Correlation between airflow limitation and airway dimensions assessed by multidetector CT in asthma

Long-term efficacy of house dust mite sublingual immunotherapy on clinical and pulmonary function in patients with asthma and allergic rhinitis

Background

A previous study reported that house dust mite (HDM) sublingual immunotherapy (SLIT) for 48 weeks was effective as add-on treatment for allergic asthma; however, data regarding its long-term efficacy are scarce.

Objective

We sought to evaluate the effect of HDM SLIT on asthma control, pulmonary function, and airway inflammation and remodeling throughout the 5-year treatment period.

Methods

A total of 140 patients with asthma and allergic rhinitis sensitized to HDM were randomized to receive either drugs alone or drugs plus SLIT for 5 years. The 5-item Asthma Control Questionnaire (ACQ-5), Asthma Quality of Life Questionnaire (AQLQ), Rhinoconjunctivitis Quality of Life Questionnaire (RQLQ), spirometry, quantitative computed tomography, and type 2 biomarkers were assessed.

Results

An improvement in the ACQ-5, AQLQ, and RQLQ scores was observed in the SLIT group compared with the control group. HDM SLIT increased lung function and reduced the percentage of airway wall area. The levels of fractional exhaled nitric oxide (Feno), blood eosinophil, serum specific IgE for HDM, and total IgE decreased and were sustained during the 5 years. The change in type 2 biomarkers correlated with change in the AQLQ score. On the basis of receiver-operating characteristic analysis for predicting responders, the area under the receiver-operating characteristic curve in FEV1% predicted, airway wall area, Feno, and specific IgE was high. Multivariate regression analysis showed that the strongest predictor of responders was Feno.

Conclusions

HDM SLIT continued to provide sustained efficacy, improve lung function, and prevent progression of airway inflammation and remodeling in asthma throughout the 5-year treatment period.

Hyperpolarized 129Xe MRI, 99mTc scintigraphy, and SPECT in lung ventilation imaging: a quantitative comparison

RATIONALE AND OBJECTIVES

The current clinical standard for functional imaging of patients with lung ailments is nuclear medicine scintigraphy and Single Photon Emission Computed Tomography (SPECT) which detect the gamma decay of inhaled radioactive tracers. Hyperpolarized (HP) Xenon-129 MRI (XeMRI) of the lungs has recently been FDA approved and provides similar functional images of the lungs with higher spatial resolution than scintigraphy and SPECT. Here we compare Technetium-99m (99mTc) diethylene-triamine-pentaacetate scintigraphy and SPECT with HP XeMRI in healthy controls, asthma, and chronic obstructive pulmonary disorder (COPD) patients.

MATERIALS AND METHODS

59 subjects, healthy, with asthma, and with COPD, underwent 99mTc scintigraphy/SPECT, standard spirometry, and HP XeMRI. XeMRI and SPECT images were registered for direct voxel-wise signal comparisons. Images were also compared using ventilation defect percentage (VDP), and a standard 6-compartment method. VDP calculated from XeMRI and SPECT images was compared to spirometry.

RESULTS

Median Pearson correlation coefficient for voxel-wise signal comparison was 0.698 (0.613-0.782) between scintigraphy and XeMRI and 0.398 (0.286-0.502) between SPECT and XeMRI. Correlation between VDP measures was r = 0.853, p < 0.05. VDP separated asthma and COPD from the control group and was significantly correlated with FEV1, FEV1/FVC, and FEF 25-75.

CONCLUSION

HP XeMRI provides equivalent information to 99mTc SPECT and standard spirometry measures. Additionally, XeMRI is non-invasive, hence it could be used for longitudinal studies for evaluating emerging treatment for lung ailments.

Novel Lung Growth Strategy with Biological Therapy Targeting Airway Remodeling in Childhood Bronchial Asthma

Anti-inflammatory therapy, centered on inhaled steroids, suppresses airway inflammation in asthma, reduces asthma mortality and hospitalization rates, and achieves clinical remission in many pediatric patients. However, the spontaneous remission rate of childhood asthma in adulthood is not high, and airway inflammation and airway remodeling persist after remission of asthma symptoms. Childhood asthma impairs normal lung maturation, interferes with peak lung function in adolescence, reduces lung function in adulthood, and increases the risk of developing chronic obstructive pulmonary disease (COPD). Early suppression of airway inflammation in childhood and prevention of asthma exacerbations may improve lung maturation, leading to good lung function and prevention of adult COPD. Biological drugs that target T-helper 2 (Th2) cytokines are used in patients with severe pediatric asthma to reduce exacerbations and airway inflammation and improve respiratory function. They may also suppress airway remodeling in childhood and prevent respiratory deterioration in adulthood, reducing the risk of COPD and improving long-term prognosis. No studies have demonstrated a suppressive effect on airway remodeling in childhood severe asthma, and further clinical trials using airway imaging analysis are needed to ascertain the inhibitory effect of biological drugs on airway remodeling in severe childhood asthma. In this review, we describe the natural prognosis of lung function in childhood asthma and the risk of developing adult COPD, the pathophysiology of allergic airway inflammation and airway remodeling via Th2 cytokines, and the inhibitory effect of biological drugs on airway remodeling in childhood asthma.

Efficacy of a house dust mite sublingual immunotherapy tablet as add-on dupilumab in asthma with rhinitis

BACKGROUND

HDM SLIT is one of the disease-modifying treatment for allergic asthma, and has demonstrated efficacy in clinical trials. Dupilumab, blocks IL-4 and IL-13 signaling, key drivers of type 2 inflammation, and is approved for patients with uncontrolled, moderate-to-severe asthma. The aim of this study was to evaluate outcomes after HDM SLIT initiation in asthma with rhinitis not optimally controlled with dupilumab in a real-world setting.

METHODS

At baseline and 48 weeks after treatment, asthma control questionnaire (ACQ)-5, asthma quality of life questionnaire (AQLQ) and rhinoconjunctivitis quality of life questionnaire (RQLQ) were assessed. Spirometry, type 2 inflammatory biomarkers and quantitative computed tomographic parameters of airway remodeling were also collected.

