The Dean Effect: An Aortic Arch Flow Artifact Mimicking Dissection.

The unique hemodynamics of the aortic arch create conditions for potential formation of a flow-related artifact that mimics disease on CT angiographic images. The hemodynamic basis for this artifact can be explained by fluid mechanics incorporating a mathematical principle known as the Dean number. Therefore, in this review, the artifact is referred to as the Dean effect. It is important for radiologists and other clinicians to recognize this artifact when encountered. It is also helpful for the interpreting radiologist to have a basic understanding of the relevant hemodynamic principles. This review provides an example of the artifact, reviews the basic underlying hemodynamics, and presents methods of how to prevent this artifact and distinguish it from pathologic mimics in clinical practice. Keywords: CT Angiography, Vascular, Thorax, Aorta, Artifacts, Blood, Dissection, Hemodynamics/Flow Dynamics © RSNA, 2022.

Intimal Sarcoma of the Great Vessels.

Intimal sarcomas of the pulmonary artery and aorta are rare entities with a poor prognosis. In many instances, pulmonary artery sarcomas are misinterpreted as acute or chronic pulmonary thromboembolism, whereas aortic intimal sarcomas are often misdiagnosed as protuberant atherosclerotic disease or intimal thrombus. Discernment of intimal sarcomas from these and other common benign entities is essential for the timely initiation of aggressive therapy. The most useful imaging modalities for assessment of a suspected intimal sarcoma include CT angiography, fluorine 18-fluorodeoxyglucose PET, and MRI. The authors discuss the clinical features, current treatment options, characteristic imaging findings, and underlying pathologic features of intimal sarcomas. The authors emphasize imaging discernment of intimal sarcomas and how their differential diagnosis is informed by knowledge of radiologic-pathologic correlation. The most reliable distinguishing imaging features are also emphasized to improve accurate and timely diagnosis. Online supplemental material is available for this article. ©RSNA, 2021.

Routes of Transdiaphragmatic Migration from the Abdomen to the Chest.

The diaphragm serves as an anatomic border between the abdominal and thoracic cavities. Pathologic conditions traversing the diaphragm are often incompletely described and may be overlooked, resulting in diagnostic delays. Several routes allow abdominal contents or pathologic processes to spread into the thorax, including along normal transphrenic structures, through congenital defects in the diaphragm, through inherent areas of weakness between muscle groups, or by pathways created by tissue destruction, trauma, or iatrogenic injuries. A thorough knowledge of the anatomy of the diaphragm can inform an accurate differential diagnosis. Often, intraperitoneal pathologic conditions crossing the diaphragm may be overlooked if axial imaging is the only approach to this complex region because of the horizontal orientation of much of the diaphragm. Multiplanar capabilities of volumetric CT and MRI provide insight into the pathways where pathologic conditions may traverse this border. Knowledge of these characteristic routes and use of multiplanar imaging are critical for depiction of specific transdiaphragmatic pathologic conditions.©RSNA, 2020.

Interventional Therapies for Thoracic Duct Injury and Intractable Chylothorax.

Injury to the thoracic duct with resultant chylothorax can cause significant patient morbidity and mortality. Conservative treatment strategies often fail to address the problem. Open surgical and percutaneous approaches are often required to manage patients with refractory chylothorax. This review describes in detail the major role of minimally invasive interventional therapies for thoracic duct (TD) injury. The review emphasizes strategies for identifying the TD on preprocedural imaging and describes various techniques for percutaneous access to the TD. The advantages and disadvantages of several approaches for accessing the duct are discussed. The technique of duct embolization is highlighted. The role of the minimally invasive percutaneous approach over open surgical approaches is discussed with a review of clinical outcomes, as reported in the literature. This review will also briefly discuss the surgical approach to TD ligation.

Innovative and Contemporary Interventions of Diaphragmatic Disorders.

