[The contribution of artificial intelligence (AI) subsequent to the processing of thoracic imaging]

The contribution of artificial intelligence (AI) to medical imaging is currently the object of widespread experimentation. The development of deep learning (DL) methods, particularly convolution neural networks (CNNs), has led to performance gains often superior to those achieved by conventional methods such as machine learning. Radiomics is an approach aimed at extracting quantitative data not accessible to the human eye from images expressing a disease. The data subsequently feed machine learning models and produce diagnostic or prognostic probabilities. As for the multiple applications of AI methods in thoracic imaging, they are undergoing evaluation. Chest radiography is a practically ideal field for the development of DL algorithms able to automatically interpret X-rays. Current algorithms can detect up to 14 different abnormalities present either in isolation or in combination. Chest CT is another area offering numerous AI applications. Various algorithms have been specifically formed and validated for the detection and characterization of pulmonary nodules and pulmonary embolism, as well as segmentation and quantitative analysis of the extent of diffuse lung diseases (emphysema, infectious pneumonias, interstitial lung disease). In addition, the analysis of medical images can be associated with clinical, biological, and functional data (multi-omics analysis), the objective being to construct predictive approaches regarding disease prognosis and response to treatment.

Clinical Presentation and Treatment of Juvenile Idiopathic Arthritis Combined with Lung Disease: A Narrative Review

Juvenile idiopathic Arthritis (JIA) is a common rheumatic disorder in children that can cause multiple systems to be affected simultaneously, leading to severe clinical symptoms and a high mortality rate in those with pulmonary involvement. Pleurisy is the most common manifestation of pulmonary involvement. At the same time, other conditions, such as pneumonia, interstitial lung disease, occlusive bronchiectasis, and alveolar protein deposition, have been increasingly reported in recent years. This review aims to provide an overview of the clinical manifestations of JIA lung damage and the current treatment options to assist in identifying and treating JIA lung involvement.

A unique presentation of Pulmonary Langerhans Cell Histiocytosis

Pulmonary Langerhans Cell Histiocytosis (PLCH) is a diffuse lung disease that primarily affects young adults, with cigarette smoking playing a significant role in developing the disease. Patients with PLCH present with characteristic CT chest findings of small irregular nodules and upper zone cysts. Previously, larger nodules greater than 10 mm and cavitation have only been reported a few times in the literature. We describe the case of a 69-year-old male who presented with dyspnea, non-productive cough and weight loss, who was found to have multiple cavitary nodules on CT imaging of the chest. Histopathologic sampling of the lung revealed Langerhans cells which stained positive for S100 and CD1a, consistent with a diagnosis of PLCH. The patient was counselled to quit smoking as the mainstay of treatment. In 3-month follow-up his symptoms had largely resolved, with evidence of decreased nodule size on repeat CT imaging.

Evolution of COVID-19 Pulmonary Fibrosis-Like Residual Changes Over Time - Longitudinal Chest CT up to 9 Months After Disease Onset: a Single-Center Case Series

The aim of the study was to evaluate the temporal evolution of fibrotic-like pulmonary interstitial abnormalities secondary to Sars-CoV-2 virus (COVID-19) pneumonia detected on chest-CTs of patients hospitalized for COVID-19 infection. We retrospectively reviewed chest-CTs obtained up to 9 months after disease onset in a group of patients with COVID-19 pneumonia and CT features suggestive of lung fibrosis at the first follow-up after hospital discharge. We observed a complete and unexpected resolution of all interstitial abnormalities, including reticulations and bronchial dilatation, in a period of about 6-9 months after discharge. Interstitial fibrotic-like changes detectable in the first months after COVID-19 pneumonia could be slowly or very slowly resolving but still completely reversible and probably secondary to an organizing pneumonia reaction.