RESULTS

Of 47 patients received HDM SLIT and 41 completed the study. Combined HDM SLIT and dupilumab improved ACQ-5 (p < 0.05), AQLQ (p < 0.05), RQLQ (p < 0.05), and increased lung function and reduced FeNO (p < 0.05) and airway percentage wall area, and wall thickness (each, p < 0.05). The change in ACQ-5 and AQLQ score correlated with both changes in FeNO and FEV₁ percent predicted. Multiple regression analysis showed that the change in FEV₁ percent predicted was independent factor for improvement of AQLQ (r² = 0.510, p = 0.012). Based on ROC analysis for predicting SLIT responders, the baseline area under the curves in serum HDM specific-IgE, total IgE and FEV₁ percent predicted were high (>0.8).

CONCLUSIONS

These results support the benefits of adding HDM SLIT to pharmacotherapy plus dupilumab in uncontrolled asthma with rhinitis.

Severe pediatric asthma with a poor response to omalizumab: a report of three cases and three-dimensional bronchial wall analysis

Omalizumab is used for the treatment of persistent severe allergic asthma in adults and children. However, some patients remain symptomatic even after omalizumab treatment. In bronchial asthma, chronic inflammation of the bronchial wall causes thickening of the airway wall, resulting from irreversible airway remodeling. Progression of airway remodeling causes airflow obstruction, leading to treatment resistance. We report three Japanese children with severe asthma who had a poor response to omalizumab treatment. They had a long period of inadequate management of asthma before initiating omalizumab. Even after omalizumab treatment, their symptoms persisted, and the parameters of spirometry tests did not improve. We hypothesized that omalizumab was less effective in these patients because airway wall remodeling had already progressed. We retrospectively evaluated the bronchial wall thickness using a three-dimensional bronchial wall analysis with chest computed tomography. The bronchial wall thickness was increased in these cases compared with six responders. Progressed airway wall thickness caused by airway remodeling may be associated with a poor response to omalizumab in children with severe asthma.

Type 2-High Severe Asthma with and without Bronchiectasis: A Prospective Observational Multicentre Study

Introduction

Type 2-high severe asthma (T2-SA) is often associated with several comorbidities. To this extent, the coexistence of T2-SA and bronchiectasis (BE) is considered an emerging phenotype.

Methods

We performed a prospective observational multicentre study, including T2-SA patients. Chest HRCT confirmed the presence of BE. Data on exacerbations, pulmonary function, Asthma Control Test (ACT), chronic mucus hypersecretion (CMH), chronic rhinosinusitis (CRS), oral corticosteroid (OCS) dosage, eosinophils in peripheral blood and FeNO were recorded. The Bhalla score was used for radiological assessment of T2-SA+BE patients and the Bronchiectasis Severity Index (BSI) was calculated.

Results

A total of 113 patients (mean age 55 ± 11 years, 59.3% female) were enrolled. Co-presence of BE was confirmed in 50/113 (44.2%) patients who identified the T2-SA+BE group. CRS and CRSwNP were more prevalent in T2-SA+BE vs T2-SA [respectively, 42/50 (84%) vs 37/63 (58.7%), p = 0.004 and 27/50 (54%) vs 27/63 (42.9%), p = 0.0165]. Furthermore, T2-SA+BE patients reported more CMH compared to T2-SA [29/50 (58%) vs 15/63 (23.8%), p = 0.0004], were more frequently on chronic OCSs intake [28/50 (56%) vs 22/63 (34.9%), p = 0.0357] and experienced more exacerbations/year [10 (4-12) vs 6 (4-12), p = 0.0487]. In a multivariate logistic regression model, the presence of CRS, CMH and daily OCS intake were associated with BE presence with a 78% (95% CI: 69-88) accuracy. Median Bhalla score was 18.3 (16-20) (Mild radiological severity). Median BSI was 6 (4-8) and only 6/50 (12%) had a BSI score ≥9. Significant inverse linear relationship between BSI and ACT (r = -0.6095, p < 0.0001), FEV₁% (r = -0.3297, p = 0.0353) and FEV₁ mL (r = -0.4339, p = 0.0046) were found.

Conclusion

Type 2 inflammation could have a causative role in BE development. Chest HRCT is mandatory when a diagnosis of T2-SA is made, especially in presence of CRS, CMH and chronic OCS intake. Early BE detection may be crucial to improve T2-SA patients' outcomes.

Similarities in Quantitative Computed Tomography Imaging of the Lung in Severe Asthma with Persistent Airflow Limitation and Chronic Obstructive Pulmonary Disease

Background: Severe asthma with persistent airflow limitation (SA-PAL) and chronic obstructive pulmonary disease (COPD) are characterised by irreversible airflow limitation and the remodelling of the airways. The phenotypes of the diseases overlap and may cause diagnostic and therapeutic concerns. Methods: There were 10 patients with SA-PAL, 11 patients with COPD, and 10 healthy volunteers (HV) enrolled in this study. The patients were examined with a 128-multislice scanner at full inspiration. Measurements were taken from the third to ninth bronchial generations. Results: The thickness of the bronchial wall was greater in the SA-PAL than in the COPD group for most bronchial generations (p < 0.05). The mean lung density was the lowest in the SA-PAL group (−846 HU), followed by the COPD group (−836 HU), with no statistical difference between these two groups. The low-attenuation volume percentage (LAV% < −950 HU) was significantly higher in the SA-PAL group (15.8%) and COPD group (10.4%) compared with the HV group (7%) (p = 0.03). Conclusion: Severe asthma with persistent airflow limitation and COPD become similar with time within the functional and morphological dimensions. Emphysema qualities are present in COPD and in SA-PAL patients.

Airway wall thickness and airflow limitations in asthma assessed in quantitative computed tomography

Background:

Asthma is a frequent chronic disease of the airways. In spite of the fact that symptoms of asthma are well known, the pathogenesis has not yet been fully understood. Quantitative computed tomography (qCT) of the lung allows for the measurment of a set of parameters. The aim of this study was to evaluate the usefulness of quantitative computed tomography in the assessment of airway wall thickness in asthma.