The diaphragm is an inconspicuous fibromuscular septum, and disorders may result in respiratory impairment and morbidity and mortality when untreated. Radiologists need to accurately diagnose diaphragmatic disorders, understand the surgical approaches to diaphragmatic incisions/repairs, and recognize postoperative changes and complications. Diaphragmatic defects violate the boundary between the chest and abdomen, with the risk of herniation and strangulation of abdominal contents. In our surgical practice, patients with diaphragmatic hernias present acutely with incarceration and/or strangulation. Bochdalek hernias are commonly diagnosed in asymptomatic older adults on computed tomography; however, when viscera or a large amount of fat herniates into the chest, surgical intervention is strongly advocated. Morgagni hernias are rare in adults and typically manifest acutely with bowel obstruction. Patients with traumatic diaphragm injury may have an acute, latent, or delayed presentation, and radiologists should be vigilant in inspecting the diaphragm on the initial and all subsequent thoracoabdominal imaging studies. Almost all traumatic diaphragm injury are surgically repaired. Finally, with porous diaphragm syndrome, fluid, air, and tissue from the abdomen may communicate with the pleural space through diaphragmatic fenestrations and result in a catamenial pneumothorax or large pleural effusion. When the underlying disorder cannot be effectively treated, the goal of surgical intervention is to establish the diagnosis, incite pleural adhesions, and close diaphragmatic defects. Diaphragmatic plication may be helpful in patients with eventration or acquired injuries of the phrenic nerve, as it can stabilize the affected diaphragm. Phrenic nerve pacing may improve respiratory function in select patients with high cervical cord injury or central hypoventilation syndrome.

Presence of subpleural pulmonary interstitial emphysema as an indication of single or multiple alveolar ruptures on CT in patients with spontaneous pneumomediastinum.

Background There are no previous reports regarding the computed tomography (CT) findings of subpleural pulmonary interstitial emphysema (PIE) in patients with spontaneous pneumomediastinum. Purpose To evaluate CT findings of subpleural PIE that may indicate a direct site of terminal alveolar rupture. Material and Methods We retrospectively evaluated chest CT and the medical records of 34 patients with spontaneous pneumomediastinum. Subpleural PIE was defined as the presence of an interstitial air collection in the subpleural portion of the lungs excluding the bronchovascular bundle. Results Subpleural PIE on CT was identified in six of 34 patients (17.6%) with spontaneous pneumomediastinum. In four of these (66.7%), subpleural PIE was present in multiple lobes suggesting multiple simultaneous ruptures of terminal alveoli. The shape of subpleural PIE was elongated linear (4/6), branching and linear (1/6), and elliptical (1/6). Conclusion The presence of subpleural PIE on CT suggests an origin of pneumomediastinal air from alveolar rupture.

The IASLC/ITMIG Thymic Epithelial Tumors Staging Project: proposal for an evidence-based stage classification system for the forthcoming (8th) edition of the TNM classification of malignant tumors.

A universal and consistent stage classification system, which describes the anatomic extent of a cancer, provides a foundation for communication and collaboration. Thymic epithelial malignancies have seen little progress, in part because of the lack of an official system. The International Association for the Study of Lung Cancer and the International Thymic Malignancies Interest Group assembled a large retrospective database, a multispecialty international committee and carried out extensive analysis to develop proposals for the 8th edition of the stage classification manuals. This tumor, node, metastasis (TNM)-based system is applicable to all types of thymic epithelial malignancies. This article summarizes the proposed definitions of the T, N, and M components and describes how these are combined into stage groups. This represents a major step forward for thymic malignancies.

Imaging of whole-organ pancreas transplants.

Whole pancreas transplantation is an established treatment for selected patients with diabetic nephropathy or poorly controlled diabetes. Surgical techniques vary and have evolved over the past 4 decades. Imaging evaluation of the whole-pancreas transplant should begin with an understanding of the most commonly used surgical techniques and the spectrum of postoperative complications. Ultrasonography (US) should be the first-line modality in evaluating the pancreas allograft and vasculature. Computed tomography (CT) is useful in the assessment of extra-allograft processes, particularly in ruling out abscess formation or evaluating suspected bowel complications. Magnetic resonance (MR) imaging is reserved for cases in which complete evaluation with US or CT is not possible. MR angiography can help provide an accurate assessment of vascular abnormalities. The radiologist must be familiar with the spectrum of surgical techniques and the normal postoperative imaging appearances of the whole-pancreas transplant so as to be able to recognize abnormal postoperative findings. Supplemental material available at http://radiographics.rsna.org/lookup/suppl/doi:10.1148/rg.322115144/-/DC1.

The unicornuate uterus and its variants: clinical presentation, imaging findings, and associated complications.

This article will describe the different variants of the unicornuate uterus, their clinical presentation and imaging findings, as well their associated complications. We will also review the associated renal anomalies. Patients' symptoms and their imaging findings will vary depending on the unicornuate subtype. Radiologic evaluation includes a combination of hysterosalpingography, sonography, and magnetic resonance imaging. Complications include obstetric ones related to the small uterine size and endometriosis and ectopic pregnancies when a cavitary rudimentary uterine horn is present. Radiologists should be familiar with all variants of the unicornuate uterus as well as their clinical presentation and associated imaging findings.

