ABSTRACT
Objective To compare the efficacy of 18F-FDG PET/CT, 99Tcm-MDP bone scintigraphy (BS), and combination of the two techniques (PET/CT + BS) for detecting bone metastasis by ROC curve analysis. Methods All 296 patients with various cancers, who underwent both 99Tcm-MDP BS and 18F-FDG PET/CT within two months, were retrospectively analyzed. These images were interpreted according to 5-point scale (0: definitely negative, 1: probably negative, 2: equivocal, 3: probably positive, 4:definitely positive for bone metastasis), and the scale of PET/CT + BS was the sum of PET/CT and BS. In light of the confirmed diagnosis derived from pathology or follow-up, ROC curve analysis was performed.The area under the ROC curve (AUC) was compared by z-test. Results Of 296 cases, 61 (20.6%) were confirmed as bone metastases and 235 (79.4%) were negative. The AUC were 0. 919 (95% confidence interval (95% CI) :0. 867 - 0. 971) for BS, 0. 949 (95% CI: 0. 906 - 0. 991) for PET/CT, and 0. 994 (95% CI: 0.988-0.999) for PET/CT + BS, rctrospectively. The AUC of PET/CT + BS was statistically significantly larger than that of BS (z=2. 866, P=0.004) or PET/CT (z =2.027, P=0.043), while the AUC of PET/CT was larger than that of BS, but no statistically significance (z = 0. 881, P = 0. 378) was showed. The optimal sensitivity, specificity, accuracy, positive predictive value (PPV), negative predictive value(NPV) were 90. 2% (55/61), 85. 1% (200/235), 86. 1% (255/296), 61. 1% (55/90), 97. 1%(200/206) for BS, 88.5% (54/61), 97.0% (228/235), 95.3% (282/296), 88.5% (54/61), 97.0% for PET/CT, and 98.4% (60/61), 95.7% (225/235), 96.3% (285/296), 85.7% (60/70) for PET/CT + BS,respectively. The specificity (χ2 = 19.862, P<0. 001), accuracy (χ2 = 23. 361, P<0.001) and PPV (χ2 =11. 791, P =0.001) of PET/CT + BS were significantly higher than those of BS, the sensitivity of PET/CT +BS was significantly higher than that of PET/CT (χ2 =4.167, P=0.031). Compared with BS, PET/CT had a higher specificity (χ2 = 19.600, P<0. 001), accuracy (χ2 = 13. 755, P <0. 001), PPV (χ2 = 13. 608, P <0. 001), but their sensitivity showed no statistically significant difference (χ2 = 0, P = 1. 000). Conclusions The efficacy of 18F-FDG PET/CT for detecting malignant bone metastasis was superior to that of 99Tcm-MDP BS alone. The detection ability can be obviously improved by combination of the two techniques.