Imaging of Small Airways Disease.

Bronchiolitis refers to a small airways disease and may be classified by etiology and histologic features. In cellular bronchiolitis inflammatory cells involve the small airway wall and peribronchiolar alveoli and manifest on CT as centrilobular nodules of solid or ground glass attenuation. Constrictive bronchiolitis refers to luminal narrowing by concentric fibrosis. Direct CT signs of small airway disease include centrilobular nodules and branching tree-in-bud opacities. An indirect sign is mosaic attenuation that may be exaggerated on expiratory CT and represent air trapping. Imaging findings can be combined with clinical and pathologic data to facilitate a more accurate diagnosis.

Diagnostic and Imaging Approaches to Chest Wall Lesions.

Chest wall lesions are relatively uncommon and may be challenging once they are encountered on images. Radiologists may detect these lesions incidentally at examinations performed for other indications, or they may be asked specifically to evaluate a suspicious lesion. While many chest wall lesions have characteristic imaging findings that can result in an accurate diagnosis with use of imaging alone, other entities are difficult to distinguish at imaging because there is significant overlap among them. The interpreting radiologist should be familiar with the imaging features of both "do not touch" benign entities (which can be confidently diagnosed with imaging only, with no need for biopsy or resection unless the patient is symptomatic) and lesions that cannot be confidently characterized and thus require further workup. CT and MRI are the main imaging modalities used to assess the chest wall, with each having different benefits and drawbacks. Chest wall lesions can be classified according to their predominant composition: fat, calcification and ossification, soft tissue, or fluid. The identification or predominance of signal intensities or attenuation for these findings, along with the patient age, clinical history, and lesion location, can help establish the appropriate differential diagnosis. In addition, imaging findings in other organs, such as the lungs or upper abdomen, can at times provide clues to the underlying diagnosis. The authors review different chest wall lesions classified on the basis of their composition and highlight the imaging findings that can assist the radiologist in narrowing the differential diagnosis and guiding management. ©RSNA, 2022.

Smooth Muscle Conditions of the Chest: A Clinical, Radiologic, and Pathologic Review.

Smooth muscle conditions of the chest have diverse clinical and imaging manifestations and may involve nearly every thoracic structure. Differentiation among these conditions requires the integration of clinical, radiologic, and histopathologic data. Histologic examination in conjunction with immunohistochemistry is essential for differentiation from other spindle cell neoplastic mimics. Familiarity with these entities will ensure the inclusion of smooth muscle conditions in the differential diagnosis of thoracic soft tissue lesions and potentially guide the clinician in appropriate management. We review the clinical, imaging, and histopathologic features of thoracic smooth muscle-related conditions organized by the anatomic structures affected.

Uncommon thoracic manifestations from extrapulmonary tumors: Computed tomography evaluation - Pictorial review.

Although metastasis can occur at a variety of sites, pulmonary involvement is common in patients with cancer. Depending on the source and type of tumor, pulmonary metastases present with a wide range of radiologic appearances. Hematogenous dissemination through the pulmonary arteries to the pulmonary capillary network is the most common form of spread in pulmonary metastases. However, they may also reach the lung via lymphatic dissemination, secondary airway involvement, vessel tumor embolism, and direct chest invasion. In the evaluation of patients with known extrathoracic tumors, CT is the state-of-the-art imaging modality for detecting and characterize pulmonary metastases as well as to predict resectability. Although CT limitations are well known, knowledge of growth rates of various tumors and understanding the pattern of spread may be helpful clues in suggesting and even establish the specific diagnosis. The purpose of this pictorial review is to discuss the imaging appearances of different patterns of intrathoracic tumoral dissemination.

Imaging of the trachea.

Numerous benign and malignant tracheal diseases may affect the trachea primarily and secondarily. While the posterior anterior (PA) and lateral chest radiograph is the conventional study for initial evaluation of the trachea and central airways, findings may not always be apparent on conventional radiographs, and further evaluation with cross sectional imaging is usually necessary. Computed tomography (CT) is the imaging modality of choice for imaging the trachea and bronchi. Familiarity with the imaging appearances of the normal and diseased trachea will enhance diagnostic evaluation.

Missed Lung Cancer.

