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Radiation recall pneumonitis is an inflammatory reaction of previously radiated lung parenchyma triggered by systemic pharmacological agents (such as chemotherapy and immunotherapy) or vaccination. Patients present with non-specific symptoms such as cough, shortness of breath, or hypoxia soon after the initiation of medication or vaccination. Careful assessment of the patient's history, including the thoracic radiation treatment plan and timing of the initiation of the triggering agent, in conjunction with CT findings, contribute to the diagnosis. Once a diagnosis is established, treatment includes cessation of the causative medication and/or initiation of steroid therapy. Differentiating this relatively rare entity from other common post-therapeutic complications in oncology patients, such as recurrent malignancy, infection, or medication-induced pneumonitis, is essential for guiding downstream clinical management.

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Chest radiography is one of the most commonly performed imaging tests, and benefits include accessibility, speed, cost, and relatively low radiation exposure. Lung cancer is the third most common cancer in the United States and is responsible for the most cancer deaths. Knowledge of the role of chest radiography in assessing patients with lung cancer is important. This article discusses radiographic manifestations of lung cancer, the utility of chest radiography in lung cancer management, as well as the limitations of chest radiography and when computed tomography (CT) is indicated.

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Imaging plays a key role in clinical staging of lung cancer and guiding therapy. A thorough understanding of the staging system including the nomenclature and updates is necessary to tailor treatment plans and optimize patient care. The 9th edition of the Tumor, Node, Metastasis staging system for lung cancer has no changes for T classification and subdivides N2 and M1c categories. In nodal staging, N2 splits into N2a, ipsilateral mediastinal single station involvement and N2b, ipsilateral mediastinal multiple stations involvement. In the staging of multiple extrathoracic metastases, M1c splits into M1c1, multiple extrathoracic metastases in one organ system and M1c2, multiple extrathoracic metastases in multiple organ systems. Awareness of the proposed changes in TNM-9 staging classification is essential to provide methodical and accurate imaging interpretation.

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Positron emission tomography/computed tomography (PET/CT) using [18F]-fluoro-2-deoxy-D-glucose (FDG) has become the mainstay imaging modality for evaluating oncology patients with certain cancers. The most common FDG PET/CT applications include staging/restaging, assessing response to therapy and detecting tumor recurrence. It is important to be aware of potential pitfalls and technical artifacts on PET/CT in the chest and abdomen to ensure accurate interpretation, avoid unnecessary intervention and optimize patient care.

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Staging classification is essential in cancer management and is based on three components: tumor extent (T), lymph node involvement (N), and distant metastatic disease (M). For thymic epithelial malignancies, clinical Tumour, Node, Metastasis (cTNM) staging is primarily determined by imaging, making radiologists integral to clinical practice, treatment decisions, and maintaining the quality of staging databases. The ninth edition of the TNM classification for thymic epithelial tumors will be implemented in January 2025. This review outlines the definitions for the TNM categories in the updated edition, provides examples, and elaborates on the radiologist's role and imaging considerations.

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Lung cancer remains one of the leading causes of mortality worldwide, as well as in the United States. Clinical staging, primarily with imaging, is integral to stratify patients into groups that determine treatment options and predict survival. The eighth edition of the tumor, node, metastasis (TNM-8) staging system proposed in 2016 by the International Association for the Study of Lung Cancer remains the current standard for lung cancer staging. The system is used for all subtypes of lung cancer, including non-small cell lung cancer, small cell lung cancer, and bronchopulmonary carcinoid tumors.

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The pericardium comprises a double-walled fibrous-serosal sac that encloses the heart. Reflections of the serosal layer form sinuses and recesses. With advances in multidetector computed tomography (CT) technology, pericardial recesses are frequently detected with thin-section CT. Knowledge of pericardial anatomy on imaging is crucial to avoid misinterpretation of fluid-filled pericardial sinuses and recesses as adenopathy/pericardial metastasis or aortic dissection, which can impact patient management and treatment decisions. The authors offer a comprehensive review of pericardial anatomy and its variations observed on CT, potential pitfalls in image interpretation, and implications for the pulmonologist with respect to unnecessary diagnostic procedures or interventions.

