Extent Of Air Trapping Research Articles

Time to Start Up: CT-Basted Radiomics in Children’s Lung Diseases

Time to Start Up: CT-Basted Radiomics in Children’s Lung Diseases

Lung Parenchymal and Tracheal CT Morphology: Evaluation before and after Bariatric Surgery.

Background There is significant pulmonary functional deficit related to obesity, but no prospective CT studies have evaluated the effects of obesity on the lungs and trachea. Purpose To evaluate lung parenchymal and tracheal CT morphology before and 6 months after bariatric surgery, with functional and symptomatic correlation. Materials and Methods A prospective longitudinal study of 51 consecutive individuals referred for bariatric surgery was performed (from November 2011 to November 2013). All individuals had undergone limited (three-location) inspiratory and end-expiratory thoracic CT before and after surgery, with concurrent pulmonary function testing, body mass index calculation, and modified Medical Research Council (mMRC) dyspnea scale and Epworth scoring. Two thoracic radiologists scored the CT extent of mosaic attenuation, end-expiratory air trapping, and tracheal shape. The inspiratory and end-expiratory cross-sectional areas of the trachea were measured. The paired t test or Wilcoxon signed-rank test was used for pre- and postsurgical comparisons. Spearman correlation and logistic regression were used to evaluate correlations between CT findings and functional and symptom indexes. Results A total of 51 participants (mean age, 52 years ± 8 [standard deviation]; 20 men) were evaluated. Before surgery, air trapping extent correlated most strongly with decreased total lung capacity (Spearman rank correlation coefficient [rs] = -0.40, P = .004). After surgery, there were decreases in percentage mosaic attenuation (0% [interquartile range {IQR}: 0%-2.5%] vs 0% [IQR: 0%-0%], P < .001), air trapping (9.6% [IQR: 5.8%-15.8%] vs 2.5% [IQR: 0%-6.7%], P < .001), and tracheal collapse (201 mm2 [IQR: 181-239 mm2] vs 229 mm2 [186-284 mm2], P < .001). After surgery, mMRC dyspnea score change correlated positively with air trapping extent change (rs = 0.46, P = .001) and end-expiratory tracheal shape change (rs = 0.40, P = .01). At multivariable analysis, air trapping was the main determinant for decreased dyspnea after surgery (odds ratio, 1.2; 95% confidence interval: 1.1, 1.2; P = .03). Conclusion Dyspnea improved in obese participants after weight reduction, which correlated with less tracheal collapse and air trapping at end-expiration chest CT. © RSNA, 2020 Online supplemental material is available for this article.

Air trapping in early cystic fibrosis lung disease-Does CT tell the full story?

Mosaic attenuation on expiratory chest computed tomography (CT) is common in early life cystic fibrosis (CF) and often referred to as "air trapping". It is presumed to be localized hyperinflation due to small airway obstruction. In order to test this assumption, we compared air trapping extent to lung volumes measured on CT in young children with CF. Children aged below 7 years undergoing inspiratory/expiratory CT were recruited from the Australian Respiratory Early Surveillance Team for Cystic Fibrosis cohort. Automated lung segmentation was used to determine functional residual capacity (FRC), total lung capacity (TLC), and their ratio (FRC/TLC). Structural lung disease (%Disease) and air trapping (%TrappedAir) extent were assessed using PRAGMA-CF. Lung clearance index (LCI), an index of ventilation heterogeneity, was measured. Linear mixed model analysis was used to determine associations. Seventy-three scans from 55 patients were obtained. %TrappedAir was associated with %Disease (0.19 [0.07, 0.31]; P = 0.003) and LCI (0.22 [0.04, 0.39]; P = 0.016), but not FRC/TLC (0.00 [-0.02, 0.02]; P = 0.931). CT mosaic attenuation is associated with CF lung disease, however it is not always accompanied by physiologic hyperinflation. Other pathologies may contribute to mosaic attenuation. A better understanding of these factors could guide future therapies.

