Bronchiolitis: A Practical Approach for the General Radiologist.

Radiologists consciously or unconsciously encounter bronchiolitis on images frequently. The purpose of this article is to simplify the concept of bronchiolitis to facilitate the formulation of a succinct and accurate differential diagnosis and suggest potential causes for the imaging findings. Direct and indirect signs of bronchiolitis that are seen on computed tomographic images are detailed. The most common causes of bronchiolitis are covered, including several distinct entities to be considered in specific clinical scenarios. In order of prevalence, the top two causes of bronchiolitis are infection and aspiration. Less common entities include respiratory bronchiolitis and hypersensitivity pneumonitis, which tend to manifest with ground-glass centrilobular nodules. Some types of bronchiolitis affect specific ethnic groups or are associated with a characteristic clinical history. For example, diffuse panbronchiolitis typically affects Japanese subjects. Constrictive bronchiolitis should be considered in lung transplant recipients with ongoing rejection. Given the high frequency of bronchiolitis, radiologists should develop a systematic approach to both cellular and constrictive bronchiolitis. Recognition of specific clinical or imaging characteristics may be sufficient for providing a relevant differential diagnosis. ©RSNA, 2017.

Multimodality Imaging Findings in Carcinoid Tumors: A Head-to-Toe Spectrum.

Carcinoid tumors are a rare biologically heterogeneous group of neuroendocrine tumors with a spectrum ranging from benign indolent to aggressive metastatic tumors. They belong to the category of amine precursor uptake and decarboxylase tumors, or apudomas. The most common sites for primary locations are the gastrointestinal and respiratory tracts; however, any organ can be involved. The clinical presentation depends on location, aggressiveness, production of biologically active amines and peptides, paraneoplastic syndromes, and tendency for metastasis. Their reported age-adjusted incidence has increased in recent years, partly due to improved detection at radiologic imaging and endoscopy. Not a ll neuroendocrine cell tumors are carcinoids. Numerous systems have been proposed regarding their nomenclature and classification. Cross-sectional and functional imaging plays an important role in diagnosis, lesion characterization, and staging. Awareness of nomenclature, classification, common sites of involvement, and imaging presentation are pivotal for making the diagnosis. Knowledge of the diverse clinical, pathologic, and radiologic spectrum of carcinoid tumors involving various organs of the body is important for diagnosis and patient management. ©RSNA, 2017.

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.

The 'wandering appendicolith'.

Acute appendicitis is a common pediatric surgical emergency. Successful surgical appendectomy requires removal of the appendix and its contents. A retained appendicolith is a complication that occurs when the appendicolith is expulsed from the appendix as a result of perforation or failure of removal during surgery. An ectopic appendicolith can migrate to a variety of ectopic locations, acting as a nidus for abscess. Clinical presentation may be delayed by days, weeks or even months after surgery. We present and discuss an unusual case of empyema caused by migration of an appendicolith into the chest cavity. Management of these retained appendicoliths requires drainage of the abscess and extraction of the appendicolith.

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.

Salvage Esophagectomy Definition Influences Comparative Outcomes in Esophageal Squamous Cell Cancers.

BACKGROUND: In retrospective studies the definition of salvage esophagectomy has been inconsistent and is a source of bias. We sought to describe how variability in the definition of salvage affects comparative outcomes of trimodality therapy (TMT) and bimodality therapy (BMT). METHODS: Patients with locally advanced esophageal squamous cell carcinoma who completed chemoradiation therapy (CRT) from 2002 to 2017 were identified. TMT included patients who had a planned esophagectomy after CRT. BMT included patients treated with CRT only plus salvage esophagectomy, variably defined as an esophagectomy occurring (A) 3 months after CRT; (B) 3 months after CRT, excluding delayed recovery; (C) 3 months after CRT, excluding delayed workup; or (D) 6 months after CRT. Long-term survival outcomes between the TMT and BMT groups were compared for each definition of salvage esophagectomy. Time to surgery was included a priori in a multivariable model for overall survival. RESULTS: Of 143 patients, 90 (63%) underwent esophagectomy and 53 (37%) received CRT only. Although the total patients remained the same, the composition of the TMT and BMT groups varied by salvage definitions A through D. Various definitions resulted in different 5-year survival rates for TMT vs BMT groups: (A) 56% vs 39%, (B) 61% vs 34%, (C) 50% vs 42%, and (D) 51% vs 39%. In a Cox multivariable analysis age and proximal/middle esophageal tumors were associated with worse postoperative survival, but time to surgery was not. CONCLUSIONS: Slight variations in the definition of salvage esophagectomy can influence the interpretation of TMT and BMT outcomes. Future studies should consistently define treatment groups.

