Liver Injury in Patients With Distal Esophageal Carcinoma After Precision Radiation Therapy: Systematic Review of FDG-PET/CT Patterns.

OBJECTIVE: To determine the incidence and various patterns of radiation-induced liver injury (RILI) and its temporal evolution on fluorodeoxiglucose-positron emission tomography/computed tomography (FDG-PET/CT) after neoadjuvant chemoradiation using precision radiation in patients with esophageal carcinoma. MATERIAL AND METHODS: We evaluated 639 patients with locally advanced esophageal carcinoma who had serial FDG-PET/CTs after neoadjuvant chemoradiation. Two readers reviewed the imaging studies in consensus and recorded the cases where new foci of increased FDG uptake were identified within the radiated liver parenchyma. RILI was confirmed by follow-up imaging or percutaneous biopsy. RESULTS: FDG-avid RILI developed in 39/639 (6%) of patients. The caudate and left hepatic lobe were involved in all cases. There were various patterns of increased FDG uptake: 38% of patients had a single focus of increased FDG uptake and 62% had 2 regions of increased FDG uptake, which were focal nodular or diffuse or a combination of focal nodular and diffuse FDG uptake. On CT, 72% of patients had a poorly-marginated region of low attenuation and 28% had a well-defined region of low attenuation with sharp, well-defined linear borders in the location of the radiation, as confirmed by the treatment plan. CONCLUSION: The caudate and left hepatic lobes were involved in all cases of RILI. The various imaging patterns of RILI on FDG-PET/CT include 1 or 2 regions of increased FDG uptake with a nodular, diffuse, or combined appearance. Awareness of this potential complication of radiation therapy and knowledge of the imaging manifestations of RILI is important to avoid misinterpretation as a metastasis.

Pitfalls and Pearls in Esophageal Carcinoma.

The management of patients with esophageal carcinoma (EC) requires accurate clinical staging and post-therapeutic evaluation. Currently, esophagogastroduodenoscopy/endoscopic ultrasound (EGD/EUS), endoscopic ultrasound-fine needle aspiration (EUS-FNA), computed tomography (CT), 18F- fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography (FDG-PET/CT) and magnetic resonance (MR) imaging are used for the initial clinical staging, evaluation of therapeutic response and follow-up in patients with EC. However, there are limitations and pitfalls that are commonly encountered when imaging these patients that can limit accurate assessment. Knowledge of the limitations and pitfalls associated with the use of these different imaging modalities is essential in avoiding misinterpretation and guaranteeing the appropriate management for patient with EC.

Pearls and Pitfalls in the Imaging of Targeted Therapy and Immunotherapy in Lung Cancer.

Most lung cancers are diagnosed at advanced stage when the cancer has metastasized outside the lung. These patients are not eligible for curative surgery or radiation therapy and treated with systemic therapy. Advances in the understanding of the biology of lung cancer has resulted in the development of targeted therapy aimed at specific genetic mutations identified with non-small cell lung cancer and immunotherapy that helps the immune system recognize tumors as foreign, stimulates the immune system, and removes the inhibition that allows growth and spread of cancer cells. Tumors treated with targeted or immunotherapies respond differently when compared with traditional chemotherapy and not captured by conventional response criteria such as the World Health Organization criteria and Response Evaluation Criteria in Solid Tumors. Therefore, several modified criteria have been developed to appropriately address the treatment response when using these novel agents. Numerous treatment-related side effects have been described that are important to recognize to avoid misinterpretation as worsening tumor and to ensure appropriate management.

Imaging of Malignant Pleural Mesothelioma: Pearls and Pitfalls.

Malignant pleural mesothelioma is a rare tumor arising from the pleural mesothelial cells. Imaging plays a crucial role in the diagnosis, staging, and management of patients with mesothelioma. Accurate staging to stratify patients into homogeneous groups is required to evaluate the effectiveness of multimodality therapeutic regimens. CT and PET/CT are recommended for the initial staging of MPM. MRI adds value to further assess invasion of the tumor into the diaphragm, chest wall, and mediastinum. This review will discuss pearls and pitfalls in the imaging of mesothelioma with emphasis on the roles of CT, MRI, and PET/CT.

Imaging of the Chest After Radiotherapy and Potential Pitfalls.

Radiotherapy is one of the cornerstones for the treatment of thoracic malignancies. The goal of radiotherapy is to deliver maximal dose to the tumor while minimizing damage to surrounding normal anatomical structures. Although advances in radiotherapy technology have considerably improved radiation delivery, potential adverse effects are still common. Post radiation changes to the chest may include different structures such as the lung, heart, great vessels, and esophagus. The purpose of this manuscript is to illustrate the post radiotherapy changes to these anatomical structures resulting from external beam radiotherapy, as well as discuss imaging pitfalls to prevent radiologist's interpretation errors.

