Quantitative computed tomography assessment of lung structure and function in pulmonary emphysema

Ct-defined emphysema prevalence in a Chinese and Dutch general population

PURPOSE

We determine and compare the prevalence, subtypes, severity, and risk factors for emphysema assessed by low-dose CT(LDCT) in Chinese and Dutch general populations.

METHODS

This cross-sectional study included LDCT scans of 1143 participants between May and October 2017 from a Chinese Cohort study and 1200 participants with same age range and different smoking status between May and October 2019 from a Dutch population-based study. An experienced radiologist visually assessed the scans for emphysema presence (≥trace), subtype, and severity. Logistic regression analyses, overall and stratified by smoking status, were performed and adjusted for fume exposure, demographic and smoking data.

RESULTS

The Chinese population had a comparable proportion of women to the Dutch population (54.9 % vs 58.9 %), was older (61.7 ± 6.3 vs 59.8 ± 8.1), included more never smokers (66.4 % vs 38.3 %), had a higher emphysema prevalence ([58.8 % vs 39.7 %], adjusted odds ratio, aOR = 2.06, 95 %CI = 1.68-2.53), and more often had centrilobular emphysema (54.8 % vs 32.8 %, p < 0.001), but no differences in emphysema severity. After stratification, only in never smokers an increased odds of emphysema was observed in the Chinese compared to the Dutch (aOR = 2.55, 95 %CI = 1.95-3.35). Never smokers in both populations shared older age (aOR = 1.59, 95 %CI = 1.25-2.02 vs 1.26, 95 %CI = 0.97-1.64) and male sex (aOR = 1.50, 95 %CI = 1.02-2.22 vs 1.93, 95 %CI = 1.26-2.96) as risk factors for emphysema.

CONCLUSIONS

Only never smokers had a higher prevalence of mainly centrilobular emphysema in the Chinese general population compared to the Dutch after adjusting for confounders, indicating that factors other than smoking, age and sex contribute to presence of CT-defined emphysema.

Artificial Intelligence-Based Emphysema Quantification in Routine Chest Computed Tomography: Correlation With Spirometry and Visual Emphysema Grading

OBJECTIVE

The aim of the study is to assess the correlation between artificial intelligence (AI)-based low attenuation volume percentage (LAV%) with forced expiratory volume in the first second to forced vital capacity (FEV1/FVC) and visual emphysema grades in routine chest computed tomography (CT). Furthermore, optimal LAV% cutoff values for predicting a FEV1/FVC < 70% or moderate to more extensive visual emphysema grades were calculated.

METHODS

In a retrospective study of 298 consecutive patients who underwent routine chest CT and spirometry examinations, LAV% was quantified using an AI-based software with a threshold < -950 HU. The FEV1/FVC was derived from spirometry, with FEV1/FVC < 70% indicating airway obstruction. The mean time interval of CT from spirometry was 3.87 ± 4.78 days. Severity of emphysema was visually graded by an experienced chest radiologist using an established 5-grade ordinal scale (Fleischner Society classification system). Spearman correlation coefficient between LAV% and FEV1/FVC was calculated. Receiver operating characteristic determined the optimal LAV% cutoff values for predicting a FEV1/FVC < 70% or a visual emphysema grade of moderate or higher (Fleischner grade 3-5).

RESULTS

Significant correlation between LAV% and FEV1/FVC was found (ϱ = -0.477, P < 0.001). Increasing LAV% corresponded to higher visual emphysema grades. For patients with absent visual emphysema, mean LAV% was 2.98 ± 3.30, for patients with trace emphysema 3.22 ± 2.75, for patients with mild emphysema 3.90 ± 3.33, for patients with moderate emphysema 6.41 ± 3.46, for patients with confluent emphysema 9.02 ± 5.45, and for patients with destructive emphysema 16.90 ± 8.19. Optimal LAV% cutoff value for predicting a FEV1/FVC < 70 was 6.1 (area under the curve = 0.764, sensitivity = 0.773, specificity = 0.665), while for predicting a visual emphysema grade of moderate or higher, it was 4.7 (area under the curve = 0.802, sensitivity = 0.766, specificity = 0.742). Furthermore, correlation between visual emphysema grading and FEV1/FVC was found. In patients with FEV1/FVC < 70% a high proportion of subjects had emphysema grade 3 (moderate) or higher, whereas in patients with FEV1/FVC ≥ 70%, a larger proportion had emphysema grade 3 (moderate) or lower. The sensitivity for visual emphysema grading predicting a FEV1/FVC < 70% was 56.3% with an optimal cutoff point at a visual grade of 4 (confluent), demonstrating a lower sensitivity compared with LAV% (77.3%).

CONCLUSIONS

A significant correlation between AI-based LAV% and FEV1/FVC as well as visual CT emphysema grades can be found in routine chest CT suggesting that AI-based LAV% measurement might be integrated as an add-on functional parameter in the evaluation of chest CT in the future.

Bidimensional ensemble entropy: Concepts and application to emphysema lung computerized tomography scans

BACKGROUND AND OBJECTIVE

Bidimensional entropy algorithms provide meaningful quantitative information on image textures. These algorithms have the advantage of relying on well-known one-dimensional entropy measures dedicated to the analysis of time series. However, uni- and bidimensional algorithms require the adjustment of some parameters that influence the obtained results or even findings. To address this, ensemble entropy techniques have recently emerged as a solution for signal analysis, offering greater stability and reduced bias in data patterns during entropy estimation. However, such algorithms have not yet been extended to their two-dimensional forms.

METHODS

We therefore propose six bidimensional algorithms, namely ensemble sample entropy, ensemble permutation entropy, ensemble dispersion entropy, ensemble distribution entropy, and two versions of ensemble fuzzy entropy based on different models or parameters initialization of an entropy algorithm. These new measures are first tested on synthetic images and further applied to a biomedical dataset.

RESULTS

The results suggest that ensemble techniques are able to detect different levels of image dynamics and their degrees of randomness. These methods lead to more stable entropy values (lower coefficients of variations) for the synthetic data. The results also show that these new measures can obtain up to 92.7% accuracy and 88.4% sensitivity when classifying patients with pulmonary emphysema through a k-nearest neighbors algorithm.

CONCLUSIONS

This is a further step towards the potential clinical deployment of bidimensional ensemble approaches to detect different levels of image dynamics and their successful performance on emphysema lung computerized tomography scans. These bidimensional ensemble entropy algorithms have potential to be used in various imaging applications thanks to their ability to distinguish more stable and less biased image patterns compared to their original counterparts.

Impact of Noise Level on the Accuracy of Automated Measurement of CT Number Linearity on ACR CT and Computational Phantoms

Background

Methods for segmentation, i.e., Full-segmentation (FS) and Segmentation-rotation (SR), are proposed for maintaining Computed Tomography (CT) number linearity. However, their effectiveness has not yet been tested against noise.

Objective

This study aimed to evaluate the influence of noise on the accuracy of CT number linearity of the FS and SR methods on American College of Radiology (ACR) CT and computational phantoms.

Material and Methods

This experimental study utilized two phantoms, ACR CT and computational phantoms. An ACR CT phantom was scanned by a 128-slice CT scanner with various tube currents from 80 to 200 mA to acquire various noises, with other constant parameters. The computational phantom was added by different Gaussian noises between 20 and 120 Hounsfield Units (HU). The CT number linearity was measured by the FS and SR methods, and the accuracy of CT number linearity was computed on two phantoms.

Results

The two methods successfully segmented both phantoms at low noise, i.e., less than 60 HU. However, segmentation and measurement of CT number linearity are not accurate on a computational phantom using the FS method for more than 60-HU noise. The SR method is still accurate up to 120 HU of noise.

Conclusion

The SR method outperformed the FS method to measure the CT number linearity due to its endurance in extreme noise.

Chest CT scan for the screening of air anomalies at risk of pulmonary barotrauma for the initial medical assessment of fitness to dive in a military population

Introduction: The presence of intra-pulmonary air lesions such as cysts, blebs and emphysema bullae, predisposes to pulmonary barotrauma during pressure variations, especially during underwater diving activities. These rare accidents can have dramatic consequences. Chest radiography has long been the baseline examination for the detection of respiratory pathologies in occupational medicine. It has been replaced since 2018 by the thoracic CT scan for military diving fitness in France. The objective of this work was to evaluate the prevalence of the pulmonary abnormalities of the thoracic CT scan, and to relate them to the characteristics of this population and the results of the spirometry.

