Two-stage hybrid network for segmentation of COVID-19 pneumonia lesions in CT images: a multicenter study.

COVID-19 has been spreading continuously since its outbreak, and the detection of its manifestations in the lung via chest computed tomography (CT) imaging is essential to investigate the diagnosis and prognosis of COVID-19 as an indispensable step. Automatic and accurate segmentation of infected lesions is highly required for fast and accurate diagnosis and further assessment of COVID-19 pneumonia. However, the two-dimensional methods generally neglect the intraslice context, while the three-dimensional methods usually have high GPU memory consumption and calculation cost. To address these limitations, we propose a two-stage hybrid UNet to automatically segment infected regions, which is evaluated on the multicenter data obtained from seven hospitals. Moreover, we train a 3D-ResNet for COVID-19 pneumonia screening. In segmentation tasks, the Dice coefficient reaches 97.23% for lung segmentation and 84.58% for lesion segmentation. In classification tasks, our model can identify COVID-19 pneumonia with an area under the receiver-operating characteristic curve value of 0.92, an accuracy of 92.44%, a sensitivity of 93.94%, and a specificity of 92.45%. In comparison with other state-of-the-art methods, the proposed approach could be implemented as an efficient assisting tool for radiologists in COVID-19 diagnosis from CT images.

Elevated Extracellular Volume Fraction and Reduced Global Longitudinal Strains in Participants Recovered from COVID-19 without Clinical Cardiac Findings.

Background It is unknown if there are cardiac abnormalities in persons who have recovered from coronavirus disease 2019 (COVID-19) without cardiac symptoms or in those who have normal biomarkers and normal electrocardiograms. Purpose To evaluate cardiac involvement in participants who had recovered from COVID-19 without clinical evidence of cardiac involvement by using cardiac MRI. Materials and Methods This prospective observational cohort study included 40 participants who had recovered from COVID-19 with moderate (n = 24) or severe (n = 16) pneumonia and who had no cardiovascular medical history, were without cardiac symptoms, had normal electrocardiograms, had normal serologic cardiac enzyme levels, and had been discharged for more than 90 days between May and September 2020. Demographic characteristics were recorded, serum cardiac enzyme levels were measured, and cardiac MRI was performed. Cardiac function, native T1, extracellular volume fraction (ECV), and two-dimensional (2D) strain were quantitatively evaluated and compared with values in control subjects (n = 25). Comparisons among the three groups were performed by using one-way analysis of variance with Bonferroni-corrected post hoc comparisons (for normal distribution) or Kruskal-Wallis tests with post hoc pairwise comparisons (for nonnormal distribution). Results Forty participants (mean age, 54 years ± 12 [standard deviation]; 24 men) were enrolled; participants had a mean time between admission and cardiac MRI of 158 days ± 18 and between discharge and cardiac MRI examination of 124 days ± 17. There were no left or right ventricular size or functional differences between participants who had recovered from COVID-19 and healthy control subjects. Only one (3%) participant had positive late gadolinium enhancement located at the mid inferior wall. Global ECV values were elevated in participants who had recovered from COVID-19 with moderate or severe pneumonia compared with those in healthy control subjects (median ECV, 29.7% vs 31.4% vs 25.0%, respectively; interquartile range, 28.0%-32.9% vs 29.3%-34.0% vs 23.7%-26.0%, respectively; P < .001 for both). The 2D global left ventricular longitudinal strain was reduced in both groups of participants (moderate COVID-19 group, -12.5% [interquartile range, -15.5% to -10.7%]; severe COVID-19 group, -12.5% [interquartile range, -15.4% to -8.7%]) compared with the healthy control group (-15.4% [interquartile range, -17.6% to -14.6%]) (P = .002 and P = .001, respectively). Conclusion Cardiac MRI myocardial tissue and strain imaging parameters suggest that a proportion of participants who had recovered from COVID-19 had subclinical myocardial abnormalities detectable months after recovery. © RSNA, 2021 Online supplemental material is available for this article.

Herd immunization with childhood vaccination may provide protection against COVID-19.

It may take time to obtain a vaccine for the current COVID-19, and the virus genome may keep an evolution and mutations, so a universal and effective vaccine for the coronavirus may not be possible. Epidemiological studies reveal the infection of SARS and COVID-19 in children is less frequent and less severe than in adults. Childhood vaccine-mediated cross cellular immunity and immunomodulation might provide protection against the infections of COVID-19. These data suggest that herd immunization with children vaccines in adults may improve the adult cross cellular immunity and immunomodulation and improve their clinical presentation and prognosis. This can be also useful to cope with future pandemics.

Timely Diagnosis and Treatment Shortens the Time to Resolution of Coronavirus Disease (COVID-19) Pneumonia and Lowers the Highest and Last CT Scores From Sequential Chest CT.

OBJECTIVE. This study aims to assess correlations of the time from symptom onset to diagnosis and treatment with the time to disease resolution and CT scores as based on findings from sequential chest CT examinations. MATERIALS AND METHODS. Thirty patients with coronavirus disease (COVID-19) confirmed by reverse transcription-polymerase chain reaction analysis underwent chest CT examinations. Five patients who did not have positive CT findings or who had not yet fulfilled criteria for discharge from the hospital were excluded. CT scores were determined according to CT findings and lung involvement. The time from symptom onset to diagnosis and treatment was recorded for each patient, and on the basis of this information, patients with COVID-19 were divided into group 1 (patients for whom this interval was ≤ 3 days) and group 2 (those for whom this interval was > 3 days). The CT scores for each group were fitted using a Lorentzian line-shape curve to show the variation tendency during treatment. The differences in age, sex, and last CT scores determined before discharge between the two groups were analyzed, and correlations of the time from symptom onset to diagnosis and treatment with the time to disease resolution as well as with the highest CT score also underwent statistical analysis. RESULTS. A total of 25 subjects were enrolled in the study. The fitted tendency curves for group 1 and group 2 were significantly different, with peak points showing that the estimated highest CT score was 10 and 16 for each group, respectively, and the time to disease resolution was 6 and 13 days, respectively. The Mann-Whitney test showed that the last CT scores were lower for group 1 than for group 2 (p = 0.025), although the chi-square test found no difference in age and sex between the groups. The time from symptom onset to diagnosis and treatment had a positive correlation with the time to disease resolution (r = 0.93; p = 0.000) as well as with the highest CT score (r = 0.83; p = 0.006). CONCLUSION. Timely diagnosis and treatment are key to providing a better prognosis for patients with COVID-19.