Imaging Patterns of Pneumonia.

Imaging findings of pneumonia are diverse, with frequent overlap between the various infectious etiologies of pneumonia, as well as various other disease conditions, including inflammatory conditions, vasculitis, and malignancy. In the appropriate clinical context, a number of imaging findings and the patterns that they form on imaging may provide clues that enable radiologists and clinicians to narrow the differential diagnostic considerations. Although a definite diagnosis can rarely be provided based on imaging findings alone, the combination of clinical, imaging, and laboratory findings are usually sufficient for accurate diagnosis and management decisions. It is important for radiologists to recognize the wide variety of imaging patterns that occur with different causes of pneumonia, and recognize specific imaging signs of certain infections when present, thereby facilitating diagnosis and optimizing patient care.

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.

Multimodality Imaging of Focal and Diffuse Fibrosing Mediastinitis.

Fibrosing mediastinitis is a rare benign but potentially life-threatening process that occurs because of proliferation of fibrotic tissue in the mediastinum. The focal subtype is more common and typically is associated with an abnormal immunologic response to Histoplasma capsulatum infection. Affected patients are typically young at presentation, but a wide age range has been reported, without a predilection for either sex. The diffuse form may be idiopathic or associated with autoimmunity, usually affects middle-aged and/or elderly patients, and is more common in men. For both subtypes, patients present with signs and symptoms related to obstruction or compression of vital mediastinal structures. The most common presenting signs and symptoms are cough, dyspnea, recurrent pneumonia, hemoptysis, and pleuritic chest pain. Patients with the diffuse subtype may have additional extrathoracic symptoms depending on the other organ systems involved. Because symptom severity is variable, treatment should be individualized with therapies tailored to alleviate compression of the affected mediastinal structures. Characteristic imaging features of fibrosing mediastinitis include infiltrative mediastinal soft tissue (with or without calcification) with compression or obstruction of mediastinal vascular structures and/or the aerodigestive tract. When identified in the appropriate clinical setting, these characteristic features allow the radiologist to suggest the diagnosis of fibrosing mediastinitis. Careful assessment is crucial at initial and follow-up imaging for exclusion of underlying malignancy, assessment of disease progression, identification of complications, and evaluation of treatment response. Online supplemental material is available for this article. ©RSNA, 2019.

Evaluation after Orthotopic Heart Transplant: What the Radiologist Should Know.

Orthotopic heart transplant (OHT) is the treatment of choice for end-stage heart disease. As OHT use continues and postoperative survival increases, multimodality imaging evaluation of the transplanted heart will continue to increase. Although some of the imaging is performed and interpreted by cardiologists, a substantial proportion of images are read by radiologists. Because there is little to no consensus on a systematic approach to patients after OHT, radiologists must become familiar with common normal and abnormal posttreatment imaging features. Intrinsic transplant-related complications may be categorized on the basis of time elapsed since transplant into early (0-30 days), intermediate (1-12 months), and late (>12 months) stages. Although there can be some overlap between stages, it remains helpful to consider the time elapsed since surgery, because some complications are more common at certain stages. Recognition of differing OHT surgical techniques and their respective postoperative imaging features helps to avoid image misinterpretation. Expected early postoperative findings include small pneumothoraces, pleural effusions, pneumomediastinum, pneumopericardium, postoperative atelectasis, and an enlarged cardiac silhouette. Early postoperative complications also can include sternal dehiscence and various postoperative infections. The radiologist's role in the evaluation of allograft failure and rejection, endomyocardial biopsy complications, cardiac allograft vasculopathy, and posttransplant malignancy is highlighted. Because clinical manifestations of disease may be delayed in transplant recipients, radiologists often recognize postoperative complications on the basis of imaging and may be the first to suggest a specific diagnosis and thus positively affect patient outcomes. Online supplemental material is available for this article. ©RSNA, 2019.

Postcardiovascular Surgery Findings of the Thoracic Aorta.

