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Both signs are sensitive for the diagnosis, however; “Double halo sign” has more specificity for the diagnosis of loose screws than “halo zone sign”
| Sensitivity | Specificity | Positive predictive value | Negative predictive value | |
|---|---|---|---|---|
| Halo zone sign | 1 | 0.8047 | 0.155 | 1 |
| Double Halo sign | 1 | 0.940 | 0.375 | 1 |
Specificity difference was significant with Z value of 4.604 at CI 95%. Predictive values are low because of the low incidence of screw loosening among the patients cohort
