Chest x-ray findings and temporal lung changes in patients with COVID-19 pneumonia

An outbreak of severe cases of pneumonia from an unidentified origin emerged in Wuhan, China in December 31, 2019. The illness rapidly spread in China and in many other countries. In January 2020, the World Health Organization (WHO) declared it a pandemic [1]. A virus was identified and isolated from the epithelial cells of the respiratory system of infected individuals and was named as Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) and the outbreak was named coronavirus disease (COVID-19) [2].

Coronaviruses are enveloped, positive-sense, single strand, non-segmented, and ribonucleic acid viruses that belong to the coronaviridae family [3]. The viruses have characteristic morphology under the electron microscope with presence of viral spike peplomers arising from the viral envelope giving a crown appearance [4]. The coronaviruses are widely distributed among humans and mammals [5]. Six coronaviruses are identified, four of which cause mild common cold symptoms, and two strains were responsible for Severe Acute Respiratory Syndrome (SARS) that began in southern China in 2003 and Middle East Respiratory Syndrome (MERS) that originated in Saudi Arabia in 2012 [6].

The most common symptoms of COVID-19 include fever, cough, dyspnea, fatigue, and myalgia, less common symptoms are sputum, hemoptysis, headache, and gastrointestinal symptoms [5].COVID-19 infection is confirmed in many countries by Reverse Transcription Polymerase Chain Reaction (RT-PCR) on nasopharyngeal and throat swabs, with a positive rate of 30–70% [7, 8]. Chest CT scan was found to be more sensitive than RT-PCR in confirming the diagnosis of COVID-19 reaching 98% [8]. Chest x-ray was found to have limited value in the initial diagnosis of COVID-19 with a sensitivity of about 69% [9, 10]. Patients with COVID-19 had typical radiological findings on chest imaging including multifocal and bilateral ground glass opacities and consolidations with peripheral and basal predominance. Septal thickening, bronchiectasis, pleural effusion, lymphadenopathy, and cavitation were less commonly seen [1, 6, 11‐14].

The outbreak of COVID-19 began in March 2020 in Jordan. RT-PCR was used in the diagnosis and chest x-ray was used in the follow up of patients. Information on chest x-ray findings in patients with COVID-19 pneumonia is still limited in the literature and the majority of the reports described the lung changes on chest CT scan. This study aimed to report the chest x-ray findings in 88 patients with confirmed COVID-19 and to describe the temporal changes of the chest radiological findings throughout the disease course.

RT-PCR was the first line of diagnosis in patients with COVID-19 in Jordan. In previous reports, chest CT scan was found to be a more sensitive diagnostic tool than RT-PCR even in asymptomatic patients reaching 98% [1, 7, 8]. However, many researchers found that patients with a positive RT-PCR may have a negative chest CT scan, and patients with a negative RT-PCR may have positive chest CT scan [4, 7, 12]. Chest x-ray was regarded an insensitive tool reaching 69% [8, 9, 14, 17]. The American College of Radiologists (ACR) and the Fleischner Society have suggested that imaging is not advised for patients who tested positive by RT-PCR who were asymptomatic or have mild symptoms, and CT scan should be reserved for patients with a progressive disease course [18, 19]. Due to the high infectious rate of COVID-19 virus; infection control in radiology departments becomes a challenge in the CT scan suite, therefore, the ACR has also recommended that portable chest x-ray may be considered to minimize the risk of cross infection [14, 18].

In our study, every patient had at least one chest x-ray done during their stay in the hospital, no chest CT scan was performed in any of the patients. Only one patient (1/88, 12.5%) with positive chest x-ray findings and positive RT-PCR remained asymptomatic throughout the illness. Asymptomatic patients with positive RT-PCR results and chest CT scan findings were reported in the literature [10, 20] and may be as a result of acquiring immunity from a previous infection or being in the healing phase [20]. Normal chest x-rays in RT-PCR positive patients was seen in 25% and 31% in previous reports [14, 21]. In our study, 85% of the patients who tested positive for COVID-19 had negative chest x-rays, 50% of them were asymptomatic the other half had mild symptoms. Identifying patients with COVID-19 positive RT-PCR is essential in containing the disease by isolating the patients to prevent further spread of the disease.

The most common symptom among our patients was cough followed by fever, which is the common presentation among patients with COVID-19 pneumonia worldwide [5, 22]. Three percent of our patients suffered from diarrhea which was described by the patients as the worst diarrhea ever experienced. Diarrhea was also an uncommon symptom in previously reported patients [5, 17, 23].

The most common chest x-ray finding in our patients was GGO in a peripheral distribution with bilateral lung involvement, there was a lower lobe predilection of the opacities, with the right lower lobe more common than the left lower lobe (70% vs. 50%). Our findings are in consensus with previous studies on chest x-ray and chest CT scans [4, 8, 11‐13, 17, 21‐26]. Only two patients had pleural effusion which is not a common finding on chest imaging [14, 27]. Two patients developed reticulations in the second week from the onset of symptoms, this finding was reported on chest CT scan [7, 23, 25, 28]. However, it was reported earlier in the course of the disease on chest x-ray in one large study [21].

The chest x-ray severity scores changed over time, peaking at day 5–10 of symptom onset with transformation of the GGO into focal areas of consolidations and into nodular consolidations. A phase of improvement of the findings with decrease in the size and number of the GGO/consolidation and lobes involved and regression of consolidations into GGO was observed in 69% of the patients at day 10–15 from onset of symptoms. The peak and the absorption phases in our study were observed to be earlier than those reported previously [peak phase range at days 6–15, absorption phase range at days 14–17] [1, 23‐25].

Chest x-ray severity score was found in a previous report to be a predictive index of risk for hospital admission and intubation in patients with COVID-19 pneumonia [29], and mobile chest x-rays were found to be beneficial in the follow up of critically ill COVID-19 patients in another study [27]. In our study, the radiographic findings on chest x-ray in COIVD-19 pneumonia patients are consistent with the radiographic findings detected on chest CT scans and on chest x-rays in previous reports. Also, in our study the presence of symptoms correlated significantly with abnormal chest x-ray findings suggesting that chest x-ray may be helpful as an aiding tool in the diagnosis and follow up in patients with COVID-19 pneumonia.

The limitations of our study include small sample size of the patients with positive chest x-ray findings and short follow up period. In addition, the interval between the chest x-rays obtained was not uniform in all patients which may have led to undiagnosed abnormalities. And the lack of correlation between chest x-ray and chest CT scan findings.

Almost half of the patients with COVID-19 had abnormal chest x-ray findings, GGO in a peripheral distribution with lower lobe predilection being the most common findings on chest x-ray. The radiographic findings peaked at day 5–10 of symptom onset reaching the highest severity score. Presence of symptoms correlated significantly with abnormal chest x-ray findings. Chest x-ray may be helpful as an aiding tool in the diagnosis and follow up in patients with COVID-19 pneumonia.