COVID-19 is an emerging disease which is caused by SARS-CoV-2. It causes extensive edema of the interlobular septae with lymphocytic infiltration in the pulmonary interstitium. Although the early airspace and alveolar exudate accumulation are not significant, the disease may progress dramatically .
CT has a cornerstone in the diagnosis of COVID-19 patients in many situations. A study by Dawoud et al.  recommended CT chest CT for diagnosis and follow-up of COVID-19 pneumonia. A study conducted by Ali et al.  who studied COVID-19-associated pneumonia in asymptomatic patients coming for routine oncologic 18F-FDG PET/CT during the COVID-19 outbreak and found that about 11% of patients had chest findings suggestive of COVID-19 pneumonia and confirmed their findings by RT-PCR.
In our study, the CT characteristics were consistent with that published in the literature [13,14,15,16,17,18]. In COVID-19 pneumonia, the most common chest CT findings were ground-glass opacities followed by consolidation. The most common site of distribution was the lung periphery. The interlobular septal thickening was often seen. Crazy paving and reverse halo signs were characteristic of COVID 19 pneumonia; however, they were uncommon. Also, enlarged mediastinal lymph nodes and pleural effusion were rare to be encountered.
The multifocal affection was characteristic of COVID-19 pneumonia in multiple ground-glass and consolidation patches seen scattered in multiple lobes. This feature helps in the diagnosis of COVID-19 pneumonia rather than bacterial pneumonia [13, 19, 20]. The most common affected lobes were the lower lobes, mainly the dorsal segments. This agrees with Wu et al. , who found that the most commonly affected lung segments were the lower lobes’ dorsal and basal segments.
The reported negative initial CT rate in patients with positive COVID-19 PCR reached 17–28% [7, 22]. A study by Sabri et al.  found that normal CT interpreted as negative for COVID-19 in 26.1% of RT-PCR proved COVID-19 cases. Similar findings were found in our study, as negative CT was encountered in 26.8% of patients. The relatively low negative predictive value suggests that CT may not be valuable as a screening test for COVID-19, at least in earlier disease stages .
We found that older age is a significant predictor of death. This is in agreement with the widely known high death rate in the elderly [24, 25]. Laboratory tests usually reveal normal or reduced counts of peripheral blood leukocytes and lymphocytes at the early stages of the disease. Most patients have increased C-reactive protein and D-dimer levels . In the present study, leucocytic and lymphocytic counts and, more significantly, D-dimer predict death in COVID-19 patients. D-dimer test is a good negative test with high sensitivity that can rule out pulmonary embolism in patients with low clinical risk . However, it has very low specificity, especially in the intensive care unit (ICU) patients, as many other conditions are associated with raised D-dimer level . Recent guidelines recommend non-contrast CT chest for only in-patient symptomatic patients for specific indications, e.g., assessing disease severity and follow-up . In suspected cases, CT pulmonary angiography (CTPA) should be done as it is considered the gold standard for the diagnosis of pulmonary embolism with sensitivity and specificity of 92% and 98%, respectively .
This study has several limitations. First, given the small sample size, further studies with a larger sample size are still recommended. Second, it was retrospective. Further prospective cohort studies could better assess the risk factors and avoid the selection bias. Third, the current results were not correlated with the duration of illness. Further investigations are needed to clarify the time-related course of COVID-19 pneumonia.