Imaging approach to COVID-19 associated pulmonary embolism

Emergency Presentations of COVID-19: A Review of the Literature and Radiologic Perspective

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is responsible for the debilitating global pandemic known as Coronavirus disease (COVID-19). In this paper, we highlight the widespread manifestations and complications across disease systems. In addition, we present their relevant imaging findings to inform appropriate investigations and management in patients presenting to the Emergency Department with COVID-19 and its respective sequalae. Of note, we outline considerations for diagnosis of long COVID, an important medium to long term sequalae in patients with previous COVID-19 infections.

Mechanisms of COVID-19 Associated Pulmonary Thrombosis: A Narrative Review

COVID-19, the infectious disease caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), is frequently associated with pulmonary thrombotic events, especially in hospitalized patients. Severe SARS-CoV-2 infection is characterized by a proinflammatory state and an associated disbalance in hemostasis. Immune pathology analysis supports the inflammatory nature of pulmonary arterial thrombi composed of white blood cells, especially neutrophils, CD3+ and CD20+ lymphocytes, fibrin, red blood cells, and platelets. Immune cells, cytokines, chemokines, and the complement system are key drivers of immunothrombosis, as they induce the damage of endothelial cells and initiate proinflammatory and procoagulant positive feedback loops. Neutrophil extracellular traps induced by COVID-19-associated “cytokine storm”, platelets, red blood cells, and coagulation pathways close the inflammation–endotheliopathy–thrombosis axis, contributing to SARS-CoV-2-associated pulmonary thrombotic events. The hypothesis of immunothrombosis is also supported by the minor role of venous thromboembolism with chest CT imaging data showing peripheral blood clots associated with inflammatory lesions and the high incidence of thrombotic events despite routine thromboprophylaxis. Understanding the complex mechanisms behind COVID-19-induced pulmonary thrombosis will lead to future combination therapies for hospitalized patients with severe disease that would target the crossroads of inflammatory and coagulation pathways.

CTPA ordering trends in local emergency departments: are they increasing and did they increase as a result of COVID-19?

PURPOSE

Ordering trends for computed tomographic pulmonary angiogram (CTPA) studies by local emergency departments were assessed, along with the impact of the COVID-19 pandemic on these ordering trends and CTPA positivity rates.

METHODS

A retrospective quantitative analysis was performed on all CTPA studies ordered between February 2018 - January 2022 by three local tertiary care emergency rooms to investigate for pulmonary embolism. Data collected from the first two years of the COVID-19 pandemic was compared to the two years prior to the pandemic to assess for significant changes in ordering trends and positivity rates.

RESULTS

The overall number of CTPA studies ordered increased from 534 studies in 2018-2019 to 657 in 2021-2022 and the rate of positive diagnosis of acute pulmonary embolism varied between 15.8% to 19.5% over the four years studied. There was no statistically significant difference in the number of CTPA studies ordered when comparing the first two years of the COVID-19 pandemic to the two years immediately prior; however, the positivity rate was significantly higher during the first two years of the pandemic.

CONCLUSION

Over the studied period from 2018-2022, the overall number of CTPA studies ordered by local emergency departments has increased, in line with literature reports from other locations. There was also a correlation between the onset of the COVID-19 pandemic and CTPA positivity rates, possibly secondary to the prothrombotic nature of this infection or the increase in sedentary lifestyles during lockdown periods.

In Situ Pulmonary Arterial Thrombosis-Literature Review and Clinical Significance of a Distinct Entity

Filling defects identified in the pulmonary arterial tree are commonly presumed to represent an embolic phenomenon originating from thrombi formed in remote veins, particularly lower-extremity deep venous thrombosis (DVT). However, accumulating evidence supports an underappreciated cause for pulmonary arterial thrombosis (PAT), namely, de novo thrombogenesis-where thrombosis arises within the pulmonary arteries in the absence of DVT. Although historically underrecognized, in situ PAT has become of heightened importance with the emergence of SARS-CoV-2 infection. In situ PAT is attributed to endothelial dysfunction, systemic inflammation, and acute lung injury, and has been described in a range of conditions including COVID-19, trauma, acute chest syndrome in sickle cell disease, pulmonary infections, and severe pulmonary arterial hypertension. The distinction between pulmonary embolus and in situ PAT may have important implications regarding management decisions and clinical outcomes. In this review, we summarize the pathophysiology, imaging appearances, and management of in situ PAT in various clinical situations. This understanding will promote optimal tailored treatment strategies for this increasingly recognized entity.

Imaging approach to COVID-19 associated pulmonary embolism

The novel coronavirus disease-2019 (COVID-19) illness and deaths, caused by the severe acute respiratory syndrome coronavirus-2, continue to increase. Multiple reports highlight the thromboembolic complications, such as pulmonary embolism (PE), in COVID-19. Imaging plays an essential role in the diagnosis and management of COVID-19 patients with PE. There continues to be a rapid evolution of knowledge related to COVID-19 associated PE. This review summarises the current understanding of prevalence, pathophysiology, role of diagnostic imaging modalities, and management, including catheter-directed therapy for COVID-19 associated PE. It also describes infection control considerations for the radiology department while providing care for patients with COVID-19 associated PE.