Faculty Bibliography

BACKGROUND:Mediastinal lesions are uncommon; studies on their distribution are in general small and from a single institution. Furthermore, these studies are usually based on pathology or surgical databases and therefore miss many lesions that are not biopsied and/or resected. Our aim was to identify the distribution of lesions in the mediastinum in a large international, multi-institutional cohort. MATERIAL AND METHODS/METHODS:At each participating institution, a standardized retrospective radiology database search for interpretations of CT, PET-CT and MRI scans including any of the following terms: "mediastinal nodule", "mediastinal lesion", "mediastinal mass" or "mediastinal abnormality" was performed (2011-2014). Standardized data were collected. Statistical analysis was performed. RESULTS:Amongst 3,308 cases, thymomas (27.8%), benign mediastinal cysts (20.0%) and lymphomas (16.1%) were most common. The distribution of lesions varied amongst mediastinal compartments; thymomas (38.3%), benign cysts (16.8%) and neurogenic tumors (53.9%) were the most common lesions in the prevascular, visceral and paravertebral mediastinum, respectively (p<0.001). Mediastinal compartment was associated with age; patients with paravertebral lesions were the youngest (p<0.0001). Mediastinal lesions differed by continent/country with benign cysts being the most common mediastinal lesions in China, thymomas in Europe and lymphomas in North America and Israel (p<0.001). Benign cysts, thymic carcinomas, and metastases were more commonly seen in larger hospitals, while lymphomas and thymic hyperplasia occurred more often in smaller hospitals (p<0.01). CONCLUSIONS:Our study confirmed that spectrum and frequency of mediastinal lesions depends on mediastinal compartment and age. This information provides helpful demographic data and is important when considering the differential diagnosis of a mediastinal lesion.

Anterior mediastinal lesions while rare, are heterogeneous in etiology, with broad differential considerations that may be narrowed by drawing on discriminating clinical, radiologic, and histopathologic features. This manuscript will review the radiographic and pathologic correlation of anterior mediastinal lesions of thymic, lymphomatous, and germ-cell origin.

SESSION TITLE: Tuesday Electronic Posters 3 SESSION TYPE: Original Inv Poster Discussion PRESENTED ON: 10/22/2019 01:00

Background: Anterior mediastinal lesions may be radiographically challenging to diagnose. Helpful imaging findings for the radiologist and pathologist, and relevant reporting information for the clinician will be reviewed. * Educational Goals/Teaching Points: Review multimodality imaging of thymic lesions with histopathologic correlation * Thymic hyperplasia * Thymic cyst * Thymolipoma * Staging of thymic carcinoma * Highlight distinguishing features between common anterior mediastinal lesions * Lymphoma * Germ Cell tumor * Thyroid * Present atypical anterior mediastinal lesions * Ectopic Parathyroid * Lymphangioma * Lipoma and Lipomatosis * Sarcoma * Nodal mesothelioma
Conclusion(s): Pathologists and radiologists often work in tandem to arrive at a unifying diagnosis, and understanding the radiopathologic correlation of anterior mediastinal lesions will serve to improve diagnosis and reporting