ACR Appropriateness Criteria® Diffuse Lung Disease

Diffuse lung disease, frequently referred to as interstitial lung disease, encompasses numerous disorders affecting the lung parenchyma. The potential etiologies of diffuse lung disease are broad with several hundred established clinical syndromes and pathologies currently identified. Imaging plays a critical role in diagnosis and follow-up of many of these diseases, although multidisciplinary discussion is the current standard for diagnosis of several DLDs. This document aims to establish guidelines for evaluation of diffuse lung diseases for 1) initial imaging of suspected diffuse lung disease, 2) initial imaging of suspected acute exacerbation or acute deterioration in cases of confirmed diffuse lung disease, and 3) clinically indicated routine follow-up of confirmed diffuse lung disease without acute deterioration. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Transbronchial lung cryobiopsy (TBLC) in the diagnosis of interstitial lung disease: experience of first 100 cases performed under conscious sedation with flexible bronchoscope

BACKGROUND

Diagnosing the aetiology of interstitial lung disease (ILD) may require histology via a surgical lung biopsy (SLB). SLB is associated with significant complications. Transbronchial lung cryobiopsy (TBLC) can provide large, adequate biopsies with fewer complications offering a potential alternative to SLB.

AIMS

This study evaluated the safety, diagnostic yield and impact of TBLC on diagnostic certainty in the multidisciplinary diagnosis (MDD) of ILD within routine clinical practice.

METHODS

A retrospective study of all TBLC performed in a tertiary institute from March 2014 to December 2016 was performed. Procedures were performed using a flexible bronchoscope and cryoprobe without fluoroscopic guidance.

RESULTS

One hundred procedures were performed on 85 patients. A total of 272 cryobiopsies were obtained with a mean biopsy diameter of 5.9 ± 3.2 mm. Ninety-seven percent contained alveolated lung tissue. Diagnosis based against MDD gold standard was confirmed using TBLC in 67.1% of patients and in 72/100 procedures. Three patients proceeded to SLB. The addition of histological information changed the clinic-radiological diagnosis in twelve patients. The most common diagnosis based on clinical-radiologic-pathologic correlation at MDD was idiopathic pulmonary fibrosis (IPF) (51.2%) and hypersensitivity pneumonitis (15.9%). Moderate bleeding occurred in 18% of cases and five patients (5%) developed pneumothorax requiring intervention. Eleven patients required admission, with a mean length of stay of 1.3 ± 0.9 days.

CONCLUSION

TBLC aids the diagnosis of ILD in the appropriate patient and may be an acceptable alternative to SLB with fewer complications. Further work on standardizing the procedure is required.

Transbronchial Cryobiopsy in the Diagnosis of Diffuse Lung Disease

Transbronchial cryobiopsy, a new diagnostic procedure in patients with diffuse lung disease, provides larger and better-preserved lung specimens compared to forceps biopsy. The diagnostic yield of cryobiopsy is much better than that of forceps biopsy and slightly lower than that of surgical lung biopsy, but with a lower complication rate compared to the latter. Literature suggests that in the multidisciplinary approach to patients with diffuse lung disease cryobiopsy provides diagnostic and prognostic information similar to surgical lung biopsy. Cryobiopsy can also be performed in some patients unsuitable for surgical biopsy, yet in whom histologic input is needed.

Risk factors for disease-related deterioration following diagnostic bronchoalveolar lavage procedures in diffuse lung disease: a case-control study

Background

Although the risk factors for diagnostic bronchoalveolar lavage (BAL)-induced acute exacerbations in patients with idiopathic pulmonary fibrosis (IPF) have been previously reported, no study has assessed these in patients with non-IPF. We aimed to identify the risk factors for BAL-induced disease deterioration (BAL-DD) in all types of diffuse lung disease.

Methods

Patients with diffuse lung disease who underwent BAL at our hospital from April 2012 to November 2017 were retrospectively analyzed. The patient information, laboratory data, radiological findings, and BAL fluid analysis results in patients who developed BAL-DDs were compared with those in patients who did not.

Results

BAL-DDs occurred in 14 (3.3%) of the 429 patients included the study. The BAL-DD group had a significantly poorer performance status, higher C-reactive protein level, lower partial pressure of oxygen in the arterial blood at rest, greater proportion of desaturation on exertion and cases having followed a progressive clinical course before BAL, and more extensive consolidation and ground-glass opacity on chest high-resolution computed tomography (HRCT) than the non-BAL-DD group. A high total cell concentration and an increased number of eosinophils in the BAL fluid were more frequently found in patients with BAL-DD than in those without.

Conclusions

Patients with decreased physical activity level, increased level of inflammatory markers, low oxygenation status, and extensive lung involvements on chest HRCT and following a progressive clinical course before BAL may be warned of the BAL-DD risk. Elevated eosinophil counts in the BAL fluid could be associated with the triggering of BAL-DDs.