Various disease processes may affect the ascending thoracic aorta, aortic arch, and/or descending thoracic aorta, including aneurysms, dissections, intramural hematomas, penetrating atherosclerotic ulcers, and aortic transection/rupture. Many of those conditions require surgical intervention for repair. Multiple open and endovascular techniques are used for treatment of thoracic aortic pathology. It is imperative that the cardiothoracic radiologist have a thorough knowledge of the surgical techniques available, the expected postoperative imaging findings, and the complications that may occur to accurately diagnose life-threatening pathology when present, and avoid common pitfalls of misinterpreting normal postoperative findings as pathologic conditions.

Post-operative imaging of pulmonary vessels.

Complications following cardiothoracic surgery are responsible for prolonged hospital stay, increase cost in patient care and increased morbidity and mortality. Vascular complications in particular are significant contributors to poor patient outcome due to either hemorrhage or thrombosis and ischemia. Evaluation of vascular complications in the postoperative patient requires a rapid and reliable imaging approach. Vascular complications after cardiothoracic surgery include pulmonary artery thrombosis, pseudoaneurysm, pulmonary vein thrombosis, vascular fistulas, stenosis and infarction. Multidetector CT (MDCT), often the imaging modality of choice, offers a one-stop-shop capability to visualize the entire cardiothoracic vasculature, airways, lung parenchyma, mediastinum and chest wall with excellent temporal and spatial resolution.

Primary Pulmonary Anaplastic Large Cell Lymphoma: A Rare Malignancy and Rare Cause of the Luftsichel Sign.

Primary pulmonary lymphomas are rare with primary pulmonary non-Hodgkin lymphoma accounting for only 0.3% of primary lung neoplasms. Of these, the large majority are made up of marginal zone B-cell lymphoma and diffuse large B-cell lymphoma. We present a case of a very rare primary pulmonary anaplastic large cell lymphoma presenting as the luftsichel sign on chest radiograph. Pertinent imaging and pathology findings are discussed.

Emerging Concepts in Intramural Hematoma Imaging.

Intramural hematoma (IMH) is included in the spectrum of acute aortic syndrome and appears as an area of hyperattenuating crescentic thickening in the aortic wall that is best seen at nonenhanced computed tomography. IMH is historically believed to originate from ruptured vasa vasorum in the aortic media without an intimal tear, but there are reports of small intimomedial tears identified prospectively at imaging or found at surgery in some cases of IMH. These reports have blurred the distinction between aortic dissection and IMH and raise questions about what truly distinguishes the entities that compose acute aortic syndrome. The pathophysiology of these subgroups and the controversies surrounding their differentiation are discussed. The natural history of IMH is highly variable; it may resolve or progress to aneurysm, dissection, or rupture. The authors review various imaging prognostic factors that should be reported by the radiologist, including Stanford classification, maximum aortic diameter, maximum IMH thickness, focal contrast enhancement (including ulcerlike projection and intramural blood pool), and pleural or pericardial effusion. Medical (nonsurgical) versus surgical treatment strategies depend primarily on the Stanford classification, although more recent studies of Asian cohorts report success of initial medical treatment in patients with Stanford type A IMH, with timed (delayed) surgery for patients who develop complications. Understanding the imaging appearance and prognostic factors of IMH helps the radiologist and surgeon identify patients at greatest risk for complications to ensure appropriate treatment and improve patient outcomes. (©)RSNA, 2016.

Thoracic Metastases From Primary Hepatobiliary and Pancreatic Malignancies: Predictable Patterns of Metastatic Spread.

This article reviews common and uncommon patterns of thoracic metastatic disease in primary hepatobiliary and pancreatic malignancies that are often overlooked or improperly diagnosed because of atypical location or imaging appearance. An understanding of the pathophysiology and routes of tumor spread aids in tailoring a search pattern allowing for more accurate evaluation of disease activity.

Imaging features of thoracic metastases from gynecologic neoplasms.