Virtual autopsy: two- and three-dimensional multidetector CT findings in drowning with autopsy comparison.

PURPOSE: To retrospectively determine the multidetector computed tomographic (CT) virtual autopsy findings of death by drowning in comparison with autopsy findings. MATERIALS AND METHODS: The institutional review board of the Armed Forces Institute of Pathology approved this HIPAA-compliant study and did not require informed consent by the next of kin. Total-body multidetector CT was performed, immediately prior to routine autopsy, in 28 consecutive male subjects (mean age, 24.2 years) who died of drowning and a control group of 12 consecutive male subjects (mean age, 50.8 years) who died of sudden death from atherosclerotic coronary artery disease. Images were evaluated for the presence of fluid and sediment in the paranasal sinuses and airways, mastoid air cell fluid, frothy fluid in the airways, pulmonary opacity (ground-glass opacity or airspace consolidation), interlobular septal thickening, and gastric distention and contents (fluid or sediment). Image findings were compared with findings from autopsy reports and photographs. RESULTS: All drowning subjects had fluid in the paranasal sinuses and mastoid air cells and had ground-glass opacity within the lungs. Twenty-six subjects (93%) had fluid in the subglottic trachea and main bronchi. Fourteen subjects (50%) had high-attenuation sediment in the subglottic airways. Frothy fluid in the airways was present in six subjects (21%). Twenty-five (89%) of the drowning subjects had pulmonary ground-glass opacity with septal lines, which was mild with apical and perihilar distribution in 12 subjects, severe and diffuse in nine, posterior and basilar in three, and limited to the apices in one (not assessed in three of 28 subjects because of decomposition). Control subjects showed mastoid cell fluid (25%), sinus fluid (83%), subglottic airway fluid (92%), and pulmonary ground-glass opacity (100%) but did not have evidence of frothy airway fluid or high-attenuation sediment in the airways. CONCLUSION: The multidetector CT finding of frothy airway fluid or high-attenuation airway sediment is highly suggestive of drowning; multidetector CT findings of pan sinus fluid, mastoid cell fluid, subglottic tracheal and bronchial fluid, and ground-glass opacity within the lung at multidetector CT are supportive of drowning in the appropriate scenario.

Primary pulmonary and mediastinal synovial sarcoma: a clinicopathologic study of 60 cases and comparison with five prior series.

Primary pulmonary and mediastinal synovial sarcoma is rare and poses a diagnostic challenge particularly when unusual histological features are present. We present 60 cases of primary pulmonary and mediastinal synovial sarcoma (29 male and 27 female subjects; mean age, 42 years) and compare our results with five prior series to better define unusual histological features. Clinically, patients with mediastinal synovial sarcoma were younger with a male gender bias. Radiologically, tumors were well delineated with distinctive magnetic resonance imaging features and little vascular enhancement. In all, 21/46 patients died of disease within 5 years. Histologically, all tumors had dense cellularity, interlacing fascicles, hyalinized stroma, and mast cell influx. Hemangiopericytoma-like vasculature (48/60), focal myxoid change (30/60), and entrapped pneumocytes (23/60) were seen. Calcification was not prevalent (10/60). Unusual histological features included Verocay body-like formations (7/60), vague rosettes (6/60), well-formed papillary structures (3/60), adenomatoid change (3/60), and rhabdoid morphology (2/60). Immunohistochemistry demonstrated expression of pancytokeratin (39/58), epithelial membrane antigen (29/53), cytokeratin 7 (26/40), cytokeratin 5/6 (5/7), calretinin (15/23), CD99 (19/23), bcl-2 (24/24), CD56 (11/11), S-100 (9/51), and smooth muscle actin (8/32). In total, 92% (36/39) of primary pulmonary and mediastinal synovial sarcomas studied were positive for t(x;18). In conclusion, our study confirms the clinical, histological, immunohistochemical, and molecular data from previous large series of primary pulmonary and mediastinal synovial sarcoma. Compared with soft tissue synovial sarcoma, primary pulmonary and mediastinal synovial sarcoma has less calcification, less obvious mast cell influx, and less radiologic vascularity, but similar magnetic resonance imaging features, percentage of poorly differentiated tumors, and number of t(x;18)-positive tumors. Awareness of focal unusual histology can prevent misdiagnosis particularly in t(x;18)-negative tumors.