DOI 10.25176/RFMH.v20i4.3034



Silvia Lucía Mayanga-Sausa1,2,a,b, Raúl Max Steve Guerra-Tueros1,2,a, Daniel Alcides Lira-Villasante1,3,a, Dayana Kim Pastor-Gutiérrez2,4,a

1Hospital Nacional Edgardo Rebagliati Martins-EsSalud, Lima-Perú.
2Clínica Internacional, Lima-Perú.
3Clínica Centenario Peruano Japonesa, Lima-Perú.
4Clínica Ricardo Palma, Lima-Perú.
bMaster in Education and Research in Health-UNMSM.


In the current SARS-COV-2 pandemic, the choice of an imaging modality to aid diagnosis is based on the patient's clinical conditions, laboratory tests, and the availability of imaging equipment in health facilities. Tomography (CT) and chest radiography (CXR) are the most widely used imaging modalities; CXR, with less sensitivity than CT, is an accessible method, less expensive and less exposure to health personnel, its use is recommended in emergencies and in hospital services. The objective of the article is to guide decision-making to choose an imaging modality according to scenarios, taking into account its potential benefits and deepening in the description of the radiographic characteristics of suspected SARS-COV-2 infection that may serve in emergencies and we assess disease progression using a scoring system.

Key words: Chest radiography; SARS-COV-2; Medical imaging (Source: MeSH NLM).


In the current situation of the SARS-COV-2 pandemic, Peru faces scenarios that change dynamically daily due to the increase in cases and the need to require health services. It is not supplied due to the over-demand of clinically serious patients and non-serious patients with the presence or absence of risk factors or associated comorbidities, who require medical attention and an imaging diagnosis if pneumonia is suspected(1).

From the beginning of the SARS-COV-2 pandemic to date, according to the published scientific literature, the pillars for the management of the patient suspected of SARS-COV-2 infection is based on the clinical characteristics and the availability of the tests laboratory, which confirm or rule out COVID-19. These two variables generate different action and decision scenarios for the correct and timely indication of imaging that corroborates the clinical diagnosis of suspected pulmonary involvement and that allows an objective assessment of the patient's evolution(2), such as computed tomography (CT) with an indication in hospitalized and symptomatic patients. However, CT is not affordable for all patients, nor is it available in all health facilities in the country. Other factors that must be considered are the availability of radiology equipment, the risk of contamination of personnel and the radiological diagnosis support room, as well as the use and availability of personal protective equipment (PPE)(3).

Therefore, in this article we propose management by scenarios to choose an imaging modality, focusing on the usefulness of chest radiography.


Chest radiography (CXR) is an imaging modality present in most health facilities and is the first imaging study to identify pulmonary pathology. In the 2003 SARS-VOC coronavirus epidemic, CXR helped to assess lung involvement and to predict the risk of mechanical ventilation or death(4,5). In the current coronavirus type 2 pandemic of 2019 (SARS-COV-2), The American College of Radiology (ACR) recommends the use of CXR in the portable modality(6) for hospitalized patients; however, in the United States emergency services, CXR is performed on all dyspneic patients with/without SARS-COV-2 infection(7,8).

The reported sensitivity for CXR is 69%(9) and for CT it is 97%(10); However, the CXR exceeds the results of the serological test to detect SARS-COV-2 infection applied in the first week of onset of symptoms (50% positive tests), which depends on the variability of producing antibodies in each individual(11). Despite the greater sensitivity of CT, the ACR does not recommend its use as a first-line test to diagnose SARS-VOC-2 lung involvement and should be reserved for hospitalized and symptomatic patients with specific clinical indications(6). Many health facilities prefer CT because it has a greater ability to detect pulmonary alterations in the presymptomatic and early symptomatic phase of COVID-19(12).

The greater diagnostic capacity of CT contrasts with the lower availability of CT scanners in health facilities, greater downtime of the CT environment due to the need for cleaning and disinfection after each patient, risk of transmission to health workers and other patients during the transfer, use of a greater number of personal protective equipment (PPE) and greater exposure to radiation for the patient(2,6).