The chest radiograph is one of the most commonly used imaging studies and is the modality of choice for initial evaluation of many common clinical scenarios. Over the last two decades, chest computed tomography has been increasingly used for a wide variety of indications, including respiratory illnesses, trauma, oncologic staging, and more recently lung cancer screening. Diagnostic radiologists should be familiar with the common causes of missed lung cancers on imaging studies in order to avoid detection and interpretation errors. Failure to detect these lesions can potentially have serious implications for both patients as well as the interpreting radiologist.

Bedside Chest Radiographs in the Intensive care Setting: Wireless Direct Radiography Compared to Computed Radiography.

OBJECTIVES: To compare image quality, visibility of anatomic landmarks, tubes and lines, and other clinically significant findings on portable (bedside) chest radiographs acquired with wireless direct radiography (DRw) and computed radiography (CR). METHODS: In a prospective IRB-approved and HIPAA-compliant study, portable DRw (DRX-1C mobile retrofit portable wireless direct radiography, CareStream Inc., Rochester, NY) and portable CR (AGFA CR (DXG) version; NIM2103, AGFA Healthcare, Ridgefield Park, NJ) images of the chest were acquired within 24-hours in 80 patients in the intensive care unit (ICU). Image pairs of 75 patients (37% female) with a mean age of 60.7±16 years were independently compared side-by-side by 7 experienced thoracic radiologists using a five-point scale. When tubes and lines were present, the radiologist also compared an edge-enhanced copy of the DRw image to the CR image. RESULTS: Most radiologists found significantly fewer artifacts on DRw images compared to CR images and all readers agreed that when present, these artifacts did not significantly preclude the ability to evaluate anatomic landmarks, tubes and lines, or clinically significant findings. None of the radiologists (0/7) reported superior visibility of anatomic structures on CR images compared to DRw images and some radiologists (3/7) found DRw images significantly better for visibility of anatomic landmarks such as the carina (p=0.01-0.001). Most radiologists (6/7) found DRw images to be better or clearly better than CR images for position of tubes and lines, and edge-enhanced DRw images to be especially helpful for evaluation of central venous catheters and esophageal tubes (p=0.027-0.001). None of the radiologists deemed CR images superior for visibility of clinically significant findings. CONCLUSIONS: Critical care chest radiography with a portable DRw system can provide similar or superior information compared to a CR system regarding clinically significant findings and position of tubes and lines.

Imaging Evaluation of Malignant Chest Wall Neoplasms.

Neoplasms of the chest wall are uncommon lesions that represent approximately 5% of all thoracic malignancies. These tumors comprise a heterogeneous group of neoplasms that may arise from osseous structures or soft tissues, and they may be malignant or benign. More than 50% of chest wall neoplasms are malignancies and include tumors that may arise as primary malignancies or secondarily involve the chest wall by way of direct invasion or metastasis from intrathoracic or extrathoracic neoplasms. Although 20% of chest wall tumors may be detected at chest radiography, chest wall malignancies are best evaluated with cross-sectional imaging, principally multidetector computed tomography (CT) and magnetic resonance (MR) imaging, each of which has distinct strengths and limitations. Multidetector CT is optimal for depicting bone, muscle, and vascular structures, whereas MR imaging renders superior soft-tissue contrast and spatial resolution and is better for delineating the full extent of disease. Fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT is not routinely performed to evaluate chest wall malignancies. The primary functions of PET/CT in this setting include staging of disease, evaluation of treatment response, and detection of recurrent disease. Ultrasonography has a limited role in the evaluation and characterization of superficial chest wall lesions; however, it can be used to guide biopsy and has been shown to depict chest wall invasion by lung cancer more accurately than CT. It is important that radiologists be able to identify the key multidetector CT and MR imaging features that can be used to differentiate malignant from benign chest lesions, suggest specific histologic tumor types, and ultimately guide patient treatment. (©)RSNA, 2016.

Multimodality imaging for characterization, classification, and staging of malignant pleural mesothelioma.

