GROUND GLASS OPACITIES ON CT OF THE CHEST IN THE PRACTICE OF THE CLINICIAN: PATHOGENESIS, SIGNIFICANCE, DIFFERENTIAL DIAGNOSE
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Abstract:
Ground glass opacities, mosaic perfusion, areas of air-trapping on a computed tomography of the lung are one of the most frequent x-ray syndromes. It`s are one of the kind of syndromes increase the density of pulmonary parenchyma. It is important to remember that the syndromes of ground glass opacities, mosaic perfusion, areas of air-trapping involve the differential diagnosis and not a diagnosis in itself. Differential diagnostic range very wide, since this syndrome commonly occurs in diseases that affect small bronchi, pulmonary vessels, alveoli and interstitial tissue. It is often observed a combination of lesions of various components of the pulmonary parenchyma. These combinations often help the doctor find the key to the correct diagnosis. Another problem in the evaluation of these syndromes are the distinction between pathological and “healthy” areas of lung tissue. Thus, in certain diseases, regions with higher density of the lung tissue may be normal lung parenchyma. The aim of this lecture is to analyze the reasons for the formation of the CT-types of ground glass opacities, mosaic perfusion, areas of air-trapping in norm and pathology, selection of distinctive features, allowing determining the elements of the lung parenchyma, the underlying pathological process, thereby narrowing the differential diagnosis of several diseases.Keywords:
Parenchyma
Air trapping
Ground-glass opacity
The authors assess the utility of postexpiratory high-resolution computed tomography (HRCT) scans in the evaluation of air trapping in patients with obstructive lung disease. Thirteen healthy volunteers and 14 patients with obstructive lung disease (OLD) were examined using inspiratory and postexpiratory HRCT scans. All had pulmonary function tests. Lung attenuation was measured on both inspiration and expiration, and the extent of air trapping on postexpiratory scans was visually assessed. The results of the healthy volunteers were compared with those of patients with OLD, and HRCT findings were correlated with pulmonary function tests. Lung attenuation on expiration, its change from inspiration to expiration, and air-trapping scores of patients with OLD were significantly different from those of the healthy volunteers. When the healthy participants and patients with OLD were combined and analyzed as one group, the lung attenuation change and air-trapping score both significantly correlated with pulmonary function tests (p < 0.001) and correlation values were similar (r = 0.61–0.89). Air trapping was found in 61% of healthy participants and all the patients with OLD, although the extent was significantly greater in the patients with OLD. Inspiratory and postexpiratory HRCT can be used to evaluate air trapping in patients with OLD. Measurements of lung attenuation and estimates of air-trapping extent are both valuable methods of analysis.
Air trapping
Expiration
High-resolution computed tomography
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Ground glass opacities, mosaic perfusion, areas of air-trapping on a computed tomography of the lung are one of the most frequent x-ray syndromes. It`s are one of the kind of syndromes increase the density of pulmonary parenchyma. It is important to remember that the syndromes of ground glass opacities, mosaic perfusion, areas of air-trapping involve the differential diagnosis and not a diagnosis in itself. Differential diagnostic range very wide, since this syndrome commonly occurs in diseases that affect small bronchi, pulmonary vessels, alveoli and interstitial tissue. It is often observed a combination of lesions of various components of the pulmonary parenchyma. These combinations often help the doctor find the key to the correct diagnosis. Another problem in the evaluation of these syndromes are the distinction between pathological and “healthy” areas of lung tissue. Thus, in certain diseases, regions with higher density of the lung tissue may be normal lung parenchyma. The aim of this lecture is to analyze the reasons for the formation of the CT-types of ground glass opacities, mosaic perfusion, areas of air-trapping in norm and pathology, selection of distinctive features, allowing determining the elements of the lung parenchyma, the underlying pathological process, thereby narrowing the differential diagnosis of several diseases.
Parenchyma
Air trapping
Ground-glass opacity
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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.
Air trapping
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PURPOSE: To determine the test performance and longitudinal evolution of air trapping for diagnosing bronchiolitis obliterans syndrome (BOS). MATERIALS AND METHODS: Over 7 years, 111 combined inspiratory and expiratory computed tomographic examinations were performed in eight healthy control subjects and 38 heart-lung transplant recipients. Functional impairment was assessed with the BOS classification. Receiver operating characteristic (ROC) analysis was performed to determine the optimal threshold of air trapping to distinguish between patients with and those without BOS and to compute sensitivity and specificity for diagnosing BOS. RESULTS: The extent of air trapping increased with BOS severity (P = .001). A threshold of 32% of air trapping is optimal for distinguishing between patients with and those without BOS and provides a sensitivity of 83%, a specificity of 89%, and an accuracy of 88%. The prevalence of BOS and positive predictive value of air trapping increased with postoperative time, but the negative predictive value of air trapping remained high throughout the study. Patients without BOS who had air trapping exceeding 32% of the parenchyma were at significantly increased risk of developing BOS (P = .004). CONCLUSION: At the threshold of 32%, air trapping is sensitive, specific, and accurate for diagnosing BOS. Patients with air trapping below 32% are unlikely to have BOS. Air trapping exceeding 32% may be an early indicator of future BOS.
