L/S and CT scores
The median time interval from the onset of symptoms of the disease to the first chest CT scan was 2 days (range 1–4 days). The median time interval between the first and second chest CT scans for the study population were 8 days (range 2–29 days). The median time interval between the first and second chest CT scans were 12 days (range 4–26) and 7.5 days (range 2–29) for the non-progressive group and progressive group, respectively. Table 4 shows lung CT scores, L/S, and liver densities on CT of the two groups of patients for the two time points. The mean L/S of the progressive group was lower than that of the non-progressive group at hospital admission but there was no significant difference between the two groups (p = 0.547). However, L/S was found to be significantly different between the two groups of patients at follow-up (p = 0.009) (Fig. 3). For the intragroup analysis, there was a significant change in L/S in patients with increased lung CT score (p = 0.014). In the progressive group, as the median lung CT score was increased from 6.5 (range 0–14) to 12 (range 5–24) in two consecutive scans, the mean L/S was decreased from 1.13 ± 0.3 to 1.02 ± 0.23. For the non-progressive group, L/S was elevated in the second CT scan, however the change in L/S was not statistically significant for the intragroup analysis (p = 0.465). The change between the baseline and follow-up L/S was found to be statistically significant for the progressive group (p = 0.028).
Table 4 Liver-to-spleen ratio of the two groups of COVID-19 patients
Non-progressive group (n = 7) Progressive group (n = 20)
At hospital admission Follow-up At hospital admission Follow-up
CT score 1 (0–19) 1 (0–19) 6.5 (0–14) 12 (5–24)
L/S 1.21 ± 0.29a 1.25 ± 0.29a 1.13 ± 0.3b 1.02 ± 0.23b
Liver density (HU) 52.52 ± 12.4
56.67 (30.33–65.33) 55.19 ± 12.83
58 (38–73.67) 52.6 ± 12.8
55.5 (17.33–65) 49.87 ± 11.09
52 (17.33–66)
Data are median (minimum–maximum) and mean ± standard deviation. L/S liver-to-spleen ratio
aIn the non-progressive group, there was no significant difference between the comparison of L/S values that were obtained at hospital admission and follow-up (p = 0.465) (paired t-test)
bIn the progressive group, there was a significant difference between the comparison of L/S values that were obtained at hospital admission and follow-up (p = 0.014) (paired t-test)
There was no significant difference of L/S between the two groups at hospital admission (p = 0.547) (independent samples t-test)
Follow-up L/S was significantly different between the two groups (p = 0.009) (covariance analysis)
The change between the baseline and follow-up L/S was statistically significant for the progressive group (p = 0.028) (independent samples t-test)
Fig. 3 66-year old woman with COVID-19. (a) CT lung score was 0 at hospital admission. (b) Liver-to-spleen ratio at hospital admission was calculated as 1.2. (c) CT lung score was 12 at follow-up CT scan which was obtained 10 days later. (d) Liver-to-spleen ratio at follow-up was calculated as 0.82