Methods:

The prospective study was performed on a group of 83 patients with well-defined, long-term asthma between 2016 and 2018. The control group was composed of 30 healthy volunteers. All examined subjects were non-smokers. All computed tomography (CT) studies were performed using a 128 multi-slice CT scanner with no contrast, following a chest scanning protocol in the supine position, at full inspiration and breath-holds.

Results:

Quantitative bronchial tree measurements were obtained from the third up to the ninth generation of the posterior basal bronchi (B10) of the right lung in a blinded fashion. The value of the wall thickness in patients with asthma was significantly higher in all measured generations of the bronchial tree (third to ninth generation). The lumen area and the inner diameter significantly correlated with the lung function tests and were substantially smaller in the examined group from the seventh to the ninth generation of the bronchi (p < 0.05).

Conclusions:

We conclude that airway remodelling occurs in most patients with long-term asthma and is associated mainly with the medium and small airways. Imaging techniques, especially qCT can be useful in the diagnosis and management of asthma.

The reviews of this paper are available via the supplemental material section.

Optimizing airway wall segmentation and quantification by reducing the influence of adjacent vessels and intravascular contrast material with a modified integral-based algorithm in quantitative computed tomography

Introduction

Quantitative analysis of multi-detector computed tomography (MDCT) plays an increasingly important role in assessing airway disease. Depending on the algorithms used, airway dimensions may be over- or underestimated, primarily if contrast material was used. Therefore, we tested a modified integral-based method (IBM) to address this problem.

Methods

Temporally resolved cine-MDCT was performed in seven ventilated pigs in breath-hold during iodinated contrast material (CM) infusion over 60s. Identical slices in non-enhanced (NE), pulmonary-arterial (PA), systemic-arterial (SA), and venous phase (VE) were subjected to an in-house software using a standard and a modified IBM. Total diameter (TD), lumen area (LA), wall area (WA), and wall thickness (WT) were measured for ten extra- and six intrapulmonary airways.

Results

The modified IBM significantly reduced TD by 7.6%, LA by 12.7%, WA by 9.7%, and WT by 3.9% compared to standard IBM on non-enhanced CT (p<0.05). Using standard IBM, CM led to a decrease of all airway parameters compared to NE. For example, LA decreased from 80.85±49.26mm² at NE, to 75.14±47.96mm² (-7.1%) at PA (p<0.001), 74.96±48.55mm² (-7.3%) at SA (p<0.001), and to 78.95±48.94mm² (-2.4%) at VE (p = 0.200). Using modified IBM, the differences were reduced to -3.1% at PA, -2.9% at SA and -0.7% at VE (p<0.001; p<0.001; p = 1.000).

Conclusions

The modified IBM can optimize airway wall segmentation and reduce the influence of CM on quantitative CT. This allows a more precise measurement as well as potentially the comparison of enhanced with non-enhanced scans in inflammatory airway disease.

Asthma and Lung Mechanics

This article will discuss in detail the pathophysiology of asthma from the point of view of lung mechanics. In particular, we will explain how asthma is more than just airflow limitation resulting from airway narrowing but in fact involves multiple consequences of airway narrowing, including ventilation heterogeneity, airway closure, and airway hyperresponsiveness. In addition, the relationship between the airway and surrounding lung parenchyma is thought to be critically important in asthma, especially as related to the response to deep inspiration. Furthermore, dynamic changes in lung mechanics over time may yield important information about asthma stability, as well as potentially provide a window into future disease control. All of these features of mechanical properties of the lung in asthma will be explained by providing evidence from multiple investigative methods, including not only traditional pulmonary function testing but also more sophisticated techniques such as forced oscillation, multiple breath nitrogen washout, and different imaging modalities. Throughout the article, we will link the lung mechanical features of asthma to clinical manifestations of asthma symptoms, severity, and control. © 2020 American Physiological Society. Compr Physiol 10:975-1007, 2020.

The Link between Asthma and Bronchiectasis: State of the Art

The nonrecognition of asthma-associated comorbidities is often responsible for the therapeutic failure and the worsening of symptoms, and it is associated with frequent exacerbations, higher disease severity, and increased health costs. Bronchiectasis, one of the most frequent asthma-associated comorbidities, can increase airways inflammation and exacerbation rates and cause respiratory functional impairment. The aim of this article is to review the interactions between bronchiectasis and asthma, in order to better identify patients in the overlap between the 2 diseases and to select an "ad hoc" therapy. A literature search on PubMed/MEDLINE was performed using the following search terms: bronchiectasis in asthma, the association between asthma and bronchiectasis, comorbidities in asthma, and severe asthma. This review analyzed the following items: incorrect or underestimated diagnosis of asthma and bronchiectasis, prevalence of bronchiectasis in asthma, the impact of bronchiectasis in asthma, radiological imaging features of the 2 diseases, etiopathogenesis, and common causes (such as gastroesophageal reflux disease, immune deficits, chronic rhinosinusitis and allergic bronchopulmonary aspergillosis, and treatment of asthma and bronchiectasis). The concomitant presence of bronchiectasis and asthma should be suspected and investigated in patients with severe asthma, frequent exacerbations, and not responding to standard therapy. This clinical phenotype, characterized by a more severe disease, worse outcomes, and functional decline, must be readily recognized in order to choose the most appropriate therapeutic approach, able to potentially improve the management of bronchial asthma, to prevent the onset of exacerbations as well the functional decline, and to reduce health costs.

Bronchial wall thickening is associated with severity of chronic rhinosinusitis

BACKGROUND

Though the relationship between chronic rhinosinusitis (CRS) and lower airway diseases is well recognized, the impact of CRS on bronchial wall structure has not been elucidated. Here, we evaluated the bronchial wall structure of CRS patients with or without diagnosed airway diseases by three-dimensional computed tomography (3D-CT).

METHODS

Subjects who underwent both chest CT and sinus CT within a year were recruited from consecutive medical records. CRS was defined as a Lund-Mackay score (LMS) of over 5 points. Airway dimensions were measured using validated software. Standard blood tests and pulmonary function tests were performed, and their correlation with airway thickness was examined.