Post-infectious bronchiolitis obliterans in children: CT features that predict responsiveness to pulse methylprednisolone.

Intravenous pulse methylprednisolone therapy (IPMT) is an important treatment option for post-infectious obliterative bronchiolitis (OB), although it must be used carefully and only in selected patients because of its drawbacks. This study evaluated whether CT and clinical features of children with post-infectious OB can predict their responsiveness to IPMT. We searched the medical records for patients (less than 18 years of age) who were diagnosed with post-infectious OB between January 2000 and December 2011. 17 children who received IPMT were included in this study. All underwent chest CT before and after IPMT. The radiological features seen on pre-treatment CT were recorded. The air-trapping area percentages on pre- and post-treatment CT images were determined. The nine patients who exhibited decreased air trapping on post-treatment CT scans relative to pre-treatment scans were classed as responders. The patient ages and time from initial pneumonia to IPMT were recorded. All responders and only four non-responders had thickened bronchial walls before treatment (p = 0.029). The two groups did not differ significantly in terms of bronchiolitis, bronchiectasis or the extent of air trapping, although the responders had a significantly shorter median interval between initial pneumonia and IPMT (4 vs 50 months; p = 0.005) and were significantly younger (median, 2.0 vs 7.5 years; p = 0.048). Immediate IPMT may improve the degree of air trapping in children with post-infectious OB if they show a thickened bronchial wall on CT. Children with post-infectious OB may respond favourably to IPMT when pre-treatment CT indicates bronchial-wall thickening.

Utility of expiratory thin-section CT for fibrotic interstitial pneumonia

Collagen vascular disease-associated interstitial lung disease (CVD-ILD) must be differentiated from idiopathic pulmonary fibrosis (IPF) since prognosis and treatment strategies differ between these two conditions. However, differentiating between CVD-ILD and IPF is often difficult. To examine the utility of expiratory high-resolution computed tomography (HRCT) for differentiating between CVD-ILD and IPF. Seventy patients were examined with expiratory and inspiratory HRCT with CVD-ILD (n = 36) or IPF (n = 34). Associated diagnoses in patients with CVD-ILD were rheumatoid arthritis (n = 22), Sjögren syndrome (n = 3), scleroderma (n = 2), polymyositis/dermatomyositis (n = 1), and unspecified connective tissue disease (n = 8). Parenchymal abnormalities on inspiratory HRCT and visual extent of air trapping on expiratory HRCT were evaluated, statistical differences in HRCT findings between the two conditions were determined, and air trapping CT scores were correlated with the results of pulmonary function testing. Air trapping was found in 27 (75%) of 36 cases of CVD-ILD and four (12%) of 34 cases of IPF. Seventeen of the 27 cases for which air trapping was exhibited with CVD-ILD were diagnosed with rheumatoid arthritis. A significant difference in frequency of air trapping was seen between CVD-ILD and IPF (P < 0.0001). Frequency of centrilobular nodules was significantly higher in CVD-ILD than in IPF (P = 0.021). In contrast, frequencies of interlobular interstitial thickening and traction bronchiectasis were significantly higher in IPF than in CVD-ILD (P = 0.005, P = 0.007, respectively). Correlations were seen between visual extent of air trapping and pulmonary function test results such as air trapping index (P = 0.004, r = 0.34), closing volume/vital capacity (P = 0.0002, r = -0.47), and closing capacity/total lung capacity (P < 0.0001, r = -0.51). The presence of air trapping on expiratory HRCT suggests CVD-ILD rather than IPF.

