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Handbook of COVID-19 Prevention and Treatment-- Imaging Findings of COVID-19 Patients

2020-03-25

Ill. Imaging Findings of COVID-19 Patients

Thoracic imaging is of great value in the diagnosis of C0VID-19, monitoring of therapeutic

efficacy, and patient discharge assessment. A high-resolution CT is highly preferable. Portable

chest X-rays are helpful for critically ill patients who are immobile. CT for baseline evaluation

of patients with C0VID-19 is usually performed on the day of admission, or if ideal therapeutic

efficacy is not reached, it can be re-performed after 2 to 3 days. If symptoms are stable or

improved after treatment, the chest CT scan can be reviewed after 5 to 7 days. Daily routine

portable chest X-rays are recommended for critically ill patients.

C0VID-19 at the early stage often presents with multifocal patchy shadows or ground glass

opacities located in the lung periphery, subpleural area, and both lower lobes on chest CT

scans. The long axis of the lesion is mostly parallel to the pleura. Interlobular septa I thickening

and intralobular interstitial thickening, displaying as subpleural reticulation namely a "crazy

paving" pattern, is observed in some ground glass opacities. A small number of cases may

show solitary, local lesions, or nodular/ patchy lesion distributed consistent with bronchus

with peripheral ground glass opacities changes. Disease progression mostly occurs in the

course of 7-10 days, with enlarged and increased density of the lesions compared with

previous images, and consolidated lesions with air bronchogram sign. Critical cases may show

further expanded consolidation, with the whole lung density showing increased opacity,

sometimes known as a "white lung". After the condition is relieved, the ground glass opacities

can be completely absorbed, and some consolidation lesions will leave fibrotic stripes or

subpleural reticulation. Patients with multiple lobular involvement, especially those with

expanded lesions should be observed for disease exacerbation. Those with typical CT pulmo

nary manifestations should be isolated and undergo continuous nucleic acid tests even if the

nucleic acid test of SAR-CoV-2 is negative.

Typical CT features of C0VID-19 :

Figure 1, Figure 2: patchy ground glass opacities;

Figure 3: nodules and patchy exudation;

Figure 4, Figure 5: multifocal consolidation lesions;

Figure 6: diffuse consolidation, "white lung''.

IV. Application of Bronchoscopy in the Diagnosis and

Management of COVID-19 Patients

Flexible bronchoscopy is versatile, easy to use, and well tolerated in mechanically ventilated

COVID-19 patients. Its applications include:

(1) Collection of respiratory specimens from the lower respiratory tract (i.e. sputum,

endotracheal aspirate, bronchoalveolar lavage) for SARS-CoV-2 or other pathogens guides

the selection of appropriate antimicrobials, which may lead to clinical benefits. Our experi

ence indicates that lower respiratory specimens are more likely to be positive for SAR-CoV-2

than upper respiratory specimens.

(2) Can be used for localization of the site of bleeding, cessation of hemoptysis, sputum or

blood clots removal; if the site of bleeding is identified by bronchoscopy, local injection of

cold saline, epinephrine, vasopressin, or fibrin as well as laser treatment can be performed

via the bronchoscope.

(3) Assist in the establishment of artificial airways; guide tracheal intubation or percutane

ous tracheotomy.

(4) Drugs such as infusion of a-interferon and N-acetylcysteine can be administrated via the

bronchoscope.

Bronchoscopic views of extensive bronchial mucosa[ hyperemia, swelling, mucus-like

secretions in the lumen and jelly-like sputum blocking the airway in critically ill patients.

(Figure 7)

V. Diagnosis and Clinical Classification of COVID-19

Early diagnosis, treatment and isolation should be carried out whenever possible. Dynamic

monitoring of lung imaging, oxygenation index and cytokine levels are helpful for early

identification of patients who may develop into severe and critical cases. A positive result of

the nucleic acid of SARS-CoV-2 is the gold standard for the diagnosis of COVID-19. However,

considering the possibility of false negatives in nucleic acid detection, suspected cases

characteristic manifestations in CT scans can be treated as confirmed cases even if the nucleic

acid test is negative. Isolation and continuous tests of multiple specimens should be carried

out in such cases.

The diagnostic criteria follow Protocols for the Diagnosis and Treatment of CDVID-2019. A

confirmed case is based on epidemiological history (including cluster transmission), clinical

manifestations (fever and respiratory symptoms), lung imaging, and results of SARS-CoV-2

nucleic acid detection and serum-specific antibodies.

Clinical Classifications:

Mild Cases

The clinical symptoms are mild and no pneumonia manifestations can be found in

imaging.

Moderate Cases

Patients have symptoms such as fever and respiratory tract symptoms, etc. and

pneumonia

manifestations can be seen in imaging.

Severe Cases

Adults who meet any of the following criteria: respiratory rate ;;, 30 breaths/min;

oxygen saturations; 93% at a rest state; arterial partial pressure of oxygen (PaO,)/oxy

gen concentration (FiO,) s; 300 mm Hg. Patients with> 50% lesions progression within 24

to 48 hours in lung imaging should be treated as severe cases.

Critical Cases

Meeting any of the following criteria: occurrence of respiratory failure requiring

mechanical ventilation; presence of shock; other organ failure that requires monitoring

and treatment in the ICU.

Critical cases are further divided into early, middle and late stages according to the

oxygenation index and compliance of respiratory system.

• Early stage: 100 mmHg <oxygenation index s;lSO mm Hg; compliance of respiratory

system ;;,30 ml/ cmH,O; without organ failure other than the lungs. The patient has a

great chance of recovery through active antiviral, anti-cytokine storm, and supportive

treatment.

• Middle stage: 60 mmHg < oxygenation index s;lOO mmHg; 30 mL/cmH,O >

compliance of respiratory system ;;el 5 mL/cmH,O; may be complicated by other mild or

moderate dysfunction of other organs.

• Late stage: oxygenation index s; 60 mmHg; compliance of respiratory system <15

mL/cmH,O; diffuse consolidation of both lungs that requires the use of ECMO; or failure

of other vital organs. The mortality risk is significantly increased.