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Table of Contents
IMAGING SECTION
Year : 2020  |  Volume : 3  |  Issue : 5  |  Page : 80-85

Imaging and COVID-19: Preparing the radiologist for the pandemic


1 Department of Radiodiagnosis and Imaging, InnoVision Imaging, Tata Memorial Centre, Tata Memorial Hospital, Mumbai, Maharashtra, India
2 Department of Radiodiagnosis and Imaging, Tata Memorial Centre, Tata Memorial Hospital, Mumbai, Maharashtra, India

Date of Submission06-Apr-2020
Date of Decision07-Apr-2020
Date of Acceptance08-Apr-2020
Date of Web Publication25-Apr-2020

Correspondence Address:
Abhishek Mahajan
Department of Radiodiagnosis and Imaging, Tata Memorial Centre, Tata Memorial Hospital, Mumbai - 400 012, Maharashtra
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/CRST.CRST_134_20

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  Abstract 


Diagnosing COVID-19 cases poses a challenge. The viral nucleic acid detection using real-time polymerase chain reaction (RT-PCR) remains the standard of reference. As the world is hit by this pandemic, the health resources are facing tremendous pressure. Though imaging has a role to play in the management of COVID-19, one must judiciously use the health and imaging resources which would take us a long way in combating this pandemic. In this article we will discuss the role of imaging in management of COVID-19 infection. Imaging guidelines are also given that will aid in precise communication with other health-care providers and efficient use of health resources.

Keywords: Coronavirus, COVID-19, Imaging, radiology, CXR, CT, POCUS, LMIC


How to cite this article:
Ahuja A, Mahajan A. Imaging and COVID-19: Preparing the radiologist for the pandemic. Cancer Res Stat Treat 2020;3, Suppl S1:80-5

How to cite this URL:
Ahuja A, Mahajan A. Imaging and COVID-19: Preparing the radiologist for the pandemic. Cancer Res Stat Treat [serial online] 2020 [cited 2020 Jun 1];3, Suppl S1:80-5. Available from: http://www.crstonline.com/text.asp?2020/3/5/80/283301




  Introduction Top


The pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been designated as coronavirus disease 2019 (COVID-19) by the World Health Organization on February 11, 2020. This novel virus is very contagious and has quickly spread globally. Symptoms include fever, cough, shortness of breath, and pneumonia or breathing difficulties in severe cases and can be fatal. While a lot is still unknown about the virus, we do know that its transmission is through direct contact with respiratory droplets of an infected person and also from touching their face (e.g., eyes, nose, and mouth) after touching surfaces contaminated with the virus. Diagnosing COVID-19 cases poses a challenge. Detection of the viral nucleic acid using real-time polymerase chain reaction (RT-PCR) is the reference standard. As the world is hit by this pandemic, the health system resources are facing tremendous pressure. Although imaging is contributory in the management of COVID-19, one must judiciously use the health and imaging resources which would take us a long way toward combating this pandemic. In this article, we discuss the role of imaging in managing COVID-19.


  Imaging Modalities Top


The various imaging modalities available for evaluation include chest radiographs, computed tomography (CT) scan, and portable bedside ultrasonography (point-of-care ultrasound [POCUS]). Chest radiographs have been used in some countries as the initial triage tool due to the delay in RT-PCR reports. Portable radiographs are safe, easy, and an essential modality, although limited evidence is available regarding chest X-rays. Portable bedside ultrasound also allows triage, risk stratification, and follow-up of patients with COVID-19. Both modalities are portable and thus can avoid unnecessary transport of the patients to the department.

CT is of utility in certain specific situations. If required, a noncontrast chest CT scan with reconstructions of the volume at 0.625 mm to 1.5 mm slice thickness is recommended. In situ ations where iodinated contrast is indicated as the case of a patient with frank hemoptysis in whom a CT pulmonary angiogram is planned, a noncontrast scan should be done first before contrast is injected as the contrast may make the ground-glass opacity (GGO) patterns difficult to interpret. A CT brain may be considered in cases with neurological symptoms as there has been an association of COVID-19 with acute hemorrhagic necrotizing encephalitis.[1],[2]

The frequency of imaging has to be decided based on the clinical status of patient and used as and when needed. Routine daily imaging is not recommended.