Thoracic manifestations of inflammatory bowel disease.

OBJECTIVE: The purpose of this article is to present the spectrum of inflammatory bowel disease manifestations in the chest, including the airways, lung parenchyma, pulmonary vasculature, and serosal surfaces. CONCLUSION: The spectrum of inflammatory bowel disease manifestations in the chest is broad, and the manifestations may mimic other diseases. Knowledge of these manifestations in conjunction with pertinent clinical data is essential for establishing the correct diagnosis and treatment.

Lipoid pneumonia: spectrum of clinical and radiologic manifestations.

OBJECTIVE: Lipoid pneumonia results from accumulation of lipids in the alveoli and can be either exogenous or endogenous in cause based on the source of the lipid. Exogenous lipoid pneumonia is caused by inhalation or aspiration of animal fat or vegetable or mineral oil. Endogenous lipoid pneumonia is usually associated with bronchial obstruction. The purpose of this article is to review the pathogenesis and clinical and radiologic manifestations of exogenous and endogenous lipoid pneumonia. CONCLUSION: The ability to recognize the radiologic manifestations of lipoid pneumonia is important because, in the appropriate clinical setting, these findings can be diagnostic.

MR Imaging of Pleural Neoplasms.

The pleura may be affected by primary tumors or metastatic spread of intrathoracic or extrathoracic neoplasms. Primary pleural neoplasms represent ∼10% of all pleural tumors, and malignant lesions are more common than benign lesions. The most common primary tumors include malignant pleural mesothelioma and solitary fibrous tumor. Although pleural neoplasms may initially be evaluated with computed tomography (CT) and/or fluorodeoxyglucose positron emission tomography (PET)/CT, magnetic resonance (MR) imaging is complementary to these other imaging modalities for disease staging and evaluation of patients. In this article, we discuss the etiology, clinical presentation, and imaging of pleural neoplasms, with specific attention given to the role of MR imaging.

MR Imaging of Mediastinal Masses.

The mediastinum contains vital vascular and nonvascular structures and organs, and a wide variety of abnormalities may arise from this region of the thorax. Although mediastinal masses may be initially detected on chest radiography, cross-sectional imaging plays an important role in the identification and evaluation of mediastinal lesions, enabling the formulation of focused differential diagnoses and ultimately guiding management. Computed tomography (CT) is considered the imaging modality of choice for evaluating most mediastinal masses; however, the role of magnetic resonance (MR) imaging continues to expand, as it is superior to CT in differentiating between cystic and solid masses, identifying cystic and solid components within complex lesions, and distinguishing thymic hyperplasia and normal thymus from thymic epithelial neoplasms and other neoplasms. In addition, it facilitates the staging and restaging of patients with thymic epithelial neoplasms and other tumors that cannot undergo contrast-enhanced CT imaging due to severe contrast allergy and/or impaired renal function. As division of the mediastinum into specific compartments is beneficial for diagnostic and treatment planning purposes and facilitates communication between clinicians in a multidisciplinary setting, a new classification model based on cross-sectional imaging has been developed by the International Thymic Malignancy Interest Group (ITMIG) and accepted as a new standard. In this article, we describe the role of MR imaging in the evaluation of mediastinal masses in conjunction with the new mediastinal compartment classification system introduced by ITMIG.

Characterizing proton-activated materials to develop PET-mediated proton range verification markers.

