Lobar Distribution of COVID-19 Pneumonia Based on Chest Computed Tomography Findings; A Retrospective Study

Introduction: computed tomography (ct) imaging has quickly found its place as a beneficial tool in the detection of coronavirus disease 2019 (covid-19). to date, only a few studies have reported the distribution of lung lesions by segment. this study aimed to evaluate the lobar and segmental distribution of covid-19 pneumonia based on patients’ chest ct scan. methods: this was a retrospective study performed on 63 iranian adult patients with a final diagnosis of covid-19. all patients had undergone chest ct scan on admission. demographic data and imaging profile, including segmental distribution, were evaluated. moreover, a scoring scale was designed to assess the severity of ground-glass opacification (ggo). the relationship of ggo score with age, sex, and symptoms at presentation was investigated. results: among included patients, mean age of patients was 54.2 ± 14.9 (range: 26 - 81) years old and 60.3% were male. overall, the right lower lobe (87.3%) and the left lower lobe (85.7%) were more frequently involved. specifically, predominant involvement was seen in the posterior segment of the left lower lobe (82.5%). the most common findings were peripheral ggo and consolidation, which were observed in 92.1% and 42.9% of patients, respectively. according to the self-designed ggo scoring scale, about half of the patients presented with mild ggo on admission. ggo score was found to be equally distributed among different sex and age categories; however, the presence of dyspnea on admission was significantly associated with a higher ggo score (p= 0.022). cavitation, reticulation, calcification, bronchiectasis, tree-in-bud appearance and nodules were not identified in any of the cases. conclusion: covid-19 mainly affects the lower lobes of the lungs. ggo and consolidation in the lung periphery is the imaging hallmark in patients with covid-19 infection. absence of bronchiectasis, solitary nodules, cavitation, calcifications, treein-bud appearance, and reversed halo-sign indicates that these features are not common findings, at least in the earlier stages.