CME INDIA Presentation by Admin.

Dr Bijay Patni, Diabetologist, Kolkata observes:

1. COVID-19 has taken another toll – CT SCAN machines😀

2. CT scan machines collapses for being overworked.

3. Scan being advised left, right and centre.

4. Immediate govt. interference necessary to deal with this unforeseen radiation pandemic 😀

Some questions spontaneously arise:

  1. Should we do HRCT in cases of suspected COVID?
  2. If we choose to do selectively, which will be the best time to do it?
  3. Can Chest X-Ray be done in all cases before advising HRCT?

CME INDIA tried to understand the scenario…

Dr Akash Kumar Singh, Internist and Dr Ankur Bhavsar, FCCM EDIC, Chief Intensivist, Spandan Multispecialty Hospital, Vadodara:

HRCT CHEST – Our center’s experience:

After the onset of COVID-19, HRCT chest has become rampant in investigation with many healthcare providers and many centers doing it compulsorily in all patients suspected to have COVID-19 or diagnosed with COVID-19 and I have seen some centers doing it periodically in the admitted patients.

At our Centre, we are not at all following this policy and using HRCT chest in very specific situations:

  • For early diagnosis if the patient is quite ill requiring admission and there is not enough time to get RT-PCR for COVID19 done (As RT-PCR report takes 12-24 hours post collection depending on the time of collection of samples) In many situations you cannot wait for such a long time and immediately like diagnosis is required. For all the other patients who are stable with mild symptoms, RT-PCR in suspected cases is good enough and chest x-ray PA view suffices for management purposes.
  • Once the patient is admitted, we do not need to do HRCT chest. At our Centre, the entire management of COVID-19 patients is done with the help of Chest X-ray. Only in very specific situations, we go for HRCT chest. These situations are:
    • Insistence of relatives who have been advised by someone and they tell us they want to do it.
    • To investigate alternative pathology like some pre-existing lung disease, bullae, barotrauma to lungs, atypical opacities in lungs.
    • If RT PCR is negative and we are still suspecting COVID-19 infection. These situations are very few as per our experience.
  • In the follow up of our discharged patients, if the saturation or the exertional dyspnea of the patient does not improve, we get the HRCT chest done after a satisfactory course of treatment (which may be 1-2 months). This is done to know the long-term prognosis by assessing the extent of fibrosis ad non reversible changes.                                                       
  • Limitations of HRCT Chest – In many cases the extent of lung involvement or the lung involvement by HRCT Chest Score does not correlate well with the clinical outcomes of the patient i.e. some patients with more extensive lung involvement on HRCT do better than some with less extensive lung involvement.
  • Clinical assessment and follow up of the patient give better prognostication of the patient.

Dr Chandrakar Tarke Pulmonologist, Hyderabad:

  • It is not uncommon in COVID to see patients with no or mild CT chest changes, becoming severe in second week of illness.
  • CT chest in COVID should be done between day 7 to 12…ideal time in proven cases (for identifying extent of lung involvement).
  • It should be done earlier in cases where PCR is negative and COVID 19 is strongly suspected (for diagnosis).
  • CT chest is not required in non-high-risk patients (young, without co-morbidities) with mild symptoms with normal inflammatory markers.
  • My policy is to do CT chest in most of moderate to severe cases COVID 19 patients. And chest x-rays later on, while hospitalisation, for monitoring for worsening COVID pneumonitis, secondary infections, to identify complications such as pneumothorax, pneumomediastinum especially if patient on NIV/IMV.
  • Reason for recommending CT in moderate cases is to find out high risk patients which can become severe and land-up in cytokine storm. X ray in such cases can show mild changes only. But CT gives better idea. Patients with CT findings of multi-focal/multi-lobar involvement, consolidation/dense opacities are more likely to go into cytokine storm than patients with ground glass opacities.
  • CTPA (CT Pulmonary angiography) should be considered in all patients with suspected pulmonary embolism.
  • CTPA with HRCT in 2nd to 3rd week, in patients with severe hypoxia and raised D Dimer gives clue regarding cause of persistent hypoxia (Pulmonary embolism/ongoing pneumonitis/organizing pneumonia/lung fibrosis/secondary bacterial or fungal pneumonia). So that focused treatment can be given to patient.

What you think of these CT pics (Answer given above CME INDIA Tail Piece section below)

HRCT Thorax Quiz

Dr Virendra Singh, Pulmonologist, Jaipur: My take…

  1. In patient with high suspicion but COVID RTPCR negative, I prefer to do HRCT if:
    • Patients with troublesome respiratory symptoms and or desaturation.
    • In second week in patients with comorbidities.
  2. X Ray chest: In all above 40.

