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Objectives: To assess the diagnostic performances of chest CT for triage of patients in multiple emergency departments during COVID-19 epidemic, in comparison with reverse transcription polymerase chain reaction (RT-PCR) test. Method: From March 3 to April 4, 2020, 694 consecutive patients from three emergency departments of a large university hospital, for which a hospitalization was planned whatever the reasons, i.e., COVID- or non-COVID-related, underwent a chest CT and one or several RT-PCR tests. Chest CTs were rated as "Surely COVID+," "Possible COVID+," or "COVID−" by experienced radiologists. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated using the final RT-PCR test as standard of reference. The delays for CT reports and RT-PCR results were recorded and compared. Results: Among the 694 patients, 287 were positive on the final RT-PCR exam. Concerning the 694 chest CT, 308 were rated as "Surely COVID+", 34 as "Possible COVID+," and 352 as "COVID−." When considering only the "Surely COVID+" CT as positive, accuracy, sensitivity, specificity, PPV, and NPV reached 88.9%, 90.2%, 88%, 84.1%, and 92.7%, respectively, with respect to final RT-PCR test. The mean delay for CT reports was three times shorter than for RT-PCR results (187 ± 148 min versus 573 ± 327 min, p < 0.0001). Conclusion: During COVID-19 epidemic phase, chest CT is a rapid and most probably an adequately reliable tool to refer patients requiring hospitalization to the COVID+ or COVID− hospital units, when response times for virological tests are too long. Key Points: • In a large university hospital in Lyon, France, the accuracy, sensitivity, specificity, PPV, and NPV of chest CT for COVID-19 reached 88.9%, 90.2%, 88%, 84.1%, and 92.7%, respectively, using RT-PCR as standard of reference. • The mean delay for CT reports was three times shorter than for RT-PCR results (187 ± 148 min versus 573 ± 327 min, p < 0.0001). • Due to high accuracy of chest CT for COVID-19 and shorter time for CT reports than RT-PCR results, chest CT can be used to orient patients suspected to be positive towards the COVID+ unit to decrease congestion in the emergency departments. [ABSTRACT FROM AUTHOR]

Magnetic resonance angiography (MRA) is a cost effective technique able to detect and quantify stenoses, provide sub-millimeter resolution with full arterial coverage, and show true vessel delineation without artifacts.The quality of images obtained with gadoliniumenhanced MRA depends on the gradient system, coil, sequence design, and contrast agent (volume, dose and injection rate). MRA protocols are evolving from standard k-space sampling (linear from the periphery or the center) to elliptic centric view ordering and to time-resolved MRA. Finally, the gadolinium-based contrast agent Gd-BOPTA (gadobenate dimeglumine, MultiHance; Bracco Imaging, Milan, Italy) offers considerably greater imaging efficacy compared to conventional gadolinium chelates, because identical results can be obtained at lower doses. In conclusion, MRA of the peripheral vasculature is a simple and fast technique, which permits evaluation of a large field of view without risk of radiation exposure. [ABSTRACT FROM AUTHOR]