Quantitative CT Measures of Bronchiectasis in Smokers

3D airway geometry analysis of factors in airway navigation failure for lung nodules

BACKGROUND

This study aimed to quantitatively reveal contributing factors to airway navigation failure during radial probe endobronchial ultrasound (R-EBUS) by using geometric analysis in a three-dimensional (3D) space and to investigate the clinical feasibility of prediction models for airway navigation failure.

METHODS

We retrospectively reviewed patients who underwent R-EBUS between January 2017 and December 2018. Geometric quantification was analyzed using in-house software built with open-source python libraries including the Vascular Modeling Toolkit ( http://www.vmtk.org ), simple insight toolkit ( https://sitk.org ), and sci-kit image ( https://scikit-image.org ). We used a machine learning-based approach to explore the utility of these significant factors.

RESULTS

Of the 491 patients who were eligible for analysis (mean age, 65 years +/- 11 [standard deviation]; 274 men), the target lesion was reached in 434 and was not reached in 57. Twenty-seven patients in the failure group were matched with 27 patients in the success group based on propensity scores. Bifurcation angle at the target branch, the least diameter of the last section, and the curvature of the last section are the most significant and stable factors for airway navigation failure. The support vector machine can predict airway navigation failure with an average area under the curve of 0.803.

CONCLUSIONS

Geometric analysis in 3D space revealed that a large bifurcation angle and a narrow and tortuous structure of the closest bronchus from the lesion are associated with airway navigation failure during R-EBUS. The models developed using quantitative computer tomography scan imaging show the potential to predict airway navigation failure.

Biomarkers in bronchiectasis

Bronchiectasis is a heterogeneous disease with multiple aetiologies and diverse clinical features. There is a general consensus that optimal treatment requires precision medicine approaches focused on specific treatable disease characteristics, known as treatable traits. Identifying subtypes of conditions with distinct underlying biology (endotypes) depends on the identification of biomarkers that are associated with disease features, prognosis or treatment response and which can be applied in clinical practice. Bronchiectasis is a disease characterised by inflammation, infection, structural lung damage and impaired mucociliary clearance. Increasingly there are available methods to measure each of these components of the disease, revealing heterogeneous inflammatory profiles, microbiota, radiology and mucus and epithelial biology in patients with bronchiectasis. Using emerging biomarkers and omics technologies to guide treatment in bronchiectasis is a promising field of research. Here we review the most recent data on biomarkers in bronchiectasis.

Bronchiectasis is associated with lower lung function in lung cancer screening participants

BACKGROUND AND OBJECTIVE

Bronchiectasis is a frequent incidental finding on chest computed tomography (CT), but its relevance in lung cancer screening is not fully understood. We investigated the association between bronchiectasis and respiratory symptoms, pulmonary function, and emphysema in lung cancer screening participants with and without chronic obstructive pulmonary disease (COPD).

METHODS

We included 3260 (ex-)smokers from the Dutch-Belgian lung cancer screening trial (NELSON). Bronchiectasis was scored by chest radiologists. The relationship with pulmonary function (FEV1%predicted, FEV1/FVC), respiratory complaints (cough, dyspnea, wheezing, mucus hypersecretion), and CT-quantified emphysema (15th percentile) was examined with independent t-tests and multivariate regression.

RESULTS

Bronchiectasis was present in 5.4% (n = 175/3260). There was no difference in prevalence between subjects with and without COPD (68/1121 [5.9%] vs. 109/2139 [5.1%]; p = .368). COPD subjects with bronchiectasis had a lower FEV1%predicted (76.2% vs. 85.0%; p < .001), lower FEV1/FVC (0.58 vs. 0.62; p < .001), and more emphysema (- 938 HU vs. - 930 HU; p = .001) than COPD subjects without bronchiectasis. In COPD subjects, bronchiectasis was independently associated with a lower FEV1%predicted (B =  - 7.7; CI [- 12.3, - 3.3]), lower FEV1/FVC (B =  - 2.5; CI [- 4.3, - 0.8]), more cough (OR 2.4; CI [1.3, 4.3]), more mucus hypersecretion (OR 1.8; CI [1.0, 3.1]) and more dyspnea (OR 2.3; CI [1.3, 3.9]). In those without COPD (n = 2139), bronchiectasis was associated with more cough, mucus hypersecretion, and wheezing, but not with deteriorating lung function.

CONCLUSION

Bronchiectasis was present in 5.4% of our lung cancer screening participants and was associated with more respiratory symptoms and, in those with COPD, with lower lung function and more emphysema.

CLINICAL RELEVANCE STATEMENT

In a lung cancer screening population, bronchiectasis has a prevalence of 5.4% with a mainly mild severity. This finding is of little clinical relevance unless mild COPD is also present. In those subjects, bronchiectasis was associated with a lower lung function, more respiratory symptoms, and more emphysema.

KEY POINTS

• Bronchiectasis was found in 5.4% of lung cancer screening participants, consisting of (ex-)smokers with and without mild COPD. • In those with mild COPD, bronchiectasis was associated with a lower lung function, more respiratory symptoms, and more emphysema. • Incidental findings of mild bronchiectasis are not very relevant in a lung cancer screening population, unless COPD is also present.

Clinical Characteristics and Outcomes of the Phenotypes of COPD-Bronchiectasis Association

INTRODUCTION

Although COPD may frequently co-exist with bronchiectasis [COPD-bronchiectasis associated (CBA)], little is known regarding the clinical heterogeneity. We aimed to identify the phenotypes and compare the clinical characteristics and prognosis of CBA.

METHODS

We conducted a retrospective cohort study involving 2928 bronchiectasis patients, 5158 COPD patients, and 1219 patients with CBA hospitalized between July 2017 and December 2020. We phenotyped CBA with a two-step clustering approach and validated in an independent retrospective cohort with decision-tree algorithms.

RESULTS

Compared with patients with COPD or bronchiectasis alone, patients with CBA had significantly longer disease duration, greater lung function impairment, and increased use of intravenous antibiotics during hospitalization. We identified five clusters of CBA. Cluster 1 (N=120, CBA-MS) had predominantly moderate-severe bronchiectasis, Cluster 2 (N=108, CBA-FH) was characterized by frequent hospitalization within the previous year, Cluster 3 (N=163, CBA-BI) had bacterial infection, Cluster 4 (N=143, CBA-NB) had infrequent hospitalization but no bacterial infection, and Cluster 5 (N=113, CBA-NHB) had no hospitalization or bacterial infection in the past year. The decision-tree model predicted the cluster assignment in the validation cohort with 91.8% accuracy. CBA-MS, CBA-BI, and CBA-FH exhibited higher risks of hospital re-admission and intensive care unit admission compared with CBA-NHB during follow-up (all P<0.05). Of the five clusters, CBA-FH conferred the worst clinical prognosis.

CONCLUSION

Bronchiectasis severity, recent hospitalizations and sputum culture findings are three defining variables accounting for most heterogeneity of CBA, the characterization of which will help refine personalized clinical management.

