High-Resolution Computed Tomography Features of Smoking-Related Interstitial Lung Disease

Brazilian Thoracic Society recommendations for the diagnosis and monitoring of asbestos-exposed individuals

Asbestos was largely used in Brazil. It is a mineral that induces pleural and pulmonary fibrosis, and it is a potent carcinogen. Our objective was to develop recommendations for the performance of adequate imaging tests for screening asbestos-related diseases. We searched peer-reviewed publications, national and international technical documents, and specialists' opinions on the theme. Based on that, the major recommendations are: Individuals exposed to asbestos at the workplace for ≥ 1 year or those with a history of environmental exposure for at least 5 years, all of those with a latency period > 20 years from the date of initial exposure, should initially undego HRCT of the chest for investigation. Individuals with pleural disease and/or asbestosis should be considered for regular lung cancer monitoring. Risk calculators should be adopted for lung cancer screening, with a risk estimate of 1.5%.

Smoking-related interstitial lung disease

Exposure to smoke is associated with the development of diseases of the airways and lung parenchyma. Apart from chronic obstructive pulmonary disease (COPD), in some individuals, tobacco smoke can also trigger mechanisms of interstitial damage that result in various pathological changes and pulmonary fibrosis. A causal relation has been established between tobacco smoke and a group of entities that includes respiratory bronchiolitis-associated interstitial lung disease (RB-ILD), desquamative interstitial pneumonia (DIP), Langerhans cell histiocytosis (LCH), and acute eosinophilic pneumonia (AEP). Smoking is considered a risk factor for idiopathic pulmonary fibrosis (IPF); however, the role and impact of smoking in the development of this differentiated clinical entity, which has also been called combined pulmonary fibrosis and emphysema (CPFE) as well as nonspecific interstitial pneumonia (NIP), remains to be determined. The definition of smoking-related interstitial fibrosis (SRIF) is relatively recent, with differentiated histological characteristics. The likely interconnection between the mechanisms involved in inflammation and pulmonary fibrosis in all these processes often results in an overlapping of clinical, radiological, and histological features in the same patient that can sometimes lead to radiological patterns of interstitial lung disease that are impossible to classify. For this reason, a combined approach to diagnosis is recommendable. This combined approach should be based on the joint interpretation of the histological and radiological findings while taking the clinical context into consideration. This paper aims to describe the high-resolution computed tomography (HRCT) findings in this group of disease entities in correlation with the clinical manifestations and histological changes underlying the radiological pattern.

High-Resolution Computed Tomography of Cystic Lung Disease

The cystic lung diseases (CLD) are characterized by the presence of multiple, thin-walled, air-filled spaces in the pulmonary parenchyma. Cyst formation may occur with congenital, autoimmune, inflammatory, infectious, or neoplastic processes. Recognition of cyst mimics such as emphysema and bronchiectasis is important to prevent diagnostic confusion and unnecessary evaluation. Chest CT can be diagnostic or may guide the workup based on cyst number, distribution, morphology, and associated lung, and extrapulmonary findings. Diffuse CLD (DCLDs) are often considered those presenting with 10 or more cysts. The more commonly encountered DCLDs include lymphangioleiomyomatosis, pulmonary Langerhans' cell histiocytosis, lymphoid interstitial pneumonia, Birt-Hogg-Dubé syndrome, and amyloidosis/light chain deposition disease.

The Octopus Sign—A New HRCT Sign in Pulmonary Langerhans Cell Histiocytosis

Background: Fibrosis in pulmonary Langerhans cell histiocytosis (PLCH) histologically comprises a central scar with septal strands and associated airspace enlargement that produce an octopus-like appearance. The purpose of this study was to identify the octopus sign on high-resolution computed tomography (HRCT) images to determine its frequency and distribution across stages of the disease. Methods: Fifty-seven patients with confirmed PLCH were included. Two experienced chest radiologists assessed disease stages as early, intermediate, or late, as well as the lung parenchyma for nodular, cystic, or fibrotic changes and for the presence of the octopus sign. Statistical analysis included Cohen’s kappa for interrater agreement and Fisher’s exact test for the frequency of the octopus sign. Results: Interobserver agreement was substantial for the octopus sign (kappa = 0.747). Significant differences in distribution of the octopus sign between stages 2 and 3 were found with more frequent octopus signs in stage 2 and fewer in stage 3. In addition, we only found the octopus sign in cases of nodular und cystic lung disease. Conclusions: The octopus sign in PLCH can be identified not only on histological images, but also on HRCT images. Its radiological presence seems to depend on the stage of PLCH.

Severe pulmonary hypertension associated with lung disease is characterised by a loss of small pulmonary vessels on quantitative computed tomography

Background

Pulmonary hypertension (PH) in patients with chronic lung disease (CLD) predicts reduced functional status, clinical worsening and increased mortality, with patients with severe PH-CLD (≥35 mmHg) having a significantly worse prognosis than mild to moderate PH-CLD (21-34 mmHg). The aim of this cross-sectional study was to assess the association between computed tomography (CT)-derived quantitative pulmonary vessel volume, PH severity and disease aetiology in CLD.

Methods

Treatment-naïve patients with CLD who underwent CT pulmonary angiography, lung function testing and right heart catheterisation were identified from the ASPIRE registry between October 2012 and July 2018. Quantitative assessments of total pulmonary vessel and small pulmonary vessel volume were performed.

