Automatic analysis of bronchus-artery dimensions to diagnose and monitor airways disease in cystic fibrosis

Effect of inspiratory lung volume on bronchial and arterial dimensions and ratios on chest computed tomography in patients with chronic obstructive pulmonary disease

BACKGROUND

The assessment of bronchus-artery (BA) metrics on chest CT is important for detecting airway abnormalities. It is less clear how BA metrics are dependent on lung volume.

METHODS

CTs were obtained from a COPDGene substudy investigating the impact of radiation dose on lung density. Patients with chronic obstructive pulmonary disease underwent a full-dose and a reduced-dose CT in the same imaging session. CTs were automatically analyzed by measuring diameters of the bronchial outer edge (Bout), bronchial inner wall (Bin), artery (A), and bronchial wall thickness (Bwt) from segmental (G0) and distal generations. BA ratios were computed: Bout/A, Bin/A, Bwt/A, and bronchial wall area/bronchial outer area (Bwa/Boa). The total lung volume of the CT (TLC-CT) was computed. Differences between the volumes between the two CTs were expressed as % of the highest TLC-CT (ΔTLC-CT%). For the BA metrics of each CT, we computed the median of measurements in G1-6. Mixed-effect models were used to investigate the influence of TLC-CT on BA metrics adjusted for dose protocol.

RESULTS

One thousand three hundred nineteen patients with a mean (SD) age of 64.4 (8.7) years were included. Three hundred twenty-nine (124) BA pairs were analyzed per CT. No significant difference was found for TLC-CT in relation to dose (p = 0.17). A ΔTLC-CT% of >10% (found in 121, 9%) led to 0.03 and 0.05 decreases in Bout/A and Bin/A and 0.008 and 0.11 decrease in log (Bwt/A) and log (Bwa/Boa), and a 0.03 increase in Bin and 0.06, 0.12, and 0.04 decrease in Bout, log (Bwt), and log (A) (all p < 0.001).

CONCLUSIONS

Variations in TLC over 10% between time points significantly influence bronchial dimensions, affecting BA metrics. Standardizing volumes is recommended for sensitive tracking of airway disease changes over time.

KEY POINTS

Question Are BA metrics dependent on total lung capacity (TLC), and if so, how? Findings TLC variations over 10% between time points significantly influence bronchial dimensions, affecting BA metrics. Variations below 10% between CT scans have little effect on BA metrics. Clinical relevance Small lung volume differences between chest CTs have little impact on bronchus and artery metrics; it is imperative to standardize chest CT lung volumes to ensure precise diagnosis and monitoring of airway disease.

Evolution of Lung Disease Studied by Computed Tomography in Adults with Cystic Fibrosis Treated with Elexacaftor/Tezacaftor/Ivacaftor

Elexacaftor-tezacaftor-ivacaftor (ETI) has shown clinical and spirometric benefits in cystic fibrosis (CF). CT remains a vital tool for diagnosing and monitoring structural lung disease. This study aimed to assess the evolution of lung disease, as evaluated through CT, in adults with CF after at least one year of ETI treatment. This ambispective observational analysis assessed lung CT scans performed before initiating ETI and after at least one year of treatment, using the modified Bhalla scoring system. For those patients with an earlier CT scan, a pre-treatment phase analysis was performed. Epidemiological, clinical, and functional parameters were evaluated. Results: Sixty-two patients were included (35 males, median age 30.4 ± 7.87 years). After at least one year of ETI, significant improvements were observed in the global CT Bhalla score (12.2 ± 2.8 vs. 14.0 ± 2.8), peribronchial thickening (1.4 ± 0.6 vs. 1.0 ± 0.4), and mucus plugging (1.6 ± 0.7 vs. 0.8 ± 0.6) (p < 0.001). Spirometry parameters increased significantly: the percentage of the predicted forced expiratory volume in the first second (ppFEV1) increased from 66.5 ± 19.8 to 77.0 ± 20.4 (p = 0.005) and forced vital capacity (ppFVC) from 80.6 ± 16.4 to 91.6 ± 14.1 (p < 0.001). Additionally, body mass index showed a significant increase. A moderate correlation was found between the Bhalla score and spirometry results. In the pre-treatment phase (n = 52), mucus plugging demonstrated a significant worsening, whereas global CT score, other subscores, and spirometry did not change significantly. Conclusions: In adults with CF, after at least one year of ETI, a significant improvement in structural lung disease was achieved, as reflected by the CT Bhalla score.

