OBJECTIVES This study aims to trace the dynamic lung changes of coronavirus disease 2019 (COVID-19) using computed tomography (CT) images by a quantitative method .
METHODS In this retrospective study, 28 confirmed COVID-19 cases with 145 CT scans are collected . The lesions are detected automatically and the parameters including lesion volume (LeV/mL), lesion percentage to lung volume (LeV %), mean lesion density (MLeD/HU), low attenuation area lower than - 400HU (LAA-400 %), and lesion weight (LM/mL*HU) are computed for quantification . The dynamic changes of lungs are traced from the day of initial symptoms to the day of discharge . The lesion distribution among the five lobes and the dynamic changes in each lobe are also analyzed .
RESULTS LeV%, MLeD, and LM reach peaks on days 9 , 6 and 8, followed by a decrease trend in the next two weeks . LAA-400% (mostly the ground glass opacity) declines to the lowest on days 4-5, and then increases . The lesion is mostly seen in the bilateral lower lobes, followed by the left upper lobe, right upper lobe and right middle lobe (p <0.05). The right middle lobe is the earliest one (on days 6-7), while the right lower lobe is the latest one (on days 9-10) that reaches to peak among the five lobes .
CONCLUSIONS Severity of COVID-19 increases from the day of initial symptoms, reaches to the peak around on day 8, and then decreases . Lesion is more commonly seen in the bilateral lower lobes.