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Background Coronary artery calcification (CAC) is a common and important incidental finding in low-dose computed tomography (LDCT) performed for lung cancer screening (LCS). The impact of these incidental findings on patient management is unclear. Purpose The goals of our study were to determine the impact of reporting CAC on patient management and to determine whether standardized reporting of CAC affects the likelihood of future interventions. Methods In this IRB-approved retrospective study, we queried our LCS database for reports of LDCT performed between January 2016 and September 2018. All reports with significant findings of CAC designated with the letter "S" for any Lung-RADS category were selected. The grading of CAC was extracted from the reports. Medical records were reviewed for each patient to determine demographics, clinical history, medications, and cardiac-related diagnostic and interventional procedures. The changes in management after the report of significant CAC on LDCT were documented. Statistical analysis with Student t test and Pearson χ test was performed. Results A total of 756/3110 patients (mean age: 67±6.4 y; M=466, 61.6%: F=290, 38.4%) were reported to have significant CAC on LDCT for LCS. Of them, 236/756 patients (31.2%) had established coronary artery disease (CAD) at baseline, before the initial LDCT. A change in management was observed in 155/756 patients (20.5%). The most common changes in management included the following: alteration in medication regimen (n=114/155, 73.5%), stress testing (n=65/155, 41.9%), and referral to a cardiologist (36/155, 23.2%). Percutaneous coronary intervention (4, 2.6%) and surgery (3, 1.9%) were uncommon. Changes in management were more common in those without established CAD and in those whose CAC was semiquantitatively graded (35% vs. 25%, P=0.02). Conclusion CAC is a common significant finding in LDCT for LCS. Reporting of CAC in patients with nonestablished CAD and semiquantitative assessment resulted in changes in management.

The purpose of this article was to report the utility of computed tomography (CT) for detecting unsuspected cases of Coronavirus disease 2019 (COVID-19) and the utility of the Radiological Society of North America (RSNA)/Society of Thoracic Radiology (STR)/American College of Radiology (ACR) consensus guidelines for COVID-19 reporting.A total of 22 patients of the 156 reverse transcriptase polymerase chain reaction confirmed COVID-19 patients who were hospitalized between March 27, 2020 and March 31, 2020 at our quaternary care academic medical center and who underwent CT imaging within 1 week of admission were included in this retrospective study. Demographics and clinical data were extracted from the electronic medical record system. Two thoracic radiologists independently categorized each CT study on the basis of RSNA/STR/ACR consensus guidelines. Disagreement in categorization was resolved by consensus discussion with a third thoracic radiologist.At the time of imaging, 16 patients (73%) were suspected of COVID-19, and 6 patients (27%) were not. Common symptoms at presentation were fever (73%), cough (77%), and gastrointestinal symptoms (59%). An overall 63% of suspected COVID-19 patients exhibited shortness of breath, whereas 0 unsuspected COVID-19 patients did (P=0.02). On the basis of the RSNA consensus guidelines, 68%, 18%, 9%, and 5% of studies were categorized as "typical appearance," "indeterminate appearance," "atypical appearance," and "negative for pneumonia," respectively. There was no difference of category distribution between suspected and unsuspected COVID-19 patients (P=0.20), with "typical appearance" being the most prevalent in both (69% vs. 67%, respectively).It is important to recognize imaging features of COVID-19 pneumonia even in unsuspected patients. Implementation of the RSNA/STR/ACR consensus guidelines may increase consistency of reporting and convey the level of suspicion for COVID-19 to other health care providers, with "typical appearance" especially warranting further attention.