Methods: 330 records of military diving candidates who underwent an initial assessment between October 2018 and March 2021 were analyzed, in a single-center retrospective analysis. The following data were collected: sex, age, BMI, history of respiratory pathologies and smoking, treatments, allergies, diving practice, results of spirometry, reports of thoracic CT scans, as well as fitness decision.

Results: The study included 307 candidates, mostly male, with a median age of 25 years. 19% of the subjects had abnormal spirometry. We identified 25% of divers with CT scan abnormalities. 76% of the abnormal scans were benign nodules, 26% of which measured 6 mm or more. Abnormalities with an aerial component accounted for 13% of the abnormal scans with six emphysema bullae, three bronchial dilatations and one cystic lesion. No association was found between the presence of nodules and the general characteristics of the population, whereas in six subjects emphysema bullae were found statistically associated with active smoking or abnormal spirometry results.

Conclusion: The systematic performance of thoracic CT scan in a young population free of pulmonary pathology revealed a majority of benign nodules. Abnormalities with an aerial component are much less frequent, but their presence generally leads to a decision of unfitness. These results argue in favor of a systematic screening of aeric pleuro-pulmonary lesions during the initial assessment for professional divers.

Emphysema Quantification Using Ultra-Low-Dose Chest CT: Efficacy of Deep Learning-Based Image Reconstruction

Background and Objectives: Although reducing the radiation dose level is important during diagnostic computed tomography (CT) applications, effective image quality enhancement strategies are crucial to compensate for the degradation that is caused by a dose reduction. We performed this prospective study to quantify emphysema on ultra-low-dose CT images that were reconstructed using deep learning-based image reconstruction (DLIR) algorithms, and compared and evaluated the accuracies of DLIR algorithms versus standard-dose CT. Materials and Methods: A total of 32 patients were prospectively enrolled, and all underwent standard-dose and ultra-low-dose (120 kVp; CTDIvol < 0.7 mGy) chest CT scans at the same time in a single examination. A total of six image datasets (filtered back projection (FBP) for standard-dose CT, and FBP, adaptive statistical iterative reconstruction (ASIR-V) 50%, DLIR-low, DLIR-medium, DLIR-high for ultra-low-dose CT) were reconstructed for each patient. Image noise values, emphysema indices, total lung volumes, and mean lung attenuations were measured in the six image datasets and compared (one-way repeated measures ANOVA). Results: The mean effective doses for standard-dose and ultra-low-dose CT scans were 3.43 ± 0.57 mSv and 0.39 ± 0.03 mSv, respectively (p < 0.001). The total lung volume and mean lung attenuation of five image datasets of ultra-low-dose CT scans, emphysema indices of ultra-low-dose CT scans reconstructed using ASIR-V 50 or DLIR-low, and the image noise of ultra-low-dose CT scans that were reconstructed using DLIR-low were not different from those of standard-dose CT scans. Conclusions: Ultra-low-dose CT images that were reconstructed using DLIR-low were found to be useful for emphysema quantification at a radiation dose of only 11% of that required for standard-dose CT.

Association between Chest CT-defined Emphysema and Lung Cancer: A Systematic Review and Meta-Analysis

Background Given the different methods of assessing emphysema, controversy exists as to whether it is associated with lung cancer. Purpose To perform a systematic review and meta-analysis of the association between chest CT-defined emphysema and the presence of lung cancer. Materials and Methods The PubMed, Embase, and Cochrane databases were searched up to July 15, 2021, to identify studies on the association between emphysema assessed visually or quantitatively with CT and lung cancer. Associations were determined by emphysema severity (trace, mild, or moderate to severe, assessed visually and quantitatively) and subtype (centrilobular and paraseptal, assessed visually). Overall and stratified pooled odds ratios (ORs) with their 95% CIs were obtained. Results Of the 3343 screened studies, 21 studies (107 082 patients) with 26 subsets were included. The overall pooled ORs for lung cancer given the presence of emphysema were 2.3 (95% CI: 2.0, 2.6; I² = 35%; 19 subsets) and 1.02 (95% CI: 1.01, 1.02; six subsets) per 1% increase in low attenuation area. Studies with visual (pooled OR, 2.3; 95% CI: 1.9, 2.6; I² = 48%; 12 subsets) and quantitative (pooled OR, 2.2; 95% CI: 1.8, 2.8; I² = 3.7%; eight subsets) assessments yielded comparable results for the dichotomous assessment. Based on six studies (1716 patients), the pooled ORs for lung cancer increased with emphysema severity and were higher for visual assessment (2.5, 3.7, and 4.5 for trace, mild, and moderate to severe, respectively) than for quantitative assessment (1.9, 2.2, and 2.5) based on point estimates. Compared with no emphysema, only centrilobular emphysema (three studies) was associated with lung cancer (pooled OR, 2.2; 95% CI: 1.5, 3.2; P < .001). Conclusion Both visual and quantitative CT assessments of emphysema were associated with a higher odds of lung cancer, which also increased with emphysema severity. Regarding subtype, only centrilobular emphysema was significantly associated with lung cancer. Clinical trial registration no. CRD42021262163 © RSNA, 2022 See also the editorial by Hunsaker in this issue. Online supplemental material is available for this article.

Prediction of Postoperative Respiratory Complications after Lobectomy in Lung Cancer Patients with COPD by Quantitative Image Analysis: A Historical Cohort Study

PURPOSE

We examined whether preoperative assessment of percentage of low attenuation area (LAA%) on the non-resected side can predict postoperative respiratory complications (PRC) after lobectomy.

MATERIALS AND METHODS

We conducted a historical cohort study of 217 smokers (175 males and 42 females) who underwent lobectomy for primary lung cancer at our hospital between January 2014 and March 2021. First, the relationship between LAA% and respiratory function parameters (RFPs) calculated for both the bilateral and non-resected sides was used to estimate the most effective patient group. Next, multivariate analyses of the relationship between LAA% of the non-resected side and PRC were performed using logistic regression analysis after adjusting for basic patient attributes and respiratory function.

RESULTS

A correlation was found between LAA% and RFP in smoking males. Multivariate analysis showed a strong relationship between model 3, adjusted for basic patient attributes and lung function factors, and PRC (odds ratio, 2.43; 95% confidence interval, 1.05-5.63).

CONCLUSION

LAA% of the non-resected side suggested that it may be able to predict the occurrence of PRC after lung cancer lobectomy.

Diagnostic Performance of Dual-Energy Subtraction Radiography for the Detection of Pulmonary Emphysema: An Intra-Individual Comparison

PURPOSE/OBJECTIVES

To compare the diagnostic performance of dual-energy subtraction (DE) and conventional radiography (CR) for detecting pulmonary emphysema using computed tomography (CT) as a reference standard.

METHODS AND MATERIALS

Sixty-six patients (24 female, median age 73) were retrospectively included after obtaining lateral and posteroanterior chest X-rays with a dual-shot DE technique and chest CT within ±3 months. Two experienced radiologists first evaluated the standard CR images and, second, the bone-/soft tissue weighted DE images for the presence (yes/no), degree (1-4), and quadrant-based distribution of emphysema. CT was used as a reference standard. Inter-reader agreement was calculated. Sensitivity and specificity for the correct detection and localization of emphysema was calculated. Further degree of emphysema on CR and DE was correlated with results from CT. A p-value < 0.05 was considered as statistically significant.

RESULTS

The mean interreader agreement was substantial for CR and moderate for DE (kCR = 0.611 vs. kDE = 0.433; respectively). Sensitivity, as well as specificity for the detection of emphysema, was comparable between CR and DE (sensitivityCR 96% and specificityCR 75% vs. sensitivityDE 91% and specificityDE 83%; p = 0.157). Similarly, there was no significant difference in the sensitivity or specificity for emphysema localization between CR and DE (sensitivityCR 50% and specificityCR 100% vs. sensitivityDE 57% and specificityDE 100%; p = 0.157). There was a slightly better correlation with CT of emphysema grading in DE compared to CR (rDE = 0.75 vs. rCR = 0.68; p = 0.108); these differences were not statistically significant, however.

CONCLUSION

Diagnostic accuracy for the detection, quantification, and localization of emphysema between CR and DE is comparable. Interreader agreement, however, is better with CR compared to DE.