RESULTS

One-hundred-seventy-two patients were recruited (93 CRS subjects and 79 non-CRS subjects). The bronchial walls of CRS subjects were significantly thicker than those of non-CRS subjects. CRS and asthma were related to bronchial wall thickening by multivariate linear regression analysis adjusted for age, smoking status, and chest symptoms. In addition, LMS was significantly correlated with bronchial wall thickening.

CONCLUSION

Airway walls in CRS subjects were thicker than those in non-CRS subjects and associated with the severity of CRS. These data indicate strong relationship between upper and lower airways regardless of chest symptoms or diagnosed airway diseases.

Effect of Sublingual Immunotherapy on Airway Inflammation and Airway Wall Thickness in Allergic Asthma

BACKGROUND

The efficacy of the standardized quality (SQ) house dust mite (HDM) sublingual immunotherapy (SLIT) has been demonstrated for respiratory allergic disease. However, the effects of SLIT on inflammation and structural changes of the airways are still unknown.

OBJECTIVE

The aim of this study was to assess the effects of the 6 SQ-HDM SLIT on airway inflammation and airway geometry in allergic asthma and rhinitis.

METHODS

One hundred two asthmatic patients with rhinitis sensitized to HDM were randomized to receive either SLIT plus pharmacotherapy or standard pharmacotherapy alone, for 48 weeks. Fractional exhaled nitric oxide (FeNO), pulmonary function, quantitative computed tomography, and clinical symptoms were performed at baseline and end of the study.

RESULTS

Compared with pharmacotherapy, SLIT demonstrated a significant reduction of FeNO (P < .01), airway wall area/body surface area (WA/BSA, P < .001), wall thickness (T/√BSA, P < .001), percentage wall area (WA/Ao, P < .01), increase in luminal area (Ai/BSA, P < .05), improvement of airflow limitation (P < .001), and clinical symptom scores (P < .05). The change in forced expiratory volume in 1 second (FEV₁) was correlated with both changes in FeNO and airway dimensions. Multiple regression analysis showed that the change in FeNO was independently associated with an increase in FEV₁ in the SLIT group (r² = 0.623, P = .037).

CONCLUSIONS

Adding 6 SQ-HDM SLIT to standard asthma therapy provides a significant improvement in symptoms and pulmonary function compared with pharmacotherapy. Improvement of airflow limitation with SLIT was associated with the decrease in eosinophilic airway inflammation.

Dismantling the pathophysiology of asthma using imaging

Asthma remains an important disease worldwide, causing high burden to patients and healthcare systems and presenting a need for better management and ultimately prevention and cure. Asthma is a very heterogeneous condition, with many different pathophysiological processes. Better measurement of those pathophysiological processes are needed to better phenotype disease, and to go beyond the current, highly limited measurements that are currently used: spirometry and symptoms. Sophisticated three-dimensional lung imaging using computed tomography and ventilation imaging (single photon emission computed tomography and positron emission tomography) and magnetic resonance imaging and methods of lung imaging applicable to asthma research are now highly developed. The body of current evidence suggests that abnormalities in structure and ventilatory function measured by imaging are clinically relevant, given their associations with disease severity, exacerbation risk and airflow obstruction. Therefore, lung imaging is ready for more widespread use in clinical trials and to become part of routine clinical assessment of asthma.

Small airway dysfunction may be an indicator of early asthma: findings from high-resolution CT

BACKGROUND

Increasing attention is now focused on the role of the small airways in asthma. Patients with small airway asthma typically have a preserved forced expiratory volume in 1 second, with disproportionate small airway dysfunction.

OBJECTIVE

The aim of this study was to determine whether there are structural changes in the large airways in patients with small airway asthma.

METHODS

Nine patients with small airway asthma and 20 healthy controls underwent high-resolution computed tomography (HRCT) scan. The apicoposterior segmental bronchus in the left upper lobe (LB1+2) and the posterior basal segmental bronchus in the left lower lobe (LB10) were identified on HRCT images. The luminal area (LA), wall area (WA), and wall area percentage (WA%) of each bronchus were measured from the 2nd (lobar) to the 6th generation and compared between the patients with small airway asthma and the healthy controls.

RESULTS

The WA% of the 6th generation in the patients with small airway asthma was higher than that in the healthy controls; the difference was statistically significant (LB1 + 2, P = .040; LB10, P = .033).

CONCLUSION

Structural changes in the large airways of patients with small airway asthma may represent an early stage of asthma.

Comparison between montelukast and tiotropium as add-on therapy to inhaled corticosteroids plus a long-acting β2-agonist in for patients with asthma

Objective: Asthma often remains uncontrolled despite treatment with inhaled corticosteroids (ICS) alone or with ICS plus a long-acting β₂-agonist (LABA). The recommended alternative is the addition of either montelukast or tiotropium. The aim of this study was to compare the effects of montelukast and tiotropium on airway inflammation and remodeling in persistent asthma. Methods: Eighty-seven patients with asthma were treated with budesonide and formoterol (640/18 μg); then, the patients were randomly allocated to three groups to receive oral montelukast (10 mg/day), inhaled tiotropium (5 μg/day), or no add-on to the maintenance therapy for 48 weeks. Fractional exhaled nitric oxide (FeNO) and pulmonary function were measured, and quantitative computed tomography was performed. Results: Compared to the maintenance therapy, add-on montelukast significantly decreased FeNO (p < 0.05) and improved airflow obstruction (p < 0.05), whereas airway dimensions remained unchanged. Changes in FeNO were significantly correlated with changes in FEV₁ (r = -0.71, p < 0.001). In contrast, the addition of tiotropium significantly decreased airway wall area corrected for body surface area (WA/BSA) (p < 0.05), decreased wall thickness (T/√BSA) (p < 0.05) and improved airflow obstruction (p < 0.05) with no change in FeNO. Changes in WA/BSA and T/√BSA were significantly correlated with the change in percentage predicted FEV₁ (r = -0.84, p < 0.001 and r = -0.59, p < 0.01, respectively). Conclusions:Adding either montelukast or tiotropium to ICS/LABA may provide additive benefits with respect to the pulmonary function and airway inflammation or remodeling in patients with asthma.

