Dr. Shelly Sharma
CT scan examination is not a routine test, it involves exposure to harmful ionizing radiation. It is not safe in certain subsets of patient for example in pregnant women and children and should be utilized with precaution and extra care. However, during the COVID pandemic there seems to be a lot of misinformation and misconception amongst general population regarding its correct usage.
CT Scan is not indicated as a routine test just because someone is suspected to or has Covid-19, or because patients or their relatives demand a CT scan should be done. There is a lot of misinformation circulating on social media where in they are made to believe that the CT scan will make a difference in management of COVID 19 patients. And hence most of the patients queue up for CT scan examinations, sometimes on their own, putting a burden on the already burdened healthcare system.
When should someone who is COVID 19 positive, go for a CT scan examination?
The answer to this should be best left to the treating physician. Sometimes if the physician feels he may request a CT scan in an asymptomatic COVID patient who has multiple existing co-morbidities.
The Society of Chest Imaging and Intervention (SCII) recommends use of CT scan in certain subsets of Covid-19 patients.
The following indications have been modified from SCII guidelines for CT scan usage in Covid-19, these can be broadly classified into those for Diagnosis, Management and Follow-Up –
Moderate to severe symptomatic patients (breathlessness, falling O2 saturations) suspected to have Covid-19 for quick triage. Cough is NOT an indication.
Asymptomatic to minimally symptomatic patients, ONLY when a RT-PCR testing not available . RT-PCR testing is available but results are delayed due to backlog or logistical issues by more than 48 hours and the delay will change the way the patient is managed.
High clinical suspicion of Covid-19 but a negative RT-PCR report, where the findings of the CT scan will make a difference to management.
Other unique or individual situations, e.g. a patient has to undergo emergency surgery and RT-PCR testing or rapid testing is not available or the results will not be available in time and the delay will change management. However, the routine use of CT scan as a pre-admission or pre-surgical test in non-emergency situations is strongly discouraged.
1. CT scan is useful for triaging patients who have breathlessness and falling O2 saturations, but is not indicated as a routine test in patients just to check severity of disease or as part of any routine protocol.
2. CT scan is indicated when there is a true clinical need to understand the extent and severity of disease when the patient is symptomatic or when symptoms are worsening, and when the findings on the CT scan, as against on radiographs make a difference to management. CT scan is also indicated when there is high clinical suspicion of co-existing disease such as tuberculosis or interstitial lung disease that may make a difference to the management of the patient.
3. The decision of whether to scan and when to scan is best left to the treating doctor’s clinical judgment, but as a rule, CT scan should be used only when needed and not as a routine test to be done as per some “routine protocol” (there is no acceptable routine protocol that incorporates the use of routine CT scan).
Follow up scans after 6 and 9 months in the current pandemic have shown a similar temporal course in most patients, unless the patient has been mechanically ventilated or suffered from severe ARDS or superimposed infection.
The routine use of follow-up CT scan is discouraged unless there is a specific clinical indication (e.g. patient not improving or desaturation or PFTs that don’t improve or worsen).
In short, follow-up scans are left to the discretion of the treating doctor, are not indicated for routine follow-up but only when the patient is not improving as expected or is deteriorating.
Role of CT Chest in Covid-19 – A White Paper from the Society of Chest Imaging and Intervention (SCII). Website: www.sciirad.com
This information is for general guidance and reflects the opinions and experience of the author. It is not intended to replace specialist consultation or provide treatment advice for specific cases