline group (hazard ratio [95 % confidence interval] = 8.37[1.01, 69.0]) in the multivariable Cox proportional hazard model. Longitudinal changes in respiratory reactance could be associated with progressive air-trapping, exacerbation frequency, and increased mortality in patients with COPD. ● The study investigated longitudinal change in respiratory reactance in COPD. ● Longitudinal change in reactance was associated with air trapping and exacerbations. ● Greater change in reactance was associated with higher long-term mortality. [ABSTRACT FROM AUTHOR]

Nilakash Das,1 Marko Topalovic,1 Jean-Marie Aerts,2 Wim Janssens1 1Laboratory of Respiratory Diseases, Department of Chronic Diseases, Metabolism and Ageing, Katholieke Universiteit Leuven, Leuven, Belgium; 2Division of Animal and Human Health Engineering, Department of Biosystems, Katholieke Universiteit Leuven, Leuven, Belgium Background: Severe hyperinflation causes detrimental effects such as dyspnea and reduced exercise capacity and is an independent predictor of mortality in COPD patients. Static lung volumes are required to diagnose severe hyperinflation, which are not always accessible in primary care. Several studies have shown that the area under the forced expiratory flow-volume loop (AreaFE) is highly sensitive to bronchodilator response and is correlated with residual volume/total lung capacity (RV/TLC), a common index of air trapping. In this study, we investigate the role of AreaFE% (AreaFE expressed as a percentage of reference value) and conventional spirometry parameters in indicating severe hyperinflation. Materials and methods: We used a cohort of 215 individuals with COPD. The presence of severe hyperinflation was defined as elevated air trapping (RV/TLC >60%) or reduced inspiratory fraction (inspiratory capacity [IC]/TLC 60% and IC/TLC

In contrast to studies of adults with emphysema, application of fixed thresholds to determine low- and high-attenuation areas (air-trapping and parenchymal lung disease) in pediatric quantitative chest CT is problematic. We aimed to assess age effects on: (i) mean lung attenuation (full inspiration); and (ii) low and high attenuation thresholds (LAT and HAT) defined as mean attenuation and 1 SD below and above mean, respectively. Chest CTs from children aged 6–17 years without abnormalities were retrieved, and histograms of attenuation coefficients were analyzed. Eighty examinations were included. Inverse functions described relationships between age and mean lung attenuation, LAT or HAT (p < 0.0001). Predicted value for LAT decreased from −846 HU in 6-year-old to −950 HU in 13- to 17-year-old subjects (cut-off value for assessing emphysema in adults). %TLCCT with low attenuation correlated with age (rs = −0.31; p = 0.005) and was CT with high attenuation and age (r2 = 0.49; p < 0.0001); (ii) %TLCCT with low attenuation and TLCCT (r2 = 0.47; p < 0.0001); (iii) %TLCCT with high attenuation and TLCCT (r2 = 0.76; p < 0.0001). In conclusion, quantitative analysis of chest CTs from children without lung disease can be used to define age-specific LAT and HAT for evaluation of pediatric lung disease severity.

Featured Application: Authors are encouraged to provide a concise description of the specific application or a potential application of the work. This section is not mandatory. Spirometry is the gold standard to detect airflow limitation, but it does not measure airway resistance, which is one of the physiological factors behind airflow limitation. In this study, we describe the dynamics of forced expiration in spirometry using a deflating balloon and using this model. We propose a methodology to estimate ζ (zeta), a dimensionless and effort-independent parameter quantifying airway resistance. In N = 462 (65 ± 8 years), we showed that ζ is significantly (p < 0.0001) greater in COPD (2.59 ± 0.99) than healthy smokers (1.64 ± 0.18), it increased significantly (p < 0.0001) with the severity of airflow limitation and it correlated significantly (p < 0.0001) with airway resistance (r = 0.55) and specific conductance (r = −0.60) obtained from body-plethysmography. ζ also showed significant associations (p < 0.001) with diffusion capacity (r = −0.64), air-trapping (r = 0.68), and CT densitometry of emphysema (r = 0.40 against % below −950 HU and r = −0.34 against 15th percentile HU). Moreover, simulation studies demonstrated that an increase in ζ resulted in lower airflows from baseline. Therefore, we conclude that ζ quantifies airway resistance from forced expiration in spirometry—a method that is more abundantly available in primary care than traditional but expensive methods of measuring airway resistance such as body-plethysmography and forced oscillation technique. [ABSTRACT FROM AUTHOR]