Value of air trapping at inspiratory and expiratory low-dose CT in predicting early bronchiolitis obliterans syndrome after bone marrow transplantation

Objective To determine whether bronchiolitis obliterans syndrome(BOS)after bone marrow transplantation can be predicted in light of air trapping.Methods Thirty-three cases of BOS(BOS group)and 111normal patients(normal group)were comparatively reviewed for the CT characteristics(including frequency,dynamic change and diagnostic potency)of air trapping.The analysis was mainly based on the last CT scans before occurrence of BOS.Results The frequency of air trapping,especially mosaic air trapping or extensive air trapping,was higher in the BOS group than in the normal group(P= 0.03).The median total air trapping score was higher in the BOS group than in the normal group(P=0.01).The increase of air trapping extent with the progress of disease was more common in the BOS group(50.0%,9/18),whereas a decrease of air trapping extent,disappearance or intermittent appearance of air trapping was more common in the normal group(60.0%,15/ 25)during the follow-up period.When mosaic air trapping or extensive air trapping was used as the diagnostic threshold,the specificity was high(90.5%,96.7%),but the sensitivity was low(29.4%,15.8%).Conclusion Occurrence of air trapping is a clue for development of BOS in patients receiving bone marrow transplantation.Mosaic air trapping and extensive air trapping are insensitive but specific CT findings.

Air trapping is a major determinant of persistent airway obstruction in asthmatics

Chronic persistent airway obstruction has been observed in moderate-to-severe asthmatics despite treatment with inhaled corticosteroids. We investigated which airway changes were associated with this obstruction. High-resolution computed tomography (HRCT) was performed at study entry and reexamined at the time of follow-up when the FEV1 reached a maximally constant level after treatment for 1 year or more with inhaled corticosteroids. Bronchial wall area and air trapping extent were compared in the recovered group (n = 18) and the persistent airway obstruction group (n = 14). Bronchial wall area and air trapping of the initial HRCT were similar between the two groups. On follow-up HRCT, air trapping was markedly decreased in the recovered group compared with that on initial HRCT (P = 0.017), whereas bronchial wall area did not change. In the persistent-airway-obstruction group, these two parameters did not change during follow-up. When follow-up HRCT was compared, air trapping was significantly greater in the persistent-airway-obstruction group than in the recovered group (P = 0.003). Difference post-bronchodilator FEV1 value between at initial and 2nd HRCT exam was correlated with difference air trapping value between at initial and 2nd HRCT exam(%) on the follow-up HRCT (P = 0.017). The presence of persistent airflow obstruction were significantly associated with the air trapping % difference between initial and 2nd time (RR = 1.70, P = 0.018). Persistence of AT could be a main contributing factor to chronic persistent airflow obstruction in asthma.

Air Trapping on Chest CT Is Associated with Worse Ventilation Distribution in Infants with Cystic Fibrosis Diagnosed following Newborn Screening

BackgroundIn school-aged children with cystic fibrosis (CF) structural lung damage assessed using chest CT is associated with abnormal ventilation distribution. The primary objective of this analysis was to determine the relationships between ventilation distribution outcomes and the presence and extent of structural damage as assessed by chest CT in infants and young children with CF.MethodsData of infants and young children with CF diagnosed following newborn screening consecutively reviewed between August 2005 and December 2009 were analysed. Ventilation distribution (lung clearance index and the first and second moment ratios [LCI, M1/M0 and M2/M0, respectively]), chest CT and airway pathology from bronchoalveolar lavage were determined at diagnosis and then annually. The chest CT scans were evaluated for the presence or absence of bronchiectasis and air trapping.ResultsMatched lung function, chest CT and pathology outcomes were available in 49 infants (31 male) with bronchiectasis and air trapping present in 13 (27%) and 24 (49%) infants, respectively. The presence of bronchiectasis or air trapping was associated with increased M2/M0 but not LCI or M1/M0. There was a weak, but statistically significant association between the extent of air trapping and all ventilation distribution outcomes.ConclusionThese findings suggest that in early CF lung disease there are weak associations between ventilation distribution and lung damage from chest CT. These finding are in contrast to those reported in older children. These findings suggest that assessments of LCI could not be used to replace a chest CT scan for the assessment of structural lung disease in the first two years of life. Further research in which both MBW and chest CT outcomes are obtained is required to assess the role of ventilation distribution in tracking the progression of lung damage in infants with CF.