Dr Vikram Sarabhai, Pulmonologist, Delhi:

  • CT Chest is an expensive investigation and out of reach from majority of population plus radiation hazard
  • CT Chest should be restricted for only those patients whose trend on disease is worsening beyond 5-6 days of appearance of symptoms of the illness with persistence or aggravation of – Cough / Dyspnea / Oxygen Desaturation less than 92-94% or any other disturbing symptoms.
  • HRCT Chest will only show lung parenchymal effect – that is physician bias of presuming COVID affecting alveoli or interstitium which can be highly misleading and the information not utilizable for change in therapy.
  • If one has to opt for CT study of Chest – It’s logical to ask for CT Pulmonary Angiography (CTPA) along with HRCT cuts – that will reveal both pulmonary micro and macro vascular thrombosis which is the likely reason of micro and macro pulmonary embolism that coalesce to give the impression of widespread multilobe multialveolar pneumonitis or pulmonary infiltrates – Giving impression of – Acute Lung Injury (ALI) or ARDS – this investigation approach will serve the purpose of the effort and logic of a patient and physician objectives undergoing the trouble of CT.
  • CTPA+HRCT are better left not until 5-7 days of illness with shift into moderate illness. All moderate and severe COVID must be subjected for this test.
  • Those favoring early CT and serial CT Chest or HRCT can strongly argue for higher specificity of the test but at the expense of Radiation + Cost + Not much alteration of treatment options because almost all therapy is useful in mild to moderate diseases of Death is the matrix in question.
  • For research purpose – HRCT Chest or series of them or CTPA+CTPA – shall prove to be more useful than plain X-Ray Chest or any other clinical or biochemical indices both for management/ prognostication / follow up / post COVID management, however one has to discount for the logistics, cost and side effects involved.
  • In my view now earlier than 5 days and also unless the trend is suggesting worsening or non-resolving and also only once (purely from Treatment and management point of view).
  • As far as question of doing chest x-ray in all cases is concerned one can do it but the investigation has poor sensitivity and specificity.
  • My other experiences for radiology related tests:
    • Ultrasound of Extremities for Deep Vein or Arterial thrombosis.
    • Echocardiography for – Cardiac Dysfunction and Pul Art Pressure monitoring – who show Hypoxia on ABG / O2 Desaturation in pulse oximetry less than 90-92% / worsening Dyspnea and cough.

What you think of these CT pics (Answer given above CME INDIA Tail Piece section below)

HRCT Thorax Quiz


Dr (Mrs) Deb Dutta, Pulmonologist, Medanta Hospital, Ranchi:

  • HRCT thorax at presentation:
    • For all patients less than 95 percent saturation even if classical symptoms absent.
    • For patients with COVID symptoms.
    • For patients declared as COVID negative elsewhere recently within week/ 10 days but symptoms worsening.
    • Post COVID patients with new onset respiratory related symptoms.
    • For febrile patients admitted for non COVID reasons but fever not subsiding in acute phase.
  • Timing of CT:
    • At presentation in hospital with symptoms.
    • If patient is in incubation period (contact of COVID patient) and initial COVID tests are negative and patient symptomatic at any time.
    • In febrile patients, earlier CT done too early (first 5 days of symptoms onset), often are labelled as non COVID. Lung features can present later.  So, in suspicious cases, definitely repeat CT thorax.
  • Chest X-Ray:
    • Most valuable in follow up during hospital stay and after discharge.
    • Preferably at baseline so that serial follow up can be done.
    • Economical.
    • In Indian setting often more convenient and economical, when patient wants most out of single doctor visit. As doctors we can triage patients better and counsel and convince them for COVID rtpcr test and treatment (often a challenge in Indian setting) if X-Ray involvement is suggestive and patient is reluctant for ct.
  • Regarding radiology always to go through serial x-rays, previous x-rays, CT films carefully.
    • In context of upcoming flu season, we need to be more vigilant and aware of radiological differences. CORADS V and VI may be highly suggestive of COVID. CORADS II and III we need more assessments.

What you think of these CT pics (Answer given above CME INDIA Tail Piece section below)

HRCT Thorax Quiz

Dr Prabhat Agarwal, Asso. Prof. Med., Agra:

  1. If I suspect COVID I always go for it.
  2. If chest X-Ray is normal can advise CT scan.
  3. Best time for CT scan is 5th/6th day from onset of symptoms.

Dr Nishith Kumar, Pulmonologist, Orchid Medical Centre, Ranchi: Learning so far…

  • The most appropriate time for getting a HRCT is day 5 of illness.
  • HRCT Thorax is more sensitive at detecting COVID-19 than RT PCR. We have seen many patients who were RT PCR neg with typical findings on HRCT imaging. A repeat RT PCR test or IgG done later on turned out to be positive in majority of such cases. In correct clinical setting & CORAD 4/5 even if RT pcr is negative treat as COVID-19.
  • Patient’s presenting symptoms & SpO2 can be misleading. Patients may present with mild symptoms & almost normal SpO2 (94-98% on RA) with significant Pneumonitis on HRCT Thorax.
  • No point in getting a CXR done for screening. Get Low dose CT Thorax done instead & use CXR to F/U radiological improvement/deterioration.
  • Happy Hypoxia is real thing! We have seen couple of patients with oxygen saturations that are very low and they’re unaware of that. HRCT is S/o extensive disease. We wouldn’t usually see this phenomenon in influenza or community-acquired pneumonia.
  • Incidence of thromboembolism is very common in patients with raised D Dimer. In case of significantly raised D Dimer especially in patients with prolonged immobility, malignancy, major surgery, multiple trauma, prior VTE, and unexplained hypoxemia try to get CTPA done wherever possible/feasible.


