Thread by @francisdeng

You are seeing a patient with suspected #COVID19. When is imaging (CXR or CT) indicated?

A #TWEETORIAL summary of the Fleischner Society consensus statement @Radiology_RSNA: doi.org/10.1148/radiol…
Podcast: doi.org/10.1148/radiol…
#RadsInTraining

Step 1: Assess the severity of respiratory disease.

A) is there hypoxemia?
B) is the patient's dyspnea and work of breathing significant?

Step 2: Assess the patient's pre-test probability of having COVID-19. Consider not only the patient's exposure history but also community prevalence:
Low: sporadic transmission
Moderate: clustered transmission
High: sustained community transmission

(Map from JHU)

Patient 1:
Your patient has MILD respiratory symptoms without an O2 requirement. This visit to your virtual office or respiratory illness clinic occurs during the pandemic in a locale with at least moderate epidemiological risk of COVID (you live on planet Earth right now).

POLL: For which of the following situations is imaging indicated for patient 1?
A) RT-PCR unavailable, age/comorbidity risk factors for severe disease present
B) Positive RT-PCR, no risk factors for severe disease
C) Negative RT-PCR, mild symptoms persisting 5 days

Fleischner says A. If PCR unavailable, decide by pre-test probability (at least moderate here).

Step 3: identify risk factors for progression if pt has COVID, like
-age >65
-diabetes
-cardiovascular disease, eg hypertension
-chronic respiratory disease, eg COPD
-immunocompromise

KEY POINT 1: "Imaging is not indicated in patients with suspected COVID-19 and mild clinical features unless they are at risk for disease progression."

Patients with mild clinical features and without high-risk factors can be safely managed with isolation, supportive care, and self-monitoring. The yield of imaging is low. If there is clinical worsening to moderate or severe disease, then move on to the following scenarios. 👇🏽

Patient 2:
Your patient has worsening, now moderately severe dyspnea. Pulse oximetry shows SpO2 in the 80s on room air with minimal exertion. You put them in for hospital admission. Assume you work in a resource-rich environment.

POLL: For which of the following situations is imaging indicated for patient 2?
A) Positive RT-PCR only
B) Unavailable RT-PCR only
C) Either positive, negative, or unavailable RT-PCR

Fleischner says C. Hospitalized pts with mod-severe features, baseline or worsening, should have imaging regardless of COVID-19 testing to establish baseline, risk-stratify, identify alternative dx. Consider PE, bacterial PNA, heart failure.

(Cases rID: 46635, 47738, 36687)

KEY POINT 2: "Imaging is indicated in a patient with COVID-19 and worsening respiratory status."

Patient 3:
Your patient has moderate to severe disease, as patient 2 did. However, you work in a pandemic-overwhelmed area (high pre-test probability) with critical resource constraints.

(Photo by AP in Italy)

POLL: Ideally all patients like this get imaging. However, which of the following situations have lowest priority?
A) COVID-19 test positive, initial presentation, moderate
B) COVID-19 test positive, clinical worsening in hospital
C) COVID-19 test delayed, emergency dept patient

Fleischner says A. Imaging facilitates triage when rapid testing is unavailable or initially negative but unconfirmed. High pre-test probability with imaging typical of COVID-19 allows initial disposition, infection control, and management decisions.

(Case @derekrad rID: 75249)

KEY POINT 3: "In a resource-constrained environment, imaging is indicated for medical triage of patients with suspected COVID-19 who present with moderate-severe clinical features and a high pre-test probability of disease."

BONUS ROUND:
Should my patient with COVID-19 get CXR or CT?

CT is more sensitive for early disease, progression, and alternative diagnoses. However, portable CXR may be good enough or preferred considering local resource constraints/infection control measures. No strong recs

Should stable intubated patients with COVID-19 receive daily chest radiographs?

No. CXRs should be on-demand for clinical changes. Help limit exposure to rad techs and conserve PPE.

Should a patient who recovered from COVID-19 but has residual functional impairment and/or hypoxemia undergo chest CT?

YES. Distinguish expected sequelae of infection/ARDS from alternative potentially treatable diagnoses.

SUMMARY
The Role of Chest Imaging in Patient Management during the COVID-19 Pandemic: A Multinational Consensus Statement from the Fleischner Society

There is a role, based on clinical severity, change over time, test availability/result (PCR or PoC test), and local resources.