Diagnostic performance of chest CT to differentiate COVID-19 pneumonia in non-high-epidemic area in Japan

Abstract

Purpose: To evaluate the diagnostic performance of chest CT to differentiate coronavirus disease 2019 (COVID-19) pneumonia in non-high-epidemic area in Japan.

Materials and methods: This retrospective study included 21 patients clinically suspected COVID-19 pneumonia and underwent chest CT more than 3 days after the symptom onset: six patients confirmed COVID-19 pneumonia by real-time reverse-transcription polymerase chain reaction (RT-PCR) and 15 patients proved uninfected. Using a Likert scale and its receiver operating characteristic curve analysis, two radiologists (R1/R2) evaluated the diagnostic performance of the five CT criteria: (1) ground glass opacity (GGO)-predominant lesions, (2) GGO- and peripheral-predominant lesions, (3) bilateral GGO-predominant lesions; (4) bilateral GGO- and peripheral-predominant lesions, and (5) bilateral GGO- and peripheral-predominant lesions without nodules, airway abnormalities, pleural effusion, and mediastinal lymphadenopathy.

Results: All patients confirmed COVID-19 pneumonia had bilateral GGO- and peripheral-predominant lesions without airway abnormalities, mediastinal lymphadenopathy, and pleural effusion. The five CT criteria showed moderate to excellent diagnostic performance with area under the curves (AUCs) ranging 0.77-0.88 for R1 and 0.78-0.92 for R2. The criterion (e) showed the highest AUC.

Conclusion: Chest CT would play a supplemental role to differentiate COVID-19 pneumonia from other respiratory diseases presenting with similar symptoms in a clinical setting.

Keywords: COVID-19; CT criteria; Chest CT; Diagnostic performance.

Fig. 1

Typical CT findings in patients with COVID-19 pneumonia. a A transverse CT image in a 67-year-old man with fever (day 4). CT shows rounded, peripheral ground glass lesion in the right lower lobe. b CT image in a 56-year-old man presented with fever (day 11). CT shows peripheral glass opacities with superimposed fine reticular shadows in the left lower lobe

Fig. 2

CT images from patients with negative RT-PCR test for COVID-19. a A 66-year-old female patient presenting with persistent fever (day 8). CT shows curved linear consolidation with peripheral distribution as well as bronchial wall thickening. This patient was diagnosed as Moraxella Pneumonia. b A 70-year-old female patients with pancreatic cancer presenting with fever (day 7). CT shows extensive ground glass lesion with crazy paving pattern in left upper lobe. Note these shadows are not strongly in peripheral distribution. The patient was diagnosed as pnuemocystis jirovecii pneumonia

Fig. 3

The receiver operating characteristic curves of the five chest CT criteria for R1(a) and R2(b). Respective curves represent the criteria of a GGO-predominant lesions, b GGO- and peripheral-predominant lesions, c bilateral GGO-predominant lesions, d bilateral GGO- and peripheral-predominant lesions, and e bilateral GGO- and peripheral-predominant lesions without airway abnormalities, nodules, mediastinal lymphadenopathy, and pleural effusion