Abstract
2791
Introduction: Lung perfusion abnormalities are not uncommon findings in patients with COVID-19. They could be due to pulmonary embolism (PE), lung parenchymal infiltrates from COVID pneumonia and perfusion shunting. Anecdotal evidence in our facility so far has shown that some of these lung perfusion abnormalities, with mosaic hypoattenuation on CT are persistent, despite the prolonged use of therapeutic anticoagulation in patients who have been previously diagnosed with COVID-19. We suspect that these perfusion abnormalities are as a result of pulmonary micro thrombosis. Unlike other viral pneumonias with temporary matching defects, these defects in COVID-19 patients seems to persist for a long period of time. The purpose of this study is to demonstrate the usefulness of VQ SPECT/CT in the identification and follow up of these patients
Methods: We retrospectively reviewed the data of all the COVID-19 infected patients who had a VQ SPECT/CT study in our facility between July 2020 and January 2022. Initial and follow up studies from patients who had matching perfusion defects with mosaic hypoattenuation on CT were evaluated.
Results: Twenty patients who had matching perfusion defects with corresponding mosaic hypoattenuation on CT within the study period were included in the study. Nine (45%) of them had follow up studies performed between 3 -12 months after their initial study, with 6 having follow up studies at 12 months, 2 at 6 months and 1 at 3 months. All 9 (100%) patients with follow up studies showed persistent matching perfusion defects and mosaic hypoattenuation on CT. However, the ventilation studies showed some improvement.
Fig 1 – Ventilation (bottom) and perfusion (top) SPECT images of a 42 YOF, 3 months(first two images) and 12 months (last two images) post COVID-19 positive, showing persistence and matching of perfusion defects noted at baseline.
Supplemnetary information – Perfusion SPECT/CT images of a 42 YOF, 14 days post COVID-19 positive, showing multiple perfusion defects, with corresponding mosaic hypoattenuation on CT.
Conclusions: Even though the exact pathophysiology is not clear, we can confirm that there are a subset of patients that have recovered from COVID-19 but have persistent matched lung perfusion defects on a VQ SPECT/CT study. Identification of these patients might be important as persistent perfusion defects over time might lead to complications such as pulmonary hypertension and right heart failure. This study has shown that VQ SPECT/CT imaging could be useful in the identification and follow up of these patients.