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Lung cancer is the leading cause of cancer deaths in men and women in the United States. Accurate staging is needed to determine prognosis and devise effective treatment plans. The International Association for the Study of Lung Cancer (IASLC) has made multiple revisions to the tumor, node, metastasis (TNM) staging system used by the Union for International Cancer Control and the American Joint Committee on Cancer to stage lung cancer. The eighth edition of this staging system includes modifications to the T classification with cut points of 1 cm increments in tumor size, grouping of lung cancers associated with partial or complete lung atelectasis or pneumonitis, grouping of tumors with involvement of a main bronchus regardless of distance from the carina, and upstaging of diaphragmatic invasion to T4. The N classification describes the spread to regional lymph nodes and no changes were proposed for TNM-8. In the M classification, metastatic disease is divided into intra- versus extrathoracic metastasis, and single versus multiple metastases. In order to optimize patient outcomes, it is important to understand the nuances of the TNM staging system, the strengths and weaknesses of various imaging modalities used in lung cancer staging, and potential pitfalls in image interpretation.

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BACKGROUND: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) polymerase chain reaction (PCR) on nasopharyngeal swab (NPS), remains the most reliable and practical test to diagnose coronavirus disease 2019 (COVID-19). Current literature is sparse regarding the rates of discordance between NPS and bronchoalveolar lavage (BAL) in patients with cancer. METHODS: We conducted a retrospective cohort study of adult patients with cancer who had BAL samples tested for SARS-CoV-2 at a comprehensive cancer center. Patients without NPS PCR for SARS-CoV-2 before BAL were excluded. RESULTS: In a cohort of 345 patients, 12% and 17% tested positive for SARS-CoV-2 on NPS and BAL, respectively. There was a 6.3% NPS-/BAL+ discordance rate and a 9.5% NPS+/BAL- discordance rate. Patients with lymphoma (adjusted odds ratio [aOR] = 4.06; P = .007) and Hispanic patients (aOR = 3.76; P = .009) were more likely to have NPS-/BAL+ discordance on multivariate analysis. Among patients with NPS- /BAL- for SARS-CoV-2, an alternate infectious (23%) and a noninfectious etiology (16%) were identified in BAL. CONCLUSIONS: Our discordance rates between NPS and BAL were sufficient to recommend BAL in certain patients with cancer with a high clinical suspicion of COVID-19. BAL has value in identifying alternative etiologies of illness in patients with suspected or confirmed COVID-19.

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Mediastinal masses present a diagnostic challenge due to their diverse etiologies. Accurate localization and internal characteristics of the mass are the two most important factors to narrow the differential diagnosis or provide a specific diagnosis. The International Thymic Malignancy Interest Group (ITMIG) classification is the standard classification system used to localize mediastinal masses. Computed tomography (CT) and magnetic resonance imaging (MRI) are the two most commonly used imaging modalities for characterization of the mediastinal masses.

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Radiation therapy using conventional or newer high-precision dose techniques, including three-dimensional conformal radiotherapy, intensity-modulated radiation therapy, stereotactic body radiation therapy, four-dimensional conformational radiotherapy, and proton therapy, is an important component of treating patients with lung cancer. Knowledge of the radiation technique used and the expected temporal evolution of radiation-induced lung injury, as well as patient-specific parameters such as previous radiotherapy, concurrent chemoradiotherapy, or immunotherapy, is important in image interpretation. This review discusses factors that affect the development and severity of radiation-induced lung injury and its radiological manifestations, as well as the differences between conventional and high-precision dose radiotherapy techniques.

