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Radiology ; : 220069, 2022 May 24.
Article in English | MEDLINE | ID: covidwho-1861680


Background Post-Covid-19 condition describes symptoms following COVID-19 infection after four weeks. Symptoms are wide-ranging but breathlessness is common. Purpose The purpose of this study was to determine whether the previously described lung abnormalities on Hp-XeMRI in post-hospitalised COVID-19 participants are also present in non-hospitalised participants with Post-Covid-19 condition. Methods In this prospective study, non-hospitalised Post-Covid-19 condition (NHLC) and post-hospitalised COVID-19 (PHC) participants were enrolled from 06/2020 to 08/2021. Participants had chest CT, hyperpolarized pulmonary 129Xenon MRI (Hp-XeMRI), pulmonary function tests, 1-minute sit-to-stand test and breathlessness questionnaires. Control subjects underwent HP-XeMRI only. CT scans were analysed for post COVID interstitial lung disease severity using a previously published scoring system, and Full-scale Airway Network (FAN) modelling. Analysis used group and pair-wise comparisons between participants and controls, and correlations between participant clinical and imaging data. Results A total of 11 NHLC (4:7 Male: Female, 44 ± 11 years, [37-50], (mean ± SD, [95% CI]) and 12 PHC (10:2, Male: Female, 58 ± 10 years, [52-64]) participants were included, with a significant difference in age between groups, p = 0.05. NHLC participants were 287 ± 79, [240-334] and PHC 143 ± 72, [105-190] days from infection, respectively. NHLC and PHC participants had normal or near normal CT scans (0.3/25 ± 0.6, [0-0.63] and 7/25 ± 5, [4-10], respectively). Gas transfer (DLco (%)) was different between NHLC and PHC participants (76 ± 8%, [73-83] vs 86 ± 8%, [80-91] respectively, p = 0.04) but there was no evidence of other differences in lung function. Red Blood Cell:Tissue Plasma (RBC:TP) mean was different between volunteers vs PHC (0.45 ± 0.07, [0.43-0.47] vs (0.31 ± 0.10, [0.24-0.37], respectively, p = 0.02) and volunteers vs NHLC (0.37 ± 0.10, [0.31-0.44], p = 0.03) participants, but not between NHLC and PHC participants (p = 0.26). FAN results did not correlate with DLco or Hp- XeMRI. Conclusion NHLC and PHC subjects showed Hp-XeMRI RBC:TP abnormalities, with NHLC participants demonstrating lower DLco than PHC participants despite having normal CT scans. See also the editorial by Parraga and Matheson.

Radiology ; 301(1): E353-E360, 2021 10.
Article in English | MEDLINE | ID: covidwho-1430241


Background SARS-CoV-2 targets angiotensin-converting enzyme 2-expressing cells in the respiratory tract. There are reports of breathlessness in patients many months after infection. Purpose To determine whether hyperpolarized xenon 129 MRI (XeMRI) imaging could be used to identify the possible cause of breathlessness in patients at 3 months after hospital discharge following COVID-19 infection. Materials and Methods This prospective study was undertaken between August and December of 2020, with patients and healthy control volunteers being enrolled. All patients underwent lung function tests; ventilation and dissolved-phase XeMRI, with the mean red blood cell (RBC) to tissue or plasma (TP) ratio being calculated; and a low-dose chest CT, with scans being scored for the degree of abnormalities after COVID-19. Healthy control volunteers underwent XeMRI. The intraclass correlation coefficient was calculated for volunteer and patient scans to assess repeatability. A Wilcoxon rank sum test and Cohen effect size calculation were performed to assess differences in the RBC/TP ratio between patients and control volunteers. Results Nine patients (mean age, 57 years ± 7 [standard deviation]; six male patients) and five volunteers (mean age, 29 years ± 3; five female volunteers) were enrolled. The mean time from hospital discharge for patients was 169 days (range, 116-254 days). There was a difference in the RBC/TP ratio between patients and control volunteers (0.3 ± 0.1 vs 0.5 ± 0.1, respectively; P = .001; effect size, 1.36). There was significant difference between the RBC and gas phase spectral full width at half maximum between volunteers and patients (median ± range, 567 ± 1 vs 507 ± 81 [P = .002] and 104 ± 2 vs 122 ± 17 [P = .004], respectively). Results were reproducible, with intraclass correlation coefficients of 0.82 and 0.88 being demonstrated for patients and volunteers, respectively. Participants had normal or nearly normal CT scans (mean, seven of 25; range, zero of 25 to 10 of 25). Conclusion Hyperpolarized xenon 129 MRI results showed alveolar capillary diffusion limitation in all nine patients after COVID-19 pneumonia, despite normal or nearly normal results at CT. © RSNA, 2021 See also the editorial by Dietrich in this issue.

COVID-19/physiopathology , Dyspnea/physiopathology , Lung/diagnostic imaging , Lung/physiopathology , Magnetic Resonance Imaging/methods , Xenon Isotopes , Adult , Aged , Female , Follow-Up Studies , Humans , Male , Middle Aged , Prospective Studies , SARS-CoV-2
Nat Commun ; 12(1): 2055, 2021 04 06.
Article in English | MEDLINE | ID: covidwho-1171493


Identification of protective T cell responses against SARS-CoV-2 requires distinguishing people infected with SARS-CoV-2 from those with cross-reactive immunity to other coronaviruses. Here we show a range of T cell assays that differentially capture immune function to characterise SARS-CoV-2 responses. Strong ex vivo ELISpot and proliferation responses to multiple antigens (including M, NP and ORF3) are found in 168 PCR-confirmed SARS-CoV-2 infected volunteers, but are rare in 119 uninfected volunteers. Highly exposed seronegative healthcare workers with recent COVID-19-compatible illness show T cell response patterns characteristic of infection. By contrast, >90% of convalescent or unexposed people show proliferation and cellular lactate responses to spike subunits S1/S2, indicating pre-existing cross-reactive T cell populations. The detection of T cell responses to SARS-CoV-2 is therefore critically dependent on assay and antigen selection. Memory responses to specific non-spike proteins provide a method to distinguish recent infection from pre-existing immunity in exposed populations.

Antiviral Agents/pharmacology , COVID-19/immunology , COVID-19/virology , Cross Reactions/immunology , Immunoassay/methods , SARS-CoV-2/physiology , T-Lymphocytes/immunology , CD4-Positive T-Lymphocytes/immunology , CD8-Positive T-Lymphocytes/immunology , COVID-19/epidemiology , Cell Proliferation , Cytokines/metabolism , HEK293 Cells , Health Personnel , Humans , Immunoglobulin G/immunology , Immunologic Memory , Interferon-gamma/metabolism , Pandemics , Peptides/metabolism , SARS-CoV-2/drug effects