Comorbidities in COPD: Current and Future Treatment Challenges

Chronic obstructive pulmonary disease (COPD) is a heterogeneous lung condition, primarily characterized by the presence of a limited airflow, due to abnormalities of the airways and/or alveoli, that often coexists with other chronic diseases such as lung cancer, cardiovascular diseases, and metabolic disorders. Comorbidities are known to pose a challenge in the assessment and effective management of COPD and are also acknowledged to have an important health and economic burden. Local and systemic inflammation have been proposed as having a potential role in explaining the association between COPD and these comorbidities. Considering that the number of patients with COPD is expected to rise, understanding the mechanisms linking COPD with its comorbidities may help to identify new targets for therapeutic purposes based on multi-dimensional assessments.

An Automated Broncho-Arterial (BA) Pair Segmentation Process and Assessment of BA Ratios in Children with Bronchiectasis Using Lung HRCT Scans: A Pilot Study

Bronchiectasis in children can progress to a severe lung condition if not diagnosed and treated early. The radiological diagnostic criteria for the diagnosis of bronchiectasis is an increased broncho-arterial (BA) ratio. From high-resolution computed tomography (HRCT) scans, the BA pairs must be detected first to derive the BA ratio. This study aims to identify potential BA pairs from HRCT scans of children undertaken to evaluate suppurative lung disease through an automated approach. After segmenting the lung regions, the HRCT scans are cleaned using a histogram analysis-based approach followed by a potential arteries identification process comprising four conditions based on imaging features. Potential arteries and their connected components are extracted, and potential bronchi are identified. Finally, the coordinates of potential arteries and potential bronchi are matched as the last step of BA pairs extraction. A total of 8-50 BA pairs are detected for each patient. Additionally, the area and several diameters of the bronchi and arteries are measured, and BA ratios based on these are calculated. Through this approach, the BA pairs of a CT scan datasets are detected and utilizing a deep learning model, a high classification test accuracy of 98.53% is achieved, validating the robustness of the proposed BA detection approach. The results show that visible BA pairs can be identified and segmented automatically, and the BA ratio calculated may help diagnose bronchiectasis with less effort and time.

Artificial Intelligence-based CT Assessment of Bronchiectasis: The COPDGene Study

Background CT is the standard method used to assess bronchiectasis. A higher airway-to-artery diameter ratio (AAR) is typically used to identify enlarged bronchi and bronchiectasis; however, current imaging methods are limited in assessing the extent of this metric in CT scans. Purpose To determine the extent of AARs using an artificial intelligence-based chest CT and assess the association of AARs with exacerbations over time. Materials and Methods In a secondary analysis of ever-smokers from the prospective, observational, multicenter COPDGene study, AARs were quantified using an artificial intelligence tool. The percentage of airways with AAR greater than 1 (a measure of airway dilatation) in each participant on chest CT scans was determined. Pulmonary exacerbations were prospectively determined through biannual follow-up (from July 2009 to September 2021). Multivariable zero-inflated regression models were used to assess the association between the percentage of airways with AAR greater than 1 and the total number of pulmonary exacerbations over follow-up. Covariates included demographics, lung function, and conventional CT parameters. Results Among 4192 participants (median age, 59 years; IQR, 52-67 years; 1878 men [45%]), 1834 had chronic obstructive pulmonary disease (COPD). During a 10-year follow-up and in adjusted models, the percentage of airways with AARs greater than 1 (quartile 4 vs 1) was associated with a higher total number of exacerbations (risk ratio [RR], 1.08; 95% CI: 1.02, 1.15; P = .01). In participants meeting clinical and imaging criteria of bronchiectasis (ie, clinical manifestations with ≥3% of AARs >1) versus those who did not, the RR was 1.37 (95% CI: 1.31, 1.43; P < .001). Among participants with COPD, the corresponding RRs were 1.10 (95% CI: 1.02, 1.18; P = .02) and 1.32 (95% CI: 1.26, 1.39; P < .001), respectively. Conclusion In ever-smokers with chronic obstructive pulmonary disease, artificial intelligence-based CT measures of bronchiectasis were associated with more exacerbations over time. Clinical trial registration no. NCT00608764 © RSNA, 2022 Supplemental material is available for this article. See also the editorial by Schiebler and Seo in this issue.

Bronchial gene expression alterations associated with radiological bronchiectasis

OBJECTIVES

Discovering airway gene expression alterations associated with radiological bronchiectasis may improve the understanding of the pathobiology of early-stage bronchiectasis.

METHODS

Presence of radiological bronchiectasis in 173 individuals without a clinical diagnosis of bronchiectasis was evaluated. Bronchial brushings from these individuals were transcriptomically profiled and analysed. Single-cell deconvolution was performed to estimate changes in cellular landscape that may be associated with early disease progression.

RESULTS

20 participants have widespread radiological bronchiectasis (three or more lobes). Transcriptomic analysis reflects biological processes associated with bronchiectasis including decreased expression of genes involved in cell adhesion and increased expression of genes involved in inflammatory pathways (655 genes, false discovery rate <0.1, log2 fold-change >0.25). Deconvolution analysis suggests that radiological bronchiectasis is associated with an increased proportion of ciliated and deuterosomal cells, and a decreased proportion of basal cells. Gene expression patterns separated participants into three clusters: normal, intermediate and bronchiectatic. The bronchiectatic cluster was enriched by participants with more lobes of radiological bronchiectasis (p<0.0001), more symptoms (p=0.002), higher SERPINA1 mutation rates (p=0.03) and higher computed tomography derived bronchiectasis scores (p<0.0001).

CONCLUSIONS

Genes involved in cell adhesion, Wnt signalling, ciliogenesis and interferon-γ pathways had altered expression in the bronchus of participants with widespread radiological bronchiectasis, possibly associated with decreased basal and increased ciliated cells. This gene expression pattern is not only highly enriched among individuals with radiological bronchiectasis, but also associated with airway-related symptoms in those without discernible radiological bronchiectasis, suggesting that it reflects a bronchiectasis-associated, but non-bronchiectasis-specific lung pathophysiological process.

Pulmonary arterial pruning is associated with CT-derived bronchiectasis progression in smokers

Loss of small pulmonary arteries measured as the ratio of blood vessel volume in arteries <5 mm2 in cross-section to total arterial blood vessel volume (BV5a/TBVa), with lower values indicating more pruning, was associated with 5-yr progressing CT-derived bronchiectasis in smokers (Odds Ratio (OR) [95% Confidence interval], 1.28 [1.07-1.53] per 5% lower BV5a/TBVa, P = 0.007). Corresponding results in smokers with COPD were: OR 1.45 [1.11-1.89] per 5% lower BV5a/TBVa, P = 0.007. The results support a vascular factor for structural progression of bronchiectasis.

