By the end of May 2020 the pandemic of COVID-19 infected more than 6 million persons and killed more than 300.000 persons all over the world according to World Health Organizations (WHO) reports [8].
Early diagnosis of COVID-19 pneumonia is important to decrease the spread of COVID-19 pandemic. Early diagnosis helps in early isolation and treatment of the patients and so decreases the spread, morbidity and mortality of the disease. RT-PCR test has low sensitivity and high false negative results in diagnosis of COVID-19. Many recent studies showed that the use of high-resolution pulmonary CT helped in early detection of pulmonary lesions in COVID-19 infection [1,9].
This study included 100 patients tested positive for COVID-19 by RT-PCR.
Our study showed that COVID-19 pneumonia affected male (54%) more than female (46%), we also reported that adult are more affected with COVID-19 pneumonia than children with mean age of infection was about 45 years.
According to CT results in our study 10% of patients showed normal pulmonary CT and 90% showed abnormal pulmonary CT findings this is matched with Bernheim, et.al. 2020 they concluded that 9% of positive COVID-19 patients showed normal pulmonary CT in the early and asymptomatic stage of the disease [10].
In our study most of abnormal pulmonary CT showed bilateral pulmonary affection 79% of the patients and only 11% showed unilateral pulmonary affection. In our study numbers of patients with multiple pulmonary lobar affection were dramatically higher (79%) than the numbers of patients with single lobar affection (11%) this matched with Han et.al. 2020 they concluded that 65% of patients showed more than one pulmonary lobe affection [1].
In our study we reported that the lower pulmonary lobes were more affected by COVID-19 pneumonia than the upper pulmonary lobes, the right lower lobe affected in 77% of patients and left lower lobe affected in 71% of patients this was in agreement with Bernheim, et.al. 2020 who concluded that the lower lobes were more affected than upper lobes [10]. This may be due to the thicker and shorter anatomy of the right lower bronchus that accelerates its invasion by the virus [1].
In our study we reported that the posterior pulmonary segments were much more affected (69%) by COVID-19 pneumonia lesions than anterior pulmonary segments (44%). This was in agreement with Yang et.al. 2020 they concluded the posterior pulmonary segments affected more than anterior pulmonary segments by COVID-19 lesions [11].
In our study according to the distribution of the lesions in the pulmonary lobes 64% of patients showed peripheral sub-pleural pulmonary lesions and 24% showed mixed peripheral and central (peri-broncho-vascular) pulmonary lesions this was in agreement with Han et.al. 2020 and Bernheim, et.al. 2020 they concluded that the COVID-19 pneumonia lesions affected peripheral sub-plural lung zones more than central zones [1,10].
Many studies Han et.al. 2020, Bernheim et.al 2020 and Li et.al 2020, concluded that the most common pattern of COVID-19 pneumonia in pulmonary CT scan was presence of ground glass opacities with or without consolidation opacities [1,10,12]. This was in match with our study we concluded that the most common pattern of COVID-19 pneumonia in pulmonary CT scan was ground glass pattern (44%) followed by mixed pattern of both ground glass and consolidation opacities (33%) and the least pulmonary CT pattern was consolidation opacity alone (13%).
Huang et.al. 2020 reported that the pathophysiologic mechanism of coronavirus infections may be the same as SARS-CoV and MERS-CoV infections that cause diffuse alveolar damage due to inflammatory cytokine storm and this explained the ground glass opacities in early pulmonary CT [13].
In our study we reported that the most common shape of COVID-19 pneumonia opacities were ill defined patchy opacities (76%) either alone or mixed with nodular pattern and this matched with Han et.al. 2020 that concluded that 86% of the lesions showed patchy shape [1].
In our study we reported many characteristic pulmonary CT signs for COVID -19 pneumonia as reversed halo sign (28%) , air bronchogram sign (39%), crazy paving pattern (77%), and vascular thickening (66%) and all these signs were reported in many researches [1,10,12].
Many researchers Han et.al. 2020, Bernheim et.al 2020 and Li et.al 2020 reported that pulmonary fibrosis and extra-pulmonary manifestations, like pleural effusion, mediastinal, and hilar lymphadenopathy, were not detected in pulmonary CT scan of early COVID-19 pneumonia and they explained that as these findings may appear in the later and severe stage of the disease [1,10,12]. This was matched with our study as we didn’t detect signs of pulmonary fibrosis or extra-pulmonary manifestations in our study for few pleural thickening (7%).
In our study we concluded that the main pulmonary CT signs in COVID-19 infection are bilateral, peripheral, sub-pleural multi-lobar ground glass opacification with or without consolidation in patchy distribution with or without nodular pattern more on posterior and basal pulmonary segments. Other pulmonary signs may also present include crazy paving pattern, reversed halo sign vascular thickening, and air bronchogram sign with no extra-pulmonary signs except for few pleural thickening and these were in agreement with Many researchers [1,10,12].
In our study we had a limitation as there was no follow-up CT to evaluate the treatment effect and the prognosis of the disease as all positive RT-PCR patients were transferred to quarantine hospitals and isolation centers.