  Indications Top


The indication can be divided into four categories: screening, suspect case, incidental case and postive case.[3],[4]

Chest X-ray and computed tomography thorax [Figure 1]
Figure 1: Imaging approach for COVID-19 patients. COVID-19: Coronavirus 19; CXR: Chest X-ray; POCUS: Point-of-care ultrasound; ARDS: Acute respiratory distress syndrome; CT: Computed tomography; RT-PCR: Revere transcription polymerase chain reaction; SOB: Shortness of breath; ICU: Intensive care unit; SpO2: Peripheral capillary oxygen saturation; RR: Respiratory rate; BP: Blood pressure

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  1. Screening: Imaging has no definitive role in the screening for disease.
  2. Suspect cases: Imaging is not recommended in the evaluation of suspected cases. Imaging is indicated only in suspected cases with negative RT-PCR who have a strong contact history with a COVID-19 case or clinical deterioration.
  3. Incidental cases: CT thorax performed in the setting of an acute abdomen, with gastrointestinal (GI) symptoms suspicious for COVID-19
  4. Proven cases: Imaging plays a role in certain situations.


Chest X-ray

In mild cases, a chest radiograph may be considered depending on the clinical assessment in patients at high risk for developing severe disease. In moderate/severe cases, baseline chest radiograph is recommended with subsequent frequency of imaging depending on the clinical status.

Computed tomography imaging

CT scans should be reserved for hospitalized, symptomatic patients who have specific clinical indications such as organizing pneumonia versus acute respiratory distress syndrome (ARDS). CT scan of the head is indicated in patients with neurological symptoms or suspected acute necrotizing encephalopathy. In individuals with strong contact history with another COVID-19 positive patient but the RT-PCR is negative, CT may be indicated on clinical grounds such as positive signs and symptoms for COVID-19 or sudden clinical deterioration. These might be false-negative cases of RT-PCR and repeat swab testing is indicated.

Portable ultrasonography (point-of-care ultrasound)

Bedside POCUS can be considered in patients with clinical/radiological worsening for detecting other complications such as ventilator-associated pneumonia and pleural effusion. It also can be used for confirmation and monitoring the progress of ARDS.


  Imaging Features Top


Representative images can be accessed from the database of the Italian Society of Medical and Interventional Radiology, available online at https://www.sirm.org/en/.

Chest X-ray

The chest radiograph has poor sensitivity and can be normal in COVID-19 patients. The most common patterns include bilateral consolidation/GGOs predominantly in the peripheral and lower lobes [5,6] [Figure 2]a. A systematic review and meta-analysis by Rodriguez-Morales et al. revealed that the main findings were bilateral pneumonia in 72.9% and GGOs in 68.5%. Pleural effusion is not a common finding.[7]
Figure 2: A 56 year old male patient who had a contact history with COVID-19 positive family member, was admitted to the emergency department with a two day history of cough and fever with breathlessness and sudden clinical deterioration. The (a) chest radiograph shows multiple areas of ill-defined patchy consolidation (arrows). The findings were confirmed on CT thorax axial and coronal images (b and c). CT revealed patchy areas of peripheral round to ill-defined consolidation with surrounding GGOs (stars). (Courtesy Dr. Syeeda Showkat, MD , Associate Professor, Department of Radiology and Imaging, Bangabandhu Sheikh Mujib Medical University, Dhaka, Bangladesh)

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The final conclusion of the findings on chest radiograph should be labeled as one of the following:[7]

  • Typical: The common pattern seen consists of lower lobe and peripheral predominant, multiple, bilateral areas of consolidation
  • Indeterminate: The radiograph does not fit the typical/atypical descriptors
  • Atypical: Radiographs with uncommon/unreported features, such as pneumothorax, lobar pneumonia, pleural effusion, or pulmonary edema
  • Negative: The chest radiograph does not reveal any abnormal findings; however, the possibility of COVID-19 is not excluded.


Computed tomography imaging

CT is not the modality of choice for screening or diagnosis.[4] A normal CT scan, just like a chest radiograph, does not exclude the possibility of COVID-19 infection. There is a wide variation in the reported sensitivities (60%–98%) and specificities (25%–53%) of CT scans in COVID-19 patients. In a population of individuals who had a high pretest probability for disease, the positive and negative predictive values were 92% and 42%, respectively; the relatively low negative predictive value excludes the use of CT scan as a screening modality at least early in the course of disease.[8] Studies report a wide range of CT scan imaging appearances. A systematic analysis by Salehi et al. found that the characteristic patterns and distribution of CT scan findings in COVID-19 included GGOs in 88%, bilateral involvement in 87.5%, posterior involvement in 80.4%, peripheral distribution in 76.0%, and involvement of more than one lobe in 78.8% of patients. The most common findings were isolated GGO or GGO along with consolidation [Figure 2]b and [Figure 2]c. Other findings included interlobular septal thickening, pleural thickening, subpleural involvement, and bronchiectasis. The rare findings were effusions (both pleural and pericardial), lymphadenopathy, pneumothorax, cavitation, and CT halo sign.[9] Over one-fifth of COVID-19 patients may have superadded infections, which may complicate the imaging findings.