Criteria and definitions for the radiological and clinical diagnosis of bronchiectasis in adults for use in clinical trials: international consensus recommendations

Bronchiectasis refers to both a clinical disease and a radiological appearance that has multiple causes and can be associated with a range of conditions. Disease heterogeneity and the absence of standardised definitions have hampered clinical trials of treatments for bronchiectasis and are important challenges in clinical practice. In view of the need for new therapies for non-cystic fibrosis bronchiectasis to reduce the disease burden, we established an international taskforce of experts to develop recommendations and definitions for clinically significant bronchiectasis in adults to facilitate the standardisation of terminology for clinical trials. Systematic reviews were used to inform discussions, and Delphi processes were used to achieve expert consensus. We prioritised criteria for the radiological diagnosis of bronchiectasis and suggest recommendations on the use and central reading of chest CT scans to confirm the presence of bronchiectasis for clinical trials. Furthermore, we developed a set of consensus statements concerning the definitions of clinical bronchiectasis and its specific signs and symptoms, as well as definitions for chronic bacterial infection and sustained culture conversion. The diagnosis of clinically significant bronchiectasis requires both clinical and radiological criteria, and these expert recommendations and proposals should help to optimise patient recruitment into clinical trials and allow reliable comparisons of treatment effects among different interventions for bronchiectasis. Our consensus proposals should also provide a framework for future research to further refine definitions and establish definitive guidance on the diagnosis of bronchiectasis.

Detection and Classification of Bronchiectasis Through Convolutional Neural Networks

PURPOSE

Bronchiectasis is a chronic disease characterized by an irreversible dilatation of bronchi leading to chronic infection, airway inflammation, and progressive lung damage. Three specific patterns of bronchiectasis are distinguished in clinical practice: cylindrical, varicose, and cystic. The predominance and the extension of the type of bronchiectasis provide important clinical information. However, characterization is often challenging and is subject to high interobserver variability. The aim of this study is to provide an automatic tool for the detection and classification of bronchiectasis through convolutional neural networks.

MATERIALS AND METHODS

Two distinct approaches were adopted: (i) direct network performing a multilabel classification of 32×32 regions of interest (ROIs) into 4 classes: healthy, cylindrical, cystic, and varicose and (ii) a 2-network serial approach, where the first network performed a binary classification between normal tissue and bronchiectasis and the second one classified the ROIs containing abnormal bronchi into one of the 3 bronchiectasis typologies. Performances of the networks were compared with other architectures presented in the literature.

RESULTS

Computed tomography from healthy individuals (n=9, age=47±6, FEV1%pred=109±17, FVC%pred=116±17) and bronchiectasis patients (n=21, age=59±15, FEV1%pred=74±25, FVC%pred=91±22) were collected. A total of 19,059 manually selected ROIs were used for training and testing. The serial approach provided the best results with an accuracy and F1 score average of 0.84, respectively. Slightly lower performances were observed for the direct network (accuracy=0.81 and F1 score average=0.82). On the test set, cylindrical bronchiectasis was the subtype classified with highest accuracy, while most of the misclassifications were related to the varicose pattern, mainly to the cylindrical class.

CONCLUSION

The developed networks accurately detect and classify bronchiectasis disease, allowing to collect quantitative information regarding the radiologic severity and the topographical distribution of bronchiectasis subtype.

Radiology of Bronchiectasis

Bronchiectasis is a radiological diagnosis made using computed tomographic (CT) imaging. Although visual CT assessment is necessary for the diagnosis of bronchiectasis, visual assessment of disease severity and progression is challenging. Computer tools offer the potential to improve the characterization of lung damage in patients with bronchiectasis. Newer imaging techniques such as MRI with hyperpolarized gas inhalation have the potential to identify early forms of disease and are without the constraints of requiring ionizing radiation exposure.

ROSE: radiology, obstruction, symptoms and exposure - a Delphi consensus definition of the association of COPD and bronchiectasis by the EMBARC Airways Working Group

INTRODUCTION

The coexistence of COPD and bronchiectasis seems to be common and associated with a worse prognosis than for either disease individually. However, no definition of this association exists to guide researchers and clinicians.

METHODS

We conducted a Delphi survey involving expert pulmonologists and radiologists from Europe, Turkey and Israel in order to define the "COPD- [bronchiectasis] BE association".A panel of 16 experts from EMBARC selected 35 statements for the survey after reviewing scientific literature. Invited participants, selected on the basis of expertise, geographical and sex distribution, were asked to express agreement on the statements. Consensus was defined as a score of ≥6 points (scale 0 to 9) in ≥70% of answers across two scoring rounds.

RESULTS

102 (72.3%) out of 141 invited experts participated in the first round. Their response rate in the second round was 81%. The final consensus definition of "COPD-BE association" was: "The coexistence of (1) specific radiological findings (abnormal bronchial dilatation, airways visible within 1 cm of pleura and/or lack of tapering sign in ≥1 pulmonary segment and in >1 lobe) with (2) an obstructive pattern on spirometry ([forced expiratory volume in 1 s] FEV1/[forced vital capacity] FVC <0.7), (3) at least two characteristic symptoms (cough, expectoration, dyspnoea, fatigue, frequent infections) and (4) current or past exposure to smoke (≥10 pack-years) or other toxic agents (biomass, etc.)". These criteria form the acronym "ROSE" (Radiology, Obstruction, Symptoms, Exposure).

CONCLUSIONS

The Delphi process formulated a European consensus definition of "COPD-BE association". We hope this definition will have broad applicability across clinical practice and research in the future.

Imaging in non-cystic fibrosis bronchiectasis and current limitations

Non-cystic fibrosis bronchiectasis represents a heterogenous spectrum of disorders characterised by an abnormal and permanent dilatation of the bronchial tree associated with respiratory symptoms. To date, diagnosis relies on computed tomography (CT) evidence of dilated airways. Nevertheless, definite radiological criteria and standardised CT protocols are still to be defined. Although largely used, current radiological scoring systems have shown substantial drawbacks, mostly failing to correlate morphological abnormalities with clinical and prognostic data. In limited cases, bronchiectasis morphology and distribution, along with associated CT features, enable radiologists to confidently suggest an underlying cause. Quantitative imaging analyses have shown a potential to overcome the limitations of the current radiological criteria, but their application is still limited to a research setting.

In the present review, we discuss the role of imaging and its current limitations in non-cystic fibrosis bronchiectasis. The potential of automatic quantitative approaches and artificial intelligence in such a context will be also mentioned.

Chronic Bronchitis in COPD Patients Creates Worse Symptom Burden Regardless of the Presence of Bronchiectasis in the COPDGene Cohort

PURPOSE

To assess whether the presence or absence of bronchiectasis has an impact on the patient-reported symptoms of chronic obstructive pulmonary disease (COPD) patients.

METHODS

The study included participants from the COPD Genetic Epidemiology Study (COPDGene®) cohort with available high-resolution chest tomography reporting the presence or absence of bronchiectasis (BE+/BE-) and survey data reporting the presence or absence of chronic bronchitis symptoms (CB+/CB-). Patient symptoms based on the St George's Respiratory Questionnaire (SGRQ) were then compared for the different groups.