Interstitial Lung Diseases in Children, Adolescents, and Young Adults: Different from Infants and Older Adults

Childhood interstitial lung disease (chILD) in children, teenagers, and young adults presents a challenge to the clinicians and radiologist, given its rarity, diverse imaging manifestations, and often nonspecific clinical examination findings. This article discusses the utility of available imaging techniques and associated characteristic imaging findings, and reviews the 2015 chILD classification scheme, with clinical examples highlighting the imaging features to help the radiologist aid in an efficient and accurate multidisciplinary diagnosis of chILD.

Deep Learning for Pulmonary Image Analysis: Classification, Detection, and Segmentation

Image-based computer-aided diagnosis (CAD) algorithms by the use of convolutional neural network (CNN) which do not require the image-feature extractor are powerful compared with conventional feature-based CAD algorithms which require the image-feature extractor for classification of lung abnormalities. Moreover, computer-aided detection and segmentation algorithms by the use of CNN are useful for analysis of lung abnormalities. Deep learning will improve the performance of CAD systems dramatically. Therefore, they will change the roles of radiologists in the near future. In this article, we introduce development and evaluation of such image-based CAD algorithms for various kinds of lung abnormalities such as lung nodules and diffuse lung diseases.

Etiologic spectrum of interstitial lung diseases in Chinese children older than 2 years of age

Background

Childhood interstitial lung diseases (ILD) (chILD) refer to a rare heterogeneous group of disorders. Global collaborations have been working on the etiologies and classification scheme of chILD. With the development of medical technologies, some new diseases were identified to be associated with chILD and its etiologic spectrum is expanding. The aim of this study is to describe the etiologic spectrum of chILD in children older than 2 years of age and summarize the approaches to diagnosis of chILD.

Methods

We made a retrospective analysis of children older than 2 years of age with chILD who referred to Beijing Children’s Hospital from 21 provinces all over China from 2013 to 2018. After excluding pulmonary infection, congenital heart disease, bronchopulmonary dysplasia, bronchiolitis obliterans and bronchiectasis, 133 patients were included and categorized by etiology. Clinical manifestations, high-resolution computed tomography, laboratory data, genetic data and pathologic findings were all collected and reviewed.

Results

Systemic disease associated ILD were the most common causes, accounting for 49.6% of the patients, followed by alveolar structure disorder-associated ILD (27%), exposure related ILD (13.5%), and disorders masquerading as ILD (3.8%). In systemic disease associated ILD, in addition to common etiologies such as vasculitis (10.5%) and connective tissue diseases (9.0%), primary immunodeficiency diseases (PID) associated ILD (9.8%), interstitial pneumonia with autoimmune features (6.8%), and metabolic diseases (6.8%) were not rarely found. Some newly reported etiologies such as STING–associated vasculopathy with onset in infancy, COPA syndrome and STAT3 mutation were included in PID associated ILD. Genetic tests contributed to 15% of the diagnoses which mainly distributed in PID associated ILD, metabolic diseases and surfactant dysfunction disorders, and contributed to the final diagnoses more than lung biopsies (13.5%) and biopsies of rashes or other tissues (12%).

Conclusions

This study first demonstrated an etiologic spectrum of chILD in Chinese children older than 2 years of age and summarized the approaches to diagnosis. The etiologic spectrum of chILD is expanding with more genetic etiologies being recognized.

New procedure of bronchoalveolar lavage using a balloon catheter in diffuse lung diseases

BACKGROUND

Various procedures for bronchoalveolar lavage (BAL) have been developed. BAL needs a wedge between the bronchoscope and the inner surface of the bronchus. The feasibility of performing BAL at the targeted position cannot be determined until immediately before the procedure. We examined BAL performed using a balloon catheter to evaluate the stability of the procedure itself and quality of the specimen obtained.

METHODS

The main inclusion criteria were diffuse lung disease with a shadow in the B⁵a area. The tip of a disposable balloon catheter was passed through the orifice of the B⁵a bronchus, and the balloon was expanded at the B⁵a bronchus. A 50-mL syringe containing saline was instilled, and gentle hand suction was performed. This procedure was repeated two more times (total: 150 mL).