Normative values for lung, bronchial sizes, and bronchus-artery ratios in chest CT scans: from infancy into young adulthood

OBJECTIVE

To estimate the developmental trends of quantitative parameters obtained from chest computed tomography (CT) and to provide normative values on dimensions of bronchi and arteries, as well as bronchus-artery (BA) ratios from preschool age to young adulthood.

MATERIALS AND METHODS

Two independent radiologists screened a dataset of 1160 chest CT scans, initially reported as normal, from participants aged 0 to 24 years. Using an automated deep learning-based algorithm, we computed the following bronchus and artery parameters: bronchial outer diameter (Bout), bronchial inner diameter (Bin), adjacent pulmonary artery diameter (A), bronchial wall thickness (Bwt), bronchial wall area (BWA), and bronchial outer area (BOA). From these parameters, we computed the following ratios: Bout/A, Bin/A, Bwt/A, Bwt/Bout, and BWA/BOA. Furthermore, mean lung density, total lung volume, and the square root of wall area of bronchi with a 10-mm lumen perimeter (Pi10) were obtained. The effects on CT parameters of age, sex, and iodine contrast were investigated using mixed-effects or regression model analyses.

RESULTS

375 normal inspiratory chest CT scans (females / males = 156 / 219; mean age [SD] 12.7 [5.0] years) met the inclusion criteria. Bout and Bin progressively increased with age (all p < 0.05), but Bwt, Bout/A, Bin/A, Bwt/A, Bwt/Bout, or BWA/BOA did not. Total lung volume and mean lung density continuously increased with age (both p < 0.001), while Pi10 did not exhibit such a trend. Bout, total lung volume, and mean lung density were the only parameters that differed between males and females, all higher in males than females (all p < 0.03). The presence of iodinated contrast led to greater values for Bwt, Bwt/Bout, and BWA/BOA, but lower values for Bin, Bout/A, Bin/A, and Bwt/A (all p < 0.01).

CONCLUSION

Quantitative CT parameters of both lung parenchyma and bronchi exhibit growth-related changes, but from 6 to 24 years ratios between bronchus and artery dimensions remain constant. Contrast-enhanced CT scans affect the assessment of lung parenchyma and bronchial size. We propose age and technique-dependent normative values for bronchial dimensions and wall thickness.

KEY POINTS

Question What are the developmental trends of quantitative lung CT parameters in patients from childhood into young adulthood? Findings The ratio between bronchus and pulmonary artery dimensions demonstrates consistent values across age groups, indicating synchronized growth between bronchi and paired pulmonary arteries. Clinical relevance Our findings highlight the importance of standardized CT protocol and volume acquisition, and emphasize the need for ongoing collection of normal chest CT scans to refine the proposed reference values.

Introduction of Ivacaftor/Lumacaftor in Children With Cystic Fibrosis Homozygous for F508del in the Netherlands: A Nationwide Real-Life Study

INTRODUCTION

Lumacaftor/ivacaftor (lum/iva) was introduced in the Netherlands in 2017. We investigated 1-year efficacy of lum/iva on lung function and small airway and structural lung disease evaluated by multiple breath nitrogen washout and CT scan. Additionally, we investigated effects of lum/iva on exacerbations, anthropometry, sweat chloride and safety in children with CF in the Netherlands.

METHODS

Children with CF aged 6-18 years and homozygous for F508del treated in one of the seven Dutch CF centers for at least 12 months were eligible. Data were extracted from the Dutch CF Registry and electronic patient records. Primary outcome was change in percent predicted FEV1 (ppFEV1) after 12 months.

RESULTS

Nationwide, 247 children with CF were eligible for lum/iva. Eight patients discontinued lum/iva due to side effects. In total, 223/247 children (90.3%) were evaluated. Mean (range) age at baseline was 11.0 (6.0-17.1) years. There was no change in FEV1 after 12 months of lum/iva. In a subgroup, markers of small airway function and structural lung disease, such as LCI (n = 28), mean change (SD) -10.0% (15.8), and bronchus-artery (BA) analysis on CT scan (n = 81), showed significant improvement (p < 0.01). Moreover, BMI (n = 192), exacerbations (n = 219) and sweat chloride measurements (n = 105) improved.

CONCLUSION

Lum/iva was generally well tolerated in a real-life, nationwide pediatric cohort. The efficacy of lum/iva was comparable to phase 3 studies in children. LCI and BA analysis as markers of small airway and structural lung disease showed significant improvement which indicates the importance of these parameters to evaluate treatment effects of CF modulators in children.

[CT imaging of chronic obstructive pulmonary disease: What aspects and what role?]