RESULTS

The study population included 7976 participants, mean age 60, Global initiative for chronic Obstructive Lung Disease (GOLD) stages 0 to 4, 18.8% BE+, and 19.5% CB+. The presence or absence of radiographic bronchiectasis was not associated with higher frequency of chronic bronchitis (GOLD 0 group odds ratio [OR] 1.01 [0.78,1.31], GOLD 1-2 group OR 1.19 [0.95, 1.50], GOLD 3-4 group OR 1.26 [0.99, 1.60]). Similarly, CB+ participants had higher SGRQ scores than CB- participants regardless of the presence of BE.

CONCLUSIONS

Across all GOLD stages, chronic bronchitis symptoms are associated with worse pulmonary symptoms and significant impairment in quality of life. For patients with chronic bronchitis, the presence or absence of bronchiectasis is not associated with a significant difference in SGRQ symptom scores. Symptoms of chronic bronchitis impose a heavy burden on patients and should be treated regardless of the presence or absence of underlying bronchiectasis.

Diagnosis and Initial Investigation of Bronchiectasis

Bronchiectasis refers to both the name of a disease and a single radiological appearance that may, or may not, be associated with disease. As chronic respiratory disease, bronchiectasis is characterized by a variable range of signs and symptoms that may overlap with other chronic respiratory conditions. The proper identification of bronchiectasis as a disease in both primary and secondary care is of paramount importance. However, a standardized definition of radiologically and clinically significant bronchiectasis is still missing. Disease heterogeneity is a hallmark of bronchiectasis and applies not only to radiological features and clinical manifestations but also to other aspects of the disease, including the etiological and microbiological diagnosis as well as the evaluation of pulmonary function. Although the guidelines suggest a "minimum bundle" of tests, the diagnostic approach to bronchiectasis is challenging and may be driven by the "treatable traits" approach based on endotypes and biological characteristics. A broad spectrum of diagnostic tests could be used to investigate the etiology of bronchiectasis as well as other pulmonary, extrapulmonary, and environmental traits. Individualizing bronchiectasis workup according to the site of care (e.g., primary, secondary, and tertiary care) could help optimize patients' management and reduce healthcare costs.

Clinical and Radiological Phenotypes and Endotypes

Bronchiectasis is a heterogenous disease with multiple etiologies and associated comorbidities. As bronchiectasis is a complex disease, it is unsound to think of it as a single disease particularly when the differing etiologies are likely to be driving bronchiectasis through initial divergent molecular pathways, known as endotypes, that phenotypically present as the same disease due to protracted airway inflammation, but revealing potential differing underlying mechanisms that may have disparity of drug responses. Improved understanding of the cellular immune, inflammatory, and microbiological milieu associated with clinical and radiological features of bronchiectasis has resulted in the recognition of important endotypes and phenotypes that will allow for personalized treatments to improve quality of life and outcomes of patients with bronchiectasis. Here we discuss clinical and radiological phenotypes, as well as emerging molecular endotypes that are possible treatable traits in bronchiectasis.

Small Airway Disease and Emphysema Are Associated with Future Exacerbations in Smokers with CT-derived Bronchiectasis and COPD: Results from the COPDGene Cohort

Background Chronic obstructive pulmonary disease (COPD) and bronchiectasis can overlap and share pathologic features, such as small airway disease (SAD). Whether the presence of SAD and emphysema in smokers with CT-derived bronchiectasis is associated with exacerbations is unknown. Purpose To assess whether SAD and emphysema in smokers with CT-derived bronchiectasis are associated with future exacerbations. Materials and Methods SAD and emphysema were quantified using the parametric response map method in former and current heavy smokers with and without bronchiectasis at CT from the COPDGene Study (from July 2009 to July 2018). Exacerbations were prospectively assessed through biannual follow-up. An exacerbation was defined as an increase in or new onset of respiratory symptoms treated with antibiotics and/or corticosteroids. Severe exacerbations were defined as those that required hospitalization. The association of a high burden of SAD (≥15.6%) and high burden of emphysema (≥5%) at CT with exacerbations was assessed with generalized linear mixed models. Results Of 737 participants, 387 (median age, 64 years [interquartile range, 58-71 years]; 223 women) had CT-derived bronchiectasis. During a 9-year follow-up, after adjustment for age, sex, race, body mass index, current smoking status, pack-years, exacerbations before study entry, forced expiratory volume in 1 second, or FEV₁, and bronchiectasis severity CT score, high burden of SAD and high burden of emphysema were associated with a higher number of exacerbations per year (relative risk [RR], 1.89 [95% CI: 1.54, 2.33] and 1.37 [95% CI: 1.13, 1.66], respectively; P ≤ .001 for both). Results were comparable among participants with bronchiectasis meeting criteria for COPD (n = 197) (RR, 1.67 [95% CI: 1.23, 2.27] for high burden of SAD and 1.51 [95% CI: 1.20, 1.91] for high burden of emphysema; P ≤ .001 for both). Conclusion In smokers with CT-derived bronchiectasis and chronic obstructive pulmonary disease, structural damage to lung parenchyma and small airways was associated with a higher number of exacerbations per year. Clinical trial registration no. NCT00608764 © RSNA, 2021.

Bronchial Infection and Temporal Evolution of Bronchiectasis in Patients With Chronic Obstructive Pulmonary Disease

BACKGROUND

Bronchiectasis (BE) impact the clinical course and prognosis of patients with chronic obstructive pulmonary disease (COPD). Yet, the temporal evolution of BE in these patients is unknown. This study seeks to assess the temporal evolution of BE in persons with COPD.

METHODS

201 moderate-to-severe patients were recruited between 2004 and 2007 and followed up at least every 6 monts (median of 102 months). To investigate the temporal evolution of BE, in 2015 a second high-resolution computed tomography scan (HRCT) was obtained in survivors and compared with the one obtained at recruitment.

RESULTS

99 (49.3%) died during follow-up. The second HRCT could be obtained in 77 patients and showed that (1) in 27.3% of patients BE never developed, in 36.4% they remained stable, in 16.9% they increased in size and/or extension, and in 19.5% new BE emerged; and that (2) the presence of chronic purulent sputum (hazard ratio [HR], 2.8 [95% confidence interval {CI}, 1.3-5.8]), number of hospitalizations due to exacerbatons (HR, 1.2 [95% CI, 1.1-1.5]), and number of pathogenic microorganism (PPM) isolations (HR, 1.1 [95% CI, 1.02-1.3]) were independent risk factors for the progression or development of BE.

CONCLUSIONS

The presence of chronic purulent sputum production, number of PPMs isolated in sputum, and number of hospitalizations due to exacerbations of COPD are independent risk factors of BE progression in patients with COPD.

