Long COVID: Ventilation and Perfusion Are Reduced in Symptomatic Individuals Compared to Asymptomatic Patients—A V/Q Scintigraphy Study

Pulmonary dysfunction is a common sequel of COVID-19, with long-term effects on lung function even after recovery. Traditional imaging methods like computed tomography (CT) and X-ray often fail to detect subtle functional impairments. In contrast, ventilation and perfusion scintigraphy (V/Q scintigraphy) provide a sensitive assessment of regional ventilatory and perfusion abnormalities, revealing functional changes missed by anatomical imaging. To compare the regional pulmonary distribution of radiopharmaceuticals in symptomatic and asymptomatic post-COVID-19 individuals. A cross-sectional study was conducted with 33 post-COVID-19 individuals, categorized into asymptomatic (n = 10) and symptomatic groups (n = 23), classified according to symptom severity. Ventilation and perfusion scintigraphy were performed using technetium-99m radiopharmaceuticals (99mTc-DTPA for ventilation and 99mTc-MAA for perfusion). Pulmonary radiopharmaceutical activity was quantified using Regions of Interest (ROIs) in central and peripheral zones and upper, middle, and lower regions. Symptomatic patients showed significantly lower radiopharmaceutical activity in all pulmonary regions compared to asymptomatic participants (p < 0.05). Perfusion analysis revealed significantly higher total lung radiopharmaceutical counts in asymptomatic individuals (Median [IQR]: 1046.94 [447.41] Kct) compared to symptomatic individuals (765.66 [269.94] Kct, p = 0.002). No significant differences were found in the left lung regions. The total pulmonary count during the ventilation phase progressively decreases as disease severity increases. The comparison between the extremes (asymptomatic vs. severe) reveals a nearly 50% reduction in pulmonary counts. Significant differences in pulmonary radiopharmaceutical activity were observed between groups, with reduced ventilatory and perfusion functionality in symptomatic patients. These findings underscore the importance of advanced techniques for monitoring and individualized rehabilitation of post-COVID-19 patients.