Cluster analysis of emphysema for predicting pulmonary complications after thoracoscopic lobectomy

 

OBJECTIVES

Despite significant advances in surgical techniques, including thoracoscopic approaches and perioperative care, the morbidity rate remains high after lung resection. This study focused on a low attenuation cluster analysis, which represented the size distribution of pulmonary emphysema and assessed its utility for predicting postoperative pulmonary complications after thoracoscopic lobectomy.

METHODS

From April 2013 to September 2018, lung cancer patients who received spirometry and computed tomography (CT) before surgery and underwent thoracoscopic lobectomy were included. The cumulative size distribution of the low attenuation area (LAA, defined as ≤-950 Hounsfield unit on CT) clusters followed a power-law characterized by an exponent D-value, a measure of the complexity of the alveolar structure. D-value and LAA% (LAA/total lung volume) were calculated using preoperative 3-dimensional CT software. The relationship between pulmonary complications and patient characteristics, including D-value and LAA%, was investigated.

RESULTS

Among 471 patients, there were 61 respiratory complication cases (12.9%). Receiver operation characteristic curve analysis revealed that the best predictive cut-off value of D-value and LAA% for pulmonary complications was 2.27 and 16.5, respectively, with an area under the curve of 0.72 and 0.58, respectively. D-value was significantly correlated with % forced expiratory volume in 1 s. Per univariate analysis, gender, smoking history, forced expiratory volume in 1 s/forced vital capacity, LAA% and D-value were risk factors for predicting postoperative pulmonary complications. In the multivariate analysis, D-value remained a significant predictive factor.

CONCLUSION

Preoperative assessment of emphysema cluster analysis may represent the vulnerability of the operated lung and could be the novel predictor for pulmonary complications after thoracoscopic lobectomy.

Evaluation of lung densitometric and volumetric changes in silicosis patients using three-dimensional software for multidetector CT and the relationship with profusion scores

AIM

To evaluate the density and volume changes in the lungs of silicosis patients and their relationship with the disease severity classification of the International Labor Organization (ILO).

MATERIALS AND METHODS

The multidetector computed tomography (CT) images of 44 patients diagnosed with silicosis and 32 controls that underwent thoracic CT due to trauma were evaluated. Patients with silicosis were divided into three categories according to the ILO classification. Data related to the total lung volume, total lung mean density, lung opacity score, percentage of lung high opacity, and mean density in the lower and upper lobes were obtained using three-dimensional (3D) software.

RESULTS

There was no significant difference between the total lung mean densities of the silicosis and control groups (p=0.213); however, a significant difference was observed between the two groups in terms of the total lung volume (p<0.0001). According to the ILO classification, there was a significant difference between the disease severity categories in relation to the percentage of lung high opacity (p=0.000005). A strong correlation was detected between disease severity and high opacity percentage (p<0.0001, r=0.804). According to the ILO classification, there was also a significant difference between disease severity categories in terms of the lung opacity score (p=0.000144), as well as a moderate correlation between disease severity and opacity score (p<0.0001, r=0.580).

CONCLUSION

Total lung volume is a CT finding that shows variation in exposure to crystalline silica. The percentage of high opacity determined using multidetector CT is an effective parameter in evaluating disease severity.

Lung emphysema and lung cancer: what do we know about it?

Emphysema and lung cancer (LC) are two diseases which share common risk factors, e.g., smoking. In recent years, many studies have sought to analyse this association. By way of illustration, we conducted a review of the scientific literature of the studies published to date, whose main designated aim was to demonstrate the relationship between emphysema and LC, and this association's influence on the histology, prognosis and molecular mechanisms responsible. We included over 40 studies (ranging from case-control and cohort studies to systematic reviews and meta-analyses), which highlight the association between emphysema and LC, independently of smoking habit. These studies also report a possible influence on histology, with adenocarcinoma being the most frequent lineage, and an association with poor prognosis, which affects both survival and post-operative complications. Oxidative stress, which generates chronic inflammatory status as well as the presence of certain polymorphisms in various genes (CYP1A1, TERT, CLPTM1L, ERK), gives rise-in the case of patients with emphysema-to alteration of cellular repair mechanisms, which in turn favours the proliferation of neoplastic epithelial cells responsible for the origin of LC.

Artificial intelligence and radiomics in pulmonary nodule management: current status and future applications

Artificial intelligence (AI) has been present in some guise within the field of radiology for over 50 years. The first studies investigating computer-aided diagnosis in thoracic radiology date back to the 1960s, and in the subsequent years, the main application of these techniques has been the detection and classification of pulmonary nodules. In addition, there have been other less intensely researched applications, such as the diagnosis of interstitial lung disease, chronic obstructive pulmonary disease, and the detection of pulmonary emboli. Despite extensive literature on the use of convolutional neural networks in thoracic imaging over the last few decades, we are yet to see these systems in use in clinical practice. The article reviews current state-of-the-art applications of AI and in detection, classification, and follow-up of pulmonary nodules and how deep-learning techniques might influence these going forward. Finally, we postulate the impact of these advancements on the role of radiologists and the importance of radiologists in the development and evaluation of these techniques.

Systemic Complications of Acromegaly and the Impact of the Current Treatment Landscape: An Update

Acromegaly is a chronic systemic disease with many complications and is associated with increased mortality when not adequately treated. Substantial advances in acromegaly treatment, as well as in the treatment of many of its complications, mainly diabetes mellitus, heart failure, and arterial hypertension, were achieved in the last decades. These developments allowed change in both prevalence and severity of some acromegaly complications and furthermore resulted in a reduction of mortality. Currently, mortality seems to be similar to the general population in adequately treated patients with acromegaly. In this review, we update the knowledge in complications of acromegaly and detail the effects of different acromegaly treatment options on these complications. Incidence of mortality, its correlation with GH (cumulative exposure vs last value), and IGF-I levels and the shift in the main cause of mortality in patients with acromegaly are also addressed.

Quantitative severity of pulmonary emphysema as a prognostic factor for recurrence in patients with surgically resected non-small cell lung cancer

Background

Pulmonary emphysema is a major component of chronic obstructive pulmonary disease and lung cancer. However the prognostic significance of quantitative emphysema severity in patients with lung cancer is unclear. We analyzed whether numerical emphysema value is a prognostic factor for recurrence in patients with surgically resected non‐small cell lung cancer.

Methods

We quantified emphysema severity of the whole lung and regional lobes in 45 patients (mean age 68.0 years) using an automated chest computed tomography‐based program. Predictive factors for recurrence were investigated using a Cox proportional hazards model. Recurrence‐free and overall survival was compared after dichotomization of patients according to whole lung emphysema severity.

Results

The mean percentage emphysema ratio of the whole lung was 1.21 ± 2.04. Regional lobar emphysema severity was highest in the right middle lobe (1.93 ± 0.36), followed by right upper (1.35 ± 2.50), left upper (1.34 ± 2.12), left lower (1.05 ± 2.52), and right lower (0.78 ± 2.28) lobes. The low severity group showed significantly longer overall survival compared to the high severity group (log‐rank test, P = 0.018). Quantitative emphysema severity of the whole lung (hazard ratio 1.36; 95% confidence interval 1.0–1.73) and stage III (hazard ratio 6.17; 95% confidence interval 1.52–25.0) were independent predictors of recurrence after adjusting for age, gender, smoking status, and forced expiratory volume in one second.

Conclusion

The severity of whole lung emphysema was independently associated with recurrence. Patients with non‐small cell lung cancer and marginal pulmonary emphysema at lower severity survive longer after curative‐intent surgery.

Influence of the type of emphysema in the relationship between COPD and lung cancer

Introduction

There are no studies analyzing the relationship between emphysema and lung cancer (LC). With this aim and in order to make some comparisons between different clinical variables, we carried out the present study.

Methods

This is a case–control study, patients with COPD and LC being the cases and subjects with stable COPD being the controls. Clinical and functional parameters, as well as the existence of radiological emphysema, were evaluated in a qualitative and quantitative way, using a radiological density of −950 Hounsfield units as a cutoff point in the images. The existence of several different types of emphysema (centrilobular, paraseptal, panacinar, or bullae) was analyzed, allowing patients to have more than one simultaneously. The extent to which lobes were involved was evaluated and the extension of emphysema was graduated for each type and location, following a quantitative scale. Differences between cases and controls were compared by using bivariate and multivariate analyzes with results expressed as OR and 95% CI.