Thymic Epithelial Neoplasms: Tumor-Node-Metastasis Staging.

Thymic epithelial neoplasms are a group of malignant tumors that includes thymoma, thymic carcinoma, and thymic neuroendocrine tumors. Although several staging systems have been developed over the years for use with these cancers, they have been interpreted and implemented in a nonuniform manner. Recently, the International Association for the study of Lung Cancer and the International Thymic Malignancy Interest Group developed a tumor-node-metastasis staging system that has been universally accepted and correlates with patient survival and outcomes. Although pathologic staging is determined by histologic examination of the resected tumor, imaging plays an important role in clinical staging and is important for informing therapeutic decisions.

Esophageal Cancer: Tumor-Node-Metastasis Staging.

Esophageal cancer is an uncommon malignancy that ranks sixth in terms of mortality worldwide. Squamous cell carcinoma is the predominant histologic subtype worldwide whereas adenocarcinoma represents the majority of cases in North America, Australia, and Europe. Esophageal cancer is staged using the American Joint Committee on Cancer and the International Union for Cancer Control TNM system and has separate classifications for the clinical, pathologic, and postneoadjuvant pathologic stage groups. The determination of clinical TNM is based on complementary imaging modalities, including esophagogastroduodenoscopy/endoscopic ultrasound; endoscopic ultrasound-fine-needle aspiration; computed tomography of the chest, abdomen, and pelvis; and fluorodeoxyglucose PET/computed tomography.

In Situ Pulmonary Artery Thrombosis: Unrecognized Complication of Radiation Therapy.

OBJECTIVE. The purpose of this study is to evaluate the CT and clinical characteristics of in situ pulmonary artery thrombosis (PAT) associated with radiation therapy (RT). MATERIALS AND METHODS. A database search was performed to identify patients who had PAT develop after receiving RT. The CT characteristics of PAT, including the number, location, and appearance of filling defects as well as the presence of associated lung fibrosis, were recorded. The terminology (in situ thrombosis vs acute or chronic pulmonary embolism) used by the interpreting radiologists to describe PAT, the time between the completion of RT and development of PAT, the change in the size of the PAT, and observation of any new thrombi and emboli on follow-up imaging, were also recorded. RESULTS. Of the 27 patients in the study cohort, 22 (81%) had lung cancer and five (19%) had mesothelioma. Most PATs were solitary (93%) and nonocclusive (96%) and formed an obtuse angle to the vessel wall (89%). All PATs were eccentric within the involved PA and were located within the RT volume. The time from completion of RT to initial diagnosis of PAT on CT ranged from 53 to 2522 days (mean, 675 days). Radiation-induced lung fibrosis was present in the ipsilateral lung in all patients. No evidence of additional PA filling defects that suggested embolization were seen on follow-up images of any of the patients, even those who did not receive anticoagulant therapy. CONCLUSION. In situ PAT associated with RT, which to our knowledge has not previously been described in the English literature, has imaging features different from those of acute pulmonary emboli and does not appear to embolize. Radiologist awareness of PAT can facilitate accurate diagnosis and impact management.

Recognizing Radiation Therapy-related Complications in the Chest.

Radiation therapy is one of the cornerstones for the treatment of thoracic malignancies. Although advances in radiation therapy technology have improved the delivery of radiation considerably, adverse effects are still common. Postirradiation changes affect the organ or tissue treated and the neighboring structures. Advances in external-beam radiation delivery techniques and how these techniques affect the expected thoracic radiation-induced changes are described. In addition, how to distinguish these expected changes from complications such as infection and radiation-induced malignancy, and identify treatment failure, that is, local tumor recurrence, is reviewed. ©RSNA, 2019.

Leukemic Involvement in the Thorax.

Leukemias are malignancies in which abnormal white blood cells are produced in the bone marrow, resulting in compromise of normal bone marrow hematopoiesis and subsequent cytopenias. Leukemias are classified as myeloid or lymphoid depending on the type of abnormal cells produced and as acute or chronic according to cellular maturity. The four major types of leukemia are acute myeloid leukemia, chronic myeloid leukemia, acute lymphoblastic leukemia, and chronic lymphocytic leukemia. Clinical manifestations are due to either bone marrow suppression (anemia, thrombocytopenia, or neutropenia) or leukemic organ infiltration. Imaging manifestations of leukemia in the thorax are myriad. While lymphadenopathy is the most common manifestation of intrathoracic leukemia, leukemia may also involve the lungs, pleura, heart, and bones and soft tissues. Myeloid sarcomas occur in 5%-7% of patients with acute myeloid leukemia and represent masses of myeloid blast cells in an extramedullary location. ©RSNA, 2019.