Chronic obstructive pulmonary disease (COPD), commonly defined as irreversible airflow limitation, is associated with specific morphological changes involving all three parts of the lung, namely the bronchi, parenchyma and pulmonary vessels. In vivo imaging, with its ability to describe the different types of lung alterations and their regional distribution, helps to elucidate the relationship between lung structure and respiratory function. High-resolution computed tomography (CT) of the lung is the imaging modality best suited to assessing the pathological changes associated with airflow obstruction occurring in COPD. Over the last few decades, numerous studies have demonstrated the role of CT as a morphological and functional method conducive to the phenotyping of COPD patients. This review proposes to examine the data on CT imaging of COPD with a critical approach to recent data, and to determine the extent to which CT could be integrated into care or clinical research on patients with this/these disease(s).

Automated method of bronchus and artery dimension measurement in an adult bronchiectasis population

Aim

Bronchiectasis (BE) is a disease defined by irreversible dilatation of the airway. Computed tomography (CT) plays an important role in the detection and quantification of BE. The aim of this study was three-fold: 1) to assess bronchus-artery (BA) dimensions using fully automated software in a cohort of BE disease patients; 2) to compare BA dimensions with semi-quantitative BEST-CT (Bronchiectasis Scoring Technique for CT) scores for BE and bronchial wall thickening; and 3) to explore the structure-function relationship between BA-method lumen dimensions and spirometry outcomes.

Methods

Baseline CTs of BE patients who participated in a clinical trial were collected retrospectively. CTs were analysed manually with the BEST-CT scoring system and automatically using LungQ (v.2.1.0.1, Thirona, The Netherlands), which measures the following BA dimensions: diameters of bronchial outer wall (Bout), bronchial inner wall (Bin) and artery (A), and bronchial wall thickness (Bwt) and computes BA ratios (Bout/A and Bin/A) to assess bronchial widening. To assess bronchial wall thickness, we used the Bwt/A ratio and the ratio between the bronchus wall area (Bwa) and the area defined by the outer airway (Boa) (Bwa/Boa).

Results

In total, 65 patients and 16 900 BA pairs were analysed by the automated BA method. The median (range) percentage of BA pairs defined as widened was 69 (55-84)% per CT using a cut-off value of 1.5 for Bout/A, and 53 (42-65)% of bronchial wall were thickened using a cut-off value of 0.14 for Bwt/A. BA dimensions were correlated with comparable outcomes for the BEST-CT scoring method with a correlation coefficient varying between 0.21 to 0.51. The major CT BA determinants of airflow obstruction were bronchial wall thickness (p=0.001) and a narrower bronchial inner diameter (p=0.003).

Conclusion

The automated BA method, which is an accurate and sensitive tool, demonstrates a stronger correlation between visual and automated assessment and lung function when using a higher cut-off value to define bronchiectasis.

Higher small pulmonary artery and vein volume on computed tomography is associated with mortality in current and former smokers

BACKGROUND

In chronic obstructive pulmonary disease (COPD), vascular alterations have been shown to contribute to hypoxia and pulmonary hypertension, but the independent contribution of small vessel abnormalities to mortality remains unclear.

METHODS

We quantified artery and vein dimensions on computed tomography (CT) down to 0.2 mm. Small vessel volumes (<1 mmᴓ) were normalized by body surface area. In 7903 current and former smokers of the COPDGene study (53.2% male) the independent contribution of small artery and small vein volume to all-cause mortality was tested in multivariable Cox models. Additionally, we calculated the 95th percentile of small arteries and veins in 374 never smokers to create two groups: normal and high small artery or vein volume. We describe clinical, physiological and imaging characteristics of subjects with a high small artery and high small vein volume.

FINDINGS

Both high small artery and high small vein volumes were independently associated with mortality with an adjusted hazard ratio of 1.07 [1.01, 1.14] and 1.34 [1.21, 1.49] per mL/m2 increase, respectively. In COPDGene, 447 (5.7%) had high small artery volume and 519 (9.1%) subjects had high small vein volume and both had more emphysema, more air trapping and more severe coronary calcium.

INTERPRETATION

In smokers, abnormally high volumes in small arteries and veins are both relevant for mortality, which urges investigations into the aetiology of small pulmonary vessels and cardiac function in smokers.

FUNDING

Award Number U01-HL089897 and U01-HL089856 from the NHLBI. COPD Foundation with contributions from AstraZeneca, Boehringer Ingelheim, Genentech, GlaxoSmithKline, Novartis, Pfizer, Siemens, and Sunovion.

