Objective: To study non-enhanced computer tomographic features of chest imaging in 302 patients with Corona Virus Disease 2019 (COVID-19) in Jordan. Material and method: A retrospective analysis of non-enhanced computer tomographic scans has been performed in the main center for patients diagnosed with COVID-19 in Prince Hamzah Hospital for those scanned from 13th of March 2020 to 13th of May 2020. Included scans were routinely performed during 24-hs of admission apart from having respiratory complaint. CT protocol included non-enhanced 1 mm slice thickness by Philips Brilliance Big Bore scanner (Philips; Amsterdam, Netherlands). All computer tomographic scans were reviewed by two senior radiologists with more than 8 years of experience each and senior registrar. Several factors have been thoroughly studied including patient age, gender, positive versus negative pulmonary findings, laterality of lung involvement, lobar distribution, pattern of pulmonary changes on initial and follow-up scans. Results: The total number of patients evaluated was 302. There were 188 men and 114 women studied. Among the totally studied 302 cases; 181 cases (59.9 %) showed no pulmonary changes. Positive findings were present in 121 patients with a total number of 191 computer tomographic scans including initial and follow-up scans. Positive findings were present in 51 female and 70 male patients (age range, 12-87 years; mean age +/- standard deviation, 46.1 +/- 16.5). Bilateral disease was more frequently encountered presented in 86 cases (71.1 %), while unilateral disease showed two times more predilection for the right lung compared to the left. The incidence of lobar involvement in descending order: right lower (75.2 %), left lower (71.9 %), right upper (62.8 %), left upper (60.3 %) and right middle (50.4 %). The incidence of the affected lobes on the initial scans were as follow: one lobe (24 %), two lobes (10.7 %), three lobes (9.1 %), four lobes (16.5 %) five lobes (36.4 %). In cases with single lobar involvement (24 %); the left upper and right middle lobes showed lowest incidence of involvement accounting for 10.3 % & 13.8 %, respectively; on the other hand, in cases with four lobar involvement (16.5 %); the right middle lobe was most commonly spared in two third of cases (63.2 %). Several initial patterns of the pulmonary changes resulting from Corona Virus Disease 2019 (COVID-19) were present with a descending order; ground-glass pattern (96.7 %), lenticular pattern (32.2 %), Halo sign (15.7 % %), rounded (14.9 %), nodular (10.7 %), ground-glass with consolidation (8.3 %), tree-in-bud (1.7 %) and pleural effusion (1.7 %). Pathologically-enlarged lymph node was not a feature of COVID-19. The total number of patients with positive findings having follow-up scans was 57 including single (45 patients) versus two (12 patients) follow-up scans. Initial follow up scans showed regression and progression of the pulmonary changes in 35 and 22 patients, respectively. A remarkable pattern was seen in almost all regressed cases that showed patchy reticular pattern changes with septal thickening which was referred to "pulmonary synapses" (34 patients) with only one patient showed complete resolution of the parenchymal changes. Patterns seen in progressed cases were lenticular ground-glass (63.6 %) vs patchy ground-glass (36.4 %) patterns. Conclusion: Computer tomographic scan of the chest is a principal diagnostic measure for Corona Virus Disease 2019 (COVID-19). The pulmonary changes showed more propensity being bilateral disease and affecting the lower lobes, while the right middle lobe was the least likely involvement. Several pattern of pulmonary changes can be seen on initial scans including ground glass, consolidation, Halo sign, lenticular, nodular, pleural effusion and tree-in-bud patterns. The tree-in-bud is first-time described pattern of COVID-19 in the current article and thought to be an excluding criterion. In follow-up scans; the lenticular and patchy ground-glass patterns were present in cases with disease progression, compared with "pulmonary synapses" pattern encountered in cases with disease regression.
