A CT Algorithm Can Elevate the Differential Diagnosis of Interstitial Lung Disease by Non-specialists to Equal That of Specialist Thoracic Radiologists

BACKGROUND

Diagnosis of diffuse parenchymal lung diseases (DPLD) on high resolution CT (HRCT) is difficult for non-expert radiologists due to varied presentation for any single disease and overlap in presentation between diseases.

RATIONALE AND OBJECTIVES

To evaluate whether a pattern-based training algorithm can improve the ability of non-experts to diagnosis of DPLD.

MATERIALS AND METHODS

Five experts (cardiothoracic-trained radiologists), and 25 non-experts (non-cardiothoracic-trained radiologists, radiology residents, and pulmonologists) were each assigned a semi-random subset of cases from a compiled database of DPLD HRCTs. Each reader was asked to create a top three differential for each case. The non-experts were then given a pattern-based training algorithm for identifying DPLDs. Following training, the non-experts were again asked to create a top three differential for each case that they had previously evaluated. Accuracy between groups was compared using Chi-Square analysis.

RESULTS

A total of 400 and 1450 studies were read by experts and non-experts, respectively. Experts correctly placed the diagnosis as the first item on the differential versus having the correct diagnosis as one of their top three diagnoses at an overall rate of 48 and 64.3%, respectively. Pre-training, non-experts achieved a correct diagnosis/top three of 32.5 and 49.7%, respectively. Post-training, non-experts demonstrated a correct diagnosis/top three of 41.2 and 65%, a statistically significant increase (p < 0.0001). In addition, post training, there was no difference between non-experts and experts in placing the correct diagnosis within their top three differential.

CONCLUSION

The diagnosis of DPLDs by HRCT imaging alone is relatively poor. However, use of a pattern-based teaching algorithm can improve non-expert interpretation and enable non-experts to include the correct diagnosis within their differential diagnoses at a rate comparable to expert cardiothoracic trained radiologists.

Neurotrophic factors and their receptors in lung development and implications in lung diseases

Although lung innervation has been described by many studies in humans and rodents, the regulation of the respiratory system induced by neurotrophins is not fully understood. Here, we review current knowledge on the role of neurotrophins and the expression and function of their receptors in neurogenesis, vasculogenesis and during the embryonic development of the respiratory tree and highlight key implications relevant to respiratory diseases.

A preliminary study of lung abnormalities on HRCT in patients of rheumatoid arthritis-associated interstitial lung disease with progressive fibrosis

OBJECTIVE

This retrospective study evaluates lung abnormalities on high-resolution CT (HRCT) and clarifies which abnormality can predict the progressive fibrosis of rheumatoid arthritis (RA)-associated interstitial lung disease (ILD).

OBJECTS AND METHODS

We identified 1096 RA patients, and enrolled 213 patients with a diagnosis of RA-ILD who underwent serial chest HRCT. Clinical data of the patients were obtained. The presence, extent, and distribution of lung abnormalities were assessed on CT scans. Logistic regression analysis was used to determine positive indicators with predictive value for progressive fibrosis, and 2 × 2 contingency tables were constructed to assess their diagnostic efficiency.

RESULT

Of 213 RA-ILD patients, 106 (49.8%) were diagnosed as progressive fibrosis. The rates of advanced age, male, smoking history, shortness of breath, and anti-CCP antibody high titer positive were higher, and RA duration was shorter in progressive fibrosis patients. Reticular pattern (RP), peribronchovascular interstitium (PBVI) thickening, interlobular septal thickening, and traction bronchiolectasis were more common in the progressive fibrosis group (84.9% vs 42.1%, P < 0.001; 79.3% vs 45.8%, P < 0.001; 74.5% vs 43.9%, P < 0.001; 67.0% vs 40.2%, P < 0.001; respectively). Lung abnormalities demonstrated subpleural predominance, and the subpleural RP and/or interlobular septal thickening had a wide distribution in the progressive fibrosis group (71.7% vs 14.0%, P < 0.001). The overall extent of lung abnormalities was more extensive in the progressive fibrosis group (18.4% vs 14.2%, P < 0.05). Logistic regression analysis showed that a wide distribution of subpleural RP and/or interlobular septal thickening (OR, 18.15) and PBVI thickening (OR, 4.98) were independent risk factors predictive of progressive fibrosis. For the combination of these two CT abnormalities, sensitivity was 63.2%, specificity was 92.5%, positive likelihood ratio was 8.5, and negative likelihood ratio was 0.4 in predicting progressive fibrosis.