Results

We included 169 cases and 74 controls, 84% men with a FEV₁ (%) of 61.7±18.5, with 90.1% non-exacerbators. Most of them (50%) were active smokers and 47.2% were ex-smokers. Emphysema was found in 80.2% of the subjects, the most frequent type being centrilobular (34.4%). The only significantly different factor was the presence of paraseptal emphysema (alone or combined; OR =2.2 [95% CI =1.1–4.3, P = 0.03]), with adenocarcinoma being significantly more frequent in paraseptal emphysema with respect to other types (67.2% vs 32.8%, P =0.03).

Conclusion

Patients with COPD and paraseptal emphysema could be a risk group for the development of LC, especially adenocarcinoma subtype.

Associations between emphysema-like lung on CT and incident airflow limitation: a general population-based cohort study

Emphysema on CT is associated with accelerated lung function decline in heavy smokers and patients with COPD; however, in the general population, it is not known whether greater emphysema-like lung on CT is associated with incident COPD. We used data from 2045 adult participants without initial prebronchodilator airflow limitation, classified by FEV1/FVC<0.70, in the Multi-Ethnic Study of Atherosclerosis. Emphysema-like lung on baseline cardiac CT, defined as per cent low attenuation areas<-950HU>upper limit of normal, was associated with increased odds of incident airflow limitation at 5-year follow-up on both prebronchodilator (adjusted OR 2.62, 95% CI 1.47 to 4.67) and postbronchodilator (adjusted OR 4.38, 95% CI 1.63 to 11.74) spirometry, independent of smoking history. These results support investigation into whether emphysema-like lung could be informative for COPD risk stratification.

Three-dimensional computed tomographic volumetry precisely predicts the postoperative pulmonary function

PURPOSE

It is important to accurately predict the patient's postoperative pulmonary function. The aim of this study was to compare the accuracy of predictions of the postoperative residual pulmonary function obtained with three-dimensional computed tomographic (3D-CT) volumetry with that of predictions obtained with the conventional segment-counting method.

METHODS

Fifty-three patients scheduled to undergo lung cancer resection, pulmonary function tests, and computed tomography were enrolled in this study. The postoperative residual pulmonary function was predicted based on the segment-counting and 3D-CT volumetry methods. The predicted postoperative values were compared with the results of postoperative pulmonary function tests.

RESULTS

Regarding the linear correlation coefficients between the predicted postoperative values and the measured values, those obtained using the 3D-CT volumetry method tended to be higher than those acquired using the segment-counting method. In addition, the variations between the predicted and measured values were smaller with the 3D-CT volumetry method than with the segment-counting method. These results were more obvious in COPD patients than in non-COPD patients.

CONCLUSIONS

Our findings suggested that the 3D-CT volumetry was able to predict the residual pulmonary function more accurately than the segment-counting method, especially in patients with COPD. This method might lead to the selection of appropriate candidates for surgery among patients with a marginal pulmonary function.

Quantitative CT characterization of pediatric lung development using routine clinical imaging

BACKGROUND

The use of quantitative CT analysis in children is limited by lack of normal values of lung parenchymal attenuation. These characteristics are important because normal lung development yields significant parenchymal attenuation changes as children age.

OBJECTIVE

To perform quantitative characterization of normal pediatric lung parenchymal X-ray CT attenuation under routine clinical conditions in order to establish a baseline comparison to that seen in pathological lung conditions.

MATERIALS AND METHODS

We conducted a retrospective query of normal CT chest examinations in children ages 0-7 years from 2004 to 2014 using standard clinical protocol. During these examinations semi-automated lung parenchymal segmentation was performed to measure lung volume and mean lung attenuation.

RESULTS

We analyzed 42 CT examinations in 39 children, ages 3 days to 83 months (mean ± standard deviation [SD] = 42 ± 27 months). Lung volume ranged 0.10-1.72 liters (L). Mean lung attenuation was much higher in children younger than 12 months, with values as high as -380 Hounsfield units (HU) in neonates (lung volume 0.10 L). Lung volume decreased to approximately -650 HU by age 2 years (lung volume 0.47 L), with subsequently slower exponential decrease toward a relatively constant value of -860 HU as age and lung volume increased.

CONCLUSION

Normal lung parenchymal X-ray CT attenuation decreases with increasing lung volume and age; lung attenuation decreases rapidly in the first 2 years of age and more slowly thereafter. This change in normal lung attenuation should be taken into account as quantitative CT methods are translated to pediatric pulmonary imaging.

Advances in Identifying Urine/Serum Biomarkers in Alpha-1 Antitrypsin Deficiency for More Personalized Future Treatment Strategies

Alpha1-antitrypsin deficiency (AATD) is a genetic disorder characterized by reduced serum levels of alpha1-antitrypsin (AAT) and increased risk for developing both early-onset lung emphysema and chronic liver disease. Laboratory diagnosis of AATD is not just a matter of degree, although the AAT serum level is the most important determinant for risk of lung damage. While being a single-gene disease, the clinical phenotype of AATD is heterogeneous. The current standard of care for patients affected by AATD-associated pulmonary emphysema is replacement therapy with weekly i.v. infusions of pooled human purified plasma AAT. Although no treatment for liver disease caused by deposition of abnormal AAT in hepatocytes is available, innovative treatments for this condition are on the horizon. This article aims to provide a critical review of the methodological steps that have marked progress in the detection of indicators described in the literature as being "clinically significant" biomarkers of the disease. The development and routine use of specific biomarkers would help both in identifying which patients and when they are eligible for treatment as well as providing additional parameters for monitoring the disease.

Effect of total lung capacity and gender on CT densitometry indexes

OBJECTIVE

Testing the hypothesis that CT densitometry indexes could be influenced by total lung capacity (TLC), gender and height in normal individuals.

METHODS

In this ethics committee-approved prospective study, 100 healthy non-smoking volunteers who provided written informed consent were included. From a helical scan of the chest, the relative area (RA) of the lung with attenuation coefficients lower than -960 HU and the 1st and 15th percentiles of the distribution of attenuation coefficients were calculated. Regression lines were drawn between each CT index and volunteers' height and total TLC at CT.

RESULTS

In males, there was no statistically significant correlation between any CT index and height. In females, there was a statistically significant correlation between the RA of the lung with attenuation coefficients lower than -960 HU and the 1st percentile and height but not with the 15th percentile. For both genders, there were significant correlations between all CT indexes and TLC. The relationships between CT indexes and TLC were different in males and females.

CONCLUSION

CT indexes are correlated with TLC and height but more closely with TLC than with height, and differently in males and females.

ADVANCES IN KNOWLEDGE

CT indexes are influenced by TLC, gender and height in normal individuals and are more closely correlated with TLC than with height. The relationships between CT indexes and TLC or height are different in males and females. CT indexes used to quantify emphysema should thus be adjusted according to TLC and gender.

Patterns of Emphysema Heterogeneity

BACKGROUND

Although lobar patterns of emphysema heterogeneity are indicative of optimal target sites for lung volume reduction (LVR) strategies, the presence of segmental, or sublobar, heterogeneity is often underappreciated.

OBJECTIVE

The aim of this study was to understand lobar and segmental patterns of emphysema heterogeneity, which may more precisely indicate optimal target sites for LVR procedures.

METHODS

Patterns of emphysema heterogeneity were evaluated in a representative cohort of 150 severe (GOLD stage III/IV) chronic obstructive pulmonary disease (COPD) patients from the COPDGene study. High-resolution computerized tomography analysis software was used to measure tissue destruction throughout the lungs to compute heterogeneity (≥15% difference in tissue destruction) between (inter-) and within (intra-) lobes for each patient. Emphysema tissue destruction was characterized segmentally to define patterns of heterogeneity.

RESULTS

Segmental tissue destruction revealed interlobar heterogeneity in the left lung (57%) and right lung (52%). Intralobar heterogeneity was observed in at least one lobe of all patients. No patient presented true homogeneity at a segmental level. There was true homogeneity across both lungs in 3% of the cohort when defining heterogeneity as ≥30% difference in tissue destruction.

CONCLUSION

Many LVR technologies for treatment of emphysema have focused on interlobar heterogeneity and target an entire lobe per procedure. Our observations suggest that a high proportion of patients with emphysema are affected by interlobar as well as intralobar heterogeneity. These findings prompt the need for a segmental approach to LVR in the majority of patients to treat only the most diseased segments and preserve healthier ones.

Quantative computerized tomography assessment of lung density as a predictor of postoperative pulmonary morbidity in patients with lung cancer

BACKGROUND

The aim of this study was to evaluate the pulmonary reserve of the patients via preoperative quantitative computerized tomography (CT) and to determine if these preoperative quantitative measurements could predict the postoperative pulmonary morbidity.