Association between Cardiorespiratory Fitness and Bronchiectasis at CT: A Long-term Population-based Study of Healthy Young Adults Aged 18-30 Years in the CARDIA Study

Background Protective factors against the risk of bronchiectasis are unknown. A high level of cardiorespiratory fitness is associated with a lower risk of chronic obstructive pulmonary disease. But whether fitness relates to bronchiectasis remains, to the knowledge of the authors, unknown. Purpose To examine the association between cardiorespiratory fitness and bronchiectasis. Materials and Methods This was a secondary analysis of a prospective observational study: the Coronary Artery Risk Development in Young Adults cohort (from 1985-1986 [year 0] to 2015-2016 [year 30]). During a 30-year period, healthy participants (age at enrollment 18-30 years) underwent treadmill exercise testing at year 0 and year 20 visits. Cardiorespiratory fitness was determined according to the treadmill exercise duration. The 20-year difference in cardiorespiratory fitness was used as the fitness measurement. At year 25, chest CT was performed to assess bronchiectasis and was used as the primary outcome. Multivariable logistic models were performed to determine the association between cardiorespiratory fitness changes and bronchiectasis. Results Of 2177 selected participants (at year 0: mean age, 25 years ± 4 [standard deviation]; 1224 women), 209 (9.6%) had bronchiectasis at year 25. After adjusting for age, race-sex group, study site, body mass index, pack-years smoked, history of tuberculosis, pneumonia, asthma and myocardial infarction, peak lung function, and cardiorespiratory fitness at baseline, preservation of cardiorespiratory fitness was associated with lower odds of bronchiectasis at CT at year 25 (per 1-minute-longer treadmill duration from year 0 to year 20: odds ratio [OR], 0.88; 95% CI: 0.80, 0.98; P = .02). A consistent strong association was found when cough and phlegm were included in bronchiectasis (OR, 0.72; 95% CI: 0.59, 0.87; P < .001). Conclusion In a long-term follow-up, the preservation of cardiorespiratory fitness was associated with lower odds of bronchiectasis at CT. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Stojanovska in this issue.

CT Pulmonary Vessels and MRI Ventilation in Chronic Obstructive Pulmonary Disease: Relationship with worsening FEV1 in the TINCan cohort study

RATIONALE AND OBJECTIVES

The relationships between computed tomography (CT) pulmonary vascularity and MRI ventilation is not well-understood in chronic obstructive pulmonary disease (COPD) patients. Our objective was to evaluate CT pulmonary vascular and MRI ventilation measurements in ex-smokers and to investigate their associations and how such measurements change over time.

MATERIALS AND METHODS

Ninety ex-smokers (n = 41 without COPD 71 ± 10 years and n = 49 COPD 71 ± 8 years) provided written informed-consent to an ethics-board approved protocol and underwent imaging and pulmonary-function-tests twice, 31 ± 7 months apart. ³He MRI was acquired to generate ventilation-defect-percent (VDP). CT measurements of the relative area-of-the-lung with attenuation <-950 Hounsfield units (RA₉₅₀), pulmonary vascular total-blood-volume (TBV) and percent of vessels with radius < one voxel (PV₁) were evaluated.

RESULTS

At baseline, there were significant differences in RA₉₅₀ (p = 0.0001), VDP (p = 0.0001), total-blood-volume (p = 0.0001) and PV₁ (p = 0.01) between ex-smokers and COPD participants as well as for VDP (p = 0.0001) in COPD participants with and without emphysema. The annual FEV₁ change (-40 ± 93 mL/year) was not different among participant subgroups (p = 0.87), but the annual RA₉₅₀ (p = 0.01) and PV₁ (p = 0.007) changes were significantly different in participants with an accelerated annual FEV₁ decline as compared to participants with a diminished annual FEV₁ decline. There were significant but weak relationships for PV₁ with FEV_1%pred (p = 0.02), FEV₁/FVC (p = 0.001), and log RA₉₅₀ (p = 0.0001), but not VDP (p=0.20). The mean change in PV₁ was also weakly but significantly related to the change in RA₉₅₀ (p = 0.02).

CONCLUSION

CT pulmonary vascular measurements were significantly different in ex-smokers and participants with COPD and related to RA₉₅₀ but not VDP worsening over 2.5 years.

Paired CT Measures of Emphysema and Small Airways Disease and Lung Function and Exercise Capacity in Smokers with Radiographic Bronchiectasis

RATIONALE AND OBJECTIVES

Bronchiectasis (BE) is associated with chronic obstructive pulmonary disease (COPD), but emphysema and small airways disease, main pathologic features of COPD, have been sparsely studied in BE. We aimed to objectively assess those features in smokers with and without radiographic BE and examine its relationships to airflow obstruction and exercise capacity.

MATERIAL AND METHODS

We measured emphysema and small airways disease on paired inspiratory-expiratory computed tomography (CT) scans with the parametric response map (PRM^EMPH and PRM^SAD) method in 1184 smokers with and without radiographic BE. PRM^SAD and PRM^EMPH are expressed as the percentage of lung area. Clinical, spirometry, and exercise capacity data were measured with standardized methods. The differences in PRM^SAD and PRM^EMPH between subjects with and without radiographic BE were assessed using multivariable linear regression analysis, and their associations with FEV₁ and six-minute walk test (6MWT) were assessed with generalized linear models.

RESULTS

Out of 1184 subjects, 383 (32%) had radiographic BE. PRM^EMPH but not PRM^SAD was higher in subjects with radiographic BE than those without radiographic BE in adjusted models. Subjects with radiographic BE and PRM^EMPH (defined as ≥5% on paired CTs) had lower FEV₁ (least square mean, 1479 mL vs. 2350 mL p < 0.0001) and 6MWT (372 m vs. 426 m p = 0.0007) than those with radiographic BE alone in adjusted models.

CONCLUSION

Smokers with radiographic BE have an increased burden of emphysema on paired CTs, and those with radiographic BE and emphysema have lower airflow and exercise capacity.

Relationship between clinical and radiological signs of bronchiectasis in COPD patients: Results from COSYCONET

Bronchiectasis (BE) might be frequently present in COPD but masked by COPD symptoms. We studied the relationship of clinical signs of bronchiectasis to the presence and extent of its radiological signs in patients of different COPD severity. Visit 4 data (GOLD grades 1-4) of the COSYCONET cohort was used. Chest CT scans were evaluated for bronchiectasis in 6 lobes using a 3-point scale (0: absence, 1: ≤50%, 2: >50% BE-involvement for each lobe). 1176 patients were included (61%male, age 67.3y), among them 38 (3.2%) with reported physicians' diagnosis of bronchiectasis and 76 (6.5%) with alpha1-antitrypsin deficiency (AA1D). CT scans were obtained in 429 patients. Within this group, any signs of bronchiectasis were found in 46.6% of patients, whereby ≤50% BE occurred in 18.6% in ≤2 lobes, in 10.0% in 3-4 lobes, in 15.9% in 5-6 lobes; >50% bronchiectasis in at least 1 lobe was observed in 2.1%. Scores ≥4 correlated with an elevated ratio FRC/RV. The clinical diagnosis of bronchiectasis correlated with phlegm and cough and with radiological scores of at least 3, optimally ≥5. In COPD patients, clinical diagnosis and radiological signs of BE showed only weak correlations. Correlations became significant with increasing BE-severity implying radiological alterations in several lobes. This indicates the importance of reporting both presence and extent of bronchiectasis on CT. Further research is warranted to refine the criteria for CT scoring of bronchiectasis and to determine the relevance of radiologically but not clinically detectible bronchiectasis and their possible implications for therapy in COPD patients.