CONCLUSIONS

A wide distribution of subpleural RP and/or interlobular septal thickening and PBVI thickening on HRCT appear predictive of progressive fibrosis in RA-ILD. The combined evaluation of these two CT abnormalities has a good judgment value. Key Points • We designed this study to investigate the risk factors for progressive fibrosis in patients with RA-ILD. Factors including clinical, physiological, radiological and therapeutic variables were all included in the data analysis. • Our results showed HRCT abnormalities, rather than other parameters, appeared predictive of progressive fibrosis in RA-ILD. • The methods and results of image evaluation in this article would provide reference to rheumatologists in identifying early stage of progressive fibrosis which helps to improve poor prognosis of RA-ILD.

Ultrasound signs of pulmonary fibrosis in systemic sclerosis as timely indicators for chest computed tomography

OBJECTIVES

Systemic sclerosis (SSc) patients in the early stages of pulmonary fibrosis (PF) often have few or no symptoms, normal to borderline pulmonary function tests, and negative chest X-ray (CXR); high-resolution computed tomography (HRCT) is the only reliable means of detecting the early signs of PF. However, thoracic ultrasound (TUS) enables detection of pleural thickening, pleural/subpleural nodules, and other subpleural lung abnormalities across 70% of the subpleural surface. We reassessed concordance between TUS abnormalities and HRCT findings in SSc patients, to see whether TUS pleural line thickness (normally <3.0 mm) could be used to earmark those with asymptomatic PF for timely HRCT assessment.

METHOD

In total, 175 SSc patients (nine males, 166 females), aged 46.46±15.33 years, were given CXR, TUS, HRCT, echocardiography, and pulmonary function tests.

RESULTS

In the 26 patients without HRCT signs of PF, pleural line thickness was ≤3.0 mm. In diffuse SSc, 97/137 patients showed pleural line thickening (between 3.0 and 5 mm) and subpleural nodules in 32/97; and 35/137 showed major pleural line thickening (≥5.0 mm) with nodules, with good concordance with HRCT patterns indicating lung fibrosis severity. HRCT was normal in 5/137, with pleural line thickness≤3.0 mm.

CONCLUSIONS

TUS imaging of pleural/subpleural structures can detect ultrasonographic signs of initial PF prior to the onset of respiratory symptoms and function test abnormalities and, together with current criteria, could thereby enable exclusion of PF in SSc patients. Indicating some patients for selective referral to HRCT can thereby delay unwarranted procedures, provided that pulmonary function and TUS images are stable.

State of the art in the diagnosis and management of interstitial lung disease

The interstitial lung diseases (ILDs) are a diverse group of disorders characterized by a varying combination of inflammation and fibrosis of the pulmonary parenchyma. Treatment and prognosis of ILD typically depend on the underlying ILD subtype, highlighting the importance of accurate classification and diagnosis. Besides a thorough history and clinical examination, the protocol should include a 6-minute walk test, chest radiography, high-resolution computed tomography, biochemical analysis, pulmonary function tests, blood gas analysis, bronchoalveolar lavage, and, when necessary, a lung biopsy. The final diagnosis of ILD entities requires dynamic interaction between clinicians, radiologists and pathologists to reach a clinico-radiologic-pathologic diagnosis, the gold standard no longer being the histology but rather a multidisciplinary approach.