Dr Hem Shankar Sharma, Asso. Prof. Med., JLNMC, Bhagalpur:

  • All cases, who show SpO2 less than 92%, need oxygen therapy, Respiratory rate 25 or more, are subjected to HRCT Chest.
  • No specific timings as such, depending on the clinical scenario, to be decided.
  • I prefer to go for chest X-Ray in all cases.
  • Cases, RAT and RTPCR, both negative, oxygen 94, or less, HRCT Chest, showing more than 40 to 50% lung involvement, are baffling.

What you think of these CT pics (Answer given above CME INDIA Tail Piece section below)

HRCT Thorax Quiz

Dr Himalaya Jha, Internist, CMO, CGHS, Ranchi:

  • We used to diagnose suspected case of COVID-19 on the basis RT – PCR of COVID-19 within (2 – 7 days of illness. if patients cooperate.
  • RAT test also we do prefer. If its positive means Positive COVID-19 (Very specific).
    • But if RAT test is negative, we prefer to do RT – PCR if patient is symptomatic. For reconfirmation.
  • For mild and Asymptomatic cases of COVID-19 – I never used CT chest (HRCT) or X ray chest except for high risk pts or patients with comorbid conditions.
    • Usually Influenza and COVID-19 pneumonia have similar CT chest involvement pattern.
  • In COVID-19 we usually get basal, peripheral, bilateral GGO, or consolidation or mixed pattern. Influenza may have similar pattern. But Influenza usually have central and random distribution of lesions.

CME INDIA Learning Points:

  • CT score of patients is associated the severity of the systemic inflammatory response. Risk stratification based on air-space disease may help to triage patients, guide treatment, and monitor disease progression and treatment.
  • Current evidence suggests that chest CT scans and X-Rays are generally NOT specific enough to either diagnose or rule out COVID-19 on their own. 
  • Imaging does have a limited role to play: When used with lab tests, a medical history and a physical exam, CT scans or x-rays can be helpful for diagnosing COVID-19 or determining the severity of the disease in some patients.
  • As per American College of Radiology: A chest CT or X-Ray cannot accurately distinguish between COVID-19 and other respiratory infections, like seasonal flu. A significant percentage of patients with COVID-19 have normal chest CTs or x-rays. Because COVID-19 is highly contagious, using imaging equipment on COVID-19 patients is a serious hazard for healthcare providers and other patients.
  • Though CT scans and X-Rays aren’t recommended as the only way to diagnose COVID-19, they may be appropriate on a case-by-case basis.   


(All pics courtsey of Dr Akash Kumar Singh, Vadodara)

[1] Post COVID.

[2] COVID with Pericardial effusion.

[3] COVID with Pulmonary Embolism.

[4] Recurrent COVID.

[5] Active COVID.

[6] Reverse Halo Sign.

[7] A large emphysematous bullae in right lower lobe causing mediastinal shift.

[8] Cavitation.

[9] Spontaneous Pneumothorax.

[10] Spontaneous pneumomediastinum.

CME INDIA Tail Piece:


Shared by Dr Bijay Patni, Kolkata.

This is scoring, based on segmental involvement. (Finest way). But we used to do on the basis of lobar involvement. (Gross criteria).

HRCT Scoring


Consensus statement endorsed by the Society of Thoracic Radiology and the American College of Radiology (ACR) that classifies the CT appearance of COVID-19 into four categories for standardized reporting language 

  • Typical appearance
    • peripheral, bilateral, GGO +/- consolidation or visible intralobular lines (“crazy paving” pattern).
    • multifocal GGO of rounded morphology +/- consolidation or visible intralobular lines (“crazy paving” pattern).
    • reverse halo sign or other findings of organizing pneumonia.
  • Indeterminate appearance
    • absence of typical CT findings and the presence of:
      • multifocal, diffuse, perihilar, or unilateral GGO +/- consolidation lacking a specific distribution and are non-rounded or non-peripheral.
      • few very small GGO with a non-rounded and non-peripheral distribution.
  • Atypical appearance
    • absence of typical or indeterminate features and the presence of:
      • isolated lobar or segmental consolidation without GGO.
      • discrete small nodules (e.g. centrilobular, tree-in-bud).
      • lung cavitation.
      • smoother interlobular septal thickening with pleural effusion.
  • Negative for pneumonia: No CT features to suggest pneumonia, in particular, absent GGO and consolidation.

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