Gynecologic malignancies are a heterogeneous group of common neoplasms and represent the fourth most common malignancy in women. Thoracic metastases exhibit various imaging patterns and are usually associated with locally invasive primary neoplasms with intra-abdominal spread. However, thoracic involvement may also occur many months to years after initial diagnosis or as an isolated finding in patients without evidence of intra-abdominal neoplastic involvement. Thoracic metastases from endometrial carcinoma typically manifest as pulmonary nodules and lymphadenopathy. Thoracic metastases from ovarian cancer often manifest with small pleural effusions and subtle pleural nodules. Thoracic metastases to the lungs, lymph nodes, and pleura may also exhibit calcification and mimic granulomatous disease. Metastases from fallopian tube carcinomas exhibit imaging features identical to those of ovarian cancers. Most cervical cancers are of squamous histology, and while solid pulmonary metastases are more common, cavitary metastases occur with some frequency. Metastatic choriocarcinoma to the lung characteristically manifests with solid pulmonary nodules. Some pulmonary metastases from gynecologic malignancies exhibit characteristic features such as cavitation (in squamous cell cervical cancer) and the "halo" sign (in hemorrhagic metastatic choriocarcinoma) at computed tomography (CT). However, metastases from common gynecologic malignancies may be subtle and indolent and may mimic benign conditions such as intrapulmonary lymph nodes and remote granulomatous disease. Therefore, radiologists should consider the presence of locoregional disease as well as elevated tumor marker levels when interpreting imaging studies because subtle imaging findings may represent metastatic disease. Positron emission tomography/CT may be helpful in identifying early locoregional and distant tumor spread.

Primary pericardial tumors.

Primary pericardial tumors are rare and may be classified as benign or malignant. The most common benign lesions are pericardial cysts and lipomas. Mesothelioma is the most common primary malignant pericardial neoplasm. Other malignant tumors include a wide variety of sarcomas, lymphoma, and primitive neuroectodermal tumor. When present, signs and symptoms are generally nonspecific. Patients often present with dyspnea, chest pain, palpitations, fever, or weight loss. Although the imaging approach usually begins with plain radiography of the chest or transthoracic echocardiography, the value of these imaging modalities is limited. Cross-sectional imaging, on the other hand, plays a key role in the evaluation of these lesions. Computed tomography and magnetic resonance imaging allow further characterization and may, in some cases, provide diagnostic findings. Furthermore, the importance of cross-sectional imaging lies in assessing the exact location of the tumor in relation to neighboring structures. Both benign and malignant tumors may result in compression of vital mediastinal structures. Malignant lesions may also directly invade structures, such as the myocardium and great vessels, and result in metastatic disease. Imaging plays an important role in the detection, characterization, and staging of pericardial tumors; in their treatment planning; and in the posttreatment follow-up of affected patients. The prognosis of patients with benign tumors is good, even in the few cases in which surgical intervention is required. On the other hand, the length of survival for patients with malignant pericardial tumors is, in the majority of cases, dismal.

Spectrum of pulmonary neuroendocrine proliferations and neoplasms.

Neuroendocrine neoplasms are ubiquitous tumors found throughout the body, most commonly in the gastrointestinal tract followed by the thorax. Neuroendocrine cells occur normally in the bronchial and bronchiolar epithelium and may be solitary or may occur in clusters. Although neuroendocrine cell proliferations may be found in association with chronic lung disease, a broad range of neuroendocrine proliferations and neoplasms may occur and exhibit variable biologic behavior. Diffuse idiopathic neuroendocrine cell hyperplasia (DIPNECH) is a diffuse idiopathic form of neuroendocrine cell hyperplasia and is considered a preinvasive lesion that may give rise to carcinoid tumors. Patients with DIPNECH are typically older women who may be asymptomatic or may present with chronic respiratory symptoms. DIPNECH manifests as multifocal bilateral pulmonary micronodules on expiratory high-resolution computed tomographic (CT) images; the air trapping is secondary to constrictive bronchiolitis. Carcinoid tumors are low-grade malignant neoplasms that typically affect symptomatic children and young adults. Carcinoids manifest as well-defined pulmonary nodules or masses that are often closely related to central bronchi. They may exhibit intrinsic calcification and contrast material enhancement at CT, and patients with carcinoids may have postobstructive atelectasis and pneumonia. Although typical carcinoids are indolent neoplasms and patients have a good prognosis, atypical carcinoids are aggressive malignancies with a propensity for metastasis. Both are optimally treated with complete surgical excision. Large cell neuroendocrine carcinoma and small cell lung cancer are highly aggressive neuroendocrine malignancies that usually affect elderly smokers. These tumors manifest with large peripheral or central pulmonary masses. Local invasion, intrathoracic lymphadenopathy, and distant metastases are frequent at presentation. As a result, affected patients may not be candidates for surgical resection, are often treated with chemotherapy with or without radiation, and have a poor prognosis.

