Diagnostic accuracy of chest computed tomography for detecting COVID-19 pneumonia in low disease prevalence area: A local experience

Mounir Benmessaoud, Ahmed Dadouch, Maghnouj Abdelmajid, Anass Abir, Youssef el-Ouardi, Assiya Lemmassi, Khalid Nouader, Inssaf Chibani


Background: The role of computed tomography (CT) was crucial in detecting coronavirus disease 2019, their diagnostic performances were evaluated frequently in the high disease prevalence regions. In contrast, limited studies assessed the accuracy of chest CT in low disease prevalence areas.

Methods: A retrospective study was conducted at a single center from April 3 to October 16, 2020. The data were collected manually involving age, gender, symptoms, chest CT and RT-PCR results. Patients included were all suspected cases diagnosed by both chest CT and RT-PCR. The confidence intervals (95%) were estimated using the Wilson method.

Results: A total of 104 patients (mean age 59±15 years, 61 males) were included. 6/104(15%) were presented with fever, 22/104(21%) with cough, 19/104(18%) with dyspnea, 4/104(4%) with diarrhea, and 7/104(6%) with headache. Regarding reverse transcription-polymerase chain reaction (RT-PCR) tests, 34 cases were positive and 70 were negatives. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of chest CT using RT-PCR as a reference were 97% (33/34,95%CI; [85-99%]), 50% (35/70,95%CI; [38-61%]), 48% (33/68,95%CI; [37-60%]), 97% (35/36,95%CI; [85-99%]) and 65% (68/104,95%CI; [56-74%]), respectively.

Conclusion: Chest CT is an important tool that contributed to the treatment decision of the high-suspected cases, as an early intervention before the confirmation with RT-PCR.

Keywords: COVID-19; Chest Computed Tomography; Diagnostic Accuracy 

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Huang C, Wang Y, Li X, Ren L, Zhao J, et al. Clinical features of patients infected with 2019 novel coronavirus in Wuhan, China. The Lancet, (2020); 395(10223): 497–506.

Moroccan health ministry Web site. http://www.covidmaroc.ma/Documents/COM/.Accessed April 30, 2020.

Moroccan health ministry Web site. http://www.covidmaroc.ma/Documents/BULLETIN/. Accessed February 06, 2021.

Cherradi Y. About the Moroccan strategy in the fight against Covid-19 before lockdown ease period. Journal of Medical and Surgical Research, (2020); 737:40.

Interim Guidance: Healthcare Professionals 2019-nCoV | CDC; (2020).

Moroccan health ministry Web site. http://www.covidmaroc.ma/Documents/2020/coronavirus/PS/covid-19. Accessed May,04 2020.

Li Y, Xia L. Coronavirus disease 2019 (COVID-19): Role of chest CT in diagnosis and management. American Journal of Roentgenology, (2020); 214(6): 1280–1286.

Ai T, Yang Z, Hou H, Zhan C, Chen C, Lv W, Tao Q, Sun Z, Xia L. Correlation of Chest CT and RT-PCR Testing for Coronavirus Disease 2019 (COVID-19) in China: A Report of 1014 Cases. Radiology, (2020); 296(2): E32–E40.

Kim H, Hong H, Ho Yoon S. Diagnostic performance of ct and reverse transcriptase polymerase chain reaction for coronavirus disease 2019: A meta-analysis. Radiology, (2020); 296(3): E145–E155.

Eng J, Bluemke D A. Imaging publications in the COVID-19 pandemic: Applying new research results to clinical practice. Radiology, (2020); 297(1): E228–E231.

Alberg A J, Park J W, Hager B W, Brock M V, Diener-West M. The use of “overall accuracy” to evaluate the validity of screening or diagnostic tests. Journal of General Internal Medicine, (2004); 19(5 PART 1): 460–465.

Falaschi Z, Danna P S C, Arioli R, Pasché A, Zagaria D, et al. Chest CT accuracy in diagnosing COVID-19 during the peak of the Italian epidemic: A retrospective correlation with RT-PCR testing and analysis of discordant cases. European Journal of Radiology, (2020); 130(July): 109192.

Herpest G, Lederlin M, Naudin M, Ohana M, Chaumoitre K, et al. Efficacy of Chest CT for COVID-19 Pneumonia Diagnosis in France. Radiology, (2021); 298(2): E81–E87.

Himoto Y, Sakata A, Kirita M, Hiroi T, Kobayashi K, et al. Diagnostic performance of chest CT to differentiate COVID-19 pneumonia in non-high-epidemic area in Japan. Japanese Journal of Radiology, (2020); 38(5): 400–406.

Fang Y, Zhang H, Xie J, Lin M, Ying L,Pang P, Ji W. Senivity of Chest CT for COVID.19: Comparasion to RT¬¬-PCR. Radiology, (2020); 296: 15–17.

Yu F, Yan L, Wang N, Yang S, Wang L, et al. Quantitative detection and viral load analysis of SARS-CoV-2 in infected patients. Clinical Infectious Diseases, (2020); 71(15): 793–798.

Ducray V, Vlachomitrou A S, Bouscambert-Duchamp M, Si-Mohamed S, Gouttard S, et al. Chest CT for rapid triage of patients in multiple emergency departments during COVID-19 epidemic: experience report from a large French university hospital. European Radiology, (2020);31(2): 795–803.

Ranganathan P, Aggarwal R. Common pitfalls in statistical analysis: Understanding the properties of diagnostic tests – Part 1. Perspectives in Clinical Research, (2018); 9(1) : 40–43.


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