Objectives: To differentiate pulmonary tumor type by volumetric iodine quantification and texture analysis on dual-energy CT images.
Material(s) and Method(s): Radiology information system search for all contrast-enhanced DECT chest examinations from 1/1/2015-4/30/ 2018 was performed, filtering for those with pathology within 120 days, yielding 80 cases of pathologically-proven pulmonary lesions. 73 lesions meeting inclusion criteria were manually volumetrically segmented via open-source software using the low-kV DECT dataset. 3D-iodine quantification was achieved by mapping between high/low energy HU on a representative 2D-image, and applying to surrounding slices, with absolute iodine normalized to mid-descending aorta. Full Width Tenth Maximum was applied to each normalized iodine histogram, providing a single comprehensive measure of relative iodine concentration. Volumetric iodine values and first order texture features were assessed using Hoteling's T-squared multivariate analysis.
Result(s): 72 individuals (37 women, 35 men) with mean age 64 years were included. 44 primary, 25 metastatic, and 3 benign lesions were assessed; 22 with history of chemotherapy. Mean time between histopathologic sampling and imaging was 26 days. Mean, median and minimum volumetric iodine concentration were significant (P< 0.05) in distinguishing primary versus metastatic lesions, with P<0.01 for these measures between de novo primary and metastatic lesions. Metastatic lesions demonstrated higher mean iodine (1.2 mg/mL) in comparison to primary lesions (0.83 mg/mL). Mean and median 3D-iodine values significantly (P<0.05) differed between primary lung adenocarcinoma and squamous lesions (mean 0.95 mg/mL and 0.49 mg/mL, respectively). Skewness significantly differed between de novo versus treated primary (P=0.01), and metastatic versus primary lesions (P=0.03), and entropy between de novo primary and metastatic lesions (P<0.001), and treated versus non-treated metastases (P= 0.03).
Conclusion(s): Volumetric iodine quantification significantly differs between de novo primary versus metastatic, and primary lung adenocarcinoma versus squamous lesions. Texture features may also have a role in distinguishing tumor type and treatment response. Clinical Relevance Application: Potential role of DECT in distinguishing tumor type and treatment response

Background: Subsolid nodules account for 20% of lesions detected on CT lung cancer screening, and many are incidentally detected on routine CT exams. Persistent subsolid nodules may correlate with adenocarcinoma spectrum, though commonly are due to other etiologies, emphasizing the importance of accurate nodule characterization and management recommendations. This review will used a case-based approach to showcase how lesion description and management may differ from that of solid nodules, including application of Fleischner guidelines and discussion of management options. Educational Goals/Teaching Points: * Highlight technical pitfalls in evaluation of subsolid nodules * Highlight interpretive pitfalls in evaluation of subsolid nodules * Review differential considerations including adenocarcinoma spectrum: AAH, AIS, MIA, Invasive adenocarcinoma * Describe differential considerations beyond the adenocarcinoma spectrum, such as: * Neoplastic: lymphoma, metastatic disease, treatment response * Infectious/Inflammatory: organizing pneumonia, eosinophilic pneumonia, alveolar sarcoid, various infection, drug reaction * Adapt management guidelines to diverse clinical scenarios: age, multiplicity, baseline versus follow-up, incidental versus screening * Explain treatment options for subsolid adenocarcinoma lesions including emerging technology such as cryoablation
Conclusion(s): Subsolid nodules are commonly encountered clinically, with accurate interpretation based on avoiding technical pitfalls and providing relevant descriptors to differentiate actionable findings. Management guidelines and further steps must take into account nodule features, clinical risk factors, and patient specific considerations

Lung cancer remains the most common cause of cancer death in the United States of America and worldwide despite continued advances in lung cancer screening as well as surgical, medical, and radiation oncological treatments. Adenocarcinoma is the most common histological subtype of primary lung cancer and has recently been reorganized into a spectrum ranging from preinvasive lesions to invasive adenocarcinoma. An understanding of the pathology, diagnosis, and management of the spectrum of lung adenocarcinoma is more important than ever, considering the central role of the radiologist. The aim of this review is to describe the subtypes of the lung adenocarcinoma spectrum in terms of histological and imaging features, their pattern of growth on imaging, management, staging, and evolving knowledge of tumor genetics.

Diseases that are predominantly peribronchovascular in distribution on computed tomography by definition involve the bronchi, adjacent vasculature, and associated lymphatics involving the central or axial lung interstitium. An understanding of diseases that can present with focal peribronchovascular findings is useful for establishing diagnoses and guiding patient management. This review will cover clinical and imaging features that may assist in differentiating amongst the various causes of primarily peribronchovascular disease.

The ACR Incidental Findings Committee presents recommendations for managing incidentally detected mediastinal and cardiovascular findings found on CT. The Chest Subcommittee was composed of thoracic radiologists who developed the provided guidance. These recommendations represent a combination of current published evidence and expert opinion and were finalized by informal iterative consensus. The recommendations address the most commonly encountered mediastinal and cardiovascular incidental findings and are not intended to be a comprehensive review of all incidental findings associated with these compartments. Our goal is to improve the quality of care by providing guidance on how to manage incidentally detected thoracic findings.