Air trapping in Wegener’s granulomatosis: an additional finding on expiratory chest HRCT

This study was undertaken to assess the presence and extent of air trapping (AT) on high-resolution computed tomography (HRCT) in patients with Wegener's granulomatosis (WG) and to correlate the finding with the inspiratory pattern and bronchial/bronchiolar involvement. Twenty-one patients (7 M/14 F) with WG underwent inspiratory and expiratory HRCT. Images were evaluated for the presence and extent of AT and for airway involvement (bronchi/bronchioles); the predominant HRCT pattern was also documented. The attenuation difference was measured between the areas of AT on expiration and the same areas on inspiration in order to verify the finding of AT. The extent of AT was calculated by visual scoring and correlated with the predominant inspiratory patterns and bronchial/bronchiolar involvement. AT was found in seven patients (33.3%) and its extent ranged between 3% and 70% (mean 15.8±7). Two patients showed no lesions on inspiratory HRCT, and the only finding was AT on expiration. The attenuation difference between areas of AT on expiration and the same areas on inspiration ranged between 32 and 89 HU. Inspiratory HRCT was pathological in 19 patients (90.4%), and the principal lung patterns were nodular, cavitary or noncavitary (n=7, 38.9%); ground-glass opacities (n=5, 26.3%); masses (n=3, 15.8%); fibrotic (n=3, 15.8%); and consolidation with air bronchogram (n=1, 5.3%). Bronchial and bronchiolar involvement was found in 14 and five patients, respectively. No statistically significant correlation was found between AT extent and the findings on inspiration. In addition, there were no specific patterns that caused higher or lower scores of AT. Moreover, when bronchial or bronchiolar involvement was absent, the mean AT score was statistically significantly higher. Areas of AT represent a new and indirect HRCT finding--and in rare cases the only finding--of pulmonary WG. The nonsignificant correlation between AT extent and inspiratory findings may suggest AT as an additional HRCT finding in patients with WG.

Lung Hyperinflation and Its Reversibility in Patients with Airway Obstruction of Varying Severity

ABSTRACTThe natural history of lung hyperinflation in patients with airway obstruction is unknown. In particular, little information exists about the extent of air trapping and its reversibility to bronchodilator therapy in those with mild airway obstruction. We completed a retrospective analysis of data from individuals with airway obstruction who attended our pulmonary function laboratory and had plethysmographic lung volume measurements pre- and post-bronchodilator (salbutamol). COPD was likely the predominant diagnosis but patients with asthma may have been included. We studied 2,265 subjects (61% male), age 65 ± 9 years (mean ± SD) with a post-bronchodilator FEV1/FVC <0.70. We examined relationships between indices of airway obstruction and lung hyperinflation, and measured responses to bronchodilation across subgroups stratified by GOLD criteria. In GOLD stage I, vital capacity (VC) and inspiratory capacity (IC) were in the normal range; pre-bronchodilator residual volume (RV), functional residual capacity (FRC) and specific airway resistance were increased to 135%, 119% and 250% of predicted, respectively. For the group as a whole, RV and FRC increased exponentially as FEV1 decreased, while VC and IC decreased linearly. Regardless of baseline FEV1, the most consistent improvement following bronchodilation was RV reduction, in terms of magnitude and responder rate. In conclusion, increases (above normal) in airway resistance and plethysmographic lung volumes were found in those with only minor airway obstruction. Indices of lung hyperinflation increased exponentially as airway obstruction worsened. Those with the greatest resting lung hyperinflation showed the largest bronchodilator-induced volume deflation effects. Reduced air trapping was the predominant response to acute bronchodilation across severity subgroups.

