Immunity from reinfection: One of the many open questions about severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is whether an individual who has cleared the virus can be infected a second time and get sick. Chandrashekar et al. and Deng et al. generated rhesus macaque models of SARS-CoV-2 infection and tested whether natural SARS-CoV-2 infection could result in immunity to viral rechallenge. They found that animals indeed developed immune responses that protected against a second infection. Although there are differences between SARS-CoV-2 infection in macaques and in humans, these findings have key implications for public health and economic initiatives if validated in human studies. Science , this issue p. 812 , p. 818

A global pandemic of Corona Virus Disease 2019 (COVID-19) caused by severe acute respiratory syndrome CoV-2 (SARS-CoV-2) is ongoing spread. It remains unclear whether the convalescing patients have a risk of reinfection. Rhesus macaques were rechallenged with SARS-CoV-2 during an early recovery phase from initial infection characterized by weight loss, interstitial pneumonia and systemic viral dissemination mainly in respiratory and gastrointestinal tracts. The monkeys rechallenged with the identical SARS-CoV-2 strain have failed to produce detectable viral dissemination, clinical manifestations and histopathological changes. A notably enhanced neutralizing antibody response might contribute the protection of rhesus macaques from the reinfection by SARS-CoV-2. Our results indicated that primary SARS-CoV-2 infection protects from subsequent reinfection. One Sentence Summary: Neutralizing antibodies against SARS-CoV-2 might protect rhesus macaques which have undergone an initial infection from reinfection during early recovery days.

This study aims to explore computed tomography (CT) and magnetic resonance imaging (MRI) features of patients diagnosed with primary cardiac angiosarcoma. The study involved the analysis of 12 patients diagnosed with primary cardiac angiosarcoma who underwent non-contrast (8/12) or contrast-enhanced CT (10/12) or MRI (4/12). Imaging appearances, including the tumor location and adjacent infiltration, were analyzed. All 12 lesions were located in the right atrium with a broad base. Adjacent invasion including the tricuspid valve and right ventricle (2/12), inferior or superior vena cava (2/12), pericardium (10/12), and right coronary artery (7/12) was common. On unenhanced CT scans, tumors in two patients were homogeneous in density, whereas the others were inhomogeneous. Ten patients showed heterogeneous enhancement. The enhancement pattern showed no direct correlation with the differentiation degree of the tumor. Four lesions manifested as heterogeneous intensity, with hyperintense hemorrhage foci on both T1- and T2-weighted MRI. Three showed rim enhancement and one showed patchy enhancement. Primary cardiac angiosarcoma often involves the right side of the heart with infiltration of peripheral structures. CT features include typical inhomogeneous density on unenhanced scans and heterogeneous centripetal enhancement on enhanced scans. A cauliflower-like appearance on both T1- and T2-weighted MRI is common. The characteristic enhancement pattern of MRI remains to be determined.

The purpose of this study is to evaluate the hemodynamic characteristics of the true lumen (TL) and the false lumen (FL) in 16 patients with aortic dissection (AD) using 4D flow magnetic resonance imaging (MRI) and thoracic and abdominal computed tomography (CT) angiography. The quantitative parameters that were measured in the TL and FL included velocity and flow. The mean area and regurgitant fraction of the TL were significantly lesser at all four levels (p < 0.05); the average through-plane velocity, peak velocity magnitude, average net flow, peak flow, and net forward volume in the TL were considerably higher (p < 0.05). The intimal entry’s size was negatively correlated with the blood flow velocity and flow rate in the TL (p < 0.05) and positively correlated with the average through-plane velocity, average net flow, and peak flow in the FL (p < 0.05); the blood flow indices in the TL were enhanced with an increase in the intimal entry numbers (p < 0.05) and the peak flow in the FL was lowered (p = 0.025); if FL thrombosis existed, the average through-plane velocity and peak velocity magnitude in the TL were substantially higher (p < 0.05). 4D flow MRI facilitates qualitative and quantitative analysis of the alterations in the abdominal aortic blood flow patterns.

Background: Primary cardiac angiosarcoma is a rare malignancy with high predilection to involve surrounding structures such as pulmonary metastases. We analysed the chest computed tomography (CT) imaging features of patients diagnosed with primary cardiac angiosarcoma with pulmonary metastases in this study. Methods: This study retrospectively reviewed 12 patients with confirmed primary cardiac angiosarcoma, out of which eight (all men) with pulmonary metastasis were included in the analysis. The patients’ age ranged from 17 to 74 (mean: 48) years. CT was performed in all patients with unenhanced, contrast-enhanced, and both scans were done in 1, 3 and 4 patients, respectively. Results: Nodular lesions were observed in 7 patients with multiple solid nodules observed in 6 out of 7 patients. A solitary solid nodule was found in the remaining patient in the upper lobe and apical segment of the right lung with a diameter of 11.7 mm. All solid nodules were distributed along with bronchovascular bundles in the lungs, and their maximum diameter ranged from 2.3 to 19.9 mm. Nodules larger than 10 mm in diameter were heterogeneously enhanced on contrast-enhanced CT images (5/8 patients), whereas those smaller than 10 mm were homogeneously enhanced (3/8 patients). Other imaging features, namely the tree-in-bud pattern, emphysema, pleural effusion, and mediastinal lymph node enlargement, were observed in 4, 3, 3, and 2 patients, respectively. Conclusion: CT enhancement features of pulmonary metastasis in patients with primary cardiac angiosarcoma depend on the size of pulmonary nodules, with larger ones being heterogeneous and smaller ones homogeneous. Other signs are less noticed.