The radiological diagnosis of bronchiectasis: what's in a name?

Diagnosis of bronchiectasis is usually made using chest computed tomography (CT) scan, the current gold standard method. A bronchiectatic airway can show abnormal widening and thickening of its airway wall. In addition, it can show an irregular wall and lack of tapering, and/or can be visible in the periphery of the lung. Its diagnosis is still largely expert based. More recently, it has become clear that airway dimensions on CT and therefore the diagnosis of bronchiectasis are highly dependent on lung volume. Hence, control of lung volume is required during CT acquisition to standardise the evaluation of airways. Automated image analysis systems are in development for the objective analysis of airway dimensions and for the diagnosis of bronchiectasis. To use these systems, clear and objective definitions for the diagnosis of bronchiectasis are needed. Furthermore, the use of these systems requires standardisation of CT protocols and of lung volume during chest CT acquisition. In addition, sex- and age-specific reference values are needed for image analysis outcome parameters. This review focusses on today's issues relating to the radiological diagnosis of bronchiectasis using state-of-the-art CT imaging techniques.

Bronchiectasis diagnosis is expert based. Clear definitions, standardisation of lung volume and CT protocols, and reference values are needed to allow automated image analysis for its diagnosis and to be used for clinical management and clinical studies.http://bit.ly/35vASqz

Diagnosis and quantification of bronchiectasis using computed tomography or magnetic resonance imaging: A systematic review

BACKGROUND

Bronchiectasis is an irreversible dilatation of the airways caused by inflammation and infection. To diagnose bronchiectasis in clinical care and to use bronchiectasis as outcome parameter in clinical trials, a radiological definition with exact cut-off values along with image analysis methods to assess its severity are needed. The aim of this study was to review diagnostic criteria and quantification methods for bronchiectasis.

METHODS

A systematic literature search was performed using Embase, Medline Ovid, Web of Science, Cochrane and Google Scholar. English written, clinical studies that included bronchiectasis as outcome measure and used image quantification methods were selected. Criteria for bronchiectasis, quantification methods, patient demographics, and data on image acquisition were extracted.

RESULTS

We screened 4182 abstracts, selected 972 full texts, and included 122 studies. The most often used criterion for bronchiectasis was an inner airway-artery ratio ≥1.0 (42%), however no validation studies for this cut-off value were found. Importantly, studies showed that airway-artery ratios are influenced by age. To quantify bronchiectasis, 42 different scoring methods were described.

CONCLUSION

Different diagnostic criteria for bronchiectasis are being used, but no validation studies were found to support these criteria. To use bronchiectasis as outcome in future studies, validated and age-specific cut-off values are needed.

Airway tapering: an objective image biomarker for bronchiectasis

Purpose

To estimate airway tapering in control subjects and to assess the usability of tapering as a bronchiectasis biomarker in paediatric populations.

Methods

Airway tapering values were semi-automatically quantified in 156 children with control CTs collected in the Normal Chest CT Study Group. Airway tapering as a biomarker for bronchiectasis was assessed on spirometer-guided inspiratory CTs from 12 patients with bronchiectasis and 12 age- and sex-matched controls. Semi-automatic image analysis software was used to quantify intra-branch tapering (reduction in airway diameter along the branch), inter-branch tapering (reduction in airway diameter before and after bifurcation) and airway-artery ratios on chest CTs. Biomarkers were further stratified in small, medium and large airways based on three equal groups of the accompanying vessel size.

Results

Control subjects showed intra-branch tapering of 1% and inter-branch tapering of 24–39%. Subjects with bronchiectasis showed significantly reduced intra-branch of 0.8% and inter-branch tapering of 19–32% and increased airway–artery ratios compared with controls (p < 0.01). Tapering measurements were significantly different between diseased and controls across all airway sizes. Difference in airway–artery ratio was only significant in small airways.

Conclusion

Paediatric normal values for airway tapering were established in control subjects. Tapering showed to be a promising biomarker for bronchiectasis as subjects with bronchiectasis show significantly less airway tapering across all airway sizes compared with controls. Detecting less tapering in larger airways could potentially lead to earlier diagnosis of bronchiectasis. Additionally, compared with the conventional airway–artery ratio, this novel biomarker has the advantage that it does not require pairing with pulmonary arteries.

Key Points

• Tapering is a promising objective image biomarker for bronchiectasis that can be extracted semi-automatically and has good correlation with validated visual scoring methods.

• Less airway tapering was observed in patients with bronchiectasis and can be observed sensitively throughout the bronchial tree, even in the more central airways.

• Tapering values seemed to be less influenced by variety in scanning protocols and lung volume making it a more robust biomarker for bronchiectasis detection.

Electronic supplementary material

The online version of this article (10.1007/s00330-019-06606-w) contains supplementary material, which is available to authorized users.

Luminal Plugging on Chest CT Scan: Association With Lung Function, Quality of Life, and COPD Clinical Phenotypes

BACKGROUND

Mucous exudates occluding the lumen of small airways are associated with reduced lung function and mortality in subjects with COPD; however, luminal plugs in large airways have not been widely studied. We aimed to examine the associations of chest CT scan-identified luminal plugging with lung function, health-related quality of life, and COPD phenotypes.

METHODS

We randomly selected 100 smokers without COPD and 400 smokers with COPD from the COPDGene Study. Luminal plugging was visually identified on inspiratory CT scans at baseline and 5-year follow-up. The relationships of luminal plugging to FEV₁, St. George's Respiratory Questionnaire (SGRQ) score, emphysema on CT scan (defined as the percentage of low attenuation area < 950 Hounsfield units [%LAA-950]), and chronic bronchitis were assessed using linear and logistic multivariable analyses.

RESULTS

Overall, 111 subjects (22%) had luminal plugging. The prevalence of luminal plugging was higher in subjects with COPD than those without COPD (25% vs 10%, respectively; P = .001). In subjects with COPD, luminal plugging was significantly associated with FEV₁ % predicted (estimate, -6.1; SE, 2.1; P = .004) and SGRQ score (estimate, 4.9; SE, 2.4; P = .04) in adjusted models. Although luminal plugging was associated with log %LAA-950 (estimate, 0.43; SE, 0.16; P = .007), its relationship with chronic bronchitis did not reach statistical significance (P = .07). Seventy-three percent of subjects with COPD with luminal plugging at baseline had it 5 years later.

CONCLUSIONS

In subjects with COPD, CT-identified luminal plugging is associated with airflow obstruction, worse health-related quality of life, and emphysema phenotype. This imaging feature may supplement the current clinical assessment of chronic mucus hypersecretion in COPD.

Airway morphometry in COPD with bronchiectasis: a view on all airway generations

The pathophysiological processes underlying bronchiectasis in chronic obstructive pulmonary disease (COPD) are not understood. In COPD, both small and large airways are progressively lost. It is currently not known to what extent the different airway generations of patients with COPD and bronchiectasis are involved.