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An integral part of managing patients with thymoma and thymic carcinoma is imaging. At diagnosis and staging, imaging helps demonstrate the extent of local invasion and distant metastases which allows the proper stratification of patients for therapy. For decades, the predominant staging system for thymic tumors was the Masaoka-Koga staging system. More recently, however, the International Association for the Study of Lung Cancer, the International Thymic Malignancies Interest Group (ITMIG), the European Society of Thoracic Surgeons, the Chinese Alliance for Research on Thymomas, and the Japanese Association of Research on Thymus partnered together to develop a tumor-node-metastasis (TNM) staging system specifically for thymic tumors based on a retrospective database of nearly 10,000 patients. The TNM 8th edition defines specific criteria for thymic tumors. Imaging also serves to assess treatment response and detect recurrent disease after various treatment modalities. The Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1 is currently used to assess response to treatment. ITMIG recommends certain modifications to RECIST version 1.1, however, in thymic tumors due to unique patterns of spread. While there is often overlap, computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography/computed tomography (PET/CT) characteristics can help differentiate thymoma and thymic carcinoma, with newer CT and MRI techniques under evaluation showing encouraging potential.

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A wide variety of neoplastic and nonneoplastic conditions occur in the mediastinum. Imaging plays a central role in the evaluation of mediastinal pathologies and their mimics. Localization of a mediastinal lesion to a compartment and characterization of morphology, density/signal intensity, enhancement, and mass effect on neighboring structures can help narrow the differentials. The International Thymic Malignancy Interest Group (ITMIG) established a cross-sectional imaging-derived and anatomy-based classification system for mediastinal compartments, comprising the prevascular (anterior), visceral (middle), and paravertebral (posterior) compartments. Cross-sectional imaging is integral in the evaluation of mediastinal lesions. Computed tomography (CT) and magnetic resonance imaging (MRI) are useful to characterize mediastinal lesions detected on radiography. Advantages of CT include its widespread availability, fast acquisition time, relatively low cost, and ability to detect calcium. Advantages of MRI include the lack of radiation exposure, superior soft tissue contrast resolution to detect invasion of the mass across tissue planes, including the chest wall and diaphragm, involvement of neurovascular structures, and the potential for dynamic sequences during free-breathing or cinematic cardiac gating to assess motion of the mass relative to adjacent structures. MRI is superior to CT in the differentiation of cystic from solid lesions and in the detection of fat to differentiate thymic hyperplasia from thymic malignancy.

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Malignant mesothelioma is a rare tumor arising from the mesothelial cells that line the pleura, pericardium, peritoneum, and tunica vaginalis. Imaging plays a primary role in the diagnosis, staging, and management of malignant mesothelioma. Multimodality imaging, including radiography, computed tomography (CT), magnetic resonance imaging (MRI), and F-18 fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT), is used in a variety of scenarios, including diagnosis, guidance for tissue sampling, staging, and reassessment of disease after therapy. CT is the primary imaging modality used in staging. MRI has superior contrast resolution compared with CT and can add value in terms of determining surgical resectability in equivocal cases. MRI can further assess the degree of local invasion, particularly into the mediastinum, chest wall, and diaphragm, for malignant pleural and pericardial mesotheliomas. FDG PET/CT plays a role in the diagnosis and staging of malignant pleural mesothelioma (MPM) and has been shown to be more accurate than CT, MRI, and PET alone in the staging of malignant pleural mesothelioma. PET/CT can also be used to target lesions for biopsy and to assess prognosis, treatment response, and tumor recurrence.