Differences in airway structural changes assessed by 3-dimensional computed tomography in asthma and asthma-chronic obstructive pulmonary disease overlap

BACKGROUND

Asthma-chronic obstructive pulmonary disease (COPD) overlap (ACO) is a clinical phenotype sharing features of asthma and COPD. Multidetector row computed tomography (MDCT) can be used to evaluate the airway structure; however, differences between asthma and ACO seen on MDCT are poorly understood.

OBJECTIVE

To investigate the difference in airway structural between asthma and ACO, using MDCT in patients with clinical asthma.

METHODS

Sixty-four patients with asthma were allocated to an asthma group (never smokers and ex-smokers with a smoking history of < 10 pack-years) or an ACO group (patients with a ≥10-pack-year smoking history and forced expiratory volume in 1 second [FEV₁]/forced vital capacity [FVC] < 0.7). The asthma group was further divided into patients with airflow limitation (AL; FEV₁/FVC < 0.7) and those without AL. Wall thickness (WT) and airway inner luminal area in the third-generation to fifth-generation bronchi were evaluated using MDCT in both study groups and in 29 healthy controls.

RESULTS

Forty-three patients were included in the asthma group (20 with AL, 23 without AL) and 16 in the ACO group. Patients with asthma and ACO had significantly greater WT than the healthy controls. WT in the third-generation bronchi was significantly greater in the ACO group than in the asthma group. The ACO group and the asthma with AL group were matched for age, disease duration, and FEV₁/FVC. The WT in the third-generation bronchi was still greater in the ACO group than in the asthma with AL group.

CONCLUSION

Patients with ACO have a thicker airway wall than those with asthma, suggesting that airway remodeling is more prominent in ACO than in asthma. UMIN Clinical Trials Registry (UMIN-CTR) system (http://www.umin.ac.jp/ctr/UMIN000028913).

Imaging of Asthma

Asthma is one of the most common diseases of the lung. Asthma manifests with common, although often subjective and nonspecific, imaging features at radiography and high-resolution computed tomography. The primary role of imaging is not to make a diagnosis of asthma but to identify complications, such as allergic bronchopulmonary aspergillosis, or mimics of asthma, such as hypersensitivity pneumonitis. This article reviews the imaging features of asthma as well as common complications and mimics.

Evaluating Qualitative and Quantitative Computerized Tomography Indicators of Chronic Obstructive Pulmonary Disease and Their Correlation with Pulmonary Function Tests

BACKGROUND

With increasingly aging populations, chronic obstructive pulmonary disease (COPD) is the fourth leading cause of death today. Emphysematous changes, an important component of the disease, must be determined on HRCT, either qualitatively or quantitatively. The purpose of this study was to evaluate features that help determine emphysematous changes and correlate them with respiratory function tests (RFTs).

MATERIAL/METHODS

A total of thirty COPD patients and a control group of the same size, matched for age, were included in the study. The mean lung parenchyma density values on inspiration and expiration, visual HRCT scores, and pulmonary function tests were obtained. IBM SPSS statistical software (version 22) was used to perform correlation analysis (Pearson's coefficient) and the Mann-Whitney U test.

RESULTS

The most valuable RFTs for determining emphysematous changes were DLCO, FEV1, and FEV1/FVC, in that order. Quantitative measures of the mean lung density had the highest correlation with coefficient on expiration.

CONCLUSIONS

As regards the comparison between objective and subjective density values, the HRCT-based visual density values are satisfactory. On the other hand, the best assessment can be performed with the use of mean density values on expiration. DLCO, FEV1, and FEV1/FVC were found to be valuable parameters in determining parenchymal changes.

The effect of disease and respiration on airway shape in patients with moderate persistent asthma

Computational models of gas transport and aerosol deposition frequently utilize idealized models of bronchial tree structure, where airways are considered a network of bifurcating cylinders. However, changes in the shape of the lung during respiration affect the geometry of the airways, especially in disease conditions. In this study, the internal airway geometry was examined, concentrating on comparisons between mean lung volume (MLV) and total lung capacity (TLC). A set of High Resolution CT images were acquired during breath hold on a group of moderate persistent asthmatics at MLV and TLC after challenge with a broncho-constrictor (methacholine) and the airway trees were segmented and measured. The airway hydraulic diameter (Dh) was calculated through the use of average lumen area (Ai) and average internal perimeter (Pi) at both lung volumes and was found to be systematically higher at TLC by 13.5±9% on average, with the lower lobes displaying higher percent change in comparison to the lower lobes. The average internal diameter (Din) was evaluated to be 12.4±6.8% (MLV) and 10.8±6.3% (TLC) lower than the Dh, for all the examined bronchi, a result displaying statistical significance. Finally, the airway distensibility per bronchial segment and per generation was calculated to have an average value of 0.45±0.28, exhibiting high variability both between and within lung regions and generations. Mixed constriction/dilation patterns were recorded between the lung volumes, where a number of airways either failed to dilate or even constricted when observed at TLC. We conclude that the Dh is higher than Din, a fact that may have considerable effects on bronchial resistance or airway loss at proximal regions. Differences in caliber changes between lung regions are indicative of asthma-expression variability in the lung. However, airway distensibility at generation 3 seems to predict distensibility more distally.

Airway Evaluation with Multidetector Computed Tomography Post-Processing Methods in Asthmatic Patients

Asthma is a chronic inflammatory obstructive airways disease. The disease occurs regardless of age and manifests with cough, attacks of breathlessness, and tightness in the chest. The pathophysiology of asthma is complex and still not fully understood. It is essential to find answers concerning the role of each part of the bronchial tree in asthma, especially the role of small bronchioles. With the development of newer generations of multidetector computed tomography (MDCT) and advanced post-processing methods it is possible to obtain more detailed images and gain insight into further aspects of asthma. MDCT post-processing methods can be divided into two-dimensional (2D) and three-dimensional (3D). In 2D projections, visualized hypodense regions correspond to the airway flow limitations. With the more advanced methods, such as multi planar reconstructions (MPR), images in different planes (axial, coronal, or sagittal) can be created. In the MPR technique only the voxels which are adjacent to each other in the predetermined plane can be extracted from the data set. Using the minimal/maximal intensity projections and shaded surface display, the volume of interest (VOI) can be extracted. High resolution CT scans can be used to create a more advanced imaging tool - the virtual bronchoscopy (VB). Using the VB makes it possible to visualize regions of obturation in the bronchi of up to the 5-8th generation. The MDCT with advanced post-processing methods is likely to assume an important role in the differential diagnosis of asthma, particularly when the diagnosis is dubious or hard to settle due to accompanying other lung diseases.