Results

90 patients had PH-CLD including 44 associated with COPD/emphysema and 46 with interstitial lung disease (ILD). Patients with severe PH-CLD (n=40) had lower small pulmonary vessel volume compared to patients with mild to moderate PH-CLD (n=50). Patients with PH-ILD had significantly reduced small pulmonary blood vessel volume, compared to PH-COPD/emphysema. Higher mortality was identified in patients with lower small pulmonary vessel volume.

Conclusion

Patients with severe PH-CLD, regardless of aetiology, have lower small pulmonary vessel volume compared to patients with mild-moderate PH-CLD, and this is associated with a higher mortality. Whether pulmonary vessel changes quantified by CT are a marker of remodelling of the distal pulmonary vasculature requires further study.

Role of imaging in the diagnosis of diffuse and interstitial lung diseases

PURPOSE OF REVIEW

This review aims to provide a literature update focused on the role of imaging in the diagnosis, prognosis and quantification of interstitial lung diseases (ILDs). Special emphasis is given in the management of atypical cases and in the multidisciplinary team approach in reaching the diagnosis of the various ILDs.

RECENT FINDINGS

Accumulated knowledge on imaging has increased the accuracy of differential diagnosis in atypical cases, in overlap of findings and in secondary as opposed to idiopathic ILDs. There is increasing awareness about interstitial lung abnormalities in smokers' lungs from lung cancer screening and indirect evidence of linkage of fibrosis and smoking. Improvement in radiologic-pathologic correlation reveals less typical high-resolution computed tomography patterns to be predictive of pulmonary fibrosis. Major diagnostic criteria such as honeycombing may be hampered by the coexistence of emphysema. High-resolution computed tomography may predict clinical outcome and survival of patients in ILDs and is a decision maker in the multidisciplinary approach of diagnosis.

SUMMARY

High-resolution computed tomography plays a crucial role in the diagnosis, prognosis, quantification and monitoring of ILDs. It provides a definite noninvasive diagnosis in typical findings and helps in reaching the most accurate diagnosis in a multidisciplinary discussion in equivocal cases.

Smoking-related idiopathic interstitial pneumonia: A review

For many years, cigarette smoking has been considered as the leading cause of chronic obstructive pulmonary disease and lung cancer. Recently, however, it has also been associated with the development of diffuse interstitial lung diseases. In the latest classification of the major idiopathic interstitial pneumonias (IIP), the term smoking-related IIP has been introduced, including two entities, namely desquamative interstitial pneumonia (DIP) and respiratory bronchiolitis-interstitial lung disease (RB-ILD). Other entities in which smoking has a definite or suggested role include pulmonary Langerhan's cell histiocytosis, smoking-related interstitial fibrosis, combined pulmonary fibrosis and emphysema syndrome and idiopathic pulmonary fibrosis. In this review, we will focus on the mechanisms of smoking-related lung damage and on the clinical aspects of these disorders with the exception of idiopathic pulmonary fibrosis, which will be reviewed elsewhere in this review series.

Combined pulmonary fibrosis and emphysema (CPFE): an entity different from emphysema or pulmonary fibrosis alone

Chronic obstructive pulmonary disease (COPD) and idiopathic interstitial pneumonias (IIP), with different radiological, pathological, functional and prognostic characteristics, have been regarded as separate entities for a long time. However, there is an increasing recognition of the coexistence of emphysema and pulmonary fibrosis in individuals. The association was first described as a syndrome by Cottin in 2005, named "combined pulmonary fibrosis and emphysema (CPFE)", which is characterized by exertional dyspnea, upper-lobe emphysema and lower-lobe fibrosis, preserved lung volume and severely diminished capacity of gas exchange. CPFE is frequently complicated by pulmonary hypertension, acute lung injury and lung cancer and prognosis of it is poor. Treatments for CPFE patients with severe pulmonary hypertension are less effective other than lung transplantation. However, CPFE has not yet attracted wide attention of clinicians and there is no research systematically contrasting the differences among CPFE, emphysema/COPD and IIP at the same time. The authors will review the existing knowledge of CPFE and compare them to either entity alone for the first time, with the purpose of improving the awareness of this syndrome and exploring novel effective therapeutic strategies in clinical practice.

Eponyms in cardiothoracic radiology: part III--interstitium

Eponyms serve the purpose of honoring individuals who have made important observations and discoveries. As with other fields of medicine, eponyms are frequently encountered in radiology, particularly in chest radiology. However, inappropriate use of an eponym may lead to potentially dangerous miscommunication. Moreover, an eponym may honor the incorrect person or a person who falls into disrepute. Despite their limitations, eponyms are still widespread in the medical literature. Furthermore, in some circumstances, more than one individual may have contributed to the description or discovery of a particular anatomical structure or disease, whereas in others, an eponym may have been incorrectly applied initially and propagated for years in the medical literature. Nevertheless, radiologic eponyms are a means of honoring those who have made lasting contributions to the field of radiology, and familiarity with these eponyms is critical for proper reporting and accurate communication. In addition, the acquisition of some historical knowledge about those whose names are associated with various structures or pathologic conditions conveys a sense of humanity in the science of medicine. In this third installment of this series, the authors discuss a number of chest radiology eponyms as they relate to the pulmonary interstitium, including relevant clinical and imaging features, as well biographical information of the respective eponym's namesake.