Table 4.
Diagnostic accuracy of low-dose CT assessing intestinal obstruction, possible intestinal obstruction, pneumomediastinum, and combinations of these.
| TP | FP | FN | TN | Sensitivity (95% CI) | Specificity (95% CI) | |
|---|---|---|---|---|---|---|
| Discharge diagnoses | ||||||
| For all low-dose CT scans (n=643) | ||||||
| Intestinal obstruction | 141 | 2 | 36 | 464 | 80% (73–85%) | 100% (98–100%) |
| Intestinal obstruction and possible intestinal obstruction | 176 | 68 | 1 | 398 | 99% (97–100%) | 85% (82–89%) |
| Pneumoperitoneum | 42 | 3 | 2 | 596 | 95% (85–99%) | 100% (99–100%) |
| Intestinal obstruction and pneumoperitoneum | 183 | 5 | 38 | 417 | 83% (77–88%) | 99% (97–100%) |
| For the first low-dose CT scan in each patient (n=568) | ||||||
| Intestinal obstruction | 122 | 2 | 29 | 415 | 81% (74–87%) | 100% (98–100%) |
| Intestinal obstruction and possible intestinal obstruction | 145 | 60 | 1 | 362 | 99% (96–100%) | 86% (82–89%) |
| Pneumoperitoneum | 40 | 3 | 2 | 523 | 95% (84–99%) | 99% (98–100%) |
| Intestinal obstruction and pneumoperitoneum | 162 | 5 | 31 | 370 | 84% (78–89%) | 99% (97–100%) |
| Retakes | ||||||
| Intestinal obstruction and pneumoperitoneum | 4 | 0 | 1 | 17 | 80% (28–99%) | 100% (80–100) |
Note: The low-dose CT sensitivity and specificity was calculated by comparison of low-dose CT findings to the scanned patients discharge diagnoses and to standard-dose CT findings.
TP: true positive, FP: false positive, FN: false negative, TN: true negative.