Performance of Chest Computed Tomography in Differentiating Coronavirus Disease 2019 From Other Viral Infections Using a Standardized Classification

Abstract

Background: An expert consensus recently proposed a standardized coronavirus disease 2019 (COVID-19) reporting language for computed tomography (CT) findings of COVID-19 pneumonia. Purpose: The purpose of the study was to evaluate the performance of CT in differentiating COVID-19 from other viral infections using a standardized reporting classification. Methods: A total of 175 consecutive patients were retrospectively identified from a single tertiary-care medical center from March 15 to March 24, 2020, including 87 with positive reverse transcription-polymerase chain reaction (RT-PCR) test for COVID-19 and 88 with negative COVID-19 RT-PCR test, but positive respiratory pathogen panel. Two thoracic radiologists, who were blinded to RT-PCR and respiratory pathogen panel results, reviewed chest CT images independently and classified the imaging findings under 4 categories: “typical” appearance, “indeterminate,” “atypical,” and “negative” for pneumonia. The final classification was based on consensus between the readers. Results: Patients with COVID-19 were older than patients with other viral infections (P=0.038). The inter-rater agreement of CT categories between the readers ranged from good to excellent, κ=0.80 (0.73 to 0.87). Final CT categories were statistically different among COVID-19 and non-COVID-19 groups (P<0.001). CT “typical” appearance was more prevalent in the COVID-19 group (64/87, 73.6%) than in the non-COVID-19 group (2/88, 2.3%). When considering CT “typical” appearance as a positive test, a sensitivity of 73.6% (95% confidence interval [CI]: 63%-82.4%), specificity of 97.7% (95% CI: 92%-99.7%), positive predictive value of 97% (95% CI: 89.5%-99.6%), and negative predictive value of 78.9% (95% CI: 70%-86.1%) were observed. Conclusion: The standardized chest CT classification demonstrated high specificity and positive predictive value in differentiating COVID-19 from other viral infections when presenting a “typical” appearance in a high pretest probability environment. Good to excellent inter-rater agreement was found regarding the CT standardized categories between the readers.

The role of chest imaging in the diagnosis, management, and monitoring of coronavirus disease 2019 (COVID-19)

“…They also revealed that PPV of “typical appearance” was 40.0% at a prevalence of 16.7% and increased to 87.8% at 46.4% [ 61 ]. Similar trends were observed in reports from other countries, i.e., Brazil [ 60 , 63 , 66 , 67 ], Japan [ 49 ], and USA [ 64 ] and other institutions in Italy [ 61 , 62 , 65 ]. Regarding the diagnostic performance against other viral pneumonias, a retrospective cohort study from Brazil reported similar results with a sensitivity and specificity of 73.6% and 97.7%, respectively, for “typical appearance” [ 65 ].…”

“…Regarding the diagnostic performance against other viral pneumonias, a retrospective cohort study from Brazil reported similar results with a sensitivity and specificity of 73.6% and 97.7%, respectively, for “typical appearance” [ 65 ]. They also evaluated the CT classification in relation to the duration of symptoms, which showed that “indeterminate appearance” and “negative for pneumonia” were significantly more frequent in patients with symptom duration of 0–5 days than > 5 days, suggesting milder CT patterns in the early stage of infection [ 66 ]. A retrospective cohort study from Italy that compared the diagnostic performance in relation to age reported that PPV, NPV, and accuracy were not statistically different among the different age groups in their study comprising patients > 60, ≥ 50 and < 60, or < 50 [ 62 ].…”

“…Excluding categories of negative CT findings, the proportion of COVID-19 positivity for each category was roughly parallel to the level of suspicion of the category in each classification system [ 49 ]. In some studies, however, a reversed incidence was observed in the lowest two categories [ 49 , 61 , 63 , 66 , 68 – 70 , 75 ]. For example, the proportion of CO-RADS 1 (negative CT findings) was higher than CO-RADS 2 (suspected pneumonia caused by other pathogen), and a similar trend was seen in RSNA “negative for pneumonia” and RSNA “atypical appearance”, COVID-RADS 1 and 2, or BSTI “NON-COVID” and “INDETERMINATE” [ 49 , 68 – 70 , 75 ].…”

Ionizing Radiation Exposure in Patients With Covid-19: More Than Needed

“…Teles et al. reported a high specificity and positive predictive value for standardized chest CT classification ( 18 ) . Conduction of randomized controlled studies seems imperative to settle the issue.…”

Impact of the COVID-19 pandemic on the selection of chest imaging modalities and reporting systems: a survey of Italian radiologists

“…Another interesting finding was that more than half of the respondents who had predominantly used CXR indicated that they would have preferred to use chest CT to assess/exclude COVID-19 pneumonia. The desire to change the diagnostic method from CXR to chest CT is likely due to the relatively higher sensitivity of chest CT in the detection of lung abnormalities (especially in the early stage of the disease) [ 13 – 20 ], as well as its superior ability to differentiate COVID-19 pneumonia from other infectious and noninfectious interstitial diseases [ 38 – 40 ]. However, CXR does have several advantages in the management of patients with suspected or confirmed COVID-19 infection [ 6 – 13 ].…”