A comparison of clinical, laboratory and chest CT findings of laboratory-confirmed and clinically diagnosed COVID-19 patients at first admission

Abstract

Purpose: This study aims to identify chest computed tomography (CT) characteristics of coronavirus disease 2019 (COVID-19), investigate the association between CT findings and laboratory or demographic findings, and compare the accuracy of chest CT with reverse transcription-polymerase chain reaction (RT-PCR).

Methods: Overall, 120 of 159 consecutive cases isolated due to suspected COVID-19 at our hospital between 17 and 25 March 2020 were included in this retrospective study. All patients underwent both chest CT and RT-PCR at first admission. The patients were divided into two groups: laboratory-confirmed COVID-19 and clinically diagnosed COVID-19. Clinical findings, laboratory findings, radiologic features and CT severity index (CT-SI) of the patients were noted. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of chest CT were calculated for the diagnosis of COVID-19, using RT-PCR as reference.

Results: The laboratory-confirmed and clinically diagnosed COVID-19 groups consisted of 69 (M/F 43/26, mean age 50.9±14.0 years) and 51 patients (M/F 24/27, mean age 50.9±18.8 years), respectively. Dry cough (62.3% vs. 52.9%), fever (30.4% vs. 25.5%) and dyspnea (23.2% vs. 27.5%) were the most common admission symptoms in the laboratory-confirmed and clinically diagnosed COVID-19 groups, respectively. Bilateral multilobe involvement (83.1% vs. 57.5%), peripheral distribution (96.9% vs. 97.5%), patchy shape (75.4% vs. 70.0%), ground-glass opacities (GGO) (96.9% vs. 100.0%), vascular enlargement (56.9% vs. 50.0%), intralobular reticular density (40.0% vs. 40.0%) and bronchial wall thickening (27.7% vs. 45.0%) were the most common CT findings in the laboratory-confirmed and clinically diagnosed COVID-19 subgroups, respectively. Except for the bilateral involvement and white blood cell (WBC) count, no difference was found between the clinical, laboratory, and parenchymal findings of the two groups. Positive correlation was found between CT-SI and, lactate dehydrogenase (LDH) and C-reactive protein (CRP) values in the laboratory-confirmed COVID-19 subgroup. Chest CT and RT-PCR positivity rates among patients with suspected COVID-19 were 87.5% (105/120) and 57.5% (69/120), respectively. The sensitivity, specificity, PPV, NPV and accuracy rates of chest CT were determined as 94.2% (95% confidence interval [CI], 85.8-98.4), 21.57% (95% CI, 11.3-35.3), 61.90% (95% CI, 58.2-65.5), 73.3% (95% CI, 48.2-89.1) and 63.3% (95% CI, 54.1-71.9), respectively.

Conclusion: Chest CT has high sensitivity and low specificity in the diagnosis of COVID-19. The clinical, laboratory, and CT findings of laboratory-confirmed and clinically diagnosed COVID-19 patients are similar.

Figure 1

The flowchart of patients according to RT-PCR and chest CT classification.

Figure 2. a, b

Non-contrast chest CT images in a 52-year-old male COVID-19 patient presenting with dry cough. Coronal CT image (a) shows bilateral patchy ground-glass opacities in multiple lung segments. Axial image (b) shows central and peripheral distribution.

Figure 3. a–i

CT features of COVID-19 disease. Axial unenhanced chest CT images show: (a), pure peripheral ground-glass opacities (GGOs) with vascular enlargements (black arrows); (b), bilateral GGOs and fibrous bands in the lower lobes (black arrows); (c), GGO with intralobular reticular densities in the left lower lobe (black frame); (d), subpleural curvilinear lines in the right lower lobe (black arrows); (e), consolidation with air bronchograms surrounded by a ground-glass halo representing halo sign in the anterobasal segment of the right lower lobe (black frame), with another focal consolidation also seen in the medial part of the posterobasal segment of the right lower lobe; (f), bilateral (dominantly in the right lung) GGOs in the lower lobes and air bronchogram in the right subpleural area (black arrow); (g), relative sparing of the lung periphery indicating subpleural sparing sign (black arrows); (h), bilateral patchy GGOs and bronchial wall thickening in the anterior segment of the right upper lobe (black arrows); and (i), reversed halo sign defined as central GGO surrounded by denser consolidation in the left lower lobe (black frame).