Chest CT has a high sensitivity for the diagnosis of COVID-19, according to scientists, the chest CT is a routine imaging tool for the diagnosis of pneumonia. Chest CT, a routine imaging tool for the diagnosis of pneumonia, had a high sensitivity for the diagnosis of COVID-19 coronavirus disease.
And compared to the initial reverse transcription transcription polymerase chain reaction ( RT-PCR) of swab samples in the epidemic region of China. Was made. An article published in the journal Radiology. This scanning electron microscope image is shown by isolating the SARS-CoV-2 virus (yellow) from a patient in the USA. UU.
Which emerges from the surface of cultured cells (pink) in the laboratory. Image 2.0 by NIAID-RML Since December 2019, several cases of ‘unknown viral pneumonia’ have been reported in Wuhan City, Hubei Province, China.
It was suspected that a new coronavirus called SARS-CoV-2 had etiology with the phenolofus bat as its supposed origin. It shows a scanning electron microscope image (SARS-CoV-2 virus – yellow) isolated from a patient in the USA. UU., Which originates from the surface of cultured cells (pink) in the laboratory.
In just two months, the virus has spread from Wuhan throughout China and 33 other countries. In the absence of medications or specific therapeutic vaccines for COVID-19, it is necessary to detect the disease at an early stage and immediately isolate an infected patient from a healthy population.
According to the latest guidelines published by the Chinese government, the diagnosis of COVID-19 should be confirmed by RT-PCR or genetic sequencing for respiratory or blood samples, as it is the main indicator of hospitalization.
However, with the limitations of sample collection and transport, as well as kit performance, it has been reported that the total positive rate of RT-PCR throat swab samples is approximately 30% to 60% in the initial presentation
In the current public health emergency, the low sensitivity of RT-PCR implies that a large number of patients with COVID-19 are not recognized early and cannot receive adequate treatment. In addition, given the highly infectious nature of the virus, they run the risk of infecting a large population.
“The early diagnosis of COVID-19 is important for the treatment and control of diseases. Compared to RT-PCR, computed tomography of the chest can be a more reliable, practical and quick way to diagnose and evaluate COVID-19.
Especially in the epidemic area, “lead author Dr. Liming Xia told the Department of Radiology and Tongji Hospital, University of Science and Technology of Huazhong Wuhan and colleagues.
Chest whistle is fast and relatively easy. Recent research found that the sensitivity of CT for COVID-19 infection was 98%, compared to a RT-PCR sensitivity of 71%. Chest CT images of a 29-year-old man with a 6-year-old fever; The RT-PCR assay for SARS-CoV-2 was performed on February 5, 2020 with a positive effect using a swab sample:
- (A) Normal chest CT was initially obtained along the axial and coronal planes;
- (B) Chest CT along the axial and coronal planes reflects a minimum of ground vitreous opium in the bilateral lower pulmonary lobe (yellow arrow);
- (C) Chest CT along the axial and coronal planes increases the opacity of the frosted glass (yellow arrows);
- (D) Chest CT along the axial and coronal planes reflects the progression of pneumonia with mixed frosted glass opacities and linear opacities in the subpleural region;
- (E) Chest CT along the axial and coronal planes reflects both the absorption of the opacity of the frosted glass and the organization of pneumonia.
Image by Ai et al, doi: 10.1148 / radiol. 2020200642. For the present study, Dr. at Tongji Hospital in Wuhan. Xia and his co-authors set out to investigate the clinical value and stability of chest CT images compared to the RT-PCR assay in COVID-19.
The study included 1,014 patients who underwent chest CT and RT-PCR tests between January 6 and February 6, 2020. The performance of the chest CT was evaluated in the diagnosis of COVID-19, with RT-PCR as the reference standard.
For patients with multiple RT-PCR trials, the dynamic conversion (positive to positive and negative to positive, respectively) of the results of the RT-PCR test was also analyzed compared to sequential chest CT scans.
The results showed that 601 patients (59%) had positive RT-PCR results, and 888 (88%) had positive chest CT scans. The sensitivity of chest CT was 97% on the suggestion of COVID-19 based on positive RT-PCR results.
In patients with negative RT-PCR results, 75% (308 of 413 patients) had positive results of chest CT. Of these, 48% were considered as possible cases, 33% as possible cases. Based on the analysis of serial RT-PCR and CT scans, the interval between the initial negative results of positive RT-PCR was 4 to 8 days.
“In approximately 81% of patients with negative RT-PCR results, but through a thorough analysis of clinical symptoms, specific manifestations of CT and dynamic follow-up of CT, positive chest computed tomography with COVID- 19 as highly probable or probable cases It was reclassified, “the researchers said.
The fight to determine if a chest CT scan may be helpful in evaluating patients with COVID-19 infection is moving toward new research examining the use of low-dose CT images. In an April 21 study published in Radiology: Cardiothoracic Imaging, researchers, Anthony Dangis, MD, head of the Radiology Department at Imelda Hospital, Bonehead, Belgium, performed an early CT computed tomography scan using radiation doses of less than 1 mSv And precisely determined.
In emergency room patients, especially those who have exhibited symptoms for more than 48 hours. These findings are a positive step for providers who want to make a quick diagnosis without unnecessarily exposing patients to excess radiation. The results are also helpful, the team argued, since diagnosis COVID-19, the gold standard for real-time polymerase chain reaction (RT-PCR), can be as low as 70 percent.
And, according to some previously published research, chest CT can have a sensitivity of more than 90 percent. The team wrote: “Given the widespread use of chest CT to detect COVID-19, our results suggest the use of low-dose chest CT to achieve a significant reduction in radiation dose at the population level during this epidemic. Demonstrate the feasibility of doing. “
To assess how low a dose can still provide an effective diagnosis, as well as how quickly the scan can be completed, the team conducted a study with 192 emergency room patients from March 14 to 24, which COVID-19 presented with symptoms. The median age was 62 years, but the patients who finally tested positive for the virus were slightly older (67 years) and more likely to have a fever (68.7 percent compared to 45.9 percent).
Dangis’ team performed a low-dose submillisievert chest computed tomography exam using this protocol: 100 kVp, 20 mAs, a pitch of 1.2, and a gantry rotation time of 0.5 seconds. The patients also received RT-PCR tests. And, according to the results, 43.2 patients were positive for COVID-19, and 56.8 percent were negative for the virus.
Overall, the team found that low-dose chest CT offered clinically robust results, especially when evaluating patients who had demonstrated symptoms for more than 48 hours. In those patients, the CT scans were more sensitive than a general group (95.6 percent to 86.7 percent).
The images had slightly higher positive predictive values (91.5 percent to 91.1 percent) and a higher negative predictive value (96.5 percent to 90.3 percent). Accuracy was also better: 94.2 percent compared to 90.6 percent. However, the specificity was slightly lower, at 93.2 percent versus 93.6 percent.
Based on analysis of the results, the team also determined that the average effective radiation dose for the low-dose chest CT protocol was 0.56 mSv, and the average time between image capture and reports of the patients was 25 minutes, with a range from 13 minutes to 49. The limit was minutes.
Based on CT performance and outcome measurement, the team specifically recommended chest CT as a diagnostic tool for COVID-19 under certain circumstances. “Low-dose chest computed tomography may play a complementary role for RT-PCR in the early stages of patients with possible COVID-19 infection,” he said.
“Chest CT may have the added benefit of offering an alternative diagnosis in a significant subset of patients.”