Conventional proton beam range verification using positron emission tomography (PET) relies on tissue activation alone and therefore requires particle therapy PET whose installation can represent a large financial burden for many centers. Previously, we showed the feasibility of developing patient implantable markers using high proton cross-section materials ((18)O, Cu, and (68)Zn) for in vivo proton range verification using conventional PET scanners. In this technical note, we characterize those materials to test their usability in more clinically relevant conditions. Two phantoms made of low-density balsa wood (~0.1 g cm(-3)) and beef (~1.0 g cm(-3)) were embedded with Cu or (68)Zn foils of several volumes (10-50 mm(3)). The metal foils were positioned at several depths in the dose fall-off region, which had been determined from our previous study. The phantoms were then irradiated with different proton doses (1-5 Gy). After irradiation, the phantoms with the embedded foils were moved to a diagnostic PET scanner and imaged. The acquired data were reconstructed with 20-40 min of scan time using various delay times (30-150 min) to determine the maximum contrast-to-noise ratio. The resultant PET/computed tomography (CT) fusion images of the activated foils were then examined and the foils' PET signal strength/visibility was scored on a 5 point scale by 13 radiologists experienced in nuclear medicine. For both phantoms, the visibility of activated foils increased in proportion to the foil volume, dose, and PET scan time. A linear model was constructed with visibility scores as the response variable and all other factors (marker material, phantom material, dose, and PET scan time) as covariates. Using the linear model, volumes of foils that provided adequate visibility (score 3) were determined for each dose and PET scan time. The foil volumes that were determined will be used as a guideline in developing practical implantable markers.

Thoracic manifestations of tropical parasitic infections: a pictorial review.

Parasitic infections are distributed worldwide and affect hundreds of millions of individuals-primarily those living in endemic areas or in regions with a high rate of immigration from endemic areas-causing significant morbidity and mortality. A broad spectrum of parasitic infections (eg, amebiasis, malaria, trypanosomiasis, ascariasis, strongyloidiasis, dirofilariasis, cystic echinococcosis, schistosomiasis, paragonimiasis) frequently affect the lungs, mediastinum, and thoracic wall, manifesting with abnormal imaging findings that often make diagnosis challenging. Although most of these infections result in nonspecific abnormalities, familiarity with their imaging features as well as their epidemiologic, clinical, and physiopathologic characteristics may be helpful to the radiologist in formulating an adequate differential diagnosis.

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.

Endoscopic Ultrasound Estimates for Tumor Depth at the Gastroesophageal Junction Are Inaccurate: Implications for the Liberal Use of Endoscopic Resection.

BACKGROUND: Endoscopic resection is increasingly utilized for treating early stage esophageal cancer, and endoscopic ultrasound (EUS) frequently guides treatment selection. Studies report greater than 80% sensitivity and 90% specificity, but our experience suggests less accuracy at the gastroesophageal (GE) junction. The objective of this study is to determine the accuracy of EUS for depth of GE junction cancer and the potential treatment implications. METHODS: A retrospective review of a prospective database was performed for patients from 1995 to 2014 with GE junction esophageal cancer that underwent EUS staging and resection (surgical or endoscopic) without neo-adjuvant therapy. Patient, tumor, EUS, and pathologic characteristics were examined. RESULTS: For the 181 patients that met criteria, the median age was 66 years, 17% were female, 91% white, and 98% had adenocarcinoma. Concordance between EUS (u) T and pathologic (p) T was 48%, with 23% under-staged and 29% over-staged. The EUS was accurate in the following: uT0 6% (1 of 18); uT1a 56% (23 of 41); uT1b 58% (41 of 71); uT2 10% (2 of 21); and uT3 70% (21 of 30). Inaccurate EUS depth had potential to lead to over-treatment in 38% (27 of 71) of uT1b and 76% (16 of 21) of uT2. In 50% of pT1a tumors, EUS depth was T1b or greater. Logistic regression revealed tumor length (continuous variable) to be associated with inaccurate uT (p = 0.016). Accurately staged tumors were significantly longer than inaccurately staged tumors (2.7 vs 1.7 cm, p = 0.011). CONCLUSIONS: Early to intermediate GE junction tumors are frequently over-staged. This highlights the importance of diagnostic endoscopic resection for determining accurate tumor depth and selecting correct therapy.

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.