Spectrum of Chest CT Findings in Covid-19 Patients: Relationship to the Patient’s Age Group and Duration of Infection in Al-Dhafra Hospitals, Abu Dhabi

Purpose: This study aims to identify chest CT findings among asymptomatic and symptomatic COVID-19-positive patients in Al Dhafra Hospitals and review the common CT findings in relation to the different age groups of the patients and the duration of their symptoms.

Methods: Data from 301 consecutive patients whose COVID-19 infection was confirmed using an RT-PCR test, and who subsequently underwent a chest CT and presented to our hospital, were collected from April, 1 to May 31, 2020. They were further classified according to the time after the onset of the initial symptoms, namely stage-1 (0–4 days); stage-2 (5–8 days); stage-3 (9–14 days), and stage-4 (14+ days), and according to the age of the patient in four groups (Group A- <18 years, Group B- 18–44 years, Group C- 45–59 years, and Group D- ≥60 years). We analyzed the prevalence, distribution, type of abnormal lung findings, and extent of the involvement of affected lobes through Ground-Glass Opacities (GGO), crazy-paving pattern, and consolidation in five categories of percentual severity by semi-quantitative CT score (maximum CT score, 25).

Results: Multiple small patchy, rounded, pure Ground-Glass Opacities (GGO) and mixed GGO with consolidations were the main HRCT signs in 231 patients with confirmed COVID-19 infections. Both of these were predominant patterns in the young, middle, and elderly groups (<18 to >60 years). However, crazy paving patterns were more common in groups ages 45 to <60. The peripheral disease distribution was seen in 100% of cases, and both peripheral and central types of distribution of opacities were most common in the elderly group (>60 years old), at 73.3%. Bilateral involvements were common in all groups, but unilateral involvement was fairly common in groups ages <18 to 44 years old. Both the mean number of lesions and CT score were higher in 44 to <69 years and >69 years aged groups than in <18 to 44 years old, and lower lobes showed relatively higher numbers of lesions and CT score than other lobes in all age groups.

Normal CT findings among symptomatic patients were seen in the early stage (0–4 days) and progressive stage (5-8 days) of the disease, at 36.3% and 6.6%, respectively. Peripheral mixed GGO with consolidation and pure GGO were the most important imaging manifestations in the early and progressive stages of the disease. CT features of the lesions were variable in the peak (9-13 days) and late stages (14+ days), showing a mixture of GGO, crazy-paving pattern, consolidation, and linear opacities. Both the “Reverse Halo sign” and “Halo sign” were seen, predominately in the early stage of the disease (0 to 8 days) in 52 patients (22.5%) and 16 patients (6.9%), respectively. The number of lesions per capita, meaning the number of lesions in different lobes of both lungs and the CT score, were higher in the progressive and peak stages of the disease than in the early stage, and then gradually decreased in the late stage of the disease. We also observed a relatively greater number of lesions in both lower lobes compared to the upper lobes and a smaller number of lesions in the right middle lobe at all stages.

Conclusion: The most common HRCT findings in patients with COVID-19 pneumonia were peripheral, bilateral, rounded pure ground glass opacities, and mixed GGO with consolidation. The early stages of the disease may present with normal CT chest findings. Chest HRCT manifestations in patients with COVID-19 are related to the patient’s age and the duration of the symptoms, and HRCT signs are relatively milder in younger patients and in the early stage of the disease. CT could be a useful tool for evaluating the changes in pulmonary abnormalities in patients at different stages and in different age groups (especially elderly groups) for optimal management.