Airway tree reconstruction in expiration chest CT scans facilitated by information transfer from corresponding inspiration scans

PURPOSE

Analysis and comparison of airways imaged in pairs of inspiration and expiration lung CT scans provides important information for quantitative assessment of lung diseases like chronic obstructive pulmonary disease. However, airway tree reconstruction in expiration CT scans is a challenging problem. Typically, only a low number of airway branches are found in expiration scans, compared to inspiration scans. To detect more airways in expiration CT scans, the authors introduce a novel airway reconstruction approach and assess its performance.

METHODS

The method requires a pair of inspiration and expiration CT scans and utilizes information from the inspiration scan to facilitate reconstructing the airway tree in the expiration lung CT scan. First, an initial airway tree (high confidence) and airway candidates (limited confidence) are reconstructed in the expiration scan by utilizing a 3D graph-based reconstruction method. Then, the 3D airway tree is reconstructed in the inspiration scan. Second, correspondences between expiration and inspiration tree structures are identified by utilizing a novel hierarchical tree matching algorithm that utilizes a local CT image-based similarity criterion. Third, the tree information from the inspiration airway tree is used to select expiration candidates, resulting in the final expiration tree structure. The approach was evaluated on a diverse set of 40 scan pairs and compared to the baseline method, which utilizes only the expiration CT scan.

RESULTS

The proposed method produced a significant (p < 0.05) increase in airway tree length by 13.35 cm, on average, which represents an 11.21% increase relative to the baseline result using only the expiration CT scan. A detailed analysis of all additionally identified airways resulted in a true and false positive rate of 94.8% and 5.2%, respectively. The true positive rate was found to be significantly higher than the false positive rate (p < 0.05).

CONCLUSIONS

The proposed method allowed increasing the number of found airways in expiration scans significantly. In addition, the algorithm establishes correspondence between inspiration and expiration airway trees, which can facilitate label transfer between airway trees and quantitative assessment of change in airways. The approach can be adapted to facilitate airway reconstruction in several longitudinal lung CT scans by means of mutual information transfer.

Effect of treatment with inhaled corticosteroid on serum periostin levels in asthma

BACKGROUND AND OBJECTIVE

Periostin is a biomarker of eosinophilic airway inflammation and may contribute to airway remodeling in asthma. The anti-inflammatory activity of inhaled corticosteroids (ICS) for asthma control is widely recognized. The aim of this study was to assess the effects of ICS on serum periostin levels and its relationships to inflammation and airway geometry.

METHODS

Forty-two healthy controls and 20 patients with steroid-naïve asthma before and after treatment with fluticasone propionate (800 μg/day for 16 weeks) were examined. Serum periostin, lung function and inflammatory cell counts in sputum were measured. Airway dimensions were determined by quantitative computed tomography (total area of the airway (Ao), wall area (WA), wall thickness (T) and percentage wall area (WA%) ).

RESULTS

Serum periostin concentrations were significantly higher in patients with asthma than in controls. Periostin levels were correlated with airway wall thickness and sputum eosinophilia and inversely correlated with airflow limitation in asthma. ICS significantly decreased serum periostin (P < 0.01), decreased WA corrected for body surface area (WA/BSA, P < 0.05), T/√BSA (P < 0.01) and WA% (P < 0.01), reduced the percentage of sputum eosinophils (P < 0.01) and improved airflow limitation. The decrease in serum periostin levels was associated with an increased per cent predicted forced expiratory volume in 1 s (r = -0.64, P < 0.01), decreased WA/BSA (r = 0.46, P < 0.05) and decreased sputum eosinophils (r = 0.71, P < 0.01).

CONCLUSION

Serum periostin levels respond partially to ICS and may reflect a reduction in airway inflammation and wall thickening in asthma.

Computed tomography assessment of airways throughout bronchial tree demonstrates airway narrowing in severe asthma

RATIONALE AND OBJECTIVES

To analyze airway dimensions throughout the bronchial tree in severe asthmatic patients using multidetector row computed tomography (MDCT) focusing on airway narrowing.

MATERIALS AND METHODS

Thirty-two patients with severe asthma underwent automated (BronCare software) analysis of their right lung bronchi, with counts of airways >3 mm long arising from the main bronchi (airway count) and bronchial dimension quantification at segmental and subsegmental levels (lumen area [LA], wall area [WA], and WA%). Focal bronchial stenosis was defined as >50% narrowing of maximal LA on contiguous cross-sectional slices. Severe asthmatics were compared to 13 nonsevere asthmatic patients and nonasthmatic (pooled) subjects (Wilcoxon rank tests, then stepwise logistic regression). Finally, cluster analysis of severe asthmatic patients and stepwise logistic regression identified specific imaging subgroups.

RESULTS

The most significant differences between severe asthmatic patients and the pooled subjects were bronchial stenosis (subsegmental and all bronchi: P < .002) and WA% (P < .0003). Stepwise logistic regression retained WA% as the only explanatory covariable (P = .002). Two identified clusters of severe asthmatic patients differed for parameters characterizing airway narrowing (airway count: P = .0002; focal bronchial stenosis: P = .009). Airway count was as discriminant as forced expiratory volume in 1 second/forced vital capacity (P = .01) to identify patients in each cluster, with both variables being correlated (r = 0.59, P = .005).

CONCLUSIONS

Severe asthma-associated morphologic changes were characterized by focal bronchial stenoses and diffuse airway narrowing; the latter was associated with airflow obstruction. WA%, dependent on airway caliber, is the best parameter to identify severe asthmatic patients from pooled subjects.

