Table 4.
ROC analysis cut-off values for semiquantitative parameters of N-13 ammonia positron emission computed tomography-computed tomography and Tc-99m glucoheptonate single photon emission computed tomography-computed tomography
| Parametera | Cut-off value | Sensitivity (95% CI) | Specificity (95% CI) | PPV (95% CI) | NPV (95% CI) | AUC (95% CI)* |
|---|---|---|---|---|---|---|
| T/W | 2.16 | 64.3% (44.1-81.4) | 88.9% (70.8-97.6) | 85.7% (63.7-97.0) | 70.6% (52.5-84.9) | 0.798 (0.668-0.894) |
| T/G | 1.0 | 67.9% (47.6-84.1) | 96.3% (81.0-99.9) | 95.0% (75.1-99.9) | 74.3% (56.7-87.5) | 0.825 (0.698-0.914) |
| T/N | 4.24 | 82.1% (63.1-93.9) | 81.5% (61.9-93.7) | 82.1% (63.1-93.9) | 81.5% (61.9-93.7) | 0.825 (0.699-0.914) |
| T/S | 0.25 | 82.1% (63.1-93.9) | 85.2% (66.3-95.8) | 85.2% (65.8-95.9) | 82.1% (63.1-93.9) | 0.828 (0.702-0.916) |
| T/NPX | 0.27 | 85.7% (67.3-96.0) | 81.5% (61.9-93.7) | 82.8% (64.2-94.2) | 84.6% (65.1-95.6) | 0.809 (0.680-0.902) |
*Significant at a P value of 0.0001; aParameters derived on N-13 NH3 PET-CT: T/W: Tumor to white matter SUVmax ratio, T/G: Tumor to grey matter SUVmax ratio; Parameters derived on Tc-99m GHA SPECT-CT: T/N: Tumor to normal CPP ratio, T/S: Tumor to scalp CPP ratio, T/NPX: Tumor to nasopharynx CPP ratio. CI: Confidence interval, PPV: Positive predictive value, NPV: Negative predictive value, AUC: Area under the curve, Tc-99m GHA SPECT-CT: Tc-99m glucoheptonate single photon emission computed tomography-computed tomography, N-13NH3 PET-CT: N-13 ammonia positron emission computed tomography-computed tomography, CPP: Counts per pixel, SUVmax; Standardized uptake value maximum