Bronchodilation response to deep inspirations in asthma is dependent on airway distensibility and air trapping

In healthy individuals, deep inspirations (DIs) have a potent bronchodilatory ability against methacholine (MCh)-induced bronchoconstriction. This is variably attenuated in asthma. We hypothesized that inability to bronchodilate with DIs is related to reduced airway distensibility. We examined the relationship between DI-induced bronchodilation and airway distensibility in 15 asthmatic individuals with a wide range of baseline lung function [forced expired volume in 1 s (FEV(1)) = 60-99% predicted]. After abstaining from DIs for 20 min, subjects received a single-dose MCh challenge and then asked to perform DIs. The effectiveness of DIs was assessed by the ability of the subjects to improve FEV(1). The same subjects were studied by two sets of high-resolution CT scans, one at functional residual capacity (FRC) and one at total lung capacity (TLC). In each subject, the areas of 21-41 airways (0.8-6.8 mm diameter at FRC) were matched and measured, and airway distensibility (increase in airway diameter from FRC to TLC) was calculated. The bronchodilatory ability of DIs was significantly lower in individuals with FEV(1) <75% predicted than in those with FEV(1) ≥75% predicted (15 ± 11% vs. 46 ± 9%, P = 0.04) and strongly correlated with airway distensibility (r = 0.57, P = 0.03), but also with residual volume (RV)/TLC (r = -0.63, P = 0.01). In multiple regression, only RV/TLC was a significant determinant of DI-induced bronchodilation. These relationships were lost when the airways were examined after maximal bronchodilation with albuterol. Our data indicate that the loss of the bronchodilatory effect of DI in asthma is related to the ability to distend the airways with lung inflation, which is, in turn, related to the extent of air trapping and airway smooth muscle tone. These relationships only exist in the presence of airway tone, indicating that structural changes in the conducting airways visualized by high-resolution CT do not play a pivotal role.

Gravitational Gradients in Expiratory Computed Tomography Examinations of Patients With Small Airways Disease

First, to test the hypothesis that air trapping in diseased patients follows a gravitational gradient and is more extensive in dependent than in nondependent lung regions. Second, to test the hypothesis that the dependent lung regions on combined supine and prone expiratory computed tomography (CT) examinations will show more air trapping than would a supine expiratory CT examination alone. For this ethics committee-approved study, supine and prone multidetector-row CT (4×1 mm collimation, 0.5 s rotation time, 140 kVp, and effective 80 mAs) was performed at full end-expiration on 47 lung transplant recipients (mean age 41±12 y; 18 without bronchiolitis, 18 with potential bronchiolitis, and 11 with bronchiolitis). The extent of air trapping was visually quantified in the supine and prone positions, and in dependent and nondependent lung regions. Individual air trapping scores from these regions were thus available and could be combined for later analysis. Differences in the extent of air trapping between the positions and regions were tested with a Wilcoxon signed-rank test. Air trapping was significantly more extensive in the combined dependent lung regions than in the combined nondependent lung regions (15.00% vs. 5.77%; P<0.001). Air trapping was also significantly more extensive in the combined dependent regions than in the supine body position (15.00% vs. 7.50%; P<0.001). No statistically significant difference in the extent of air trapping was found between the supine and the prone positions (7.50% vs. 12.14%; P=0.735). In patients with suspected or overt small airways disease, air trapping follows a gravitational gradient. A change from the supine to the prone position can make air trapping visible in formerly nondependent lung regions. The combined readings from supine and prone CT examinations in dependent lung regions show more air trapping than a standard supine CT examination alone.

Expiratory CT: Correlation with Pulmonary Function Tests and Value for Discriminating Lung Diseases

Aim: To evaluate the factors affecting air trapping on expiratory CT, its correlation with pulmonary function tests and its value for discriminating pulmonary diseases. Method: A total of seventy-five patients 28 chronic obstructive pulmonary disease, 21 asthma, 17 interstitial lung disease, and 9 bronchiectasis patients were included in this study. All patients underwent inspiratory HRCT, expiratory HRCT, and pulmonary function tests. Expiratory scans were evaluated for the presence of air trapping. The cross-sectional area and the ratio of air-trapping was calculated. Smoking history, duration of illness were noted. Statistically a correlation between the level and extent of air trapping, its correlation with pulmonary function tests and factors affecting air trapping were evaluated. Result:Air trapping was detected in 59 patients. In ten of these patients there was no mosaic pattern on inspiratory images. Air trapping on expiratory images was mostly seen in asthma patients (7 out of 10). The level of air-trapping showed a good correlation with the extent of air trapping in general, but in asthma patients the level of air-trapping did not correlate with the extent of trapping. There was a good correlation between pulmonary function tests and the level and extent of air trapping. The duration of illness affected the extent of air-trapping. Conclusion: Expiratory images are effective for discriminating asthma from other obstructive lung disease. The level and extent of air trapping detected on expiratory images which are mainly affected by illness duration, are good predictors of pulmonary function tests.