Evolving and Novel Applications of Artificial Intelligence in Thoracic Imaging

The advent of artificial intelligence (AI) is revolutionizing medicine, particularly radiology. With the development of newer models, AI applications are demonstrating improved performance and versatile utility in the clinical setting. Thoracic imaging is an area of profound interest, given the prevalence of chest imaging and the significant health implications of thoracic diseases. This review aims to highlight the promising applications of AI within thoracic imaging. It examines the role of AI, including its contributions to improving diagnostic evaluation and interpretation, enhancing workflow, and aiding in invasive procedures. Next, it further highlights the current challenges and limitations faced by AI, such as the necessity of 'big data', ethical and legal considerations, and bias in representation. Lastly, it explores the potential directions for the application of AI in thoracic radiology.

Structural Lung Disease and Clinical Phenotype in Bronchiectasis Patients: The EMBARC CT Study

Rationale: Chest computed tomography (CT) scans are essential to diagnose and monitor bronchiectasis (BE). To date, few quantitative data are available about the nature and extent of structural lung abnormalities (SLAs) on CT scans of patients with BE. Objectives: To investigate SLAs on CT scans of patients with BE and the relationship of SLAs to clinical features using the EMBARC (European Multicenter Bronchiectasis Audit and Research Collaboration) registry. Methods: CT scans from patients with BE included in the EMBARC registry were analyzed using the validated Bronchiectasis Scoring Technique for CT (BEST-CT). The subscores of this instrument are expressed as percentages of total lung volume. The items scored are atelectasis/consolidation, BE with and without mucus plugging (MP), airway wall thickening, MP, ground-glass opacities, bullae, airways, and parenchyma. Four composite scores were calculated: total BE (i.e., BE with and without MP), total MP (i.e., BE with MP plus MP alone), total inflammatory changes (i.e., atelectasis/consolidation plus total MP plus ground-glass opacities), and total disease (i.e., all items but airways and parenchyma). Measurements and Main Results: CT scans of 524 patients with BE were analyzed. Mean subscores were 4.6 (range, 2.3-7.7) for total BE, 4.2 (1.2-8.1) for total MP, 8.3 (3.5-16.7) for total inflammatory changes, and 14.9 (9.1-25.9) for total disease. BE associated with primary ciliary dyskinesia was associated with more SLAs, whereas chronic obstructive pulmonary disease was associated with fewer SLAs. Lower FEV1, longer disease duration, Pseudomonas aeruginosa and nontuberculous mycobacterial infections, and severe exacerbations were all independently associated with worse SLAs. Conclusions: The type and extent of SLAs in patients with BE are highly heterogeneous. Strong relationships between radiological disease and clinical features suggest that CT analysis may be a useful tool for clinical phenotyping.

Children with severe asthma have substantial structural airway changes on computed tomography

Background

In adults with severe asthma (SA) bronchial wall thickening, bronchiectasis and low attenuation regions (LAR) have been described on chest computed tomography (CT) scans. The extent to which these structural abnormalities are present in children with SA is largely unknown. Our aim was to study the presence and extent of airway abnormalities on chest CT of children with SA.

Methods

161 inspiratory and expiratory CT scans, either spirometer-controlled or technician-controlled, obtained in 131 children with SA (mean±SD age 11.0±3.8 years) were collected retrospectively. Inspiratory scans were analysed manually using a semi-quantitative score and automatically using LungQ (v2.1.0.1; Thirona B.V., Nijmegen, the Netherlands). LungQ segments the bronchial tree, identifies the generation for each bronchus-artery (BA) pair and measures the following BA dimensions: outer bronchial wall diameter (Bout), adjacent artery diameter (A) and bronchial wall thickness (Bwt). Bronchiectasis was defined as Bout/A ≥1.1, bronchial wall thickening as Bwt/A ≥0.14. LAR, reflecting small airways disease (SAD), was measured automatically on inspiratory and expiratory scans and manually on expiratory scans. Functional SAD was defined as FEF25-75 and/or FEF75 z-scores <-1.645. Results are shown as median and interquartile range.

Results

Bronchiectasis was present on 95.8% and bronchial wall thickening on all CTs using the automated method. Bronchiectasis was present on 28% and bronchial wall thickening on 88.8% of the CTs using the manual semi-quantitative analysis. The percentage of BA pairs defined as bronchiectasis was 24.62% (12.7-39.3%) and bronchial wall thickening was 41.7% (24.0-79.8%) per CT using the automated method. LAR was observed on all CTs using the automatic analysis and on 82.9% using the manual semi-quantitative analysis. Patients with LAR or functional SAD had more thickened bronchi than patients without.

Conclusion

Despite a large discrepancy between the automated and the manual semi-quantitative analysis, bronchiectasis and bronchial wall thickening are present on most CT scans of children with SA. SAD is related to bronchial wall thickening.