METHODS

Fifty patients with lung cancer who underwent lobectomy/segmentectomy were included in the study. Preoperative quantitative CT scans and pulmonary function tests data were evaluated retrospectively. We compare these measurements with postoperative morbidity.

RESULTS

There were 32 males and 18 females with a mean age of 54.4±13.9 years. Mean total density was -790.6±73.4 HU. The volume of emphysematous lung was (<-900 HU) 885.2±1,378.4 cm(3). Forced expiratory volume in one second (FEV1) (r=-0.494, P=0.02) and diffusion capacity of carbon monoxide (DLCO) (r=-0.643, P<0.001) were found to be correlate with the volume of emphysematous lung. Furthermore FEV1 (r=0.59, P<0.001) and DLCO (r=0.48, P<0.001) were also found to be correlate with mean lung density. Postoperative pulmonary morbidity was significantly higher in patients with lower lung density (P<0.001), larger volume of emphysema (P<0.001) and lower DLCO (P=0.039). A cut-off point of -787.5 HU for lung density showed 86.96% sensitivity and 81.48% specificity for predicting the pulmonary morbidity (kappa =-0.68, P<0.001). Additionally a cut-off point of 5.41% for emphysematous volume showed 84.00% sensitivity and 80.00% specificity for predicting the pulmonary morbidity (kappa =0.64, P<0.001). According to logistic regression analyses emphysematous volume >5.41% (P=0.014) and lung density <-787.5 HU (P=0.009) were independent prognostic factors associated with postoperative pulmonary morbidity.

CONCLUSIONS

In this study, the patients with a lower lung density than -787.5 HU and a higher volume of emphysema than 5.41% were found to be at increased risk for developing postoperative pulmonary morbidity. More stringent precautions should be taken in those patients that were found to be at high risk to avoid pulmonary complications.

CT pulmonary densitovolumetry in patients with acromegaly: a comparison between active disease and controlled disease

OBJECTIVE

Our purpose was to compare the findings of CT pulmonary densitovolumetry and pulmonary function in patients with active acromegaly and controlled acromegaly and, secondarily, to correlate these findings.

METHODS

11 patients with active acromegaly, 18 patients with controlled acromegaly and 17 control subjects, all non-smokers, underwent quantification of lung volume using multidetector CT (Q-MDCT) and pulmonary function tests.

RESULTS

Patients with active acromegaly had larger total lung mass (TLM) values than the controls and larger amounts of non-aerated compartments than the other two groups. Patients with active acromegaly also had larger amounts of poorly aerated compartments than the other two groups, a difference that was observed in both total lung volume (TLV) and TLM. TLV as measured by inspiratory Q-MDCT correlated significantly with total lung capacity, whereas TLV measured using expiratory Q-MDCT correlated significantly with functional residual capacity.

CONCLUSION

Patients with active acromegaly have more lung mass and larger amounts of non-aerated and poorly aerated compartments. There is a relationship between the findings of CT pulmonary densitovolumetry and pulmonary function test parameters.

ADVANCES IN KNOWLEDGE

Although the nature of our results demands further investigation, our data suggest that both CT pulmonary densitovolumetry and pulmonary function tests can be used as useful tools for patients with acromegaly by assisting in the prediction of disease activity.

Correlations between forced oscillation technique parameters and pulmonary densitovolumetry values in patients with acromegaly

The aims of this study were to evaluate the forced oscillation technique (FOT) and pulmonary densitovolumetry in acromegalic patients and to examine the correlations between these findings. In this cross-sectional study, 29 non-smoking acromegalic patients and 17 paired controls were subjected to the FOT and quantification of lung volume using multidetector computed tomography (Q-MDCT). Compared with the controls, the acromegalic patients had a higher value for resonance frequency [15.3 (10.9-19.7) vs 11.4 (9.05-17.6) Hz, P=0.023] and a lower value for mean reactance [0.32 (0.21-0.64) vs 0.49 (0.34-0.96) cm H₂O/L/s², P=0.005]. In inspiratory Q-MDCT, the acromegalic patients had higher percentages of total lung volume (TLV) for nonaerated and poorly aerated areas [0.42% (0.30-0.51%) vs 0.25% (0.20-0.32%), P=0.039 and 3.25% (2.48-3.46%) vs 1.70% (1.45-2.15%), P=0.001, respectively]. Furthermore, the acromegalic patients had higher values for total lung mass in both inspiratory and expiratory Q-MDCT [821 (635-923) vs 696 (599-769) g, P=0.021 and 844 (650-945) vs 637 (536-736) g, P=0.009, respectively]. In inspiratory Q-MDCT, TLV showed significant correlations with all FOT parameters. The TLV of hyperaerated areas showed significant correlations with intercept resistance (r_s=−0.602, P<0.001) and mean resistance (r_s=−0.580, P<0.001). These data showed that acromegalic patients have increased amounts of lung tissue as well as nonaerated and poorly aerated areas. Functionally, there was a loss of homogeneity of the respiratory system. Moreover, there were correlations between the structural and functional findings of the respiratory system, consistent with the pathophysiology of the disease.

Quantitative emphysema assessment of pulmonary function impairment by computed tomography in chronic obstructive pulmonary disease

OBJECTIVE

The objective of this study was to determine the capability of quantitative emphysema by computed tomography (CT) to assess pulmonary function impairment in a population of current smokers with and without airflow limitation.

METHODS

Seventy-six subjects (30 normal smokers; 8 with mild obstruction; 17 with moderate obstruction; 13 with severe obstruction; 8 with very severe obstruction) underwent CT examinations and pulmonary function tests. For the quantitative assessment, percentages of low attenuation volume (%LAVs) of whole lung, right lung, left lung, and each lobe were obtained. Computed tomography measurements were related to lung function (forced expiratory volume in 1 second [FEV1], ratio of FEV1 to forced vital capacity, diffusing capacity for carbon monoxide [DLCO], ratio of residual volume to total lung capacity [RV/TLC]) by multivariate linear regression analysis.

RESULTS

Quantitative CT measurements of emphysema were moderately, negatively correlated to airflow limitation (FEV1 and ratio of FEV1 to forced vital capacity) (r = -0.68 to -0.52, P < 0.001). Except for right middle and lower lobes, all the quantitative CT measurements showed moderate, negative correlations with diffusing capacity (DLCO) (r = -0.63 to -0.54, P ≤ 0.001) and weak to moderate correlations with RV (RV/TLC) (r = 0.36-0.41, P < 0.01). As compared with control samples, the %LAV of whole lung, right lung, left lung, and each lobe was increased in patients with GOLD stages 2, 3, and 4 disease (P < 0.05), and the % LAV of whole lung, right lung and right upper lobe was increased in patients with GOLD stage 1 (P < 0.05).

CONCLUSIONS

Pulmonary function results, particularly DLCO and RV/TLC, were primarily affected by the % LAV of the upper lobes. Quantitative CT measurements of emphysema provides a morphological method to investigate lung function impairment in patients with chronic obstructive pulmonary disease.

Relationships between the pulmonary densitometry values obtained by CT and the forced oscillation technique parameters in patients with silicosis

OBJECTIVE

To evaluate the correlations between pulmonary densitometry values and forced oscillation technique (FOT) parameters in patients with silicosis.

METHODS

This cross-sectional study comprised 36 non-smoker patients with silicosis and 20 matched control subjects who were submitted to FOT and multidetector CT (MDCT).

RESULTS

Compared with the control subjects, the MDCT evaluation demonstrated that patients with silicosis exhibited greater total lung mass. These patients also had larger non-aerated and poorly aerated compartments, which included nodules and scarring. Compared with the control subjects, FOT evaluation demonstrated that patients with silicosis exhibited changes in both reactive and resistive properties of the respiratory system. In these patients, there was a greater heterogeneity of the respiratory system and increased work of breathing. Significant correlations between non-aerated compartment size and FOT parameters that reflect the non-homogeneity of the respiratory system were observed. The dynamic compliance of the respiratory system was negatively correlated with non-aerated compartment size, while the impedance at 4 Hz was positively correlated with non-aerated compartment size.