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The normal immune system identifies and eliminates precancerous and cancerous cells. However, tumors can develop immune resistance mechanisms, one of which involves the exploitation of pathways, termed immune checkpoints, that normally suppress T-cell function. The goal of immune checkpoint inhibitor (ICI) immunotherapy is to boost T-cell-mediated immunity to mount a more effective attack on cancer cells. ICIs have changed the treatment landscape of advanced non-small cell lung cancer (NSCLC), and numerous ICIs have now been approved as first-line treatments for NSCLC by the U.S. Food and Drug Administration. ICIs can cause atypical response patterns such as pseudoprogression, whereby the tumor burden initially increases but then decreases. Therefore, response criteria have been developed specifically for patients receiving immunotherapy. Because ICIs activate the immune system, they can lead to inflammatory side effects, termed immune-related adverse events (irAEs). Usually occurring within weeks to months after the start of therapy, irAEs range from asymptomatic abnormal laboratory results to life-threatening conditions such as encephalitis, pneumonitis, myocarditis, hepatitis, and colitis. It is important to be aware of the imaging appearances of the various irAEs to avoid misinterpreting them as metastatic disease, progressive disease, or infection. The basic principles of ICI therapy; indications for ICI therapy in the setting of NSCLC; response assessment and atypical response patterns of ICI therapy, as compared with conventional chemotherapy; and the spectrum of irAEs seen at imaging are reviewed. An invited commentary by Nishino is available online. ©RSNA, 2022.

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In the oncologic setting, misinterpretation of fluid in pericardial recesses as mediastinal adenopathy or benign pericardial findings as malignant can lead to inaccurate staging and inappropriate management. Knowledge of normal pericardial anatomy, imaging features to differentiate fluid in pericardial sinuses and recesses from mediastinal adenopathy and potential pitfalls in imaging of the pericardium on CT and PET/CT is important to avoid misinterpretation.

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Pulmonary embolism (PE) can present with a wide spectrum of clinical symptoms that can overlap considerably with other cardiovascular diseases. To avoid PE related morbidity and mortality, it is vital to identify this disease accurately and in a timely fashion. Several clinical criteria have been developed to standardize the diagnostic approach for patients with suspected PE. Computed tomographic pulmonary angiogram has significantly improved the detection of pulmonary embolism and is considered the imaging modality of choice to diagnose this disease. However, there are several potential pitfalls associated with this modality which can make diagnosis of PE challenging. In this review, we will discuss various pitfalls routinely encountered in the diagnostic work up of patients with suspected PE, approaches to mitigate these pitfalls and incidental pulmonary embolism.

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In imaging of the mediastinum, advances in computed tomography (CT), and magnetic resonance imaging (MRI) technology enable improved characterization of mediastinal masses. Knowledge of the boundaries of the mediastinal compartments is key to accurate localization. Awareness of distinguishing imaging characteristics allows radiologists to suggest a specific diagnosis or narrow the differential. In certain situations, MRI adds value to further characterize mediastinal lesions.

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Chimeric antigen receptor (CAR) T-cell therapy is a recently approved breakthrough treatment that has become a new paradigm in treatment of recurrent or refractory B-cell lymphomas and pediatric or adult acute lymphoid leukemia. CAR T cells are a type of cellular immunotherapy that artificially enhances T cells to boost eradication of malignancy through activation of the native immune system. The CAR construct is a synthetically created functional cell receptor grafted onto previously harvested patient T cells, which bind to preselected tumor-associated antigens and thereby activate host immune signaling cascades to attack tumor cells. Advantages include a single treatment episode of 2-3 weeks and durable disease elimination, with remission rates of over 80%. Responses to therapy are more rapid than with conventional chemotherapy or immunotherapy, with intervening short-interval edema. CAR T-cell administration is associated with therapy-related toxic effects in a large percentage of patients, notably cytokine release syndrome, immune effect cell-associated neurotoxicity syndrome, and infections related to immunosuppression. Knowledge of the expected evolution of therapy response and potential adverse events in CAR T-cell therapy and correlation with the timeline of treatment are important to optimize patient care. Some toxic effects are radiologically evident, and familiarity with their imaging spectrum is key to avoiding misinterpretation. Other clinical toxic effects may be occult at imaging and are diagnosed on the basis of clinical assessment. Future directions for CAR T-cell therapy include new indications and expanded tumor targets, along with novel ways to capture T-cell activation with imaging. An invited commentary by Ramaiya and Smith is available online. Online supplemental material is available for this article. ©RSNA, 2022.

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