Risk factors for persistent airflow limitation: Analysis of 306 patients with asthma

Objectives : To determine the risk factors associated with persistent airflow limitation in patients with asthma. Method s: This study was designed and carried out in the department of respiratory medicine, fourth People's Hospital of Jinan City, Shandong province, China between Jan 2012 and Dec 2012. Three hundred and six asthma patients participating in the study were divided into persistent airflow limitation group (PAFL) and no persistent airflow limitation group (NPAFL). The patients participated in pulmonary function tests and sputum induction examination. The clinical data including age, gender, onset age, disease course, smoking history, family history, regular corticosteroid inhalation, hospitalization history and presence of atopy were collected. Results : In 306 patients, 128 (40.5%) were included in PAFL group and 178(59.5%) in NPAFL group. Multivariate analysis demonstrated smoking (≥10 pack-years; OR, 7.1; 95% CI, 1.8 to 31.2), longer asthma duration (≥ 20years) (OR, 6.3; 95% CI, 1.7 to 28.5), absence of regular corticosteroid inhalation (OR, 3.5; 95% CI, 1.1 to 14.5) and neutrophil in induced sputum≥65% (OR, 1.8; 95% CI, 1.0 to 2.8) were independent risk factors for PAFL. Conclusions : Smoking, longer asthma duration and increased neutrophil in induced sputum are risk factors for PAFL, while regular corticosteroid inhalation is protective factor. Smoking cessation and regular corticosteroid inhalation may play an important role in preventing the occurrence of persistent airflow limitation group (PAFL).

Ventilation heterogeneity in asthma

Non-uniform distribution of inspired gas within the lung, termed ventilation heterogeneity, is present in patients with even mild asthma. Current evidence strongly supports ventilation heterogeneity as a fundamental derangement of lung function in asthma that contributes per se to hypoxemia and airway hyper-responsiveness. An extreme example of ventilation heterogeneity is the identification by hyperpolarized gas MRI of lung regions with no ventilation, termed filling defects. Lung filling defects in patients with asthma can persist over time, increase in size with methacholine-induced bronchospasm and more likely are caused by obstruction of the peripheral and not the proximal airways. Ventilation heterogeneity can be quantified in the conducting and acinar lung zones with the multiple gas washout method, and in the acinar zone does not fully resolve following bronchodilator treatment in patients with asthma. In prospective studies, the degree of ventilation heterogeneity at baseline predicts airway hyper-responsiveness and response to corticosteroid dose titration. An important unanswered question is the relationship of airways inflammation to ventilation heterogeneity. In consideration of the importance of ventilation heterogeneity in its pathobiology, asthma is more a focal disorder with regional pathology akin to regional ileitis and not the generalized disorder of the airways as it has been viewed in the past.

Increased C-reactive protein is associated with airway wall thickness in steroid-naive asthma

BACKGROUND

Asthma is characterized by chronic airway inflammation and remodeling. Levels of serum high-sensitivity C-reactive protein (hs-CRP) reflect airway eosinophilic inflammation. However, the relation between hs-CRP and the development of airway wall thickening remains unknown.

OBJECTIVE

To evaluate whether serum hs-CRP is associated with airway geometry in asthma.

METHODS

Forty-eight steroid-naive patients with asthma, 51 patients with asthma treated with inhaled corticosteroids, and 38 aged-matched healthy controls were studied cross-sectionally. Serum hs-CRP levels, lung function, and inflammatory cell counts in sputum were measured. Quantitative computed tomographic analysis of the apical segment of the right upper lobe was performed.

RESULTS

Serum hs-CRP levels were significantly elevated in steroid-naive patients with asthma compared with controls and steroid-treated patients with asthma and were associated with airflow limitation. In steroid-naive patients, serum hs-CRP levels were correlated with airway wall thickness (r = 0.88, P < .001) and sputum eosinophil percentage (r = 0.75, P < .001). Multivariate analysis showed a significant association between hs-cRP levels and forced expiratory volume in 1 second (percentage predicted; R(2) = 0.65, P = .001).

CONCLUSION

Serum hs-CRP may be a useful systemic biomarker of airway eosinophilia in steroid-naive asthma and has potential utility as a marker for the development of airway wall thickening.

TRIAL REGISTRATION

University Hospital Medical Information Network (www.umin.ac.jp/ctr/index/htm); identifier, UMIN000006724.

The effects of emphysema on airway disease: correlations between multi-detector CT and pulmonary function tests in smokers

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is characterized by airflow limitation caused by emphysema and small airway narrowing. Quantitative evaluation of airway dimensions by multi-detector computed tomography (MDCT) has revealed a correlation between airway dimension and airflow limitation. However, the effect of emphysema on this correlation is unclear.

OBJECTIVE

The goal of this study was to determine whether emphysematous changes alter the relationships between airflow limitation and airway dimensions as measured by inspiratory and expiratory MDCT.

METHODS

Ninety-one subjects underwent inspiratory and expiratory MDCT. Images were evaluated for mean airway luminal area (Ai), wall area percentage (WA%) from the third to the fifth generation of three bronchi (B1, B5, B8) in the right lung, and low attenuation volume percent (LAV%). Correlations between each airway index and airflow limitation were determined for each patient and compared between patients with and without evidence of emphysema.

RESULTS

In patients without emphysema, Ai and WA% from both the inspiratory and expiratory scans were significantly correlated with FEV1. No correlation was detected in patients with emphysema. In addition, emphysematous COPD patients with GOLD stage 1 or 2 disease had significantly lower changes in B8 Ai than non-emphysematous patients.

CONCLUSIONS

A significant correlation exists between airway parameters and FEV1 in patients without emphysema. Emphysema may influence airway dimensions even in patients with mild to moderate COPD.

Airway morphology from high resolution computed tomography in healthy subjects and patients with moderate persistent asthma

Models of the human respiratory tract developed in the past were based on measurements made on human tracheobronchial airways of healthy subjects. With the exception of a few morphometric characteristics such as the bronchial wall thickness (WT), very little has been published concerning the effects of disease on the tree structure and geometrical features. In this study, a commercial software package was used to segment the airway tree of seven healthy and six moderately persistent asthmatic patients from high resolution computed tomography images. The process was assessed with regards to the treatment of the images of the asthmatic group. The in vivo results for the bronchial length, diameter, WT, branching, and rotation angles are reported and compared per generation for different lobes. Furthermore, some popular mathematical relationships between these morphometric characteristics were examined in order to verify their validity for both groups. Our results suggest that, even though some relationships agree very well with previously published data, the compartmentalization of airways into lobes and the presence of disease may significantly affect the tree geometry, while the tree structure and airway connectivity is only slightly affected by the disease.