Abstract Objective To evaluate the utility of radiodensity ratio between lungs on chest X-ray for the diagnosis of radiolucent foreign body aspiration (FBA) in children. Methods X-rays of 33 patients with confirmed diagnosis of FBA by bronchoscopy were compared to 66 control patients. We divided the study group into three subgroups: symmetric (13-patients), right-oblique (RO;12-patients) and left-oblique (LO;8-patients). Results When we compared FBA-symmetric-subgroup to symmetric-control-group, FBA-RO-subgroup to RO-control-group and FBA-LO-subgroup to LO-control-group, radiodensity ratios were significantly higher in the FBA subgroups. Conclusion The calculated radiodensity ratio between lungs on X-ray would be a useful and practical tool for the diagnosis of radiolucent FBA in children. Highlights • To improve diagnostic accuracy of X-ray in evaluation for radiolucent FBA. • Foreign body aspiration increases the radiodensity ratio between lungs. • For patients with radiodensity ratio > 1.10, we would suggest bronchoscopy. • Exposure to ionizing radiation can be decreased in children with suspected FBA by avoiding CT examination. [ABSTRACT FROM AUTHOR]

Purpose: Quantitative computed tomography (QCT)‐derived measures of lung density are valued methods for objectively characterizing lung parenchymal and peripheral airways disease and are being used in a growing number of lung disease focused trials. Detector and reconstruction improvements in CT technology have allowed for significant radiation dose reduction in image acquisition with comparable qualitative image quality. We report the impact of detector type and reconstruction type on QCT lung density measures in relation to decreasing dose indices. Methods: Two sets of studies were completed in an in vivo pig model with a SOMATOM Definition Flash CT system: (a) prior to system upgrade with conventional detectors (UFC) and filtered back projection (FBP), and (b) post system upgrade with integrated electronic detectors (STELLAR) and iterative reconstruction (SAFIRE). CT data were acquired across estimated CT volume dose indices (CTDIvol) ranging from 0.75 to 15 mGy at both inspiratory and expiratory breath holds. Semiautomated lung segmentations allowed calculation of histogram median, kurtosis, and 15th percentile. Percentage of voxels below −910 HU and −950 HU (inspiratory), and −856 HU (expiratory) were also examined. The changes in these QCT metrics from dose reduction (15 mGy down to 0.75 mGy) were calculated relative to paired reference values (15 mGy). Results were compared based on detector and reconstruction type. Results: In this study, STELLAR detectors improved concordance with 15 mGy values down to 3 mGy for inspiratory scans and 6 mGy for expiratory scans. The addition of SAFIRE reconstruction in all acquired measurements resulted in minimal deviation from reference values at 0.75 mGy. Conclusion: The use of STELLAR integrated electronic detectors and SAFIRE iterative reconstruction may allow for comparable lung density measures with CT dose indices down to 0.75 mGy. [ABSTRACT FROM AUTHOR]

Spirometry is the gold standard to detect airflow limitation, but it does not measure airway resistance, which is one of the physiological factors behind airflow limitation. In this study, we describe the dynamics of forced expiration in spirometry using a deflating balloon and using this model. We propose a methodology to estimate ζ (zeta), a dimensionless and effort-independent parameter quantifying airway resistance. In N = 462 (65 ± 8 years), we showed that ζ is significantly (p < 0.0001) greater in COPD (2.59 ± 0.99) than healthy smokers (1.64 ± 0.18), it increased significantly (p < 0.0001) with the severity of airflow limitation and it correlated significantly (p < 0.0001) with airway resistance (r = 0.55) and specific conductance (r = −0.60) obtained from body-plethysmography. ζ also showed significant associations (p < 0.001) with diffusion capacity (r = −0.64), air-trapping (r = 0.68), and CT densitometry of emphysema (r = 0.40 against % below −950 HU and r = −0.34 against 15th percentile HU). Moreover, simulation studies demonstrated that an increase in ζ resulted in lower airflows from baseline. Therefore, we conclude that ζ quantifies airway resistance from forced expiration in spirometry—a method that is more abundantly available in primary care than traditional but expensive methods of measuring airway resistance such as body-plethysmography and forced oscillation technique.