COPD explant lungs with bronchiectasis were compared to COPD explant lungs without bronchiectasis and unused donor lungs as controls. In order to investigate all airway generations, a multimodal imaging approach using different resolutions was conducted. Per group, five lungs were frozen (n=15) and underwent computed tomography (CT) imaging for large airway evaluation, with four tissue cores per lung imaged for measurements of the terminal bronchioles. Two additional lungs per group (n=6) were air-dried for lobar microCT images that allow airway segmentation and three-dimensional quantification of the complete airway tree.

COPD lungs with bronchiectasis had significantly more airways compared to COPD lungs without bronchiectasis (p<0.001), with large airway numbers similar to control lungs. This difference was present in both upper and lower lobes. Lack of tapering was present (p=0.010) and larger diameters were demonstrated in lower lobes with bronchiectasis (p=0.010). MicroCT analysis of tissue cores showed similar reductions of tissue percentage, surface density and number of terminal bronchioles in both COPD groups compared to control lungs.

Although terminal bronchioles were equally reduced in COPD lungs with and without bronchiectasis, significantly more large and small airways were found in COPD lungs with bronchiectasis.

Reproducibility of an airway tapering measurement in computed tomography with application to bronchiectasis

We propose a pipeline to acquire a scalar tapering measurement from the carina to the most distal point of an individual airway visible on computed tomography (CT). We show the applicability of using tapering measurements on clinically acquired data by quantifying the reproducibility of the tapering measure. We generate a spline from the centerline of an airway to measure the area and arclength at contiguous intervals. The tapering measurement is the gradient of the linear regression between area in log space and arclength. The reproducibility of the measure was assessed by analyzing different radiation doses, voxel sizes, and reconstruction kernel on single timepoint and longitudinal CT scans and by evaluating the effect of airway bifurcations. Using 74 airways from 10 CT scans, we show a statistical difference, p = 3.4 × 10 - 4 , in tapering between healthy airways ( n = 35 ) and those affected by bronchiectasis ( n = 39 ). The difference between the mean of the two populations is 0.011    mm - 1 , and the difference between the medians of the two populations was 0.006    mm - 1 . The tapering measurement retained a 95% confidence interval of ± 0.005    mm - 1 in a simulated 25 mAs scan and retained a 95% confidence of ± 0.005    mm - 1 on simulated CTs up to 1.5 times the original voxel size. We have established an estimate of the precision of the tapering measurement and estimated the effect on precision of the simulated voxel size and CT scan dose. We recommend that the scanner calibration be undertaken with the phantoms as described, on the specific CT scanner, radiation dose, and reconstruction algorithm that are to be used in any quantitative studies.

Paediatric and adult bronchiectasis: Specific management with coexisting asthma, COPD, rheumatological disease and inflammatory bowel disease

Bronchiectasis, conventionally defined as irreversible dilatation of the bronchial tree, is generally suspected on a clinical basis and confirmed by means of chest high-resolution computed tomography. Clinical manifestations, including chronic productive cough and endobronchial suppuration with persistent chest infection and inflammation, may deeply affect quality of life, both in children/adolescents and adults. Despite many cases being idiopathic or post-infectious, a number of specific aetiologies have been traditionally associated with bronchiectasis, such as cystic fibrosis (CF), primary ciliary dyskinesia or immunodeficiencies. Nevertheless, bronchiectasis may also develop in patients with bronchial asthma; chronic obstructive pulmonary disease; and, less commonly, rheumatological disorders and inflammatory bowel diseases. Available literature on the development of bronchiectasis in these conditions and on its management is limited, particularly in children. However, bronchiectasis may complicate the clinical course of the underlying condition at any age, and appropriate management requires an integration of multiple skills in a team of complementary experts to provide the most appropriate care to affected children and adolescents. The present review aims at summarizing the current knowledge and available evidence on the management of bronchiectasis in the other conditions mentioned and focuses on the new therapeutic strategies that are emerging as promising tools for improving patients' quality of life.

Bronchiectasis: A Complex, Heterogeneous Disease

Most areas of respiratory medicine continue to use an Oslerian approach, based on signs and symptoms, in which the disease is the center of all activity. However, this paradigm is changing. Now that lung diseases have been recognized as heterogeneous and complex, we are moving towards more personalized, precise, patient-oriented medicine. The aim of this review was to define the current state of the knowledge on bronchiectasis, or, more accurately, the bronchiectasis syndrome, as a multidimensional, systemic, heterogeneous, complex disease. We explore the advances that have already been made, and above all the many steps that are still to be taken. We also propose some tools which might facilitate the application of these concepts in clinical practice, and help us continue our journey towards a more holistic view of this disease.

High-resolution CT evaluation of bronchial lumen to vertebral body, pulmonary artery to vertebral body and bronchial lumen to pulmonary artery ratios in Dirofilaria immitis-infected cats with and without selamectin administration

Objectives The bronchial lumen to pulmonary artery (BA) ratio is utilized to evaluate pulmonary pathology on CT images. The BA ratio may be unreliable when changes are present in bronchial and pulmonary arteries concurrently. Bronchial lumen to vertebral body (BV) and pulmonary artery to vertebral body (AV) ratios have been established in normal cats and may serve as an alternative. This study aimed to evaluate the BV, AV and BA ratios in cats before and after infection with Dirofilaria immitis, with and without selamectin administration, and to characterize the distribution of disease. Methods Archived CT images were reviewed from three groups of cats: D immitis-infected untreated (n = 6); infected pretreated with selamectin (n = 6); and uninfected untreated (n = 5). The BV, AV and BA ratios were calculated for all lung lobes for baseline (D0) and day 240 (D240) postinfection. Ratios and percentage change from baseline were compared between lobes and between groups. Results BV and AV ratios were more consistent in identifying abnormalities when disease was present in bronchial and arteries concurrently than BA ratios. Infected untreated cats had significant changes in both BV and AV ratios and percentage change from baseline. Abnormal BV and AV ratios were noted in the infected selamectin group, although less widely distributed. Conclusions and relevance The BV and AV ratios more accurately identified bronchial and pulmonary artery abnormalities in D immitis-infected cats. Both bronchial and pulmonary artery changes were present in infected cats, decreasing the diagnostic application of the BA ratio. Pulmonary artery changes were more widely distributed than bronchial changes in the lung. Heartworm-infected cats receiving selamectin had bronchial and pulmonary artery changes but to a lesser extent than untreated heartworm-infected cats. The CT-derived BV and AV ratios are a useful measure to evaluate lung disease of cats.

[Bronchiectasis imaging]

Bronchiectasis are defined as an irreversible focal or diffuse dilatation of the bronchi and can be associated with significant morbidity. The prevalence is currently increasing, probably due to an increased use of thoracic computed tomography (CT). Indeed, the diagnosis relies on imaging and chest CT is the gold standard technique. The main diagnosis criterion is an increased bronchial diameter as compared to that of the companion artery. However, false positives are possible when the artery diameter is decreased, which is called pseudo-bronchiectasis. Other features such as the lack of bronchial tapering, and visibility of bronchi within 1cm of the pleural surface are also diagnostic criteria, and other CT features of bronchial disease are commonly seen. Thoracic imaging also allows severity assessment and long-term monitoring of structural abnormalities. The distribution pattern and the presence of associated findings on chest CT help identifying specific causes of bronchiectasis. Lung MRI and ultra-low dose CT and are promising imaging modalities that may play a role in the future. The objectives of this review are to describe imaging features for the diagnosis and severity assessment of bronchiectasis, to review findings suggesting the cause of bronchiectasis, and to present the new developments in bronchiectasis imaging.

