Volume changes of diseased and normal areas in progressive fibrosing interstitial lung disease on inspiratory and expiratory computed tomography.

PURPOSE: The diagnosis of progressive fibrosing interstitial lung disease (PF-ILD) using computed tomography (CT) is an important medical practice in respiratory care, and most imaging findings for this disease have been obtained with inspiratory CT. It is possible that some characteristic changes in respiration may be seen in normal and diseased lung in PF-ILD, which may lead to a new understanding of the pathogenesis of interstitial pneumonia, but it has never been examined. In this study, we collected and selected inspiratory and expiratory CT scans performed in pure PF-ILD cases, and evaluated the volumes of diseased and normal lung separately by manual detection and 3-dimensional volumetry to characterize the dynamic features of PF-ILD. MATERIALS AND METHODS: Cases were collected retrospectively from a total of 753 inspiratory and expiratory CT scans performed at our hospital over a 3-year period. Sixteen cases of pure PF-ILD, excluding almost all other diseases, were included. We measured their diseased, normal, and the whole lung volumes manually and evaluated the correlation of their values and their relationship with respiratory function tests (FVC, FVC%-predicted, and DLCO%-predicted). RESULTS: The relative expansion rate of the diseased lung is no less than that of the normal lung. The "Expansion volume of total lung" divided by the "Expansion volume of normal lung" was found to be significantly associated with DLCO%-predicted abnormalities (p = 0.0073). CONCLUSION: The diseased lung in PF-ILD retained expansion capacity comparable to the normal lung, suggesting a negative impact on respiratory function.

Inspiratory and expiratory CT analyses of the diaphragmatic crus in chronic obstructive pulmonary disease.

PURPOSE: This study aimed to investigate the association between the results of pulmonary function tests (PFTs) in patients with chronic obstructive pulmonary disease (COPD) and the size of their diaphragmatic crus (DC) using inspiratory and expiratory CT. MATERIALS AND METHODS: Thirty-three patients who underwent inspiratory and expiratory CT and PFTs between July and December 2019 were studied retrospectively. The short axis, long axis, and cross-sectional area (CSA) of the bilateral DC were measured, and the percentage change of the DC after expiration (% change of DC) in the size was calculated. The correlation between the results of the PFTs (forced expiratory volume in 1 s [FEV1], FEV1/forced vital capacity [FVC], and percent predicted FEV1 [%FEV1]) and the size and % change of DC was statistically analyzed. RESULTS: Significant correlations were observed between the short axis of the right and left DC at expiration and PFTs (FEV1, r = -0.35, -0.48, p = 0.04, .007; FEV1/FVC, r = -0.52, -0.65, p = 0.002, < .001; %FEV1, r = -0.56, -0.60, p < 0.001, < 0.001; respectively), between the CSA of the right DC at expiration and PFTs (FEV1/FVC, r = -0.42, p = 0.01; %FEV1, r = -0.41, p = 0.017; respectively), and between the % change of the short axis of the left DC and the CSA of the left DC and PFTs (FEV1, r = 0.64, 0.56, p < 0.001, .001; %FEV1, r = 0.52, 0.51, p = 0.004, 0.004; respectively). The smaller the short axis of the DC and CSA at expiration and the larger the % change in DC of the CSA, the lower the airflow limitation. CONCLUSION: There were significant correlations between airflow limitation and the short axis of the bilateral DC at expiration, and the % change in the DC of the CSA. Certain CT measurements of the DC may reflect airflow limitation in patients with COPD.

Severe excessive dynamic airway collapse in a patient with primary Sjögren's syndrome.

Airway and cystic lung diseases can be observed in patients with Sjögren's syndrome. We report a case of such a patient suffering from respiratory failure due to recurrent episodes of right pneumothorax, requiring invasive mechanical ventilation. Despite thoracic drainage and adequate pneumothorax management, the patient could not be weaned from the ventilator. Fiberoptic bronchoscopy revealed severe central excessive dynamic airway collapse of the lower part of the trachea and proximal bronchi. The severity of airway collapse was maximal at the intermediate bronchus level, with a near-complete obstruction during expiration. Inspiratory and expiratory computed tomography studies confirmed the fiberoptic findings and suggested a possible expiratory posterior compression of the intermediate bronchus by parenchymal lung cysts. Stenting was considered, but the patient died from ventilator-associated pneumonia before the procedure could be performed. This case is the first description of severe central excessive dynamic airway collapse in a patient with primary Sjögren's syndrome complicated by diffuse airway and cystic lung disease.

Correlation between Expiratory Increase of Lung Attenuation and Age and Smoking in the Subjects with Normal Inspiratory Low Dose CT and Pulmonary Function Test / 결핵및호흡기질환

BACKGROUND: The attenuation of the lung parenchyma increases on expiration as a consequence of decreased air in the lung. Expiratory CT scans have been used to show air trapping in patients with chronic airway disease and diffuse parenchymal disease and also in asymptomatic smokers. Although there have been several reports investigating the regional air trapping on a expiratory CT scan, there have been only a few reports evaluating the changes of whole lung attenuation with considering its clinical significance, and especially in healthy subjects. The purpose of this study was to evaluate the correlation of an expiratory increase of lung attenuation with age and smoking in healthy subjects. METHODS: Asymptomatic subjects who underwent a low dose chest CT scan as part of a routine check-up and who showed normal spirometry and a normal inspiratory CT scan were recruited for this study. We excluded the subjects with significant regional air trapping seen on their expiratory CT scan. Lung attenuation was measured at 24 points of both the inspiratory and expiratory CT scans, respectively, for 100 subjects. The correlations between an expiratory increase of the lung attenuation and the amount of smoking, the patient's age and the results of spirometric test were assessed. RESULTS: There were 87 men and 13 women included in this study. Their median age was 49.0 years old (range: 25~71). Sixty current smokers, 24 ex-smokers and 16 non-smokers were included. As age increased, the expiratory increase of lung attenuation was reduced at every measuring points (r=-0.297~-0.487, Pearson correlation). The statistical significance was maintained after controlling for the effect of smoking. Smoking was associated with a reduction of the expiratory increase of lung attenuation. But the significance was reduced after controlling for the patient's age. The FEV1, FVC, FEV1/FVC and FEF25~75% were not associated with an expiratory increase of lung attenuation. CONCLUSION: The expiratory increase of lung attenuation in subjects with a normal inspiratory CT scan was negatively correlated with age. It was also reduced in heavy smokers. It may reflect aging and the smoking related changes.