Children who had COVID-19 infections presented with upper respiratory symptoms were difficult to diagnose. PCR is described as the gold standard for COVID-19, but it has falsely negative results due to improper sampling that requires repeated samples . It is unknown whether CT scanning has additional value as diagnostic tool to rule out COVID-19 in children presented with upper respiratory symptoms . It would require very convincing evidence to justify the introduction of ionizing radiation to rule out COVID-19 infection in children.
Most of our examined pediatric patients were in the adolescent group. Running nose and fever were the most common clinical symptoms in the examined patients, these symptoms are in concordance with previous literature that was done by Chen et al.  who reported that running nose and fever were the common symptom in children with COVID-19. Also, the clinical severity classification of the COVID-19 guidelines in China stated that pediatric patients having milder symptoms than adult .
Regarding the CT features of the enrolled cases, most of them (83%) had normal chest CT, these results were largely consistent with multiple previous studies [10,11,12], which reported that most of the pediatric patients had normal chest CT, and also had less severity than adult on imaging. Also, the study done by Steinberger et al.  in 30 pediatric patients as in our study stated that 77% of their children patients had negative CT findings. From these results, we conclude that the radiologist should not be fooled by the normal CT chest to exclude the COVID-19, subsequently CT chest cannot standalone to rule out COVID-19 infection in children, so PCR testing is essential for making the diagnosis of COVID-19 in children presented with upper respiratory tract symptoms as early isolation of these patients to reduce human to human transmission is necessary. Moreover, the Society of Thoracic Radiology and the American College of Radiology do not support the use of chest CT for routine screening of COVID-19 in children, keep in mind the hazards and potential risks of ionizing radiation .
It is noteworthy that, the most commonly lung parenchymal opacity in our pediatric patients with positive CT findings was lung consolidation which was observed in more than half (55.6%) of the cases with lung opacities followed by GGO (20%) and consolidation with GGO (20%); this also stated in previous studies that were done by Chen et al. and Liua et al. [8, 15] which reported that consolidation was observed in 50% of the examined children with COVID-19. In contrary to our study, Steinberger et al.  reported 0% of consolidation in their studied children with COVID-19. As consolidation accounts for up to half cases in many studies with positive CT findings, it should be considered as a hallmark in diagnosis of pediatric patients with COVID-19 infection.
Early radiology investigative results on COVID-19 in pediatric patients done by Chen et al. and Xia et al. [8, 16] stated that bilateral lung lobes affections were more common than unilateral affection and this is not concomitant with our results, which show that 66.7% of the examined cases with positive CT findings had unilateral lung affection, this can be explained by small number of cases with lung opacities (17%) in our study due to the selection of patients with upper respiratory tract symptoms only. However, the systematic review analysis that was done by Susan et al.  reported that unilateral lung affection was more common than bilateral affection as stated in our study. Peripheral distribution of the lung opacities was more frequent than central distribution in our patients that is also greatly consistent with the previous studies [8, 10]. Predominance of lower lung lobes affection were noted in 66.7% of our examined patients that it is consentient with previous studies that were done by Susan et al.  and Han et al. , as they stated that more than 86% of the pediatric patients with COVID-19 had lower lobe involvement. This could be explained by the anatomy of the lower lung bronchus, which is short in length and thick, making the lower bronchus easy to be catched by the virus.
Recent chest CT report on COVID-19  stated that bronchial wall thickening was more obvious on pediatric patients, and this was also prevalent in our pediatric group (43.4%) and this could be explained by the distribution of the coronavirus infection along the respiratory epithelium in children.
This study has several limitations. Firstly, the sample size was small which limited the study power. Secondly, absence of adult patients group to compare their chest CT features with the pediatric group. Thirdly, the involved patients had only upper respiratory tract infection, so the lung affection was limited.