RESULTS

In all the 13 patients, the balloon of the catheter was inflated at the B⁵a bronchus. The median recovery rate was 34.92% ± 13.22%. These values were comparable to previously obtained BAL data (control group, N = 56) from our facility. The BAL fluid findings and final diagnosis, with the exception of one undiagnosed case, were consistent. Overall, four patients suffered an adverse event during BAL (hypoxemia). All cases were managed by increasing the oxygen flow rate, and the adverse event did not affect the subsequent examinations.

CONCLUSIONS

Using a balloon catheter enabled us to perform BAL at the intended bronchus. The quality of the obtained specimen was also acceptable.

Imaging of the Thoracic Manifestations of Connective Tissue Disease

Imaging, specifically computed tomography (CT), is a key component in the characterization, management, and follow-up of patients with connective tissue disease (CTD)-related diffuse lung disease. The main role of CT is to help direct treatment by determining the primary pattern of lung injury present. Other roles include follow-up of lung disease over time, evaluation of acute symptoms, and monitoring for treatment complications. Although diagnosis is typically made using clinical and serologic criteria, CT plays an important role when lung disease is the dominant presenting feature. This article delineates the roles of CT in patients with CTD-related lung disease.

Transbronchial Lung Cryobiopsy in Interstitial Lung Diseases: Best Practice

The lung biopsy in interstitial lung disease (ILD) represents an important diagnostic step when the clinical and radiological data are insufficient for a firm diagnosis. A growing body of evidence suggests the utility of transbronchial lung cryobiopsy (TBLC) in the diagnostic algorithm of ILD as it allows, compared to transbronchial lung biopsy with conventional forceps, a better identification of complex histological patterns - such as usual interstitial pneumonia - and can provide information which has a clinical impact on the multidisciplinary discussion similar to that provided by surgical lung biopsy. Performed correctly, it appears to have a better safety profile than surgery. The decision to perform a lung biopsy should be a multidisciplinary decision process where it is felt that there is sufficient diagnostic doubt after a careful clinical evaluation including review of the computed tomograms of the thorax. The presence of severe pulmonary hypertension (> 50 mm Hg), poor lung function (FVC < 50%), or dismissed gas transfer (DLCO of < 35%) are considered relative contraindications for TBLC. Anticoagulants and antiplatelet drugs should be discontinued for the minimum period required for the specific drugs. The greatest consideration should be given to ensure the biopsy is performed safely and we recommend the use of either an endotracheal tube or rigid bronchoscopy. Deep sedation or general anesthesia allow better control of the procedure and a better patient experience. Prophylactic balloon blockers should be used to tamponade any bleeding and also to prevent overspill of blood from the segment that is being sampled. The procedure should be performed under fluoroscopy to ensure that samples are ideally obtained about 10 mm from the pleural edge. The cryoprobe is activated for about 5 s for the first biopsy and then adjusted according to the sample size obtained. With a careful standardized approach it is possible to obtain good-quality lung specimens for diagnosis in a safe manner.

CT features of diffuse lung disease in infancy

Diffuse lung disease in infancy includes a wide range of very rare and peculiar pulmonary conditions usually not seen in older children, in whom diffuse lung disease has much greater overlap with adult disorders. The acronym chILD (childhood Interstitial Lung Disease) commonly defines these disorders, although air spaces, airways, alveolar epithelium, vasculature, pleura, and pleural spaces can also be involved, besides the pulmonary interstitium. chILD can be caused by diffuse developmental disorders, alveolar growth abnormalities, surfactant dysfunction disorders, and other specific conditions of poorly understood etiology. Chest CT imaging studies play a pivotal role in the evaluation of chILD. In some conditions CT findings can be specific, and thus make it possible avoiding further testing. In other disorders, findings are nonspecific, although they may suggest a diagnostic pattern and guide further testing. Nevertheless, chILD disorders often remain unrecognized on imaging studies, as they are very rare. The aim of this article is to review the CT patterns of lung involvement in a series of infants with chILD.

A newly identified novel variant in the CSF2RA gene in a child with pulmonary alveolar proteinosis: a case report

BACKGROUND

The congenital form of pulmonary alveolar proteinosis due to colony stimulating factor 2 receptor alpha gene mutations is a rare disease with only a few cases reported worldwide. In this study we report a new case of pulmonary alveolar proteinosis with a novel variant in colony stimulating factor 2 receptor alpha gene.