Regional Heterogeneity of Air Trapping at Expiratory Thin-Section CT of Patients with Bronchiolitis: Potential Implications for Dose Reduction and CT Protocol Planning

To prospectively determine whether the regional distribution of air trapping in patients with suspected or overt bronchiolitis is heterogeneous, and to determine the effect that a simulated reduction of computed tomographic (CT) sections and of scanned anatomic regions would have on the assessment of the extent of air trapping. For this Ethical Committee-approved study, multi-detector row CT (collimation, 4 x 1 mm; rotation time, 0.5 second; 140 kVp; and 80 effective mAs) was performed in 47 lung transplant recipients (23 women, 24 men; mean age, 41 years +/- 12 [standard deviation]; 18 without bronchiolitis, 18 with potential bronchiolitis, and 11 with bronchiolitis, as determined by lung function measurements). Images were reconstructed with a thickness of 1 mm at an increment of 10 mm. The extent of air trapping in the upper, middle, and lower lung regions was correlated. Differences between regions and the interaction between patients and regions were tested with an analysis of variance. The extent of air trapping was calculated for six simulated examination protocols. Correlations between the upper and middle (r = 0.930), the upper and lower (r = 0.756), and the middle and lower lung regions (r = 0.863) were significant (P < .001). The extent of air trapping increased from the upper to the lower lung region, with significant differences between regions (P < .001). There was a significant interaction between patients and lung regions (P < .001). Simulated examination protocols resulted in significantly different extents of air trapping (P < .001). The regional distribution of the extent of air trapping in suspected or overt bronchiolitis is heterogeneous. Because the extent of air trapping can depend on the examination protocol, identical protocols are needed when air trapping is being compared within and between patients.

Air Trapping: Comparison of Standard-Dose and Simulated Low-Dose Thin-Section CT Techniques

To prospectively investigate the effect of radiation dose reduction on the visual quantification of air trapping at expiratory thin-section computed tomography (CT). In this ethical committee-approved study, 27 lung transplant recipients (12 women, 15 men; mean age, 54 years +/- 2 [standard error of the mean]) underwent expiratory thin-section CT at 140 kVp and 80 mAs (effective). All patients gave written informed consent. Dose reduction corresponding to 60, 40, and 20 mAs (effective) was simulated. The extent of air trapping in both original and dose-reduced studies was scored by three independent readers. The effects of tube current-time product, reader, reading session, and body mass index on average air trapping scores were assessed with analysis of variance. Agreements between and within observers were assessed with a weighted kappa statistic. Subjective scores for diagnostic confidence were attributed (3 = high, 2 = medium, 1 = low), and their means were calculated for each tube current-time product value. No significant effect on average air trapping scores as a result of tube current-time product (P = .222), reader (P = .217), reading session (P = .705), or body mass index (P = .505) could be detected. At 80 mAs, agreement between readers was excellent; agreement decreased to good or moderate at lower tube current settings. Agreement within readers decreased with a decrease in dose but remained good even at 20 mAs. Confidence also decreased, with mean scores decreasing from 2.33 +/- 0.73 (standard deviation) to 1.04 +/- 0.19 when dose decreased. At 140 kVp, the tube current-time product can be reduced from 80 to 20 mAs without impairing the visual quantification of air trapping at expiratory thin-section CT and with acceptable decreases in agreement between and within readers and in reader confidence.