Malignant pleural mesothelioma (MPM) is the most common primary malignancy of the pleura and is associated with asbestos exposure in approximately 80% of patients. The patient prognosis is poor, with a median survival of 9-17 months after diagnosis. However, improved survival and decreased morbidity and mortality have been demonstrated when the diagnosis is made in the early stages of disease and specific treatment strategies are implemented. A staging system that focuses on the extent of primary tumor (T), lymph node involvement (N), and metastatic disease (M) has been devised by the International Mesothelioma Interest Group and emphasizes factors related to overall survival. Radiologists should recognize the manifestations of MPM across multiple imaging modalities, translate these findings into the updated staging system, and understand the effects of appropriate staging on treatment and survival. Computed tomography (CT) remains the primary imaging modality used to evaluate MPM and efficiently demonstrates the extent of primary tumor, intrathoracic lymphadenopathy, and extrathoracic spread. However, additional imaging modalities, such as magnetic resonance (MR) imaging of the thorax and positron emission tomography (PET)/CT with fluorodeoxyglucose, have emerged in recent years and are complementary to CT for disease staging and evaluation of patients with MPM. Thoracic MR imaging is particularly useful for identifying invasion of the chest wall, mediastinum, and diaphragm, and PET/CT can accurately demonstrate intrathoracic and extrathoracic lymphadenopathy and metastatic disease.

International association for the study of lung cancer (IASLC) lymph node map: radiologic review with CT illustration.

Accurate clinical or pretreatment stage classification of lung cancer leads to optimal treatment outcomes and improved prognostication. Such classification requires an accurate assessment of the clinical extent of regional lymph node metastasis. Consistent and reproducible regional lymph node designations facilitate reliable assessment of the clinical extent of regional lymph node metastasis. Regional lymph node maps, such as the Naruke lymph node map and the Mountain-Dresler modification of the American Thoracic Society lymph node map, were proposed for this purpose in the past. The most recent regional lymph node map to be published is the International Association for the Study of Lung Cancer (IASLC) lymph node map. The IASLC lymph node map supersedes all previous maps and should be used in tandem with the current seventh edition of the tumor, node, metastasis stage classification for lung cancer.

Multimodality imaging of cardiothoracic lymphoma.

Lymphoma is the most common hematologic malignancy and represents approximately 5.3% of all cancers. The World Health Organization published a revised classification scheme in 2008 that groups lymphomas by cell type and molecular, cytogenetic, and phenotypic characteristics. Most lymphomas affect the thorax at some stage during the course of the disease. Affected structures within the chest may include the lungs, mediastinum, pleura, and chest wall, and lymphomas may originate from these sites as primary malignancies or secondarily involve these structures after arising from other intrathoracic or extrathoracic sources. Pulmonary lymphomas are classified into one of four types: primary pulmonary lymphoma, secondary pulmonary lymphoma, acquired immunodeficiency syndrome-related lymphoma, and post-transplantation lymphoproliferative disorders. Although pulmonary lymphomas may produce a myriad of diverse findings within the lungs, specific individual features or combinations of features can be used, in combination with secondary manifestations of the disease such as involvement of the mediastinum, pleura, and chest wall, to narrow the differential diagnosis. While findings of thoracic lymphoma may be evident on chest radiography, computed tomography has traditionally been the imaging modality used to evaluate the disease and effectively demonstrates the extent of intrathoracic involvement and the presence and extent of extrathoracic spread. However, additional modalities such as magnetic resonance imaging of the thorax and (18)F-FDG PET/CT have emerged in recent years and are complementary to CT in the evaluation of patients with lymphoma. Thoracic MRI is useful in assessing vascular, cardiac, and chest wall involvement, and PET/CT is more accurate in the overall staging of lymphoma than CT and can be used to evaluate treatment response.

The imaging spectrum of bronchopulmonary sequestration.

Bronchopulmonary sequestration is a rare lesion characterized by abnormal lung tissue that lacks a normal bronchial communication and is supplied by an anomalous systemic artery. It has a variety of imaging appearances, including that of consolidation, a mass, or an air or fluid-filled cystic or multicystic lesion. This article reviews the imaging spectrum of bronchopulmonary sequestration, its important parenchymal mimics, and conditions that share the feature of anomalous systemic arterial supply to the lung.

Diffuse pulmonary hemorrhage: clues to the diagnosis.