It is known that CXR has a lower sensitivity to detect patients in the pre-symptomatic phase and the early symptomatic phase(9). Shi et al.(12), analyzed 81 CTs describing the chronology of the images in patients infected with SARS-COV-2. The ground-glass opacities were present in all phases of the infection, and as focal presentation and distribution in the periphery in the first week, they were later diffused and then disappeared as they appeared. During the course of the second week, the mixture of ground-glass opacities and multifocal consolidations was more evident and extensive, which were correlated with the moderate to severe clinical stage. Toussie et al.(7), analyzed the CXR of 338 patients infected with SARS-COV-2 who attended the emergency service, finding that the median number of days from the onset of symptoms to presentation in the emergency service was four days (2 to 5 days). These studies guide the usefulness of CXR in the emergency service in patients with symptoms of moderate to severe SARS-COV-2 lung disease, and there are sufficient criteria for the affected individual to have visible manifestations on radiography.

Murphy et al.(13), publish the preliminary results of an automated chest radiography reading system using artificial intelligence (AI) software programmed to identify characteristics of SARS COV-2. The results are encouraging, achieving performance comparable to six expert readers. In the first reports, the IA system reaches a sensitivity of 85% and a specificity of 61%.

While technology tries to demonstrate the usefulness of CXR in the SARS-COV-2 epidemic, health professionals must be prepared to use this imaging modality in the context of the reality of our health system, with shortage of EEP and laboratory tests, which pose daily challenges.


In general, all imaging methods are not very specific to identify the etiology of pulmonary involvement; however, correlation studies of images and pathology have helped to establish patterns that guide us in the diagnosis(14).

Common findings in the lung parenchyma

The findings found in the CXR are described according to the glossary of terms of the Fleischner Society(15).

Uncommon findings in the lung parenchyma


Scenario 1(Figure 6)

Patient with moderate to severe pulmonary clinical picture and confirmed laboratory test for infection by SARS-COV-2.

Scenario 2 (Figure 6)

Patient with suspected SARS COV-2 infection, moderate to severe clinical picture, laboratory result is not available or a false negative is suspected or there is no availability of laboratory tests and there is no availability of tomography, then radiography could be useful with a probability diagnosis (sensitivity of the radiograph: 69%), and taking into account the time of evolution from the onset of symptoms.


Scale of evolution

The most widely accepted scale to evaluate the evolution of radiographic images is the RALE Score proposed by Warren et al, to quantify pulmonary edema and adapted by Wong et al.(9) to evaluate quantitative progression of SARS-COV-2 infection. The scale consists of dividing the lung fields into 4 equal parts in such a way that 25% is assigned to each division and in each lung separately, with this procedure 8 equal parts are achieved (4 in the right and 4 in the left pulmonary field), to which 1 point is assigned to each area and a total score of 8 is achieved if all the segments were affected. The score is determined by adding the areas with suspicious images (Figure 7).Other authors prefer to assess lung involvement by assigning a score dividing the lung fields into thirds(7) as used in the 2003 coronavirus pandemic; we prefer to use the RALE Score proposed by Wong.

From a qualitative point of view, the appearance of alveolar opacities during the course of the disease(9,12,20) and pleural effusion after the 3rd week are considered unfavorable(12).

In the report: Radiographic evolution:

  1. RALE Score (1st. CXR)
  2. Favorable radiographic evolution due to decrease in the number of compromised lung area, RALE Score (../8)
  3. Stationary radiographic evolution since…. (date), RALE Score (../8)
  4. Unfavorable radiographic evolution due to greater involvement of the pulmonary areas and / or areas with alveolar infiltrate / pleural effusion are added or increased, tomography is suggested, RALE Score (../8)

Figure 1. Common findings in CXR in the SARS-COV-2 context. A: Soft diffuse opacity. B: Alveolar opacity (∆). C: Alveolo-interstitial opacities (o).