CONCLUSION

Patients with silicosis have heavier lungs. In these patients, a larger non-aerated compartment is associated with a worsening of lung function. A more significant pulmonary involvement is associated with a loss of homogeneity and increased mechanical load of the respiratory system. Advances in knowledge The findings provided by both pulmonary densitometry and FOT may add valuable information to the subjective analysis of silicosis; however, more studies are necessary to evaluate the potential use of these methods for assessing disease progression.

Feasibility of quantitative parameters of dynamically enhanced patterns of spiral computed tomography scanning integrated into tumour progression before targeted treatment of non-small cell lung cancer

INTRODUCTION

The relationship between quantitative parameters of contrast-enhanced computed tomography (CT) and non-small cell lung cancer (NSCLC) progression remains controversial. We aimed to explore the usefulness of contrast-enhanced spiral CT scanning for confirming the time of tumour progression before targeted treatment of NSCLC.

METHODS

Contrast-enhanced spiral CT scanning was performed on 33 NSCLC patients with a biopsy-proven diagnosis of NSCLC. All the patients were divided into three groups according to times of tumour progression (<6 weeks, 6-20 weeks, and >20 weeks). The perfusion CT data were used to calculate quantitative parameters, including enhanced peak values, peak time of tumour enhancement, ratio of tumour mass and enhanced aorta peak value and perfusion value of blood flow. Variance analysis was used for statistical analysis among the three groups using SAS 9.13 statistical software.

RESULTS

Tumour perfusion values among the three group with different stage of TTP were significantly different from each other with P = 0.0129 (<6 weeks, perfusion value = 0.35 ± 0.15 mL/(min × mL); 6-20 weeks, perfusion value = 0.41 ± 0.086 mL/(min × mL); > 20 weeks, perfusion value = 0.47 ± 0.087 mL/(min × mL)). However, no significant differences were found in other parameters (enhanced peak values, peak time of tumour enhancement, ratios of tumour mass, and enhanced aorta peak value) among three groups (P > 0.05).

CONCLUSION

The NSCLC patients with high perfusion value before targeted therapy are more sensitive to targeted therapy, and further experiments with larger sample size are needed.

Cannabis smoking and respiratory health: consideration of the literature

The respiratory health effects from tobacco smoking are well described. Cannabis smoke contains a similar profile of carcinogenic chemicals as tobacco smoke but is inhaled more deeply. Although cannabis smoke is known to contain similar harmful and carcinogenic substances to tobacco smoke, relatively little is understood regarding the respiratory health effects from cannabis smoking. There is a need to integrate research on cannabis and respiratory health effects so that gaps in the literature can be identified and the more consistent findings can be consolidated with the purpose of educating smokers and health service providers. This review focuses on several aspects of respiratory health and cannabis use (as well as concurrent cannabis and tobacco use) and provides an update to (i) the pathophysiology; (ii) general respiratory health including symptoms of chronic bronchitis; and (iii) lung cancer.

Quantitative assessment of emphysematous parenchyma using multidetector-row computed tomography in patients scheduled for endobronchial treatment with one-way valves†

OBJECTIVES

To investigate the role of volume quantitative assessment using multidetector-row computed tomography to select patients scheduled for endobronchial one-way valves treatment.

METHODS

Twenty-five consecutive patients (15 with heterogeneous emphysema and 10 with giant emphysematous bulla) undergoing endobronchial valves treatment were enrolled. All patients were studied pre- and postoperatively with standard pulmonary functional tests and quantitative volume assessment of target lobe and entire lung. Emphysematous parenchyma was obtained applying density thresholds of -1.024/-950 Hounsfield units. Among different subtype of patients, we evaluated: (i) the differences between preoperative versus postoperative data; (ii) the correlation between functional and volumetric quantification changes and (iii) the critical threshold value of volumetric quantification of the target lobe in close association with clinical effects.

RESULTS

Among heterogeneous emphysematous and giant emphysematous bulla patients, a significant improvement of flow-expiratory volume in 1 s (from 36.9 ± 15.3 to 43.9 ± 10.4; P = 0.01; and from 35.8 ± 6.0 to 47.5 ± 7.9; P < 0.0001, respectively); and of forced vital capacity (from 41.9 ± 5.9 to 47.3 ± 9.3; P = 0.0009 and from 40.7 ± 5.9 to 48.8 ± 4.9; P = 0.0002, respectively); and a significant reduction of residual volume (from 185 ± 14 to 157 ± 14.7; P = 0.005; and from 196 ± 13.5 to 137 ± 21; P < 0.0001, respectively) and of total lung volume (from 166.7 ± 13 to 137 ± 18 ; P = 0.0003, and from 169 ± 15 to 134 ± 18; P < 0.0001, respectively) were seen after treatment. The volumetric measurements showed a reduction of volume of the treated lobe among heterogeneous emphysematous patients (from 1448 ± 204 to 1076 ± 364; P = 0.0008); and in those with giant emphysematous bulla (from 1668 ± 140 to 864 ± 199; P < 0.0001). The entire lung and target lobe volume changes were inversely correlated with change in forced expiratory volume in 1 s in patients with heterogeneous emphysematous (r = -0.7; P = 0.0006; and r = -0.7; P = 0.0009, respectively) and giant emphysematous bulla (r = -0.8; P = 0.001; and r = -0.7; P = 0.009, respectively). Among patients with heterogenous emphysematous and giant emphysematous bulla, the value of sensitivity and specificity were 66.6 and 83%, respectively (for a volumetric qunatification >1.5239), and of 60 and 100%, respectively (for a volumetric qunatification >1.762).

CONCLUSIONS

Our study showed that the volumetric quantification adds further informations to the routine evaluation for optimizing the selection of patients scheduled for endobronchial valve treatment.

Establishing normal reference values in quantitative computed tomography of emphysema

Quantitative computed tomography (QCT) can provide reliable and valid measures of lung structure and volumes. Similar to lung function measured by spirometry, lung measures obtained by QCT vary by demographic and anthropomorphic factors including sex, race/ethnicity, and height in asymptomatic nonsmokers. Hence, accounting for these factors is necessary to define abnormal from normal QCT values. Prediction equations for QCT may be derived from a sample of asymptomatic individuals to estimate reference values. This review article describes the methodology of reference equation development using, as an example, quantitative densitometry to detect pulmonary emphysema. The process described is generalizable to other QCT measures, including lung volumes, airway dimensions, and gas-trapping. Pulmonary emphysema is defined morphologically by airspace enlargement with alveolar wall destruction and has been shown to correlate with low lung attenuation estimated by QCT. Deriving reference values for a normal quantity of low lung attenuation requires 3 steps. First, criteria that define normal must be established. Second, variables for inclusion must be selected on the basis of an understanding of subject-specific, scanner-specific, and protocol-specific factors that influence lung attenuation. Finally, a reference sample of normal individuals must be selected that is representative of the population in which QCT will be used to detect pulmonary emphysema. Sources of bias and confounding inherent to reference values are also discussed. Reference equation development is a multistep process that can define normal values for QCT measures such as lung attenuation. Normative reference values will increase the utility of QCT in both research and clinical practice.

Changes in volume-corrected whole-lung density in smokers and former smokers during the ITALUNG screening trial

PURPOSE

To evaluate with a volume-corrected whole-lung approach changes in lung density over 2 years consistent with progression of pulmonary emphysema in smokers and former smokers enrolled in the ITALUNG trial of lung cancer screening using low-dose computed tomography (LDCT).

MATERIALS AND METHODS

A total of 103 subjects (mean age 63±4 y with a pack-year history of at least 20) underwent 2 whole-lung LDCT examinations 2 years apart. Visual assessment was made independently by 2 experienced observers on the initial LDCT examination with a 0 to 4 grading system for each of 6 regions (right and left upper, mid, and lower lung). The whole-lung 15th percentile of attenuation coefficient and relative area (RA) at -910 HU, both corrected to the individual lung volume (Perc15v and RA910v), were measured on the 2 LDCT examinations. The intrasubject variability of Perc15v and RA910v was previously determined in 32 other subjects of the trial examined using the same scanner and technique twice over a 3-month interval for suspicious nodules.

RESULTS

The 2 operators agreed on the presence of mild to severe emphysema (visual score ≥1 in at least 1 region) at initial LDCT examination in 24 (23%) of the 103 subjects. Fifteen subjects (15%) showed a Perc15v change between the 2 examinations exceeding the lower 95% limit of agreement, indicating progression of emphysema with a mean difference in lung density of -14.7%±2.6%. Ten of the 15 were identified as showing emphysema progression by RA910v as well. No association was observed between progression of emphysema and visual evidence of emphysema at initial LDCT examination, smoking status, or pack-years at baseline, or intervening changes in smoking habits.