Diagnostic approach to the anterior/prevascular mediastinum for radiologists.

The mediastinum contains vital vascular and nonvascular organs and other structures, and a wide variety of neoplasms and other abnormalities may originate from this anatomic region of the chest. Division of the mediastinum into distinct compartments helps narrow the differential diagnosis of mediastinal abnormalities detected on imaging studies, assists the planning of biopsy and surgical procedures, and facilitates communication between healthcare providers in the multidisciplinary setting. Numerous different models have been developed and used by radiologists, surgeons, and anatomists. Recently, the International Thymic Malignancy Interest Group (ITMIG) developed a new classification model of the mediastinal compartments based on cross-sectional imaging that has been accepted as a new standard. Although mediastinal pathology may be first identified on chest radiographs, cross-sectional imaging techniques such as computed tomography (CT) and magnetic resonance (MR) imaging play critical roles in the identification, localization, and characterization of mediastinal lesions. CT is considered the imaging modality of choice to evaluate most masses; however, MR imaging is superior to CT in differentiating between cystic and solid lesions, identifying cystic and solid components within complex masses, and distinguishing thymic hyperplasia and normal thymus from thymic epithelial neoplasms and other neoplasms. In this article, the new ITMIG classification of mediastinal compartments is presented along with approaches to the imaging evaluation of masses in the anterior/prevascular mediastinum.

Determining extent of invasion and follow-up of thymic epithelial malignancies.

Thymic malignancies may exhibit aggressive behavior such as invasion of adjacent structures and involvement of the pleura and pericardium. The role of imaging in the evaluation of primary thymic neoplasms is to properly assess tumor staging, with emphasis on the detection of local invasion and distant spread of disease, correctly identifying candidates for preoperative neoadjuvant therapy. Different imaging modalities are used in the initial investigation of thymic malignancies including chest radiography, computed tomography (CT), magnetic resonance imaging (MRI) and positron emission tomography (PET), in particular with [18F] fluorodeoxyglucose (FDG). At this moment, CT is the most common imaging modality on the assessment of thymic malignancies. MRI has the benefit of no emission of damaging ionizing radiation reducing the radiation dose to the patient when compared with CT. For this reason, MRI has been playing an important role in the evaluation of tumor invasion and follow up imaging studies which becomes even more relevant in young patients or those patients with prior history of radiation therapy.

Pitfalls and Misinterpretations of Cardiac Findings on PET/CT Imaging: A Careful Look at the Heart in Oncology Patients.

Positron emission tomography (PET) computed tomography (CT) with 2-[fluorine-18] fluoro-2-deoxy-d-glucose (FDG) has been established as an effective modality for evaluation of cancer. Interpretations of patterns of physiologic 18F-FDG uptake by the heart is particularly difficult given the wide normal variations of 18F-FDG metabolic activity observed. Atypical patterns of focal or diffuse physiologic cardiac 18F-FDG uptake and post-therapeutic effects after radiation therapy, systemic diseases, or cardiomyopathy may also be confused with malignant disease on 18F-FDG PET/CT. In this article, we review the variations of normal cardiac 18F-FDG uptake observed in oncology patients and the appearances of other patterns of pathologic metabolic activity, related or not related to the malignancy being investigated, that may lead to false-negative and false-positive results.

Imaging of Radiation Treatment of Lung Cancer.

Radiation therapy is an important modality in the treatment of patients with lung cancer. Recent advances in delivering radiotherapy were designed to improve loco-regional tumor control by focusing higher doses on the tumor. More sophisticated techniques in treatment planning include 3-dimensional conformal radiation therapy, intensity-modulated radiotherapy, stereotactic body radiotherapy, and proton therapy. These methods may result in nontraditional patterns of radiation injury and various radiologic appearances that can be mistaken for recurrence, infection and other lung diseases. Knowledge of radiological manifestations, awareness of new radiation delivery techniques and correlation with radiation treatment plans are essential in order to correctly interpret imaging in these patients.

Imaging on Lung Cancer and Treatment with Targeted Therapy.

The identification of genetic mutations known as oncogenic driver mutations that lead to the growth and survival of cancer cells has been an important advance in the field of oncology. Treatment in advanced non-small-cell lung cancer (NSCLC) has transitioned from a more general approach to a more personalized approach based on genetic mutations of the cancer itself. Common mutations detected in patients with advanced NSCLC include mutations of epidermal growth factor receptor and anaplastic lymphoma kinase (ALK). Targeted therapies are aimed at the products of these gene mutations and include erlotinib (used in epidermal growth factor receptor mutant NSCLC) and crizotinib (used in anaplastic lymphoma kinase positive NSCLC). In this review, we discuss common genetic mutations in advanced NSCLC, the role of targeted therapies, and imaging findings that can be associated with various genetic mutations.