CASE PRESENTATION

A 5-year-old Saudi boy presented with a history of progressive dyspnea over 6 months; he was diagnosed as having pulmonary alveolar proteinosis. A molecular study revealed a novel variation in colony stimulating factor 2 receptor alpha gene. His clinical condition showed significant improvement after whole lung lavage.

CONCLUSIONS

This case has the typical presentation of congenital pulmonary alveolar proteinosis due to colony stimulating factor 2 receptor alpha defect with a novel variant in this gene likely to be pathogenic.

Clinical, cytological and microbiological evaluation of bronchoalveolar lavage in children: A referral hospital-based study

INTRODUCTION

Diffuse lung diseases (DLD) in children involve a group of heterogeneous, rare disorders. In spite of the low diagnostic yield in pediatric DLD, bronchoalveolar lavage (BAL) can be used to diagnose specific disorders. There are few studies about microbial and cellular profiles of BAL samples in these patients. This study was conducted to evaluate the clinical, cytological and microbiological evaluation of BAL in children with DLD.

METHODS

The clinical, cytological and microbiological profiles of BAL samples of all patients with DLD who underwent the fiberoptic bronchoscopy (FOB) at Children's Medical Center, an Iranian referral pediatrics Hospital during a year were evaluated.

RESULTS

In 18 patients (18.4%) of the 98 cases studied, 22 pathogens were obtained as etiologic agents. The mean total cells count of BAL was 23.9 × 104 ± 12.9 × 104/ml. The mean percentages of cellular components were macrophages (70.2%), neutrophils (16.3%), lymphocytes (11.8%) and eosinophils (1.4%), respectively. The type of lung disease was significantly associated with the mean percentage of lymphocytes (p = 0.005) and the percentage of neutrophils (p = 0.042).

CONCLUSION

FOB and BAL evaluation in combination with clinical and radiographic imaging data may be helpful for identifying of presumptive diagnosis of DLD in children.

Childhood interstitial lung disease: A systematic review

OBJECTIVES

Childhood interstitial lung disease (chILD) is a group of rare chronic and complex disorders of variable pathology. There has been no systematic review of published chILD research. This study aimed to describe chILD classification systems, epidemiology, morbidity, treatments, outcomes, and the impact of chILD on families and the burden on health services.

METHODS

A systematic literature search for original studies on chILD was undertaken in the major biomedical databases to the end of December 2013. Epidemiological studies, case series and studies describing classification systems were included. Single case studies were excluded.

RESULTS

The search yielded 37 publications that met study criteria. Four different chILD classification systems have been proposed in the past decade. The incidence of chILD has been estimated at 0.13-16.2 cases/100,000 children/year. One to five new cases presented to individual hospitals each year. In developed countries, the median mortality was 13% (6-19%). Morbidity and outcomes were highly variable and not systematically reported. Corticosteroids and hydroxychloroquine were the most common treatments. The impact of chILD on families and the burden on health services has not been studied.

CONCLUSIONS

The heterogeneity of the chILD group of disorders, different determinations of what constitutes a chILD disorder and, a paucity of large epidemiological studies precludes consolidation of results across studies. Consensus on chILD classification is needed to support diagnosis and allow direct comparisons of research evidence. Active disease surveillance and international patient registries are required to advance understanding and management of chILD.

The radiology of diffuse interstitial pulmonary disease in children: pearls, pitfalls and new kids on the block in 2015

Diffuse interstitial lung disease in children differs markedly from interstitial lung disease in adults and is a distinct entity. The childhood interstitial lung disease (ChILD) classification, devised in 2010 separates conditions into those occurring in infancy, and those not specific to infants, the later group containing many conditions related to systemic diseases (including connective tissue diseases and depositional/storage disorders), and conditions occurring in immunocompromised children. In this article, we briefly review normal lung growth and development. We discuss our preferred technique for imaging the lungs with computed tomography in children, and review the recent literature regarding the radiological appearance of various ChILD. We illustrate this with cases from our institution and emphasize the more recently recognised conditions including pleuroparenchymal fibroelastosis and filamin A deficiency-related lung disease.