Ascending thoracic aorta: postoperative imaging evaluation.

Advances in computed tomography (CT) scanners and electrocardiographic gating techniques have resulted in superior image quality of the ascending aorta and increased the use of CT angiography for evaluating the postoperative ascending aorta. Several abnormalities of the ascending aorta and aortic arch often require surgery, and various open techniques may be used to reconstruct the aorta, such as the Wheat procedure, in which both an ascending aortic graft and an aortic valve prosthesis are implanted; the Cabrol and modified Bentall procedures, in which a composite synthetic ascending aorta and aortic valve graft are placed; the Ross procedure, in which the aortic valve and aortic root are replaced with the patient's native pulmonary valve and proximal pulmonary artery; valve-sparing procedures such as the T. David-V technique, which leaves the native aortic valve intact; and more extensive arch repair procedures such as the elephant trunk and arch-first techniques, in which interposition or inclusion grafts are implanted, with or without replacement of the aortic valve. Normal postoperative imaging findings, such as hyperattenuating felt pledgets, prosthetic conduits, and reanastomosis sites, may mimic pathologic processes. Postoperative complications seen at CT angiography that require further intervention include pseudoaneurysms, anastomotic stenoses, dissections, and aneurysms. Radiologists must be familiar with these procedures and their imaging features to identify normal postoperative appearances and complications.

Tumors of the pulmonary artery and veins.

The pulmonary vasculature may be involved by different primary and secondary tumors. Poorly differentiated and undifferentiated sarcomas are the most common primary tumors of the pulmonary arteries. They tend to affect the large caliber pulmonary vessels and present with predominantly intraluminal growth. Pulmonary and mediastinal metastasis are common, and prognosis is poor. Clinical and imaging manifestations may mimic those of pulmonary embolism. Dyspnea, chest pain, cough, and hemoptysis are the most common presenting symptoms. Primary sarcomas arising from the central pulmonary veins are less common than their arterial counterpart. Secondary involvement of the pulmonary arteries and veins by primary and metastatic pulmonary malignancies is more common. Tumoral embolism may also affect the pulmonary arteries. They may develop from different intrathoracic and extrathoracic malignancies and may be indistinguishable from venous thromboembolism. It may manifest as cor pulmonale with right cardiac strain and dilated pulmonary arteries. Computed tomography, magnetic resonance imaging, and fluorodeoxyglucose positron emission tomography may help in the differentiation between these 2 conditions.

Aortic tumors.

Increasing use of cross-sectional studies has resulted in a concomitant increase in the number of intravascular and perivascular masses found in patients being studied for a multitude of thoracic conditions. As a consequence, there needs to be an awareness of the imaging findings of certain unusual abnormalities that will help prevent erroneous treatment (eg, anticoagulation) and expedite proper therapy. Although the spectrum of conditions that may present as intravascular, mural, and extravascular abnormalities in and around the aorta is broad, imaging features like contrast enhancement, signal intensity, and metabolic activity may help in making the correct diagnosis. Examples of the imaging presentation of these rare primary tumors and more common secondary tumors that may affect the aorta are presented in this article.

The effects of ambient lighting in chest radiology reading rooms.