CONCLUSION

Once variations in inspiratory lung volumes are taken into account, changes in lung density over 2 years consistent with progression of pulmonary emphysema in elderly smokers and former smokers are uncommon.

Exertional desaturation as a predictor of rapid lung function decline in COPD

BACKGROUND

To date, no clinical parameter has been associated with the decline in lung function other than emphysema severity in COPD.

OBJECTIVES

The main purpose of this study was to explore whether the rate of lung function decline differs between COPD patients with and without exertional desaturation.

METHODS

A total of 224 subjects were selected from the Korean Obstructive Lung Disease cohort. Exertional desaturation was assessed using the 6-min walk test (6MWT), and defined as a post-exercise oxygen saturation (SpO2) of < 90% or a ≥ 4% decrease. The cohort was divided into desaturator (n = 47) and non-desaturator (n = 177) groups.

RESULTS

There was a significant difference between the desaturator and non-desaturator groups in terms of the change in pre-bronchodilator forced expiratory volume in 1 s (FEV1) over a 3-year period of follow-up (p = 0.006). The mean rate of decline in FEV1 was greater in the desaturator group (33.8 ml/year) than in the non-desaturator group (11.6 ml/year). A statistically significant difference was also observed between the two groups in terms of the change in the St. George's Respiratory Questionnaire (SGRQ) total score over 3 years (p = 0.001).

CONCLUSIONS

This study suggests, for the first time, that exertional desaturation may be a predictor of rapid decline in lung function in patients with COPD. The 6MWT may be a useful test to predict a rapid lung function decline in COPD.

Emphysema quantification by low-dose CT: potential impact of adaptive iterative dose reduction using 3D processing

OBJECTIVE

The purpose of this study is to investigate the effect of a novel reconstruction algorithm, adaptive iterative dose reduction using 3D processing, on emphysema quantification by low-dose CT.

MATERIALS AND METHODS

Twenty-six patients who had undergone standard-dose (150 mAs) and low-dose (25 mAs) CT scans were included in this retrospective study. Emphysema was quantified by several quantitative measures, including emphysema index given by the percentage of lung region with low attenuation (lower than -950 HU), the 15th percentile of lung density, and size distribution of low-attenuation lung regions, on standard-dose CT images reconstructed without adaptive iterative dose reduction using 3D processing and on low-dose CT images reconstructed both without and with adaptive iterative dose reduction using 3D processing. The Bland-Altman analysis was used to assess whether the agreement between emphysema quantifications on low-dose CT and on standard-dose CT was improved by the use of adaptive iterative dose reduction using 3D processing.

RESULTS

For the emphysema index, the mean differences between measurements on low-dose CT and on standard-dose CT were 1.98% without and -0.946% with the use of adaptive iterative dose reduction using 3D processing. For 15th percentile of lung density, the mean differences without and with adaptive iterative dose reduction using 3D processing were -6.67 and 1.28 HU, respectively. For the size distribution of low-attenuation lung regions, the ranges of the mean relative differences without and with adaptive iterative dose reduction using 3D processing were 21.4-85.5% and -14.1% to 11.2%, respectively. For 15th percentile of lung density and the size distribution of low-attenuation lung regions, the agreement was thus improved by the use of adaptive iterative dose reduction using 3D processing.

CONCLUSION

The use of adaptive iterative dose reduction using 3D processing resulted in greater consistency of emphysema quantification by low-dose CT, with quantification by standard-dose CT.

Role of computed tomography in quantitative assessment of emphysema

Pulmonary emphysema, together with chronic bronchitis is a part of chronic obstructive pulmonary disease (COPD), which is one of the leading causes of death in the United States and worldwide. There are many methods to diagnose emphysema. Unfortunately many of them, for example pulmonary function tests (PFTs), clinical signs and conventional radiology are able to detect emphysema usually in its late stages when a great portion of lung parenchyma has been already destroyed by the disease. Computed tomography (CT) allows for early detection of emphysema. CT also makes it possible to quantify the total amount of emphysema in the lungs which is important in order to precisely estimate the severity of the disease. Those abilities of CT are important in monitoring the course of the disease and in attempts to prevent its further progression. In this review we discuss currently available methods for imaging emphysema with emphasis on the quantitative assessment of emphysema. To date, quantitative methods have not been widely used clinically, however, the initial results of several research studies regarding this subject are very encouraging.

Allergic bronchopulmonary aspergillosis in a patient with chronic obstructive pulmonary disease

Allergic bronchopulmonary aspergillosis (ABPA) is a debilitating lung disease which occurs as a result of interplay between a variety of host and environmental factors. It occurs in certain susceptible individuals who develop hypersensensitivity to the colonised Aspergillus species. ABPA is a complicating factor in 2% of patients with asthma and is also seen in patients with cystic fibrosis. Asthma and chronic obstructive pulmonary disease (COPD) are known to share key elements of pathogenesis. It is well known that ABPA can occur in patients with asthma, but it has recently been reported in patients with COPD as well. We report a 55-year-old male ex-smoker who presented with complaints of exertional breathlessness and productive cough for five years and an episode of haemoptysis four days prior to presentation. Spirometery showed airflow obstruction which was not reversible with bronchodilators. Chest CT scan revealed paraseptal emphysema along with central bronchiectasis (CB) in the right upper lobe and bilateral lower lobes. A type I skin hypersensitivity reaction to Aspergillus species was elicited. He fulfilled the serological criteria for ABPA and was diagnosed as having concomitant COPD and ABPA-CB. The patient was initiated on therapy for COPD along with oral corticosteroids, on which he had remarkable symptomatic improvement.

Pulmonary magnetic resonance imaging for airway diseases

Pulmonary magnetic resonance (MR) imaging has been put forward as a new research and diagnostic tool mainly to overcome the limitations of computed tomography and nuclear medicine studies. However, pulmonary MR imaging has been difficult to use because of inherently low proton density, a multitude of air-tissue interfaces, which create significant magnetic field distortions and are commonly referred to as susceptibility artifacts; diminishing signal in the lung; and respiratory and/or cardiac motion artifacts. To overcome these drawbacks of pulmonary MR imaging, technical advances made during the last decade in sequencing, scanner and coil, adaptation of parallel imaging techniques, and utilization of contrast media have been reported as being useful for functional and morphologic assessment of various pulmonary diseases including airway diseases. This review article covers (1) pulmonary MR techniques for morphologic and functional assessment of airway diseases, and (2) pulmonary MR imaging for cystic fibrosis, asthma, and chronic obstructive pulmonary disease. Pulmonary MR imaging provides not only morphology-related but also pulmonary function-related information. It has the potential to replace nuclear medicine studies for the identification of regional pulmonary function and may perform a complementary role in airway disease assessment instead of nuclear medicine study. We believe that the findings of further basic studies as well as clinical applications of this new technique will validate the real significance of pulmonary MR imaging for the future of airway disease assessment and its usefulness for diagnostic radiology and pulmonary medicine.

Multivariate compensation of quantitative pulmonary emphysema metric variation from low-dose, whole-lung CT scans

OBJECTIVE

Emphysema is a disease of the lung characterized by the destruction of the alveolar sac walls. Several quantitative densitometric measures of emphysema from wholelung CT have been proposed for evaluating disease severity and progression. However, a concern with these quantitative measures has been the large interscan variability observed during longitudinal studies of emphysema. To account for and reduce inherent measure variability, this work implements and evaluates the use of a multivariate random-effects model for correcting longitudinal variation in densitometric scores of emphysema due to inspiration.

MATERIALS AND METHODS

The method of multivariate compensation was validated on three of the most commonly reported densitometric measures of emphysema: the emphysema index, histogram percentile, and fractal dimension. Two short-interval, zero-change datasets, one for model development (n = 105) and one for validation (n = 106), were retrospectively identified and used to ensure that all variation was caused by inherent measure variability.

RESULTS

A statistically significant (F test, p < 0.001) reduction of 42.40% in measurement limits of agreement could be obtained after model application, with compensated emphysema metric differences showing 31-33% of the variance compared with uncompensated metric variance.

CONCLUSION

Compensation was still effective when the trained model was applied to the second validation dataset. Multivariate compensation was found to be useful in reducing interscan measurement variability and should be applied to future longitudinal studies of emphysema.

