Nagpur: High resolution computerized tomography, popularly known as HRCT or
chest scan, seems to be turning out as an important alternative to inconclusive results from reverse transcription polymerase chain reaction (RT-PCR), which is considered the gold standard for confirming novel coronavirus infection.
Lack of RT-PCR testing facility beside inconclusive swab results are being seen as another reason for patients from outside district turning up with only chest scan reports for admissions to dedicated Covid hospitals in the city. There are also patients who are deliberately avoiding regular Covid tests as HRCT gains prominence.
Private hospitals as well as Government Medical College and Hospital (GMCH), where most of the Covid patients are currently admitted, have received patients who came in with ‘HRCT positive’ report but not RT-PCR report. Doctors from private DCHs said they are taking an undertaking from such patients before admitting them in Covid centre.
Dr Ashish Badkal, managing director and intensivist at IGPA Hospital and Research Centre’s Covidalaya, said, “CT scan appears to be more reliable for Covid detection for its typical findings and Covid specificity.”
GMCH medical superintendent Dr Avinash Gawande confirmed that some of the 250 Covid patients came to them with HRCT Chest report.
“HRCT Chest and RT-PCR test for Covid are complementary studies and both should be performed whenever possible. RT — PCR test is highly specific while HRCT Chest would not only indicate the diagnosis but also help in assessing severity and planning of further treatment,” said Dr MA Biviji, consultant radiologist, MRI and CT Centre in Dhantoli.
Dr Biviji said patients coming from outstation frequently carry only HRCT Chest report. “This could be because of lack of RT-PCR testing facility at those places. The doctors there have to rely on whatever is available and HRCT Chest would be an important tool to assess whether the patient could be managed locally or transferred to a higher centre in Nagpur. This is quite logical and fair,” he said.
Dr Hema Dhoble, head (medical administration), Suretech Hospital, said that hospitals in small towns like Bhandara, Gondia and Chandrapur are admitting patients with high CT score suggestive of Covid. “But most of them avoid RT-PCR tests, maybe because of waiting period of 1-2 days taken to deliver the results. Within that time patient’s lung damage may advance,” she said and added that other reason could be to avoid Covid/non-Covid dilemma while admitting patient.
“Later, these patients are transferred to higher centre for ventilator support and critical management at a late stage,” she said.
Consultant radiologist Dr Atul Dakhole, who is director of Metro Scan at Dhantoli, too said duration of result and number of advantages give HRCT an edge over swab tests. “RT-PCR is gold standard. But it still has chances of false negative result depending on technique and sample collection method,” he said.
Dr Dakhole said after collection of Covid samples follows four to five steps and processing. “If any of these go wrong, it may give false negative. RT-PCR or antigen test can only show if a person is positive or not. HRCT has three big advantages — diagnosis, severity of infection and prognosis. Irrespective of test results, even a small patch in scan confirms Covid. Unless proved otherwise, ground glass appearance with typical lesion proves it is Covid,” he said.