COVID-19 pandemic in flu season. Chest computed tomography - what we know so far.

Chest computed tomography (CT) is proven to have high sensitivity in COVID-19 diagnosis. It is available in most emergency wards, and in contrast to polymerase chain reaction (PCR) it can be obtained in several minutes. However, its imaging features change during the course of the disease and overlap with other viral pneumonias, including influenza pneumonia. In this brief analysis we review the recent literature about chest CT features, useful radiological scales, and COVID-19 differentiation with other viral infections.

The Usefulness of MRI Dynamic Flow Sequences in Differentiating High- and Low-Flow Vascular Malformations.

Peripheral arteriovenous malformations (PVMs) can be classified into high-flow malformations (HFVMs) and low-flow malformations (LFVMs). Adequate distinguishment is crucial for therapeutic decision and can be done using dynamic contrast-enhanced MRI (DCE-MRI). The main aim of this retrospective study was to determine the diagnostic value of quantitative DCE-MRI ratios for differentiation between HFVM and LFVM, their optimal cut-off points, and predictive values. DCE-MRI time-resolved angiography with stochastic trajectory (TWIST) examinations of 90 patients with PVMs were included [28 HFVM (31%), 62 LFVM (69%)]. The measurements of artery-lesion time, maximum lesion enhancement, slope of the enhancement curve, and maximum percentage increase of signal intensity (SI) were obtained. The optimal cut-offs for HFVMs calculated using the Youden index were: for slope of enhancement curve < 8.7 s (sensitivity of 86%, specificity of 89%), artery-lesion time ≤ 5.6 s (sensitivity of 89%, specificity of 77%), time to maximum enhancement ≤ 30 s (sensitivity of 94%, specificity of 100%), and maximum percentage enhancement of the lesion > 662% (sensitivity of 68%, specificity of 69%). To summarize, DCE-MRI is very valuable for differentiation between HFVM and LFVM, especially if quantitative measurements are done.