Asthma and lung structure on computed tomography: the Multi-Ethnic Study of Atherosclerosis Lung Study

BACKGROUND

The potential consequences of asthma in childhood and young adulthood on lung structure in older adults have not been studied in a large, population-based cohort.

OBJECTIVE

The authors hypothesized that a history of asthma onset in childhood (age 18 years or before) or young adulthood (age 19-45 years) was associated with altered lung structure on computed tomography in later life.

METHODS

The Multi-Ethnic Study of Atherosclerosis Lung Study recruited 3965 participants and assessed asthma history by using standardized questionnaires, guideline-based spirometry, and segmental airway dimensions and percentage of low attenuation area (%LAA) on computed tomographic scans.

RESULTS

Asthma with onset in childhood and young adulthood was associated with large decrements in FEV(1) among participants with a mean age of 66 years (-365 mL and -343 mL, respectively; P < .001). Asthma with onset in childhood and young adulthood was associated with increased mean airway wall thickness standardized to an internal perimeter of 10 mm (0.1 mm, P < .001 for both), predominantly from narrower segmental airway lumens (-0.39 mm and -0.34 mm, respectively; P < .001). Asthma with onset in childhood and young adulthood also was associated with a greater %LAA (1.69% and 4.30%, respectively; P < .001). Findings were similar among never smokers, except that differential %LAA in childhood-onset asthma were not seen in them.

CONCLUSION

Asthma with onset in childhood or young adulthood was associated with reduced lung function, narrower airways, and among asthmatic patients who smoked, greater %LAA in later life.

Changes in CT scan-estimated airway dimensions during an acute exacerbation of asthma

Asthma is a chronic airway disease characterized by reversible airflow limitation with airway wall thickening. Although some studies have reported changes in airway dimensions estimated on chest CT in patients with chronic asthma, little is known about dynamic changes in airway dimensions between acute exacerbations of asthma and recovery. Our case documents significant changes in the bronchial wall, as estimated on serial chest CT scans, over a short-term interval during an exacerbation of asthma.

Pediatric asthma phenotypes

PURPOSE OF REVIEW

There is currently limited ability to identify which infants and young children with recurrent wheezing will ultimately develop persistent asthma. In addition, it is not clear how risk factors influence the development of asthma in later childhood and adulthood. This review will discuss efforts to categorize these children with recurrent wheezing and develop asthma-predictive tools.

RECENT FINDINGS

Transient and persistent wheezing phenotypes have been identified with atopy, reduced lung function, and viral and bacterial respiratory infection as major risk factors for persistence of asthma. Children with severe asthma tend to have greater magnitude of atopy and lower lung function than those with mild-moderate asthma. These phenotypes and risk factors have been described in previous studies and are supported by the recent literature.

SUMMARY

Heterogeneity of wheezing phenotypes may account for different responses to treatment and varied outcomes. Overlap in phenotypes and instability over time also add additional challenges to defining discrete groups of children with specific outcomes. Further studies are needed to determine combinations of variables that may improve phenotype designation with the goal of improving asthma prevention and treatment as well as predicting outcomes and understanding the pathogenesis of asthma.

Computed tomographic imaging of the airways in COPD and asthma

Computed tomography (CT) is the modality of choice for imaging the airways. Volumetric data sets with isotropic spatial resolution based on multidetector thin-section CT with overlapping reconstruction should be used. Chronic obstructive pulmonary disease and asthma are the 2 most common disease entities that are defined by airflow obstruction. The morphologic correlates of airway changes are dilation of the lumen, thickening of the wall, visibility of small airways due to mucus or edema, air trapping, hypoxic vasoconstriction, and collapsibility. To assess air trapping, additional expiratory low-dose scans are recommended. In clinical routine, these findings are visually assessed and should be routinely reported. However, the interobserver variability is high, and there is a clear need for objective software-based measurements. The development of such tools is challenging, and they are just becoming available on a broader scale. Novel techniques based on dual-energy CT aim to measure iodine distribution maps to assess pulmonary perfusion as well as the distribution of inhaled xenon gas to assess the distribution and time course of pulmonary ventilation. However, these techniques are still being investigated in clinical studies. This review will provide an overview of CT for the diagnosis of chronic obstructive pulmonary disease and asthma, its role in phenotyping these diseases, and the measurement of disease severity and functional compromise.

Phenotyping airway disease with optical coherence tomography

Airway diseases are a major concern around the world. However, the pace of new drug and biomarker discovery has lagged behind those of other common disorders such as cardiovascular diseases and diabetes. One major barrier in airway research has been the inability to accurately visualize large or small airway remodelling or dysplastic/neoplastic (either pre or early cancerous) changes using non- or minimally invasive instruments. The advent of optical coherence tomography (OCT) has the potential to revolutionize airway research and management by allowing investigators and clinicians to visualize the airway with resolution approaching histology and without exposing patients to harmful effects of ionizing radiation. Thus, with the aid of OCT, we may be able to accurately determine and quantify the extent of airway remodelling in asthma and chronic obstructive pulmonary disease, detect early pre-cancerous lesions in smokers for chemoprevention, study the upper airway anatomy of patients with obstructive sleep apnea in real time while they are asleep and facilitate optimal selection of stents for those with tracheal obstruction. In this paper, we review the current state of knowledge of OCT and its possible application in airway diseases.

Lung imaging in asthmatic patients: the picture is clearer

Imaging of the lungs in patients with asthma has evolved dramatically over the last decade with sophisticated techniques, such as computed tomography, magnetic resonance imaging, positron emission tomography, and single photon emission computed tomography. New insights into current and future modalities for imaging in asthmatic patients and their application are discussed to potentially shed a clearer picture of the underlying pathophysiology of asthma, especially severe asthma, and the proposed clinical utility of imaging in patients with this common disease.