Coronavirus Diagnostics: CT Scans Provides The Best Diagnosis For COVID-19 Disease
is taking a new turn as the current nucleic acid testing protocols are turning up a high amount of false negative. In a new published study involving more than 1,000 patients, it was indicated that chest CT outperformed lab testing in the diagnosis
of 2019 novel coronavirus
disease (COVID-19). The medical researchers concluded that CT
should be used as the primary screening tool for COVID-19.
As there are no specific therapeutic drugs or vaccines for COVID-19 that is caused by the SARS-Cov-2 coronavirus
, it is critical to detect the disease at an early stage and immediately isolate an infected patient from the healthy population.
Although latest guidelines published by the Chinese government states that the diagnosis
of COVID-19 must be confirmed by reverse-transcription polymerase chain reaction (RT-PCR) or gene sequencing for respiratory or blood specimens, as the key indicator for hospitalization. However, with limitations of sample collection and transportation, as well as kit performance, the total positive rate of RT-PCR for throat swab samples has been reported to be about 30% to 60% at initial presentation.
An alarmingly amount of false negatives are occurring from these nucleic acid tests and it accuracy and usage in this crisis where containment is an essential component, is beginning to be questioned.
Considering the current critical public health emergency, the low sensitivity of RT-PCR implies that a large number of COVID-19 patients won't be identified quickly and may not receive appropriate treatment. In addition, given the highly contagious nature of the coronavirus
, they carry a risk of infecting a larger population.
The researchers told Thailand Medical News
, "Early diagnosis
of COVID-19 is crucial for disease treatment and control. Compared to RT-PCR, chest CT imaging may be a more reliable, practical and rapid method to diagnose and assess COVID-19, especially in the epidemic area."
It must be noted that Chest CT, a routine imaging tool for pneumonia diagnosis
, is fast and relatively easy to perform. Recent research found that the sensitivity of CT for COVID-19 infection was 98% compared to RT-PCR sensitivity of 71%.
In the study, medical researchers at Tongji Hospital in Wuhan, China, set out to investigate the diagnostic value and consistency of chest CT imaging in comparison to RT-PCR assay in COVID-19.
Participating in the study were 1,014 patients who underwent both chest CT and RT-PCR tests between January 6 and February 6, 2020. With RT-PCR as reference standard, the performance of chest CT in diagnosing COVID-19 was assessed. For patients with multiple RT-PCR assays, the dynamic conversion of RT-PCR test results (negative to positive and positive to negative, respectively) was also analyzed as compared with serial chest CT scans.
The study results showed that 601 patients (59%) had positive RT-PCR results and 888 (88%) had positive chest CT scans. The sensitivity of chest CT in suggesting COVID-19 was 97%, based on positive RT-PCR results. In patients with negative RT-PCR results, 75% (308 of 413 patients) had positive chest CT findings.
Of these, 48% were considered as highly likely cases, with 33% as probable cases. By analysis of serial RT-PCR assays and CT scans, the interval between the initial negative to positive RT-PCR results was 4 to 8 days.
The authors told Thailand Medical News
,"About 81% of the patients with negative RT-PCR results but positive chest CT scans were re-classified as highly likely or probable cases with COVID-19, by the comprehensive analysis of clinical symptoms, typical CT manifestations and dynamic CT follow-up.”
Thailand Medical New
s cautions all patients that not all CT machines are the same and that there are various brands and models with varying degrees of imaging and diagnostic capabilities and effectiveness. Thailand Medical News will be publishing a list of recommended brands and models and the list of hospitals that have them around the world. Patients, whether private paying or through universal healthcare or insurances or medicare or medicaid etc, have the right to choose the best hospitals for themselves and need not be forced to use hospitals with sub-standard equipment that could compromise your coronavirus diagnosis
For more on the latest in Coronavirus Diagnostics
, keep checking at: https://www.thailandmedical.news/articles/coronavirus
Reference: Tao Ai et al, Correlation of Chest CT and RT-PCR Testing in Coronavirus Disease 2019 (COVID-19) in China: A Report of 1014 Cases, Radiology
(2020). DOI: 10.1148/radiol.2020200642