This copy is for personal use only. To order printed copies, contact reprints@rsna.org I n P r e s s 2 Key Points 1. The positive rates of RT-PCR assay and chest CT imaging in our cohort were 59% (601/1014), and 88% (888/1014) for the diagnosis of suspected patients with COVID-19, respectively. 2.With RT-PCR as a reference, the sensitivity of chest CT imaging for COVID-19 was 97% (580/601). In patients with negative RT-PCR results but positive chest CT scans (n=308 patients), 48% (147/308) of patients were re-considered as highly likely cases, with 33% (103/308) as probable cases by a comprehensive evaluation. 3.With analysis of serial RT-PCR assays and CT scans, 60% to 93% of patients had initial positive chest CT consistent with COVID-19 before the initial positive RT-PCR results. 42% of patients showed improvement of follow-up chest CT scans before the RT-PCR results turning negative. Summary StatementChest CT had higher sensitivity for diagnosis of COVID-19 as compared with initial reverse-transcription polymerase chain reaction (RT-PCR) from swab samples in the epidemic area of China. Abbreviations RT-PCR = reverse transcription polymerase chain reaction NCP = novel coronavirus pneumonia PPV = positive predictive value NPV = negative predictive value I n P r e s s 3 Abstract Background: Chest CT is used for diagnosis of 2019 novel coronavirus disease (COVID-19), as an important complement to the reverse-transcription polymerase chain reaction (RT-PCR) tests. Purpose: To investigate the diagnostic value and consistency of chest CT as compared with comparison to RT-PCR assay in COVID-19. underwent both chest CT and RT-PCR tests were included. With RT-PCR as reference standard, the performance of chest CT in diagnosing COVID-19 was assessed. Besides, for patients with multiple RT-PCR assays, the dynamic conversion of RT-PCR results (negative to positive, positive to negative, respectively) was analyzed as compared with serial chest CT scans for those with time-interval of 4 days or more. Results: Of 1014 patients, 59% (601/1014) had positive RT-PCR results, and 88% (888/1014) had positive chest CT scans. The sensitivity of chest CT in suggesting COVID-19 was 97% (95%CI, 95-98%, 580/601 patients) based on positive RT-PCRresults. In patients with negative RT-PCR results, 75% (308/413) had positive chest CT findings; of 308, 48% were considered as highly likely cases, with 33% as probable cases. By analysis of serial RT-PCR assays and CT scans, the mean interval time between the initial negative to positive RT-PCR results was 5.1 ± 1.5 days; the initial positive to subsequent negative RT-PCR result was 6.9 ± 2.3 days). 60% to 93% of cases had initial positive CT consistent with COVID-19 prior (or parallel) to the initial positive RT-PCR results. 42% (24/57) cases showed improvement in follow-up chest CT scans before the RT-PCR results turning negative. Conclusion:Chest CT has a high sensitivity for diagnosis of COVID-19. Chest CT may be considered as a primary tool for the current COVID-19 detection in epidemic ar...

The severity of the pulmonary manifestations of COVID-19 can be quantitatively evaluated from chest CT using a deep-learning method. There were significant differences in lung opacification percentage, as measured by the deep learning algorithm, among patients with different clinical severity. This automated tool for quantification of lung involvement may be used to monitor the disease progression and understand the temporal evolution of COVID-19. Abbreviations ARDS = acute respiratory distress syndrome, COVID-19 = coronavirus disease 19, GGO = ground glass opacity, HRCT = high resolution computed tomography, RT-PCR = reverse transcription-polymerase chain reaction, SARS-Cov-2 = severe acute respiratory syndrome coronavirus 2, SpO2 =pulse oxygen saturation

Magnetic resonance imaging (MRI) contrast agents are pharmaceuticals used widely in MRI examinations. Gadolinium-based MRI contrast agents (GBCAs) are by far the most commonly used. To date, nine GBCAs have been commercialized for clinical use, primarily indicated in the central nervous system, vasculature, and whole body. GBCAs primarily lower the T(1) in vivo to create higher signal in T(1)-weighted MRI scans where GBCAs are concentrated. GBCAs are unique among pharmaceuticals, being water proton relaxation catalysts whose effectiveness is characterized by a rate constant known as relaxivity. The relaxivity of each GBCAs depends on a variety of factors that are discussed in terms of both the existing agents and future molecular imaging agents under study by current researchers. Current GBCAs can be divided into four different structural types (macrocyclic, linear, ionic, and nonionic) based on the chemistry of the chelating ligands whose primary purpose is to protect the body from dissociation of the relatively toxic Gd(3+) ion from the ligand. This article discusses how the chemical structure influences inherent and in vivo stability toward dissociation, and how it affects important formulation properties. Although GBCAs have a lower rate of serious adverse events than iodinated contrast agents, they still present some risk.

To analyse the high-resolution computed tomography (HRCT) early imaging features and the changing trend of coronavirus disease 2019 (COVID-19) pneumonia. Materials and Methods: Forty-six patients with COVID-19 pneumonia who had an isolated lesion on the first positive CT were enrolled in this study. The following parameters were recorded for each lesion: sites, sizes, location (peripheral or central), attenuation (ground-glass opacity or consolidation), and other abnormalities (supply pulmonary artery dilation, air bronchogram, interstitial thickening, etc.). The follow-up CT images were compared with the previous CT scans, and the development of the lesions was evaluated. Results: The lesions tended to be peripheral and subpleural. All the lesions exhibited ground-glass opacity with or without consolidation. A higher proportion of supply pulmonary artery dilation (89.13 % [41/46]) and air bronchogram (69.57 % [32/46]) were found. Other findings included thickening of the intralobular interstitium and a halo sign of ground glass around a solid nodule. Cavitation, calcification or lymphadelopathy were not observed. The reticular patterns were noted from the 14 days after symptoms onset in 7 of 20 patients (45 %). At 22-31 days, the lesions were completely absorbed only in 2 of 7 patients (28.57 %). Conclusion:The typical early CT features of COVID-19 pneumonia are ground-glass opacity, and located peripheral or subpleural location, and with supply pulmonary artery dilation. Reticulation was evident after the 2nd week and persisted in half of patients evaluated in 4 weeks after the onset. Long-term follow-up is required to determine whether the reticulation represents irreversible fibrosis.