CysLT 1 receptors are known to be involved in the pathogenesis of asthma. However, the functional roles of CysLT 2 receptors in this condition have not been determined. The purpose of this study is to develop an experimental model of CysLT 2 receptor-mediated LTC 4 -induced lung air-trapping in guinea pigs and use this model to clarify the mechanism underlying response to such trapping. Because LTC 4 is rapidly converted to LTD 4 by γ-glutamyltranspeptidase (γ-GTP) under physiological conditions, S-hexyl GSH was used as a γ-GTP inhibitor. In anesthetized artificially ventilated guinea pigs with no S-hexyl GSH treatment, i.v. LTC 4 -induced bronchoconstriction was almost completely inhibited by montelukast, a CysLT 1 receptor antagonist, but not by BayCysLT 2 RA, a CysLT 2 receptor antagonist. The inhibitory effect of montelukast was diminished by treatment with S-hexyl GSH, whereas the effect of BayCysLT 2 RA was enhanced with increasing dose of S-hexyl GSH. Macroscopic and histological examination of lung tissue isolated from LTC 4 -/S-hexyl-GSH-treated guinea pigs revealed air-trapping expansion, particularly at the alveolar site. Inhaled LTC 4 in conscious guinea pigs treated with S-hexyl GSH increased both airway resistance and airway hyperinflation. On the other hand, LTC 4 -induced air-trapping was only partially suppressed by treatment with the bronchodilator salmeterol. Although montelukast inhibition of LTC 4 -induced air-trapping was weak, treatment with BayCysLT 2 RA resulted in complete suppression of this air-trapping. Furthermore, BayCysLT 2 RA completely suppressed LTC 4 -induced airway vascular hyperpermeability. In conclusion, we found in this study that CysLT 2 receptors mediate LTC 4 -induced bronchoconstriction and air-trapping in S-hexyl GSH-treated guinea pigs. It is therefore believed that CysLT 2 receptors contribute to asthmatic response involving air-trapping. [ABSTRACT FROM AUTHOR]

Purpose: We compared the clinical and quantitative CT measurement parameters between chronic obstructive pulmonary disease (COPD) patients with and without consistent clinical symptoms and pulmonary function results. Materials and Methods: This study included 60 patients having a clinical diagnosis of COPD, who underwent chest CT scan and pulmonary function tests. These 60 patients were classified into typical and atypical groups, which were further sub-classified into 4 groups, based on their dyspnea score and the result of pulmonary function tests [typical 1: mild dyspnea and pulmonary function impairment (PFI); typical 2: severe dyspnea and PFI; atypical 1: mild dyspnea and severe PFI; atypical 2: severe dyspnea and mild PFI]. Quantitative measurements of the CT data for emphysema, bronchial wall thickness and air-trapping were performed using software analysis. Comparative statistical analysis was performed between the groups. Results: The CT emphysema index correlated well with the results of the pulmonary functional test (typical 1 vs. atypical 1, p = 0.032), and the bronchial wall area ratio correlated with the dyspnea score (typical 1 vs. atypical 2, p = 0.033). CT air-trapping index also correlated with the results of the pulmonary function test (typical 1 vs. atypical 1, p = 0.012) and dyspnea score (typical 1 vs. atypical 2, p = 0.000), and was found to be the most significant parameter between the typical and atypical groups. Conclusion: Quantitative CT measurements for emphysema and airways correlated well with the dyspnea score and pulmonary function results in patients with COPD. Air-trapping was the most significant parameter between the typical vs. atypical group of COPD patients. [ABSTRACT FROM AUTHOR]

Background: Chronic obstructive pulmonary disease (COPD) is one of the most prevalent and dangerous pulmonary diseases in the world. It is forecasted that COPD will be the third deadly disease in the future. Therefore, developing non-invasive methods for diagnosis of the disease would be helpful for physicians and patients. Methods: Based on clinical investigations and spirometry tests, ten adult patients with COPD (6 male and 4 female) with mean age of 49.8 years were enrolled as the case group. In addition, ten age and sex-matched healthy, non-COPD individuals (6 male and 4 female) with mean age of 45.4 years were recruited as the controls. Lung CT-scan images of the subjects were processed and analyzed by a computer to find a relationship. Findings: The elasticity of lung parenchyma variation was obtained with digital image processing. The normalized average of this pattern was found to be 21.6% in patients and 40.7% in controls. In addition, normalized mean value of Hounsfield unit variations in square 10 pixel × 10 pixel windows in the expiratory images were calculated as a parameter of air-trapping in COPD. Differences between the groups were shown by student t-test (P < 0.05). Conclusion: This study showed that the variation of lung parenchyma elasticity and Hounsfield units are found by processing and analysis of the full inspiration and expiration images. These factors can be used as criteria in diagnosis of COPD. Moreover, the severity of the disease can be presented by the proposed method.

