Clinical and High-Resolution CT Features of the COVID-19 Infection: Comparison of the Initial and Follow-up Changes

Abstract

Objectives: In late December 2019, an outbreak of coronavirus disease (COVID-19) in Wuhan, China was caused by a novel coronavirus, newly named severe acute respiratory syndrome coronavirus 2. We aimed to quantify the severity of COVID-19 infection on high-resolution chest computed tomography (CT) and to determine its relationship with clinical parameters.

Materials and methods: From January 11, 2020, to February 5, 2020, the clinical, laboratory, and high-resolution CT features of 42 patients (26-75 years, 25 males) with COVID-19 were analyzed. The initial and follow-up CT, obtained a mean of 4.5 days and 11.6 days from the illness onset were retrospectively assessed for the severity and progression of pneumonia. Correlations among clinical parameters, initial CT features, and progression of opacifications were evaluated with Spearman correlation and linear regression analysis.

Results: Thirty-five patients (83%) exhibited a progressive process according to CT features during the early stage from onset. Follow-up CT findings showed progressive opacifications, consolidation, interstitial thickening, fibrous strips, and air bronchograms, compared with initial CT (all P < 0.05). Before regular treatments, there was a moderate correlation between the days from onset and sum score of opacifications (R = 0.68, P < 0.01). The C-reactive protein, erythrocyte sedimentation rate, and lactate dehydrogenase showed significantly positive correlation with the severity of pneumonia assessed on initial CT (Rrange, 0.36-0.75; P < 0.05). The highest temperature and the severity of opacifications assessed on initial CT were significantly related to the progression of opacifications on follow-up CT (P = 0.001-0.04).

Conclusions: Patients with the COVID-19 infection usually presented with typical ground glass opacities and other CT features, which showed significant correlations with some clinical and laboratory measurements. Follow-up CT images often demonstrated progressions during the early stage from illness onset.

FIGURE 1

A1–A3, The HRCT images at admission of a 44-year-old male patient (5 days from onset). Multiple ground glass opacities (GGOs) and GGO with interlobular septal thickening (like reticulation or “paving stone sign”; boxes) and thin fibrous stripes (arrow) are shown in different cross-sections. B1–B3, The HRCT images of a 38-year-old male patient, who is also medical personnel (9 days from onset). Diffuse opacities and consolidation, as well as air bronchograms (arrows) can be seen.

FIGURE 2

A, The differences in area and density of the max lesion in cross-section between the initial and follow-up CT. B, Before admission and treatments, the sum score was positively correlated with the days from onset to initial CT (with age and sex as covariates, R = 0.68, P < 0.01). After regular treatments, the correlation was no longer significant (P = 0.19). C, Three different cases showing their max lesion in cross-section in the initial and follow-up CT.

FIGURE 3

A case with progression after admission. A1–A2, The HRCT images of a 57-year-old female patient (4 days from onset). Multiple GGO distributed bilaterally. B1–B2, Three days later, more opacities, also with larger size, were seen bilaterally.

FIGURE 4

A case of slight improvement after admission. A1–A2, The HRCT images of a 56-year-old female patient (9 days from onset). Multiple GGO with interstitial thickening and thin fibrous stripes are shown. B1–B2, Six days later, the lesion size is smaller, and the density is slightly increased, also with more fibrous stripes. Arrows indicated the abnormalities.

FIGURE 5

The most serious patients are usually accompanied by acute respiratory distress syndrome (A1–A2, a 57-year-old female patient, 18 days from onset; B1–B2, a 75-year-old male patient, 15 days from onset). There are diffuse lesions in the lungs bilaterally, which showed as “white lungs.”

FIGURE 6

Positive relationships were shown (A) between lactate dehydrogenase and sum score of opacifications (R = 0.78, P < 0.001) and (B) between C-reactive protein and area of max lesion in cross-section (R = 0.65, P = 0.002). R correlation coefficients are calculated using partial correlation with age and sex as covariates.