Pulmonary vascular pruning in smokers with bronchiectasis

There are few studies looking at the pulmonary circulation in subjects with bronchiectasis. We aimed to evaluate the intraparenchymal pulmonary vascular structure, using noncontrast chest computed tomography (CT), and its clinical implications in smokers with radiographic bronchiectasis. Visual bronchiectasis scoring and quantitative assessment of the intraparenchymal pulmonary vasculature were performed on CT scans from 486 smokers. Clinical, lung function and 6-min walk test (6MWT) data were also collected. The ratio of blood vessel volume in vessels <5 mm2 in cross-section (BV5) to total blood vessel volume (TBV) was used as measure of vascular pruning, with lower values indicating more pruning. Whole-lung and lobar BV5/TBV values were determined, and regression analyses were used to assess the differences in BV5/TBV between subjects with and without bronchiectasis. 155 (31.9%) smokers had bronchiectasis, which was, on average, mild in severity. Compared to subjects without bronchiectasis, those with lower-lobe bronchiectasis had greater vascular pruning in adjusted models. Among subjects with bronchiectasis, those with vascular pruning had lower forced expiratory volume in 1 s and 6MWT distance compared to those without vascular pruning. Smokers with mild radiographic bronchiectasis appear to have pruning of the distal pulmonary vasculature and this pruning is associated with measures of disease severity.

The overlap between bronchiectasis and chronic airway diseases: state of the art and future directions

Bronchiectasis is a clinical and radiological diagnosis associated with cough, sputum production and recurrent respiratory infections. The clinical presentation inevitably overlaps with other respiratory disorders such as asthma and chronic obstructive pulmonary disease (COPD). In addition, 4-72% of patients with severe COPD are found to have radiological bronchiectasis on computed tomography, with similar frequencies (20-30%) now being reported in cohorts with severe or uncontrolled asthma. Co-diagnosis of bronchiectasis with another airway disease is associated with increased lung inflammation, frequent exacerbations, worse lung function and higher mortality. In addition, many patients with all three disorders have chronic rhinosinusitis and upper airway disease, resulting in a complex "mixed airway" phenotype.The management of asthma, bronchiectasis, COPD and upper airway diseases has traditionally been outlined in separate guidelines for each individual disorder. Recognition that the majority of patients have one or more overlapping pathologies requires that we re-evaluate how we treat airway disease. The concept of treatable traits promotes a holistic, pathophysiology-based approach to treatment rather than a syndromic approach and may be more appropriate for patients with overlapping features.Here, we review the current clinical definition, diagnosis, management and future directions for the overlap between bronchiectasis and other airway diseases.

Characteristics and Health-care Utilization History of Patients With Bronchiectasis in US Medicare Enrollees With Prescription Drug Plans, 2006 to 2014

BACKGROUND

Bronchiectasis is an increasingly common chronic inflammatory airway disease. There is an urgent need to understand the epidemiology of bronchiectasis in older adults. We describe the prevalence and characteristics of patients with bronchiectasis within the US Medicare population.

METHODS

Among the 40% of Medicare enrollees with prescription drug plans from 2006 to 2014, we identified patients ≥ 65 years of age with bronchiectasis by International Classification of Diseases, Ninth Revision, Clinical Modification claims (494.0 or 494.1) from a pulmonologist and no claim for cystic fibrosis. We calculated the prevalence from 2012 to 2014. Incident or newly diagnosed patients were those enrolled in Medicare at least 12 months prior to the first bronchiectasis diagnosis. We described clinical and health-care utilization characteristics for this cohort during the prior 12-month (baseline) period, and explored differences between those with and without a COPD diagnosis.

RESULTS

We identified 252,362 patients with bronchiectasis meeting all eligibility criteria. The average annual prevalence from 2012 to 2014 was 701 per 100,000 persons. Newly diagnosed patients were a mean age of 76 years, predominately women (65%), and predominately white, non-Hispanic (84%). During the baseline period, 12% were hospitalized for respiratory infections. Fifty-one percent had a dual diagnosis of COPD. Newly diagnosed patients with bronchiectasis and COPD had significantly different characteristics and utilization, for example were more likely hospitalized for respiratory infections during the baseline period (16% vs 7%) and to have a smoking history (46% vs 17%) compared with those without a dual COPD diagnosis, respectively.

CONCLUSIONS

We confirmed a high prevalence of bronchiectasis in the United States and significant heterogeneity in patients with bronchiectasis with and without COPD that should be further explored.

Pulmonary quantitative CT imaging in focal and diffuse disease: current research and clinical applications

The frenetic development of imaging technology-both hardware and software-provides exceptional potential for investigation of the lung. In the last two decades, CT was exploited for detailed characterization of pulmonary structures and description of respiratory disease. The introduction of volumetric acquisition allowed increasingly sophisticated analysis of CT data by means of computerized algorithm, namely quantitative CT (QCT). Hundreds of thousands of CTs have been analysed for characterization of focal and diffuse disease of the lung. Several QCT metrics were developed and tested against clinical, functional and prognostic descriptors. Computer-aided detection of nodules, textural analysis of focal lesions, densitometric analysis and airway segmentation in obstructive pulmonary disease and textural analysis in interstitial lung disease are the major chapters of this discipline. The validation of QCT metrics for specific clinical and investigational needs prompted the translation of such metrics from research field to patient care. The present review summarizes the state of the art of QCT in both focal and diffuse lung disease, including a dedicated discussion about application of QCT metrics as parameters for clinical care and outcomes in clinical trials.

Bronchiectasis in COPD patients: more than a comorbidity?

Computed tomography scan images have been used to identify different radiological COPD phenotypes based on the presence and severity of emphysema, bronchial wall thickening, and bronchiectasis. Bronchiectasis is defined as an abnormal dilation of the bronchi, usually as a result of chronic airway inflammation and/or infection. The prevalence of bronchiectasis in patients with COPD is high, especially in advanced stages. The identification of bronchiectasis in COPD has been defined as a different clinical COPD phenotype with greater symptomatic severity, more frequent chronic bronchial infection and exacerbations, and poor prognosis. A causal association has not yet been proven, but it is biologically plausible that COPD, and particularly the infective and exacerbator COPD phenotypes, could be the cause of bronchiectasis without any other known etiology, beyond any mere association or comorbidity. The study of the relationship between COPD and bronchiectasis could have important clinical implications, since both diseases have different and complementary therapeutic approaches. Longitudinal studies are needed to investigate the development of bronchiectasis in COPD, and clinical trials with treatments aimed at reducing bacterial loads should be conducted to investigate their impact on the reduction of exacerbations and improvements in the long-term evolution of the disease.