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Objective: A subset of ANCA-associated vasculitis (AAV) patients are known to manifest obstructive airway disease. Using low attenuation areas (LAA) in the lung on HRCT as an imaging marker for obstructive airway disease, we analyze HRCT studies in AAV patients compared to a matched non-AAV group using visual semi-quantitative and automated quantitative analysis for presence and severity of LAA. Furthermore, HRCT and pulmonary function testing are compared to assess agreement between tests for airway obstruction., Materials and Methods: 100 randomly selected AAV patients with HRCT were compared to 100 best-fit matched control subjects. HRCT cases were visually assessed for LAA, along with additional pulmonary patterns. Automated quantitative software analyzed images for texture features and volume of attenuation values of -950 HU or less (e-950). Evidence of obstructive airway disease established by pulmonary function testing, when available, was compared to HRCT analysis for LAA. Additional clinical information, diagnostic testing and mortality data were also compared., Results: Both study groups were comprised of 57 females and 43 males with 35 smokers averaging 10.7 pk/yrs, with average age for the AAV and control groups being 59.4 yrs and 61.9 yrs, respectively. Visually, 46 AAV patients demonstrated LAA on HRCT compared to 25 control patients (p=0.0017) with the difference in LAA presence entirely within the non-smoking subgroup (25 to 3, respectively, p=<0.0001). Quantitatively, greater than 5% e-950 demonstrated similar significant differences between AAV (36/100) and controls (19/100) (p=0.0065), predominantly in non-smokers (p=0.006). Obstruction on PFTs was significantly increased in AAV (p=0.002) with moderate agreement of obstructive disease with visual LAA on CT (Kappa 0.509). Of the obstructive disease metrics, visual LAA on CT correlated best with mortality (p=0.0085)., Conclusion: Visual LAA and automated quantitative analysis for e-950 on HRCT demonstrate statistically significant increases in AAV patients compared to age, gender and smoking matched controls, with differences primarily seen in the non-smoking subset. AAV revealed statistically significant greater obstructive pulmonary disease on PFTs (Sarcoidosis Vasc Diffuse Lung Dis 2020; 37 (4): e2020016) ., (Copyright: © 2020 SARCOIDOSIS VASCULITIS AND DIFFUSE LUNG DISEASES.)

Background: Impaired peripheral oxygenation (IPO)-related variables readily achieved with cardiopulmonary exercise testing (CPET) represent cardiovascular dysfunction. These variables include peak oxygen uptake ( [Formula: see text] predicted, anaerobic threshold [Formula: see text] predicted, [Formula: see text] rate slope <8.6 mL/watt, oxygen pulse <80% predicted, and ventilatory equivalents for O2 and CO2 at nadir of >31 and >34, respectively. Some of these six variables may be normal while the others are abnormal in patients with chronic obstructive pulmonary disease (COPD). This may result in confusion when using the interpretation algorithm for diagnostic purposes. We therefore hypothesized that patients found to have abnormal values for all six variables would have worse cardiovascular function than patients with abnormal values for none or some of these variables., Methods: In this cross-sectional comparative study, 58 COPD patients attending a university teaching hospital underwent symptom-limited CPET with multiple lactate measurements. Patients with abnormal values in all six IPO-related variables were assigned to an IPO group while those who did not meet the requirements for the IPO group were assigned to a non-IPO group. Cardiovascular function was measured by two-dimensional echocardiography and [Formula: see text], and respiratory dynamics were compared between the two groups., Results: Fourteen IPO and 43 non-IPO patients were entered into the study. Both groups were similar with regard to left ventricular ejection fraction and right ventricular morphology (P>0.05 for both). At peak exercise, both groups reached a similar heart rate level and [Formula: see text]. The IPO patients had an unfavorable dead space to tidal volume ratio, mean inspiratory tidal flow, and shallow breathing (P<0.05-P<0.001)., Conclusion: Our IPO and non-IPO patients with COPD had similar cardiovascular performance at rest and at peak exercise, indicating that IPO variables are non-specific for cardiovascular function in these patients. COPD patients with full IPO variables have more deranged ventilatory function.