Equating quantitative emphysema measurements on different CT image reconstructions

PURPOSE

To mathematically model the relationship between CT measurements of emphysema obtained from images reconstructed using different section thicknesses and kernels and to evaluate the accuracy of the models for converting measurements to those of a reference reconstruction.

METHODS

CT raw data from the lung cancer screening examinations of 138 heavy smokers were reconstructed at 15 different combinations of section thickness and kernel. An emphysema index was quantified as the percentage of the lung with attenuation below -950 HU (EI950). Linear, quadratic, and power functions were used to model the relationship between EI950 values obtained with a reference 1 mm, medium smooth kernel reconstruction and values from each of the other 14 reconstructions. Preferred models were selected using the corrected Akaike information criterion (AICc), coefficients of determination (R2), and residuals (conversion errors), and cross-validated by a jackknife approach using the leave-one-out method.

RESULTS

The preferred models were power functions, with model R2 values ranging from 0.949 to 0.998. The errors in converting EI950 measurements from other reconstructions to the 1 mm, medium smooth kernel reconstruction in leave-one-out testing were less than 3.0 index percentage points for all reconstructions, and less than 1.0 index percentage point for five reconstructions. Conversion errors were related in part to image noise, emphysema distribution, and attenuation histogram parameters. Conversion inaccuracy related to increased kernel sharpness tended to be reduced by increased section thickness.

CONCLUSIONS

Image reconstruction-related differences in quantitative emphysema measurements were successfully modeled using power functions.

High-resolution computed tomography quantitation of emphysema is correlated with selected lung function values in stable COPD

BACKGROUND

The literature shows conflicting results when high-resolution computed tomography (HRCT) scores of emphysema were correlated with different indices of airflow obstruction.

OBJECTIVES

We correlated HRCT scores of emphysema with different indices of airflow obstruction.

METHODS

We performed HRCT of the chest in 59 patients, all smokers or ex-smokers, with stable chronic obstructive pulmonary disease of different severity [GOLD stages I-IV; mean age ± SD 67.8 ± 7.3 years; pack/years 51.0 ± 34.6; percent predicted forced expiratory volume in 1 s (FEV(1)% predicted) 52.3 ± 17.6; post-bronchodilator FEV(1)% predicted 56.5 ± 19.1; FEV(1)/forced vital capacity (FVC) ratio 50.8 ± 10.2; post-bronchodilator FEV(1)/FVC ratio 51.6 ± 11.0; percent diffusion lung capacity for carbon monoxide (DLCO%) 59.2 ± 21.1; DLCO/percent alveolar volume (VA%) 54.5 ± 18.2; percent residual volume 163.0 ± 35.6; percent total lung capacity (TLC%) 113.2 ± 15; residual volume/TLC 1.44 ± 0.2]. All patients were in stable phase.

RESULTS

The mean ± SD visual emphysema score in all patients was 25.6 ± 25.4%. There was a weak but significant correlation between the percentage of pulmonary emphysema and numbers of pack/years (R = +0.31, p = 0.024). The percentage of emphysema was inversely correlated with the FEV(1)/FVC ratio before and after bronchodilator use (R = -0.44, p = 0.002, and R = -0.39, p = 0.005), DLCO% (R = -0.64, p = 0.0003) and DLCO/VA% (R = -0.68, p < 0.0001). A weak positive correlation was also found with TLC% (R = +0.28, p = 0.048). When patients with documented emphysema were considered separately, the best significant correlation observed was between DLCO/VA% and HRCT scan score (p = 0.007).

CONCLUSIONS

These data suggest that in patients with stable chronic obstructive pulmonary disease of varying severity, the presence of pulmonary emphysema is best represented by the impaired gas exchange capability of the respiratory system.

Quantitative and o(2) enhanced MRI of the pathologic lung: findings in emphysema, fibrosis, and cystic fibrosis

Purpose: beyond the pure morphological visual representation, MR imaging offers the possibility to quantify parameters in the healthy, as well as, in pathologic lung parenchyma. Gas exchange is the primary function of the lung and the transport of oxygen plays a key role in pulmonary physiology and pathophysiology. The purpose of this review is to present a short overview of the relaxation mechanisms of the lung and the current technical concepts of T1 mapping and methods of oxygen enhanced MR imaging. Material and Methods: molecular oxygen has weak paramagnetic properties so that an increase in oxygen concentration results in shortening of the T1 relaxation time and thus to an increase of the signal intensity in T1 weighted images. A possible way to gain deeper insights into the relaxation mechanisms of the lung is the calculation of parameter Maps. T1 Maps based on a snapshot FLASH sequence obtained during the inhalation of various oxygen concentrations provide data for the creation of the so-called oxygen transfer function (OTF), assigning a measurement for local oxygen transfer. T1 weighted single shot TSE sequences also permit expression of the signal changing effects associated with the inhalation of pure oxygen. Results: the average of the mean T1 values over the entire lung in inspiration amounts to 1199 +/− 117 milliseconds, the average of the mean T1 values in expiration was 1333 +/− 167 milliseconds. T1 Maps of patients with emphysema and lung fibrosis show fundamentally different behavior patterns. Oxygen enhanced MRT is able to demonstrate reduced diffusion capacity and diminished oxygen transport in patients with emphysema and cystic fibrosis. Discussion: results published in literature indicate that T1 mapping and oxygen enhanced MR imaging are promising new methods in functional imaging of the lung and when evaluated in conjunction with the pure morphological images can provide additional valuable information.

CD46 protects against chronic obstructive pulmonary disease

Background

Chronic obstructive pulmonary disease and emphysema develops in 15% of ex-smokers despite sustained quitting, while 10% are free of emphysema or severe lung obstruction. The cause of the incapacity of the immune system to clear the inflammation in the first group remains unclear.

Methods and Findings

We searched genes that were protecting ex-smokers without emphysema, using microarrays on portions of human lungs surgically removed; we found that loss of lung function in patients with chronic obstructive pulmonary disease and emphysema was associated with a lower expression of CD46 and verified this finding by qRT-PCR and flow cytometry. Also, there was a significant association among decreased CD46⁺ cells with decreased CD4⁺T cells, apoptosis mediator CD95 and increased CD8⁺T cells that were protecting patients without emphysema or severe chronic obstructive pulmonary disease. CD46 not only regulates the production of T regulatory cells, which suppresses CD8⁺T cell proliferation, but also the complement cascade by degradation of C3b. These results were replicated in the murine smoking model, which showed increased C5a (produced by C3b) that suppressed IL12 mediated bias to T helper 1 cells and elastin co-precipitation with C3b, suggesting that elastin could be presented as an antigen. Thus, using ELISA from elastin peptides, we verified that 43% of the patients with severe early onset of chronic obstructive pulmonary disease tested positive for IgG to elastin in their serum compared to healthy controls.

Conclusions

These data suggest that higher expression of CD46 in the lungs of ex-smoker protects them from emphysema and chronic obstructive pulmonary disease by clearing the inflammation impeding the proliferation of CD8⁺ T cells and necrosis, achieved by production of T regulatory cells and degradation of C3b; restraining the complement cascade favors apoptosis over necrosis, protecting them from autoimmunity and chronic inflammation.

Fractal dimension analysis of MDCT images for quantifying the morphological changes of the pulmonary artery tree in patients with pulmonary hypertension

Objective

The aim of this study was to use fractal dimension (FD) analysis on multidetector CT (MDCT) images for quantifying the morphological changes of the pulmonary artery tree in patients with pulmonary hypertension (PH).

Materials and Methods

Fourteen patients with PH and 17 patients without PH as controls were studied. All of the patients underwent contrast-enhanced helical CT and transthoracic echocardiography. The pulmonary artery trees were generated using post-processing software, and the FD and projected image area of the pulmonary artery trees were determined with ImageJ software in a personal computer. The FD, the projected image area and the pulmonary artery pressure (PAP) were statistically evaluated in the two groups.

Results

The FD, the projected image area and the PAP of the patients with PH were higher than those values of the patients without PH (p < 0.05, t-test). There was a high correlation of FD with the PAP (r = 0.82, p < 0.05, partial correlation analysis). There was a moderate correlation of FD with the projected image area (r = 0.49, p < 0.05, partial correlation analysis). There was a correlation of the PAP with the projected image area (r = 0.65, p < 0.05, Pearson correlation analysis).

Conclusion

The FD of the pulmonary arteries in the PH patients was significantly higher than that of the controls. There is a high correlation of FD with the PAP.