Table 5.
Statistical analysis of diagnostic efficiency of each index of MSIS and MARS MRI in PJI.
| Variable | PJI | Non-PJI | Sensitivity | p-Value a (VS. MARS) | Specificity | p-Value a (VS. MARS) | Youden’s Index | PPV | NPV | LR+ | LR− |
|---|---|---|---|---|---|---|---|---|---|---|---|
| MARS MRI | 25/31 | 5/20 | 80.65% | N/A | 75% | N/A | 0.556 | 83.33% | 71.43% | 3.226 | 0.258 |
| Culture | 23/31 | 5/20 | 74.19% | 0.727 | 75% | 1.000 | 0.642 | 92% | 69.23% | 7.419 | 0.287 |
| Pre-OP culture | 10/31 | 3/20 | 32.26% | 0.001 | 85% | 0.625 | 0.173 | 76.92% | 44.74% | 2.151 | 0.797 |
| Intra-OP culture | 21/31 | 2/20 | 67.74% | 0.344 | 90% | 0.453 | 0.577 | 91.30% | 64.29% | 6.774 | 0.358 |
| CRP (>10 mg/L) | 26/31 | 2/20 | 83.87% | 1.000 | 90% | 0.375 | 0.739 | 92.86% | 78.26% | 8.387 | 0.179 |
| ESR (>30 mm/h) | 25/31 | 8/20 | 80.65% | 1.000 | 60% | 0.180 | 0.406 | 75.76% | 66.67% | 2.016 | 0.323 |
| SF-WBC (>3000 × 106/L) | 23/31 | 1/20 | 74.19% | 0.687 | 95% | 0.125 | 0.692 | 95.83% | 70.37% | 14.84 | 0.272 |
| SF-PMN% (>80%) | 19/31 | 0/20 | 61.30% | 0.109 | 100% | N/A | 0.613 | 100% | 62.50% | N/A | 0.387 |
| Bone destruction+ Lamellated synovitis | 26/31 | 7/20 | 83.87% | - | 65% | - | 0.489 | 78.79% | 72.22% | 2.396 | 0.248 |
| Bone destruction+ Extracapsular edema | 28/31 | 9/20 | 90.32% | - | 55% | - | 0.453 | 75.68% | 78.57% | 2.007 | 0.176 |
| Lamellated synovitis+ Extracapsular edema | 29/31 | 10/20 | 93.55% | - | 50% | - | 0.435 | 74.36% | 83.33% | 1.871 | 0.129 |
a McNemar’s test; Youden’ s index = sensitivity + specificity − 1; MARS: Metal artifact reduction sequence, PJI: Prosthetic joint infection, LR+: Positive likelihood ratio, LR−: Negative likelihood ratio, NPV: Negative predictive value, PPV: Positive predictive value, N/A: Not applicable, SF-WBC: Synovial fluid white blood cell, SF-PMN: Synovial fluid polymorphonuclear, OP: operative.