Excessive Collapsibility of Bronchi in Bronchiectasis

To evaluate the frequency and severity of bronchomalacia, defined as excessive collapsibility of bronchi, in bronchiectasis; to compare the extent of air trapping in bronchiectasis patients with/without bronchomalacia; and to correlate the severity of bronchomalacia and the extent of air trapping versus pulmonary function. Forty-six patients with bronchiectasis evaluated by volumetric expiratory high-resolution computed tomography (CT) and pulmonary function tests were studied. The presence and severity of bronchomalacia were evaluated on contiguous axial high-resolution CT images using a 4-point scale. The extent of air trapping was graded on coronal reformations using a 5-point scale. Differences in the extent of air trapping in patients with/without bronchomalacia and the correlation between the severity of bronchomalacia and the extent of air trapping were investigated. The severity of bronchomalacia and the extent of air trapping were correlated with pulmonary function. Of 46 patients with bronchiectasis, 32 patients (70%) had bronchomalacia. Air trapping was present in 43 patients (93%). The extent of air trapping in patients with bronchomalacia was significantly greater compared with the patients without bronchomalacia (P=0.0308). The correlation between the severity of bronchomalacia and extent of air trapping was not statistically significant (rs=0.029, P=0.8457). The extent of air trapping in bronchiectasis patients with bronchomalacia was significantly greater compared with bronchiectasis patients without bronchomalacia, suggesting that the bronchomalacia is one of the underlying mechanisms of air trapping in bronchiectasis.

Silicosis: Expiratory Thin-Section CT Assessment of Airway Obstruction

To prospectively evaluate if findings on paired inspiratory and expiratory thin-section computed tomographic (CT) scans in patients with silicosis correlate with pulmonary function test results. Institutional review board approval and patient consent were obtained. Thirty-seven men (mean age, 71 years; range, 53-88 years) with silicosis were included. All patients had undergone inspiratory and expiratory thin-section CT and spirometry. Silicotic nodules, large opacity, emphysema, reticular opacities, bronchiectasis, and air trapping were graded subjectively on CT images. Emphysema was quantified on these images with built-in software. CT numbers were correlated with spirometric findings by using Spearman rank correlation analyses. Ten healthy volunteers (three men and seven women; mean age, 58 years) served as control subjects. After exclusion of three patients with inadequate image quality, 34 patients (mean age, 70 years; range, 53-88 years) were enrolled in the study group. Spirometric values did not differ significantly between patients with simple (n = 20) and patients with complicated (n = 14) silicosis but were significantly lower in patients than in control subjects. CT findings included air trapping (n = 33), emphysema (n = 26), nodules (n = 32), bronchiectasis (n = 22), large opacity (n = 19), and reticulation (n = 5). The extent of both air trapping and emphysema correlated negatively with spirometric values; the air trapping score showed the strongest correlation (ratio of forced expiratory volume in 1 second to forced vital capacity [FVC]: rho = -0.632, P < .001; forced expiratory flow at 50% of the FVC: rho = -0.576, P = .001). Silicotic nodule, large opacity, and bronchiectasis scores did not correlate with obstructive functional impairments. In comparison with the spirometric value, the extent of air trapping proved the best CT index in the assessment of obstructive derangement in workers with exposure to silica dust.

Pulmonary Sarcoidosis: Comparison of Findings of Inspiratory and Expiratory High-Resolution CT and Pulmonary Function Tests Between Smokers and Nonsmokers