Under typical dark chest radiography reading room conditions, a radiologist's pupils contract and dilate as their visual focus intermittently shifts between the high luminance monitor and the darker background wall, resulting in increased visual fatigue and degradation of diagnostic performance. A controlled increase of ambient lighting may minimize these visual adjustments and potentially improve comfort and accuracy. This study was designed to determine the effect of a controlled increase of ambient lighting on chest radiologist nodule detection performance. Four chest radiologists read 100 radiographs (50 normal and 50 containing a subtle nodule) under low (E=1 lx) and elevated (E=50 lx) ambient lighting levels on a DICOM-calibrated, medical-grade liquid crystal display. Radiologists were asked to identify nodule locations and rate their detection confidence. A receiver operating characteristic (ROC) analysis of radiologist results was performed and area under ROC curve (AUC) values calculated for each ambient lighting level. Additionally, radiologist selection times under both illuminance conditions were determined. Average AUC values did not significantly differ (p>0.05) between ambient lighting levels (estimated mean difference=-0.03; 95% CI, (-0.08, 0.03)). Average selection times decreased or remained constant with increased illuminance. The most considerable decreases occurred for false positive identification times (35.4±18.8 to 26.2±14.9 s) and true positive identification times (29.7±18.3 to 24.5±15.5 s). No performance differences were statistically significant. Study findings suggest that a controlled increase of ambient lighting within darkly lit chest radiology reading rooms, to a level more suitable for performance of common radiological tasks, does not appear to have a statistically significant effect on nodule detection performance.

Nonvascular, nontraumatic mediastinal emergencies in adults: a comprehensive review of imaging findings.

Given their high frequency, mediastinal emergencies are often perceived as being a result of external trauma or vascular conditions. However, there is a group of nonvascular, nontraumatic mediastinal emergencies that are less common in clinical practice, are less recognized, and that represent an important source of morbidity and mortality in patients. Nonvascular, nontraumatic mediastinal emergencies have several causes and result from different pathophysiologic mechanisms including infection, internal trauma, malignancy, and postoperative complications, and some may be idiopathic. Some conditions that lead to nonvascular, nontraumatic mediastinal emergencies include acute mediastinitis; esophageal emergencies such as intramural hematoma of the esophagus, Boerhaave syndrome, and acquired esophagorespiratory fistulas; spontaneous mediastinal hematoma; tension pneumomediastinum; and tension pneumopericardium. Although clinical findings of nonvascular, nontraumatic mediastinal emergencies may be nonspecific, imaging findings are often definitive. Awareness of various nonvascular, nontraumatic mediastinal emergencies and their clinical manifestations and imaging findings is crucial for making an accurate and timely diagnosis to facilitate appropriate patient management.

Chest neoplasms with infectious etiologies.

A wide spectrum of thoracic tumors have known or suspected viral etiologies. Oncogenic viruses can be classified by the type of genomic material they contain. Neoplastic conditions found to have viral etiologies include post-transplant lymphoproliferative disease, lymphoid granulomatosis, Kaposi's sarcoma, Castleman's disease, recurrent respiratory papillomatosis, lung cancer, malignant mesothelioma, leukemia and lymphomas. Viruses involved in these conditions include Epstein-Barr virus, human herpes virus 8, human papillomavirus, Simian virus 40, human immunodeficiency virus, and Human T-lymphotropic virus. Imaging findings, epidemiology and mechanism of transmission for these diseases are reviewed in detail to gain a more thorough appreciation of disease pathophysiology for the chest radiologist.

Silicone pulmonary embolism: report of 10 cases and review of the literature.

OBJECTIVE: To assess patient outcome and imaging findings of patients with pulmonary embolism of fluid silicone. METHODS: Medical records and imaging examinations of 10 patients with respiratory distress after illicit injection of fluid silicone were reviewed. Population consisted of 8 male (6 male-to-female transsexuals) and 2 female subjects. RESULTS: Average age was 29 years. Most common injection sites were gluteal and trochanteric. Respiratory symptoms developed between 15 minutes and 2 days after silicone injection. Five referred fever, 6 developed adult respiratory distress syndrome, and 2 subsequently died. Alveolar hemorrhage was demonstrated on pathological examination in 6, with silicone vacuoles in the lung parenchyma in 3. Computed tomography demonstrated peripheral ground glass opacities with interlobular septal thickening in all and peripheral airspace disease in 7. CONCLUSIONS: Illicit injection of large volumes of fluid silicone for cosmetic purposes is associated with pulmonary embolism and acute alveolar hemorrhage and is associated with a significant mortality.