PURPOSE: The purpose of this article was to report the utility of computed tomography (CT) for detecting unsuspected cases of Coronavirus disease 2019 (COVID-19) and the utility of the Radiological Society of North America (RSNA)/Society of Thoracic Radiology (STR)/American College of Radiology (ACR) consensus guidelines for COVID-19 reporting. MATERIALS AND METHODS: A total of 22 patients of the 156 reverse transcriptase polymerase chain reaction confirmed COVID-19 patients who were hospitalized between March 27, 2020 and March 31, 2020 at our quaternary care academic medical center and who underwent CT imaging within 1 week of admission were included in this retrospective study. Demographics and clinical data were extracted from the electronic medical record system. Two thoracic radiologists independently categorized each CT study on the basis of RSNA/STR/ACR consensus guidelines. Disagreement in categorization was resolved by consensus discussion with a third thoracic radiologist. RESULTS: At the time of imaging, 16 patients (73%) were suspected of COVID-19, and 6 patients (27%) were not. Common symptoms at presentation were fever (73%), cough (77%), and gastrointestinal symptoms (59%). An overall 63% of suspected COVID-19 patients exhibited shortness of breath, whereas 0 unsuspected COVID-19 patients did (P=0.02). On the basis of the RSNA consensus guidelines, 68%, 18%, 9%, and 5% of studies were categorized as "typical appearance," "indeterminate appearance," "atypical appearance," and "negative for pneumonia," respectively. There was no difference of category distribution between suspected and unsuspected COVID-19 patients (P=0.20), with "typical appearance" being the most prevalent in both (69% vs. 67%, respectively). CONCLUSIONS: It is important to recognize imaging features of COVID-19 pneumonia even in unsuspected patients. Implementation of the RSNA/STR/ACR consensus guidelines may increase consistency of reporting and convey the level of suspicion for COVID-19 to other health care providers, with "typical appearance" especially warranting further attention.

Nonuniform contrast opacification of vasculature is frequently encountered on thoracic computed tomographic angiography. The purpose of this pictorial essay is to discuss the appearance of, and factors underlying mixing artifacts, which we term "smoke." We provide an approach to distinguish it from pathology including pulmonary embolism, aortic dissection, and thrombus. Smoke results from a combination of technical factors, abnormal physiology, or inflow of unopacified blood. Smoke produces ill-defined filling defects that may be confidently diagnosed in many cases if these fundamentals are applied.

PURPOSE The objective of this study was to assess the reliability of ancillary imaging findings in distinguishing acute from chronic aortic dissection (AD) and intramural hematoma (IMH) using computed tomography angiography (CTA). MATERIALS AND METHODS Two radiologists specializing in cardiothoracic and vascular imaging reviewed paired CTAs of patients with AD or IMH who underwent CTA in the acute (within 24 h of presentation) and chronic settings. The radiologists were blinded to the temporal order of the CTAs. Minimum and maximum flap thicknesses and presence or absence of pleural effusion, pericardial effusion, mediastinal hematoma or fat standing, and mediastinal lymphadenopathy were recorded. RESULTS Patients included 25 male individuals and 13 female individuals with a mean age of 59 years (range: 34 to 87 y). The group included 29 AD and 9 IMH cases. The median interval between the paired CTs was 542 days (range: 100 to 2533 d). Respectively, the mean minimum flap thicknesses in the acute and chronic AD were 1.3 and 1.4 mm (P=0.3), and the mean maximum flap thicknesses were 2.7 and 2.9 mm (P=0.29). The incidences of ancillary findings in acute and chronic AD and IMH were as follows: pleural effusion (55% vs. 37%, P=0.143), pericardial effusion (8% vs. 11%, P=1.0), lymphadenopathy (47% vs. 47%, P=1.0), and periaortic fat stranding (87% vs. 76%, P=0.344). CONCLUSIONS Ancillary CT imaging findings traditionally ascribed to acute AD and IMH are also often found in the chronic setting and are not reliable indicators of acuity. Flap thickness in AD may not be a reliable imaging indicator of acuity of AD.

Interstitial lung disease (ILD) is a common cause of morbidity and mortality in patients with connective tissue disease (CTD). In a minority of patients the ILD may be the presenting (or only) manifestation of an underlying CTD. Diagnosis of CTD-related ILD relies on a multidisciplinary team including pulmonologists, pathologists, radiologists, and rheumatologists, as the imaging and pathologic findings may be indistinguishable from idiopathic interstitial pneumonias. Moreover, many patients with ILD are suspected of having an underlying CTD but do not meet all of the necessary criteria for a specific disorder. This article provides a pattern-based approach to the imaging of CTD-related ILD and also reviews relevant clinical, pathologic, and serologic data that radiologists should be familiar with as part of a multidisciplinary team.

