Table 2. ROC analysis results of size, shape and first order texture parameters to discriminate COVID-19 related lesions from atypical pneumonia.
| Parameter | COVID-19 (mean ± SD) | Atypicala* (mean ± SD) | Cut-off | Sensitivity (%) | Specificity (%) | AUC | 95% CI |
|---|---|---|---|---|---|---|---|
| Size and Shape Parameters | |||||||
| Sphericity | 0,446±0,110 | 0,390±0,084 | >0,405 | 60,1 | 64,3 | 0,643 | 0,586–0,698 |
| Compactness 1 | 0,016±0,006 | 0,013±0,006 | >0,013 | 60,8 | 63,6 | 0,637 | 0,579–0,692 |
| Compactness 2 | 0,104±0,079 | 0,068±0,045 | >0,109 | 36,6 | 86,7 | 0,633 | 0,575–0,688 |
| Elongation | 0,685±0,150 | 0,648±0,144 | >0,754 | 37,9 | 79,0 | 0,579 | 0,520–0,636 |
| Flatness | 0,477±0,154 | 0,412±0,130 | >0,493 | 46,4 | 74,1 | 0,614 | 0,556–0,670 |
| Surface area (cm2) | 9,23±9,49 | 12,45±11,22 | ≤8,35 | 67,3 | 51,8 | 0,600 | 0,541–0,656 |
| Area/Volume ratio | 0,508±0,135 | 0,532±0,166 | ≤0,638 | 85,6 | 21,7 | 0,529 | 0,471–0,587 |
| Spherical disproportion | 2,385±0,598 | 2,690±0,594 | ≤2,572 | 68,0 | 57,3 | 0,645 | 0,588–0,700 |
| Major axis (mm) | 53,08±23,52 | 50,42±26,47 | ≤39,68 | 41,8 | 74,8 | 0,596 | 0,538–0,652 |
| Minor axis (mm) | 35,76±14,61 | 32,53±14,75 | ≤36,42 | 69,9 | 45,5 | 0,571 | 0,513–0,628 |
| Least axis (mm) | 22,39±10,27 | 21,63±9,00 | ≤22,66 | 67,3 | 45,5 | 0,512 | 0,454–0,570 |
| First Order Texture Parameters | |||||||
| Skewness | 0,152±0,489 | 0,114±0,672 | >-0,331 | 85,0 | 28,0 | 0,519 | 0,461–0,577 |
| Kurtosis | 3,356±0,961 | 3,460±1,370 | ≤3,107 | 53,0 | 55,0 | 0,504 | 0,446–0,563 |
| Energy | 9019±11856 | 17030±22052 | ≤3408 | 47,0 | 70,6 | 0,615 | 0,557–0,671 |
| Total Energy | 8222±10776 | 16258±22125 | ≤7846 | 69,3 | 48,3 | 0,608 | 0,550–0,664 |
| Entropy | 5,153±0,240 | 5,136±0,258 | >5,135 | 59,5 | 53,9 | 0,527 | 0,468–0,585 |
| Minimum** | 0,073±0,077 | 0,058±0,096 | >-0,028 | 92,2 | 20,3 | 0,526 | 0,467–0,584 |
| 10th percentile** | 0,354±0,116 | 0,380±0,142 | ≤0,496 | 86,9 | 25,2 | 0,554 | 0,496–0,612 |
| 90th percentile** | 0,768±0,161 | 0,857±0,207 | ≤0,889 | 74,5 | 49,7 | 0,637 | 0,579–0,692 |
| Maximum** | 1,221±0,192 | 1,344±0,229 | ≤1,342 | 81,7 | 50,3 | 0,672 | 0,615–0,725 |
| Mean** | 0,561±0,139 | 0,622±0,179 | ≤0,668 | 75,8 | 42,0 | 0,603 | 0,544–0,659 |
| Median** | 0,561±0,149 | 0,625±0,202 | ≤0,742 | 86,9 | 31,5 | 0,590 | 0,531–0,646 |
| Range** | 1,149±0,199 | 1,284±0,234 | ≤1,321 | 86,9 | 45,5 | 0,686 | 0,630–0,739 |
| Interquartile Range** | 0,220±0,057 | 0,257±0,085 | ≤0,296 | 92,1 | 26,6 | 0,622 | 0,564–0,677 |
| Standard deviation | 0,161±0,035 | 0,187±0,045 | ≤0,161 | 50,3 | 74,8 | 0,664 | 0,607–0,717 |
| Mean absolute deviation | 0,129±0,030 | 0,151±0,041 | ≤0,165 | 89,5 | 33,6 | 0,649 | 0,591–0,703 |
| Robust mean deviation | 0,091±0,023 | 0,107±0,034 | ≤0,121 | 92,2 | 28,7 | 0,630 | 0,572–0,685 |
| Root mean squared | 0,585±0,138 | 0,651±0,179 | ≤0,657 | 71,9 | 47,6 | 0,612 | 0,554–0,668 |
| Variance | 0,027±0,011 | 0,037±0,017 | ≤0,027 | 52,3 | 72,7 | 0,666 | 0,609–0,720 |
| Uniformity | 0,035±0,008 | 0,033±0,006 | ≤0,034 | 66,7 | 48,3 | 0,552 | 0,493–0,609 |
*Atypical: Atypical pneumonia group.
** Standardized data. Figures were not given in Hounsfield unit.