Staging Lung Cancer: Metastasis.

The updated eighth edition of the tumor, node, metastasis (TNM) classification for lung cancer includes revisions to T and M descriptors. In terms of the M descriptor, the classification of intrathoracic metastatic disease as M1a is unchanged from TNM-7. Extrathoracic metastatic disease, which was classified as M1b in TNM-7, is now subdivided into M1b (single metastasis, single organ) and M1c (multiple metastases in one or multiple organs) descriptors. In this article, the rationale for changes in the M descriptors, the utility of preoperative staging with PET/computed tomography, and the treatment options available for patients with oligometastatic disease are discussed.

Lung Cancer: Posttreatment Imaging: Radiation Therapy and Imaging Findings.

In this review, we discuss the different radiation delivery techniques available to treat non-small cell lung cancer, typical radiologic manifestations of conventional radiotherapy, and different patterns of lung injury and temporal evolution of the newer radiotherapy techniques. More sophisticated techniques include intensity-modulated radiotherapy, stereotactic body radiotherapy, proton therapy, and respiration-correlated computed tomography or 4-dimensional computed tomography for radiotherapy planning. Knowledge of the radiation treatment plan and technique, the completion date of radiotherapy, and the temporal evolution of radiation-induced lung injury is important to identify expected manifestations of radiation-induced lung injury and differentiate them from tumor recurrence or infection.

MR Imaging of Thymic Epithelial Neoplasms.

Thymic epithelial neoplasms are malignant lesions that originate from the thymus and include thymoma, thymic carcinoma, and thymic neuroendocrine tumors. Although computed tomography (CT) is typically considered the imaging modality of choice for identifying thymic tumors, characterizing the primary neoplasm, and staging of disease, the role of magnetic resonance (MR) imaging continues to expand. MR imaging is effective in distinguishing thymic epithelial neoplasms and other malignant tumors from benign lesions in the prevascular mediastinum, can be used to characterize and stage thymic tumors in those patients with contraindications to contrast-enhanced CT, and can reveal morphologic features of thymic tumors. At least 15 different stage classifications have been proposed for thymic epithelial neoplasms and used to varying degrees in clinical practice. Recently, an official, consistent tumor node metastasis (TNM) staging system has been recognized by the American Joint Committee on Cancer (AJCC) and the Union for International Cancer Control (UICC), based on an analysis of a retrospective database performed by the International Association for the Study of Lung Cancer (IASLC) and the International Thymic Malignancy Interest Group (ITMIG). In this article, we discuss the appropriate utilization of MR imaging in the evaluation of patients with thymic epithelial neoplasms, key imaging features of the tumors, and the impact of imaging findings on overall staging.

Clinicoradiographic Predictors of Aggressive Biology in Lung Cancer With Ground Glass Components.

BACKGROUND: Ground glass opacities pose diagnostic challenges, and even after malignancy is confirmed, prognosis is often unclear. We sought to identify clinicoradiographic features that could predict aggressive tumor biology in lung adenocarcinoma with associated ground glass components. METHODS: A retrospective review of patients with resected lung adenocarcinoma from 2008 to 2013 was performed. Detailed radiographic features were reviewed by two radiologists. Logistic regression was used to identify risks of poor differentiation or a composite outcome of nodal metastases and lymphovascular invasion. RESULTS: In all, 79 patients met criteria for analysis. Larger tumor size (p = 0.04), increasing solid component (p = 0.01), pleural tags (p = 0.03), spiculation (p = 0.01), lobulation (p < 0.05), history of coronary artery disease (p = 0.04), and increasing number of pack-years smoking (p < 0.05) were associated with poorly differentiated tumors. However, after adjustment for size of the solid component, the associations between pleural tags, spiculation, and lobulation with poorly differentiated tumors were negated, whereas number of pack-years and history of coronary artery disease remained statistically significant (p = 0.01 and p = 0.03, respectively). There were no identified clinical or radiographic features associated with lymphovascular invasion/nodal metastasis. CONCLUSIONS: Several radiographic features were associated with aggressive tumor biology, a well-known finding. However, we found that none of these radiographic features remained relevant after we adjusted for the size of the solid component, indicating that radiographic features are not as important as previously believed. Further research will be required to identify reliable markers associated with favorable tumor biology. These studies will ultimately be critical in informing prognosis or guiding extent of resection.

Case Report: Metastatic Phyllodes Tumor.

This report describes the clinical presentation, imaging findings, and treatment options of a case of metastatic malignant phyllodes.