Table 2.
Receiver operating characteristic analyses of sensor diagnostic performance. Ability of integration metrics from the sensor TACs to predict whether an infiltration will be visible on ensuing PET: infiltration visible (n = 4); infiltration not visible (n = 6).
| TAC interval | Sensor arm | ROC area | Sensitivity | Specificity | Cut-off value | PPV | NPV |
|---|---|---|---|---|---|---|---|
| Peak only | Injection | 0.71 | 50% | 100% | 1.76 × 105 | 100% | 75.0% |
| Peak only | I/C ratio | 0.58 | 50% | 100% | 29.20 | 100% | 75.0% |
| 0–10 min | Injection | 0.92 | 75% | 100% | 3.34 × 105 | 100% | 85.7% |
| 0–10 min | I/C ratio | 0.92 | 75% | 100% | 2.62 | 100% | 85.7% |
| 0–20 min | Injection | 0.92 | 75% | 100% | 5.40 × 105 | 100% | 85.7% |
| 0–20 min | I/C ratio | 0.92 | 75% | 100% | 1.87 | 100% | 85.7% |
| 0–30 min | Injection | 0.88 | 75% | 100% | 7.48 × 105 | 100% | 85.7% |
| 0–30 min | I/C ratio | 0.88 | 75% | 100% | 1.61 | 100% | 85.7% |
| 0–40 min | Injection | 0.83 | 75% | 100% | 9.45 × 105 | 100% | 85.7% |
| 0–40 min | I/C ratio | 0.83 | 75% | 100% | 1.47 | 100% | 85.7% |
| 30–40 min | Injection | 0.79 | 75% | 100% | 1.97 × 105 | 100% | 85.7% |
| 30–40 min | I/C ratio | 0.88 | 75% | 100% | 1.31 | 100% | 85.7% |
TAC, time activity curve; ROC, receiver operating characteristic; I/C, injection arm/control arm; PPV, positive predictive value; NPV, negative predictive value.