Jin et al. described five temporal stages and their corresponding characteristic CT findings. The five stages were ultra-early, early, rapid progression, consolidation, and dissipation. The CT findings in the ultra-early stage (which occurred 1–2 weeks postexposure; asymptomatic stage) include single or multiple focal GGOs, patchy consolidation, pulmonary nodules surrounded by GGO, and air bronchograms. Findings in the early stage (early after the onset of symptoms) include single or multiple GGOs alone, or GGO along with interlobular septal thickening. In the stage of rapid progression (third to the seventh day of onset of symptoms), CT findings include large, light consolidative opacities and air bronchograms. In the consolidation phase (week two of the onset of symptoms) the density and size of consolidative opacities may decrease. In the dissipation stage (approximately 2–3 weeks from disease onset), the CT scan may show dispersed patchy consolidative shadows, reticular opacities (called 'strip-like opacities'), and thickening of the bronchial wall interlobular septa.[9],[10]

CT findings have been described according to the patient's age. In patients below 50 years old, GGO's were the more common finding; Song et al. reported that GGOs were noted in 77% and consolidative opacities in 23% of patients. However, in patients over the age of 50 years old, GGO and consolidation occurred equally commonly; GGO in 55%, and consolidative opacities in 45% of the patients.[9],[11] The findings do not change in background of prior carcinoma of the lung. The COVID-related lesions (GGO's and consolidation) show the same course as seen in individuals without lung cancer.[12]

The CT scan report in suspected and proven COVID-19 patients must conclude the findings as:[8]

  • Typical: These include commonly seen findings which are bilateral peripheral GGO's with or without consolidation, rounded morphology or visible interlobular lines [Figure 2]
  • Indeterminate: There is an absence of typical imaging features with nonspecific less commonly identified imaging features, like GGO's with nonrounded morphology, and lack of specific distribution
  • Atypical: There is a lack of typical and indeterminate features with uncommon/unreported imaging features, like cavitation, and small nodules
  • Negative for pneumonia: No CT features suggestive of pneumonia.


The differential diagnosis of the imaging findings of COVID-19 include pneumocystis carinii pneumonia, cryptogenic organizing pneumonia, drug toxicities, other viral pneumonias, fungal pneumonia and alveolar hemorrhage [Figure 3].
Figure 3 (a-d): COVID Mimics: (a) A 6-year old child with acute leukemia who presented with history of high-grade fever spikes. CT imaging revealed multiple nodular opacities with surrounding ground glass opacities in both lungs. The diagnosis was angioinvasive fungal infection. (b) A 72-year old male, case of Hodgkin lymphoma presented with complaints of breathlessness. CT imaging showed ground glass haziness in both lungs with septal thickening giving crazy paving pattern (left > right). The diagnosis was cryptogenic organizing pneumonia. (c) A 65-year old male, case of carcinoma stomach presented with complaints of shortness of breath, cough and fever. CT imaging revealed multiple ground glass opacities diffusely scattered in both the lungs with perihilar distribution, with patchy consolidation in right hilar region and bilateral pleural effusion. The diagnosis was pneumocystis carinii pneumonia. (d) A 14-year old female, case of acute lymphocytic leukemia on induction chemotherapy. CT scan was done to rule out infection. CT showed multiple scattered centrilobular nodules with tree in bud appearance in the right middle and predominantly in the lower lobe. The diagnosis was fungal pneumonia

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  Ultrasonography (Point-Of-Care Ultrasound) Top


Bedside POCUS is an easy modality and can help in rapid patient assessment. It can also limit the transmission of infection by reducing the transport of patients. The characteristic findings are commonly seen in the posterior lower lung fields which include thickened pleural line with irregularity, focal/multifocal/confluent B lines, patterns of consolidation, appearance of A lines during recovery, and reduced blood supply on Doppler.[13],[14],[15] Pleural effusions are uncommon.[13]


  Covid-19 Reporting and Data System (Cov-Rads) Top


New COVID-19 RADS has also been proposed and can be used for reporting clinical trials and research. It can be accessed at covid19action-radiology.github.io.