Unclassifiable interstitial lung disease: an unresolved diagnostic dilemma

Interstitial lung disease (ILD) classification requires a multidisciplinary review that includes input from an ILD clinician, chest radiologist, and lung pathologist. We report a case of ILD that remained unclassifiable due to discordant clinical, radiological, and pathological findings despite a thorough evaluation that included examination of explanted lung tissue. This case demonstrates that ILD can remain unclassifiable even with a complete evaluation and illustrates one approach to the management of such patients.

Acute respiratory failure secondary to eosinophilic pneumonia following influenza vaccination in an elderly man with chronic obstructive pulmonary disease

Acute respiratory failure with diffuse pulmonary opacities is an unusual manifestation following influenza vaccination. We report herein a patient with chronic obstructive pulmonary disease who developed fever with worsening of respiratory symptoms and severe hypoxemia requiring ventilatory support shortly after influenza vaccination. Bronchoalveolar lavage was compatible with acute eosinophilic pneumonia. Rapid clinical improvement was observed 2 weeks after systemic corticosteroid treatment, followed by radiographic improvement at 4 weeks. No disease recurrence was observed at the 6-month follow-up.

[Bronchioloalveolar carcinoma: an exceptional cause of diffuse lung disease in a patient with acute myeloid leukemia]

INTRODUCTION

Bronchiolo-alveolar carcinoma is a primary pulmonary adenocarcinoma developing in the terminal respiratory unit.

CASE REPORT

An 84-year-old non-smoker woman with a history of untreated acute myeloid leukaemia was referred to the intensive care unit for pneumonia and acute respiratory failure. The patient reported dyspnoea and a productive cough for 3 months, treated by antibiotics and steroids without improvement. Thoracic CT-scan showed alveolar condensations and multiple nodular lesions. All microbiological samples were negative and the evolution was fatal within 72 hours despite empirical antibiotic therapy and noninvasive ventilation. Post-mortem lung biopsies gave a diagnosis of mucinous and non-mucinous bronchiolo-alveolar carcinoma with typical lepidic growth pattern of tumor cells and discrete septal thickening but no fibrosis, inflammation or local invasion.

CONCLUSION

Bronchiolo-alveolar carcinoma is an alternative diagnosis in alveolar condensations associated with pulmonary nodules even in a patient with immunosupression. Early diagnosis allows effective treatment in some cases.

Candidate gene analysis of the surfactant protein D gene in pediatric diffuse lung disease

Mutations in surfactant-associated genes cause childhood diffuse lung disease. Mice lacking surfactant protein D develop lung disease with age. However, we identified no novel surfactant protein D gene (SFTPD) coding or splice region variants in 73 unrelated children with diffuse lung disease from a cohort enriched for genetic surfactant dysfunction.

Interstitial lung disease in children

Children's interstitial lung disease (ILD) includes a wide range of rare respiratory disorders associated with high morbidity and mortality. Genetic factors, systemic disease processes, nonspecific inflammatory or fibrotic patterns of repair seen in a number of clinical settings are involved in the ILD pathogenesis. Specific disorders more prevalent in young children include diffuse developmental disorders, alveolar growth abnormalities, genetic surfactant disorders, pulmonary interstitial glycogenosis and neuroendocrine cell hyperplasia of infancy. It may be difficult to recognize these entities and this can lead to delayed treatment. The diagnostic approach is based on a combination of history/physical examinations, imaging studies, pulmonary function testing, genetic testing, bronchoalveolar lavage (BAL) and in most cases an open lung biopsy. Although some disease types overlap with those seen in adults, in this review emphasis is placed on entities unique to the pediatric population focusing on clinical characteristics, histologic definitions, radiologic-pathologic correlation and therapeutic strategies.

A practical approach to high-resolution CT of diffuse lung disease

Diffuse lung disease presents a variety of high-resolution CT findings reflecting its complex pathology, and provides diagnostic challenge to radiologists. Frequent modification of detailed pathological classification makes it difficult to keep up with the latest understanding. In this review, we describe a practical approach to high-resolution CT diagnosis of diffuse lung disease, emphasizing (1) analysis of "distribution" of the abnormalities, (2) interpretation of "pattern" in relation to distribution, (3) utilization of associated imaging findings and clinical information, and (4) chronicity of the findings. This practical approach will help radiologists establish a way to interpret high-resolution CT, leading to pin-point diagnosis or narrower differential diagnoses of diffuse lung diseases.