Deposition and distribution of radiolabeled aerosol in individuals post COVID-19 infection

<bold>Aim:</bold> To quantify the deposition and distribution of radiolabeled aerosol in individuals post COVID-19 infection. <bold>Material and methods:</bold> Cross-sectional study, post-COVID-19 patients were divided into two groups (symptomatic and asymptomatic) and evaluated after inhalation with technetium-labeled diethylenetriaminepentaacetic acid (99mTc-DTPA), with radioactivity of 5 millicurie, associated with 0.9% saline solution up to a total dose volume of 1.5 ml, using a membrane nebulizer. Aerosol inhalation was performed in the upright seated position for 3 minutes. Immediately after inhalation completion, aerosol deposition was analyzed using a gamma camera with a 256 x 256 matrix, at five distinct incidences, with a duration of 300s each. Aerosol deposition analysis was performed using Xeleris 3 Functional Imaging Workstation software. <bold>Results:</bold> The study included 20 patients matched for sex and age (mean age, 43.35±13) and 40% of symptomatic patients had moderate disease severity. Time post COVID-19, we observed a mean time of 35.4 months since the first virus infection. In static images post-inhalation, it was possible to observe greater total lung deposition for the asymptomatic patient group in the anterior region (690.55± 229.02 vs. 308.90 ±154.46; Cohen´s d = 0.69, p<0.001) and posterior region (680.14± 243.26 vs. 428.11 ±181.04; Cohen´s d = 0.50, p=0.001). <bold>Conclusion:</bold> This study showed a significant difference in total anterior and posterior lung deposition in individuals post COVID-19 infection, demonstrating that the pulmonary effects of COVID-19 can last much longer than the acute phase of the disease and impact the concentration of medication administered by this route.