  Precautions Top


It is logistically challenging to safely use imaging modalities for evaluating COVID-19 cases which can overwhelm available resources.[4],[16],[17] Even with proper cleaning protocols, Health-care professionals and radiologic equipment, particularly the CT scan equipment may act as a source of nosocomial spread of disease.[16]

Radiography

Portable radiographic equipment must be dedicated to the isolation wards/intensive care units which should be used only for scanning the COVID-19 cases, thus limiting the transportation of the patients and limiting the possibility of the equipment acting as a source of infection.[4] If patients come to the department for scanning, they should wear a surgical mask. The equipment should be disinfected after every single use. The radiographic technologist involved in acquiring the radiographs should use personal protective equipment (PPE) which includes face shield, goggles, a fit-tested N95 mask, fluid-resistant long-sleeved gown, gloves, head cover, and shoe covers.[16]

Computed tomography scanners

Before and during the scan

The referring clinicians should not send physical paper CT requisition forms especially those filled in COVID-19 wards as these may have a high chance of contamination and may act as disease vectors. Patients should wear masks before entering the radiology department and during the imaging. During the scanning, two technologists (T-1 and T-2) and one attending doctor (AD) are involved. The imaging table is covered with a disposable surgical sheet. T-1 and AD don personal PPE and get the patient situated on the CT imaging table; T-2 operates the CT console. After setting up the patient, the T-1 and AD remove and dispose of their PPE inside the CT scan area and then carefully wash their hands. After this, they exit the CT scanner room and enter the CT console where T-2 performs the study. The T-1 and AD put on new PPE outside the CT scanner and then they transfer the patient off the CT scan table. The patient and AD exit the CT scanner room.[18]

Postscan

After completion of the scan, deep cleaning of the room is to be performed. The scanner and console rooms should be sanitized with 1% sodium hypochlorite solution. After leaving the CT suite, the high-frequency contact surfaces including the consoles, doorknobs, handles, and switches are carefully wiped with an alcohol-based disinfectant-soaked cloth. The CT suite is shut for an hour to thoroughly ventilate and exchange the air inside. Air exchange processes are not used as the patients wear masks. After a scan has been completed, the CT room should undergo decontamination and passive air exchange for half an hour to 1 hour. Airborne precautions must be strictly followed if the patient is seriously ill or is planned for a procedure that can generate aerosols such as open suction, nebulization, intubation, or bronchoscopy. Airborne precautions do not need to be followed if the patient is on the ventilator, as this is a closed system.

The entire process is logistically challenging. Thus, wherever feasible, a CT scanner/room should be dedicated exclusively to COVID-19 (suspected) patients.[18]

Sonography

Portable bedside ultrasonography is ideally done with one dedicated ultrasound machine stationed in the isolation ward. The radiologist performing the ultrasound should wear the PPE, and in the absence of PPE, the medical officer/nurse can perform the ultrasound with understanding of the single page pictorial guide for chest sonography. The probes and wires should be covered with single-use plastic covers which should be disposed after the scan.[15],[16]


  Conclusion Top


This goal of our article was to provide imaging recommendations and guidelines about the role of imaging during the COVID-19 pandemic. We must remember that imaging does not play a role in screening or diagnosis of COVID-19. Dedicated portable radiographs and bedside ultrasound in the isolation wards could limit the spread of infection. We have highlighted the precautions that need to be taken to prevent the healthcare professionals and imaging equipment from becoming disease vectors.

Acknowledgments

Dr. Anuradha Shulka, Junior resident, Department of Radiodiagnosis, Tata Memorial Hospital, Parel, Mumbai.

Dr. Syeeda Showkat, MD, Associate Professor, Department of Radiology and imaging, Bangabandhu Sheikh Mujib Medical University, Dhaka, Bangladesh.

Indian Radiological and Imaging Association (IRIA) and Indian College of Radiology and Imaging (ICRI) for COVID-19 Imaging Guidelines: Dr. Ashu Seth Bhalla, Dr. Vimal Raj, Dr. Abhishek Mahajan, Dr Leena R V, Dr. Lalendra Upreti, Dr. Priyanka Naranje, Dr. Gh Mohammad Wani, Dr. Anant Mohan, Dr. Mandeep Garg, Dr. Anindita Sinha, Dr Aparna Irodi and Dr Smita Manchanda.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
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    Figures

  [Figure 1], [Figure 2], [Figure 3]



 

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Introduction
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Imaging Features
Ultrasonography ...
Covid-19 Reporti...
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