Air trapping
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Summary Air trapping is a common finding radiologists encounter on CT imaging of the thorax. This term is used when there are geographic areas of differing attenuation within the lung parenchyma. Most commonly, this is the result of abnormal retention of air due to complete or partial airway obstruction from small airway pathologies. Perfusional differences due to underlying vascular diseases could also result in these appearances, and hence, inspiratory and full expiratory phase CT studies are required to accurately diagnose air trapping. It is important to note that this can occasionally be present in healthy patients. Multiple diseases are associated with air trapping. Determining the aetiology relies on accurate patient history and concomitant findings on CT. There is currently no consensus on accurate assessment of the severity of air trapping. The ratio of mean lung density between expiration and inspiration on CT and the change in lung volume have demonstrated a positive correlation with the presence of small airway disease. Treatment and resultant patient outcome depend on the underlying aetiology, and hence, radiologists need to be familiar with the common causes of air trapping. This paper outlines the most common disease processes leading to air trapping, including Constrictive bronchiolitis, Hypersensitivity pneumonitis, DIPNECH, and Post‐infectious (Swyer‐James/Macleod). Various diseases result in the air trapping pattern seen on the expiratory phase CT scan of the thorax. Combining patient history with other concomitant imaging findings is essential for accurate diagnosis and to further guide management.
Air trapping
Hypersensitivity pneumonitis
Thorax (insect anatomy)
Airway obstruction
Concomitant
Expiration
Parenchyma
Respiratory tract
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To test the hypothesis that diffuse and/or focal air trapping are sensitive indicators of airflow obstruction in smoker's small airways disease, when age, gender and presence of emphysematous lesions were allowed for.Fifty-eight smokers and 34 never smokers, recruited from a randomized population study of men born in 1933, were investigated by HRCT and by extended pulmonary function tests, including a sensitive test for small airways disease (N2 slope). Diffuse air trapping was evaluated by calculating a quotient of mean lung density at expiration and inspiration. Focal air trapping was scored visually by consensus.Diffuse air trapping did not differ between non-emphysematous smokers and never smokers. Furthermore, diffuse air trapping correlated well to the quotient between the residual volume and total lung capacity (RV/TLC, p = 0.01) and was consequently higher in emphysematous smokers than in never smokers. Focal air trapping was found as frequently in smokers without emphysema as in never smokers. Smokers with emphysema showed significantly less focal air trapping. Neither the N2 slope nor any of the other lung function variables differed between those with and without focal air trapping among non-emphysematous smokers.Neither diffuse nor focal air trapping are sensitive indicators of smoker's small airways disease.
Air trapping
Value (mathematics)
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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.
Air trapping
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Ground-glass opacity is a frequent but nonspecific finding on high-resolution CT scans of the lung parenchyma. The underlying abnormality is diverse; any condition that decreases the air content of the lung parenchyma without totally obliterating the alveoli can produce ground-glass opacity. These processes are not visible on high-resolution CT scans. However, in specific clinical settings, the information provided by high-resolution CT is considerable when the anatomic distribution and associated structural changes to the lung parenchyma are analyzed. This pictorial essay illustrates the pathologic basis of ground-glass opacity and provides a guide to the differential diagnosis of the disorders that can produce this appearance.
Parenchyma
Ground-glass opacity
Opacity
Abnormality
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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
Room air distribution
Exhaled air
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The objective of our study was to evaluate whether 0.3-second cine CT can be used to detect air trapping in the lungs of young children.In 30 children (mean age, 25 months), 0.3-second cine CT was performed at six levels during 3 seconds of quiet breathing. The study population was divided into an air trapping group (n = 24) and a no-air trapping group (n = 6). Lung density was measured at an abnormal area (with or without air trapping) and an adjacent normal area on inspiratory and expiratory phase images. Lung density differences between inspiration and expiration were calculated and compared in abnormal areas (with or without air trapping) and in normal areas. Their percentages were calculated and compared between the two groups. In addition, lung density differences between abnormal and adjacent normal areas were calculated and compared between the two groups.Lung density differences between inspiration and expiration were smaller in areas with air trapping (mean +/- SD, -19 +/- 34 H) than in abnormal areas without air trapping (138 +/- 36 H) (p < 0.001) or in normal areas (111 +/- 49 H) (p < 0.001). Their percentages were smaller in the group with air trapping (-27% +/- 54%) than in the group with no air trapping (120% +/- 87%) (p < 0.001). In the group with air trapping, lung density differences were larger at the expiratory phase (260 +/- 77 H) than at the inspiratory phase (129 +/- 69 H) (p < 0.001), but did not change through the respiratory cycle in the group with no air trapping (p > 0.05).Air trapping can be accurately detected in the lungs of free-breathing young children using 0.3-second cine CT.
Air trapping
Expiration
Room air distribution
Respiratory tract
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Citations (39)