PURPOSE To examine the current radiographic follow-up recommendations of thoracic radiologists after detection of a new opacity, suspected to be "pneumonia," on chest radiography. MATERIALS AND METHODS An anonymized, Institutional Review Board-approved, Internet-based survey was sent to the 735 members of the Society of Thoracic Radiology by e-mail. Questions focused on individual practices and institutional policies after radiographic detection of suspected pneumonia. Univariate and multivariable logistic regression analyses were used to evaluate for possible associations between recommendation practices and demographic variables, various clinical situations, and radiographic features. RESULTS Of the 209 radiologists who responded, 42% "always" recommended follow-up radiographs for new opacities detected on chest radiographs, 55% "sometimes" recommended follow-up, and 2% "never" recommended follow-up. Univariate logistic regression analysis revealed that "years in practice" (P=0.0043) and "number of outpatient posterior-anterior and lateral chest radiographs interpreted per week" (P=0.027) were significant predictors of the recommendation practices. In addition, the multivariable logistic regression analysis pointed to the type of practice (academic vs. private) as an additional independent predictor of the recommendation practices (P=0.0294). The recommendations of those radiologists recommending follow-up "sometimes" were most often influenced by the radiographic appearance of the opacity and patient age. Only 4% reported an institutional policy. CONCLUSIONS The majority of responding radiologists recommended follow-up on a case-by-case basis, influenced by multiple factors. Only a small minority reported a standardized practice at their institution. This lack of consistency demonstrates the need for a uniform, evidence-based approach.

Hibernomas are rare heterogeneous fatty tumors arising from brown fat precursors. Intrathoracic hibernomas are extremely rare. We detail a case of pathologically proven intrathoracic hibernoma in a 67-year-old woman. Chest radiography, computed tomography, fluorodeoxyglucose positron emission tomography, and angiography are presented. A short review of the literature and discussion of imaging and histologic diagnosis of hibernomas are provided.

Appearance: Extrapulmonary lesions often show indistinct borders along at least a portion of their margins at chest radiography. This classic sign has been termed the “incomplete border sign.” Explanation: At radiography, visibility of a sharp border depends on (a) a difference in density between a lesion and adjacent structures, and (b) an edge tangent to the x-ray beam.When not directly adjacent to the pleura, intrapulmonary lesions satisfy both conditions, with a tissue density much greater than surrounding air, and edges tangent to the beam in any projection (Fig. 1, top). Extrapulmonary (pleural or extrapleural) lesions or lung lesions abutting the pleura do not meet these criteria, often creating an incomplete border. First, the density between the mass and adjacent soft tissue is insufficient to differentiate on radiographs. Second, these lesions often have unique geometry – an oblong shape and obtuse margins conforming to the pleura – creating a smooth gradient of density without a sharp tangent to the beam. The gradually sloping margins of a pleural or extrapleural lesion viewed en facemay not have any discernible borders, as there is no true tangent edge to the lesion (Fig. 1A, middle). Other lesions may have a sharp border along the lesion’s interface with air in the lung or outside the thorax, but an indistinct border at the interface with the soft tissues, where a tangent to the beam is not created (Fig. 1, bottom; Figure 1B). Discussion: Mendelson first used the term “incomplete border sign” as a way to localize abdominal wall and chest wall masses on radiographs.1 Since then, various authors have highlighted the importance of this sign in differentiating pulmonary versus extrapulmonary lesions.2–6 The differential diagnosis for the incomplete border sign is broadly divided into pulmonary lesions with pleural abutment or extension, pleural lesions, and extrapleural lesions. Pulmonary masses involving the pleura and possibly extending to the chest wall can be seen with invasive malignancies and certain aggressive infections. Pleural lesions capable of showing incomplete borders include any pleural mass (e.g. metastasis, fibrous tumor), pleural plaque, or loculated fluid.6 A pleural effusion within the major fissure can also have an incomplete border on the frontal radiograph, as the lentiform shape and oblique orientation preclude true tangents to the X-ray beam. Extrapleural lesions arise from tissues superficial to the parietal pleura. Rib lesions are probably the most common (such as metastases or rib fractures with hematoma and callus), but lipomas and nerve sheath tumors are also routinely encountered. Nipples or other skin lesions may also simulate a nodule and demonstrate incomplete borders. The incomplete border sign is created by the unique geometry of an extrapulmonary mass, or extrapulmonary extension of a pulmonary parenchymal lesion. Recognition of the sign can guide the radiologist in formulating appropriate differential considerations for such masses.