Table 1.
Diagnostic Accuracy According to Variable Cut-off Values for Rectal Gas Volume and Rectal Gas Maximum Area CT Images for Predicting Rectal Evacuation Disorders
| Cut-off value | Sensitivity | Specificity | PPV | NPV | OR (95% CI) |
|---|---|---|---|---|---|
| RGV>50mL | 17.5% | 96.4% | 84.6% | 50.5% | 5.6 (1.2~26.5) |
| RGV>40mL | 20.6% | 92.7% | 76.5% | 50.5% | 3.3 (1.0~10.9) |
| RGV>30mL | 27.0% | 90.9% | 77.3% | 52.8% | 3.7 (1.3~10.8) |
| RGV>20mL | 38.1% | 89.1% | 80.0% | 55.7% | 5.0 (1.9~13.5) |
| RGV>10mL | 54.0% | 76.4% | 72.3% | 59.2% | 3.8 (1.7~8.4) |
| MRGTA>15cm2 | 15.9% | 94.6% | 76.9% | 79.5% | 3.3 (0.9~12.6) |
| MRGTA>10cm2 | 24.6% | 90.9% | 75.0% | 52.1% | 3.1 (1.1~9.3) |
| MRGTA>5cm2 | 54.0% | 80.0% | 76.6% | 60.3% | 4.7 (2.1~10.7) |
| RGA on scout>8cm2 | 20.6% | 59.1% | 68.4% | 49.5% | 2.1 (0.75~6.0) |
| RGA on scout>9cm2 | 17.5% | 92.3% | 68.8% | 53.6% | 2.1 (0.7~6.5) |
| RGA on scout>10cm2 | 17.5% | 90.9% | 58.8% | 49.0% | 2.1 (0.7~6.5) |
RGV, rectal gas volume on CT; MRGTA, maximal rectal gas transaxial area on CT; RGA on scout, area of rectal gas on the 2-dimensional abdominal film (scout); PPV, positive predictive value; NPV, negative predictive value; OR, odd ratio; CI, confidence interval