Faculty Bibliography

BACKGROUND:RSNA expert consensus guidelines provide a framework for reporting CT findings related to COVID-19, but have had limited multireader validation. PURPOSE/OBJECTIVE:To assess the performance of the RSNA guidelines and quantify interobserver variability in application of the guidelines in patients undergoing chest CT for suspected COVID-19 pneumonia. MATERIALS AND METHODS/METHODS:A retrospective search from 1/15/20 to 3/30/20 identified 89 consecutive CT scans whose radiological report mentioned COVID-19. One positive or two negative RT-PCR tests for COVID-19 were considered the gold standard for diagnosis. Each chest CT scan was evaluated using RSNA guidelines by 9 readers (6 fellowship trained thoracic radiologists and 3 radiology resident trainees). Clinical information was obtained from the electronic medical record. RESULTS:There was strong concordance of findings between radiology training levels with agreement ranging from 60 to 86% among attendings and trainees (kappa 0.43 to 0.86). Sensitivity and specificity of "typical" CT findings for COVID-19 per the RSNA guidelines were on average 86% (range 72%-94%) and 80.2% (range 75-93%), respectively. Combined "typical" and "indeterminate" findings had a sensitivity of 97.5% (range 94-100%) and specificity of 54.7% (range 37-62%). A total of 163 disagreements were seen out of 801 observations (79.6% total agreement). Uncertainty in classification primarily derived from difficulty in ascertaining peripheral distribution, multiple dominant disease processes, or minimal disease. CONCLUSION/CONCLUSIONS:The "typical appearance" category for COVID-19 CT reporting has an average sensitivity of 86% and specificity rate of 80%. There is reasonable interreader agreement and good reproducibility across various levels of experience.

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.

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.