Figure 2. Common findings and lesions suggestive of SARS COV-2. A: Faint, multifocal peripheral opacities in bilateral middle third. B: Peripheral multifocal alveolo-interstitial opacities. C: Faint diffuse peripheral opacity in both pulmonary fields predominantly on the left.

Figure 3. Location and distribution of the CXR findings in the SARS-COV-2 context. A: Location by segments in the RxT B: Focal distribution (★). C: Diffuse distribution (in the circle).

Figure 4. Location of the different types of lesions that conditions SARS COV-2, predominantly peripheral and bilateral.

Figure 5. Cases of high suspicion of SARS COVID-2. A: Diffuse bilateral alveolo-interstitial opacities of peripheral and basal distribution. B: Focal opacities in the right lung field with areas of peripheral parenchymal consolidation and left perihilar linear opacities. C: Faint bilateral peripheral opacities predominantly on the left, associating areas of alveolo-interstitial involvement.

Table 1. Diagnostic classification of SARS-COV-2 on chest radiograph.

SARS-COV-2 classification Chest X-ray Findings Recommendations
High Suspicion ("Typical") Radiographic Findings for Atypical SARS COV-2 Pneumonia
  • Faint multifocal opacities of peripheral location uni / bilateral predominantly of the lower lobes
  • Mixed multifocal / diffuse interstitial-alveolar opacities of uni / bilateral peripheral location with a predominance of the lower lobes
Request confirmation with laboratory tests and possibility of CT
Radiographic finding with intermediate suspicion ("Atypical") for atypical pneumonia due to SARS-COV-2
  • Faint diffuse perihilar or unilateral opacities, without specific distribution
  • Diffuse perihilar or unilateral alveolo-interstitial opacities, without specific distribution
Request confirmation with laboratory tests and possibility of CT
Low suspicion / inconclusive radiographic findings for atypical SARS COV-2 pneumonia
  • Unilobar alveolar opacity
  • Soft diffuse central opacity with butterfly wing pattern
  • Presence of mass
  • Cavitation
  • Pleural effusion
Request confirmation with laboratory tests and consider another alternative diagnosis according to the clinical picture and history
Normal X-ray (asymptomatic patients or with symptoms less than 5 days) Absence of injuries SARS-COV-2 infection is not ruled out. Request laboratory and / or CT tests
Source: Adopted from the basic guide for indications of imaging tests in COVID-19 infection (SERAM).

Figure 6. SARS-COV-2 clinical picture (moderate-severe).

Score rale RxT SARS-COV-2   Score RxT SARS-COV-2
Total score Severity   Total score Severity
/8 0 points Normal   6/8 0 points Normal
1-2 points Mild   1-2 points Mild
3-6 points Moderate   3-6 points Moderate
> 6 points Grave   > 6 points Serious

Figure 7. Actual score. Determination by score assigned 1 point for every 25% of each lung.


  1. In laboratory-confirmed SARS-COV-2 infection with a moderate to severe clinical picture, the radiographic evaluation will be aimed at providing a scale of the degree of initial pulmonary involvement and for the evolution in hospitalization.
  2. In the suspicion of infection with a moderate to severe clinical picture, but with a negative or unavailable laboratory result, our radiographic evaluation will establish the degree of suspicion for SARS-COV-2 infection until confirmation with laboratory tests.

Author’s contributions: The authors participated in the genesis of the idea, project design, data collection and interpretation, analysis of results, and preparation of the final version of this research article.
Funding: Self-financed. .
Conflict of interest: The authors declare that they have no conflicts of interest in the publication of this article.
Recibido: May 20, 2020
Aprobado: June 07, 2020

Correspondence: Silvia Lucía Mayanga Sausa
Address: Calle J.J. Pardo 151 Urb. Astete la Perla–Callao, Lima-Perú
Telephone: 987800982
Email: lumaysa@gmail.com


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