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.
ABSTRACT
<p><b>OBJECTIVE</b>To study the pattern of blood-brain barrier (BBB) permeability changes during whole brain radiotherapy (WBRT) for metastatic brain tumor.</p><p><b>METHODS</b>Twenty patients with metastatic brain tumors receiving WBRT by 6 MV X-ray underwent (99)mTc-DTPA brain SPECT before and during WBRT (20, 40 Gy) and at 2 weeks after the end of irradiation. A frame of transverse (99)mTc-DTPA brain SPECT image that best displayed the brain metastasis was chosen, and the regions of interest (ROI) were defined in the tumor foci (T), the contralateral normal brain tissue (N) and the background outside the soft tissues around the cranium (B). The radioactive counts of every ROI were measured and the ratios of the total counts (T/B and N/B) before and during WBRT (20 Gy, 40 Gy) and at 2 weeks after the irradiation were calculated.</p><p><b>RESULTS</b>The average T/B and N/B in the 20 patients with 30 brain metastases was 142.2-/+51.1 and 82.6-/+42.3 before WBRT, 260.3-/+121.5 and 150.7-/+72.5 during 20 Gy WBRT, 251.6-/+118.3 and 161.8-/+68.4 during 40 Gy WBRT, and 250.3-/+117.2 and 158.6-/+73.5 at 2 weeks after the irradiation, respectively. The measurements during WBRT (20 and 40 Gy) and at 2 weeks after the irradiation group underwent no significant variations (P>0.05), but showed significant differences from those before WBRT (P<0.05).</p><p><b>CONCLUSIONS</b>Irradiation causes direct damage of the BBB function, and the permeability of the BBB increases significantly during and within 2 weeks following 20 and 40 Gy WBRT, which provides the optimal time window for interventions with chemotherapy.</p>
Subject(s)
Adult , Aged , Female , Humans , Male , Middle Aged , Blood-Brain Barrier , Diagnostic Imaging , Brain Neoplasms , Diagnostic Imaging , Radiotherapy , Capillary Permeability , Physiology , Cranial Irradiation , Sodium Pertechnetate Tc 99m , Tomography, Emission-Computed, Single-PhotonABSTRACT
<p><b>BACKGROUND AND OBJECTIVE</b>Monitoring the therapeutic effects of radiotherapy for nasopharyngeal carcinoma (NPC) is critical to providing individualized treatment. This in-vivo study was initially designed to evaluate the therapeutic effect of radiotherapy using 18F-fluorodeoxyglucose positron emission tomography with computed tomography (18F-FDG PET-CT) imaging.</p><p><b>METHODS</b>18F-FDG PET-CT imaging was performed on all of the 10 nude mice bearing NPC xenografts before radiotherapy, and early-phase and delayed-phase PET-CT images were performed on 7 of the 10 mice. All mice were randomly divided into either a control group or a radiotherapy group. The 5 mice in the control group were immediately killed after the imaging and pathology were performed. After receiving radiotherapy of 12 Gy, 5 animals in the radiotherapy group were given 18F-FDG PET-CT imaging on days 2, 4, and 6, and then were killed for pathologic evaluation. Regions of interest (ROI) technology was used to measure the tumor target/non-target (T/NT) ratio and the volume of the tumors.</p><p><b>RESULTS</b>The average T/NT ratios of early- and delayed-phase imaging were 1.806 +/- 0.532 and 1.777 +/- 0.597, respectively, with no significance (P > 0.05). For the radiotherapy group, the average T/NT ratios for 18F-FDG PET-CT before radiotherapy, and on days 2, 4, and 6 after radiotherapy, were 1.735 +/- 0.466, 1.818 +/- 0.396, 1.096 +/- 0.101, and 0.604 +/- 0.108, respectively, The tumor volumes were (1.48 +/- 0.27) cm3, (1.57 +/- 0.31) cm3, (1.59 +/- 0.31) cm3 and (1.60 +/- 0.29) cm3, respectively. The average T/NT ratios of day 6 after radiotherapy and the other time points were significant (P < 0.05). The average death ratio of the tumor cells was (93.00 +/- 7.42)% after 6 days of post-radiotherapy.</p><p><b>CONCLUSIONS</b>18F-FDG PET-CT imaging can be used for the early assessment of radiotherapeutic effect of NPC in vivo. Day 6 after radiotherapy may be an appropriate time point for the imaging. However, the T/NT ratio measurement of delayed-phase imaging might make no sense for the diagnosis of NPC.</p>