Incidence and follow-up of persistent lung perfusion abnormalities as a result of suspected air trapping or microthrombosis in non-hospitalised COVID-19 patients during the early half of the pandemic - experience in a tertiary institution in South Afr.

BACKGROUND: Available clinical data have revealed that COVID-19 is associated with a risk of pulmonary microthrombosis and small airway disease, especially in patients with severe disease. These patients present with persistent pulmonary symptoms after recovery, with ventilation and perfusion abnormalities present on several imaging modalities. Few data are available on the occurrence of this complication in patients who earlier presented with a milder form of COVID-19, and their long-term follow-up. OBJECTIVE: To assess the incidence of persistent lung perfusion abnormalities as a result of suspected air trapping or microthrombosis in non-hospitalised patients diagnosed with COVID-19. The long-term follow-up of these patients will also be investigated. METHODS: This was a retrospective study conducted at the nuclear medicine department of Universitas Academic Hospital, Bloemfontein. We reviewed the studies of 78 non-hospitalised patients with SARS-CoV-2 infection referred to our department from July 2020 to June 2021 for a perfusion-only single-photon emission computed tomography/computed tomography (SPECT/CT) study or a ventilation perfusion (VQ) SPECT/CT study. All 78 patients were suspected of having pulmonary embolism, and had raised D-dimer levels, with persistent, worsening or new onset of cardiopulmonary symptoms after the diagnosis of COVID-19. RESULTS: Seventy-eight patients were studied. The median (interquartile range) age was 45 (41 - 58) years and the majority (88.5%) were females. Twenty-two (28.2%) of these patients had matching VQ defects with mosaic attenuation on CT. All 9 of the patients who had follow-up studies had abnormalities that persisted, even after 1 year. CONCLUSION: We confirm that persistent ventilation and perfusion abnormalities suspicious of small airway disease and pulmonary microthrombosis can occur in non-hospitalised patients diagnosed with a milder form of COVID-19. Our study also shows that these complications remain present even 1 year after the initial diagnosis of COVID-19.

The prevalence of pulmonary embolism in non-hospitalised de-isolated patients diagnosed with mild COVID-19 disease.

BACKGROUND: Pulmonary embolism (PE) is a known complication of COVID-19 disease. The mechanism of thromboembolic events appears to be stimulated by excessive thrombin production, inhibition of fibrinolysis and deposition of antiphospholipids and thrombi, as well as microvascular dysfunction in multiple vascular beds. The occurrence of PE has been well demonstrated in hospitalised patients with severe disease. Very few data are available on its incidence or prevalence in non-hospitalised patients diagnosed with a milder form of the disease. OBJECTIVES: To assess the prevalence of PE in non-hospitalised patients diagnosed with mild COVID-19 who presented with raised D-dimer levels and persistent or new-onset cardiopulmonary symptoms. METHODS: This was a retrospective study conducted in the Department of Nuclear Medicine at Universitas Academic Hospital, Bloemfontein, South Africa. We reviewed the studies of 65 non-hospitalised patients with COVID-19 referred to the department from July 2020 to January 2021 for a perfusion-only single-photon emission computed tomography/computed tomography (SPECT/CT) study or a ventilation/perfusion (VQ) SPECT/CT study. All 65 patients had raised D-dimer levels with persistent, worsening or new-onset cardiopulmonary symptoms after the diagnosis of COVID-19. RESULTS: Sixty-five patients were studied. The median (interquartile range) age was 46 (41 - 54) years and the majority (88.2%) were female. There were 22 patients (33.8%) with lung perfusion defects in keeping with PE. Two of these patients had a false-negative computed tomography pulmonary angiography (CTPA) study for PE performed the same day as their VQ SPECT/CT study. CONCLUSIONS: We confirm a high prevalence of PE in non-hospitalised patients diagnosed with mild COVID-19 who presented with raised D-dimer levels and persistent or new-onset cardiopulmonary symptoms. We recommend that irrespective of disease severity, hospitalised and non-hospitalised patients with COVID-19 presenting with persistent or new-onset cardiopulmonary symptoms and raised D-dimer levels should be investigated further for PE.

Lung perfusion findings on perfusion SPECT/CT imaging in non-hospitalized de-isolated patients diagnosed with mild COVID-19 infection

Background: The aim of this retrospective study is to assess the incidence and type of lung perfusion abnormalities in non-hospitalized patients diagnosed with mild COVID-19 infection after de-isolation. Data from 56 non-hospitalized patients diagnosed with COVID-19 infection referred to our nuclear medicine department from July–December 2020 for a perfusion only SPECT/CT study or a ventilation perfusion SPECT/CT study were collected. Images were assessed for the presence and type of perfusion defects. The CT component of the study was also assessed for the presence of mosaic attenuation and COVID pneumonia changes. Results: Thirty-two (57.1%) cases had perfusion defects. There were 20 (35.7%) cases with defects in keeping with pulmonary embolism, 17 (30.4%) cases with defects associated with mosaic attenuation but not due to pulmonary embolism, and 6 (10.7%) of cases with defects due to pulmonary infiltrates from COVID pneumonia. A total of 24 (42.9%) cases had mosaic attenuation on CT, with 10 (17.9%) of them showing a pattern likely consistent with shunting on the perfusion images. Conclusion: Lung perfusion abnormalities are a common finding in non-hospitalized COVID-19 patients with mild disease. They are usually either due to pulmonary embolism, parenchymal infiltrates, or other causes of mosaic attenuation related to, but not specific to the pathophysiology of COVID-19 infection. The value of VQ SPECT/CT imaging is also shown in this study, in detecting and differentiating the various types of perfusion abnormalities. © 2021, The Author(s).