The purpose of our study was to compare the high-resolution CT and pulmonary function test findings of smokers and nonsmokers with pulmonary sarcoidosis. Full inspiratory and expiratory high-resolution CT of the thorax and pulmonary function tests were performed in 46 patients (23 smokers and 23 lifelong nonsmokers) with histologically proven sarcoidosis. The median interval between high-resolution CT and pulmonary function tests was 8 days (range, 0-27 days). High-resolution CT findings were categorized into six patterns, and the overall extent of each pattern was scored independently (high-resolution CT score). Correlation between each high-resolution CT score with each pulmonary functional parameter was performed using Spearman's rank correlation and stepwise multiple regression analysis. Air trapping on expiration (45/46 patients, 98%) and small nodules on inspiration (all 46 patients, 100%) were the most common findings. Smokers had a greater extent of emphysema than nonsmokers (p = 0.002). No significant difference was seen in the extent of air trapping, consolidation, ground-glass attenuation, reticular opacities, or small nodules between smokers and nonsmokers. On Spearman's rank correlation, the extent of air trapping negatively correlated with forced vital capacity in smokers (p < 0.05) but not in nonsmokers. The extent of small nodules negatively correlated with forced vital capacity and positively correlated with the ratio of forced expiratory volume in 1 sec to forced vital capacity in nonsmokers (p < 0.05, both) but not in smokers, respectively. On stepwise multiple regression analysis, the extent of air trapping on CT was independently associated with decreased forced vital capacity (p < 0.05), and cigarette smoking was the main determinant of decrease in maximum midexpiratory flow and forced expiratory flow at 50% of vital capacity (p < 0.01). Cigarette smoking confounds the correlation between the CT and pulmonary function test findings in patients with sarcoidosis. Therefore, smoking history must be taken into account when correlating the extent of parenchymal sarcoidosis on CT with functional impairment.

Bronchomalacia in Sarcoidosis: Evaluation on Volumetric Expiratory High-resolution CT of the Lung 1

The aim of this study is to investigate the frequency of bronchomalacia associated with sarcoidosis and compare the extent of air trapping in patients with sarcoidosis with and without bronchomalacia. Eighteen consecutive patients (6 men, 12 women; age, 29-64 years; mean age, 47 years) with pathologically proven sarcoidosis who underwent clinical volumetric expiratory high-resolution computed tomography were studied. On contiguous end-expiratory images, the presence and severity of bronchomalacia and extent of air trapping were evaluated. The extent of air trapping was compared between patients with sarcoidosis with and without bronchomalacia. Bronchomalacia was noted in 11 of 18 patients (61%) with sarcoidosis (grade 1 [mild], n = 6; grade 2 [moderate], n = 4; and grade 3 [severe], n = 1). Air trapping was observed in 17 of 18 patients (94%; grade 1 [1%-25%], n = 8; grade 2 [26%-50%], n = 9). The extent of air trapping in patients with bronchomalacia was significantly greater than that in patients without bronchomalacia (P = .027, chi-squared test). Bronchomalacia frequently was associated with sarcoidosis, and the extent of air trapping was significantly greater in patients with sarcoidosis with bronchomalacia compared with those without bronchomalacia.

Air trapping in heart-lung transplant recipients: variability of anatomic distribution and extent at sequential expiratory thin-section CT.

To evaluate the intrapatient reproducibility of the extent and anatomic distribution of air trapping at sequential expiratory thin-section computed tomographic (CT) examinations in heart-lung transplant recipients. Nineteen heart-lung transplant recipients (eight with and 11 without bronchiolitis obliterans syndrome [BOS]) underwent three expiratory CT examinations within 1 hour. Residual volumes were measured at CT. Anatomic distribution and extent of air trapping were scored by two observers at two independent readings, and the reproducibility of observations was calculated for each feature. CT examination results were compared by using an analysis of variance that took into account interobserver and BOS and non-BOS effects. The Spearman rank correlation coefficient was calculated to test the association between variability of residual volumes and variability of the extent of air trapping. Residual volumes did not significantly differ between the three CT examinations (P =.556). Reproducibility values for findings of anatomic distribution of air trapping ranged from 84% to 95%, with a tendency toward improved reproducibility in patients without BOS. Mean reproducibility values for the extent of air trapping ranged from 97.1% to 97.7%, and no substantial difference in these values between patients with and those without BOS was observed. The Spearman rank coefficient for the correlation between variability of residual volumes and variability of extent of air trapping ranged from 0.382 to 0.568 (P =.105-.016). No interobserver effect was detected (P =.944). Anatomic distribution and extent are reproducible characteristics of air trapping. No substantial variability of air trapping occurs in functionally stable heart-lung transplant recipients.