Abstract
2002
Objectives: COVID-19 pneumonia is documented to produce pulmonary thromboembolism. Despite achieving COVID negative status, few patients continue to be symptomatic, especially with respiratory distress. This has been noted particularly in those patients who had severe pulmonary involvement requiring high flow oxygen administration at the time of admission. It often becomes challenging to correlate the clinical findings, D-dimer values and ultrasonographic evaluation to rule out deep vein thrombosis related acute pulmonary embolism in these patients. Computed tomography pulmonary angiography has many limitations in assessing pulmonary embolism in these patients as there are several other lung findings which can be seen in this cohort. Lung perfusion scintigraphy with SPECT/CT is a valuable tool in evaluation of pulmonary embolism. Lung perfusion scintigraphy in these patients, as a part of evaluation of pulmonary thromboembolism after recovering from COVID-19 pneumonia shows a multitude of findings. The aim of this exhibit is to acquaint the imaging physicians with these findings and hence improve the diagnostic accuracy of pulmonary embolism in these patients.
Methods: Records of lung perfusion scintigraphy with SPECT/CT done in patients with post COVID-19 pneumonia were reviewed. Those patients who had severe symptoms clinically were reviewed for the imaging findings. Typical perfusion finding of a wedge shaped perfusion defect in the planar imaging along with no lung parenchymal changes should be easy to identify as well as strongly suggests the diagnosis of pulmonary embolism. However, some patients might show difficult to interpret images in the planar and SPECT/CT imaging which requires careful analysis of both the perfusion and corresponding CT images.
Results: Different possible findings of lung perfusion scintigraphy with SPECT/CT are presented. These includes classical wedge shaped segmental defects in the planar as well as SPECT/CT imaging with (matched defects) or without (mismatched defects) corresponding various lung parenchymal findings (diffuse ground glassing, subpleural ground glassing, subsegmental cystic areas, parenchymal consolidation, fibrosis, interlobular reticulation) in the CT images. Apart from the classical segmental defects, a good number of subsegmental perfusion defects are also noted in many cases, which poses a challenge in diagnosing the pulmonary embolism in these patients.
Conclusions: In the wake of COVID-19 pandemic, ventilation scintigraphy carries an inherent risk of COVID-19 exposure to the imaging personnel. However, the lung perfusion scintigraphy with added SPECT/CT imaging serves to overcome the deficiency of ventilation imaging. This exhibit illustrates the common and uncommon perfusion and computed tomography lung findings in those patients who recovered from COVID-19 infection and continue to be symptomatic, requiring supportive therapy. The knowledge of these findings will help the readers in interpreting the clinical and laboratory findings and correlate it with the lung perfusion imaging in any patient who have recovered from COVID-19 infection.