Diffuse pulmonary hemorrhage (DPH) refers to an uncommon but significant condition of bleeding into the alveolar space. Anemia and hemoptysis are important clinical features, but they may be absent. Although the radiographic and computed tomography findings are often varied and nonspecific, the imaging manifestations of pulmonary hemorrhage and the associated findings in the thorax often provide important diagnostic information that may lead to a specific diagnosis. DPH significantly influences patient management and has important prognostic implications. This review article explores the imaging findings in DPH and its differential diagnosis, highlighting important clues to this diagnosis and to its underlying etiology. DPH is an uncommon condition characterized by bleeding into the alveolar space that, when recognized on imaging, provides important diagnostic and prognostic information.

Clear vision through the haze: a practical approach to ground-glass opacity.

Ground-glass opacity (GGO) is a common, nonspecific imaging finding on chest computed tomography that may occur in a variety of pulmonary diseases. GGO may be the result of partial filling of alveolar spaces, thickening of the alveolar walls or septal interstitium, or a combination of partial filling of alveolar spaces and thickening of the alveolar walls and septal interstitium at the histopathologic level. Diseases that commonly manifest on chest computed tomography as GGO include pulmonary edema, alveolar hemorrhage, nonspecific interstitial pneumonia, hypersensitivity pneumonitis, and pulmonary alveolar proteinosis. Generating an extensive list of possible causes of GGO in radiologic reports would not be helpful to referring physicians. Preferably, a more concise and focused list of differential diagnostic possibilities may be constructed using a systematic approach to further classify GGO based on morphology, distribution, and ancillary imaging findings, such as the presence of cysts, traction bronchiectasis, and air trapping. Correlation with clinical history, such as the chronicity of symptoms, the patient's immune status, and preexisting medical conditions is vital. By thorough analysis of imaging patterns and consideration of relevant clinical information, the radiologist can generate a succinct and useful imaging differential diagnosis when confronted with the nonspecific finding of GGO.

Nonvascular thoracic magnetic resonance imaging: the current state of training, utilization, and perceived value: survey of the Society of Thoracic Radiology membership.

PURPOSE: The aim of the study was to determine the current state of training, utilization, and perceived value of nonvascular thoracic magnetic resonance imaging (MRI). MATERIALS AND METHODS: The URL link for this anonymous, IRB-approved survey was e-mailed to all Society of Thoracic Radiology members with available e-mail addresses (733), of whom 693 were qualified to respond as per the survey's instructions. Survey questions focused on MRI training, interpretation volume, perceived value of thoracic MRI, and barriers to its utilization. Study data were collected and managed using Research Electronic Data Capture (REDCap) electronic data capture tools and analyzed with χ tests. RESULTS: The survey response rate was 27% (190/693). Thirty-seven percent (67/180) of respondents reported that they interpreted and reported zero thoracic MRIs and 64% (116/182) interpreted or reported <10 MRIs over the prior year. The perceived value of thoracic MRI was highest for chest wall and neurovascular involvement and evaluation of the mediastinum, particularly thymus, next highest for assessment of pleural or diaphragmatic lesions, and lowest for assessment of lung function with hyperpolarized gases. Seventy-three percent (121/166) of respondents felt it would be of value to increase utilization of thoracic MRI. Perceived obstacles to increasing thoracic MRI utilization included lack of: awareness of referring health care providers as to the value of thoracic MRI (59%, 98/166), radiologist proficiency or comfort with thoracic MRI (46%, 77/166), standardized protocols (38%, 64/166), technologist experience (38%, 63/166), and sufficient training during residency and/or fellowship (32%, 54/166). Twenty-five percent (41/166) of respondents reported insufficient thoracic MRI literature and limited CME courses and lectures in this field as an additional impediment. CONCLUSIONS: The majority of survey respondents reported limited experience in thoracic MRI interpretation, a recognition of thoracic MRI's value, and an interest in increasing its utilization. Improved education of radiologists, technologists, and referring clinicians would ameliorate the current state.

Imaging pulmonary infection: classic signs and patterns.

OBJECTIVE: The purposes of this article are to describe common and uncommon imaging signs and patterns of pulmonary infections and to discuss their underlying anatomic and pathophysiologic basis. CONCLUSION: Imaging plays an integral role in the diagnosis and management of suspected pulmonary infections and may reveal useful signs on chest radiographs and CT scans. Detected early, these signs can often be used to predict the causative agent and pathophysiologic mechanism and possibly to optimize patient care.