Computed tomography: revolutionizing the practice of medicine for 40 years

Computed tomography (CT) has had a profound effect on the practice of medicine. Both the spectrum of clinical applications and the role that CT has played in enhancing the depth of our understanding of disease have been profound. Although almost 90 000 articles on CT have been published in peer-reviewed journals over the past 40 years, fewer than 5% of these have been published in Radiology. Nevertheless, these almost 4000 articles have provided a basis for many important medical advances. By enabling a deepened understanding of anatomy, physiology, and pathology, CT has facilitated key advances in the detection and management of disease. This article celebrates this breadth of scientific discovery and development by examining the impact that CT has had on the diagnosis, characterization, and management of a sampling of major health challenges, including stroke, vascular diseases, cancer, trauma, acute abdominal pain, and diffuse lung diseases, as related to key technical advances in CT and manifested in Radiology.

Pulmonary Langerhans cell histiocytosis: the many faces of presentation at initial CT scan

Objectives

Pulmonary Langerhans cell histiocytosis (PLCH) is a rare interstitial granulomatous disease that usually affects young adults who are smokers. Chest computed tomography (CT) allows a confident diagnosis of PLCH only in typical presentation, when nodules, cavitated nodules and cysts coexist and predominate in the upper and middle lungs.

Methods

This article includes a pictorial essay of typical and atypical presentations of PLCH at initial chest CT. Various appearances of PLCH are illustrated and possible differential diagnosis is discussed.

Results

PLCH can present with some aspecific features that may cause diagnosis of the initial disease to be overlooked or other pulmonary diseases to be suspected. In cases of nodule presentation alone, the main differential diagnosis should include lung metastasis, tuberculosis and other infections, sarcoidosis, silicosis and Wegener’s disease. In cases of cysts alone, the most common diseases to be differentiated are centrilobular emphysema and lymphangiomyomatosis. Clinical symptoms are usually non-specific, although a history of cigarette smoking, coupled with the presence of typical or suggestive findings at imaging, is key to suspecting the disease. Atypical presentations require surgical biopsy for diagnosis.

Conclusions

The radiologist should be familiar with PLCH imaging features to correctly diagnose the disease or need for further investigation.

Teaching Points

• PLCH is a rare interstitial smoking-related disease that usually affects young adults.

• The typical first CT shows a mix of nodules, cavitary nodules and cysts in the upper-middle lungs.

• Atypical appearance, either cysts or nodules alone, mandates that other diagnoses be considered.

• Lung cystic involvement correlates with lung function abnormalities and predicts functional decline.

• Integration of the clinical history and imaging results is key to diagnosis.

Quantitative stratification of diffuse parenchymal lung diseases

Diffuse parenchymal lung diseases (DPLDs) are characterized by widespread pathological changes within the pulmonary tissue that impair the elasticity and gas exchange properties of the lungs. Clinical-radiological diagnosis of these diseases remains challenging and their clinical course is characterized by variable disease progression. These challenges have hindered the introduction of robust objective biomarkers for patient-specific prediction based on specific phenotypes in clinical practice for patients with DPLD. Therefore, strategies facilitating individualized clinical management, staging and identification of specific phenotypes linked to clinical disease outcomes or therapeutic responses are urgently needed. A classification schema consistently reflecting the radiological, clinical (lung function and clinical outcomes) and pathological features of a disease represents a critical need in modern pulmonary medicine. Herein, we report a quantitative stratification paradigm to identify subsets of DPLD patients with characteristic radiologic patterns in an unsupervised manner and demonstrate significant correlation of these self-organized disease groups with clinically accepted surrogate endpoints. The proposed consistent and reproducible technique could potentially transform diagnostic staging, clinical management and prognostication of DPLD patients as well as facilitate patient selection for clinical trials beyond the ability of current radiological tools. In addition, the sequential quantitative stratification of the type and extent of parenchymal process may allow standardized and objective monitoring of disease, early assessment of treatment response and mortality prediction for DPLD patients.