Diagnostic Value of Dynamic ¹⁸F-Fluorodeoxyglucose Positron Emission Tomography-Computed Tomography (¹⁸F-FDG PET-CT) in Cervical Lymph Node Metastasis of Nasopharyngeal Cancer

• Published in: Diagnostics
• Main Authors: Guanglie Li, Shuai Yang, Siyang Wang, Renwei Jiang, Xiwei Xu
• Format: Article
• Language: English
• Published: MDPI AG 2023-07-01
• Subjects: dynamic PET-CT; SUV-max; K_i-mean; K_i-max; nasopharyngeal cancer; cervical lymph nodes
• Online Access: https://www.mdpi.com/2075-4418/13/15/2530

Background and purpose: Dynamic ¹⁸F-FDG PET-CT scanning can accurately quantify ¹⁸F-FDG uptake and has been successfully applied in diagnosing and evaluating therapeutic effects in various malignant tumors. There is no conclusion as to whether it can accurately distinguish benign and malignant lymph nodes in nasopharyngeal cancer. The main purpose of this study is to reveal the diagnostic value of dynamic PET-CT in cervical lymph node metastasis of nasopharyngeal cancer through analysis. Method: We first searched for cervical lymph nodes interested in static PET-CT, measured their SUV-Max values, and found the corresponding lymph nodes in magnetic resonance images before and after treatment. The valid or invalid groups were included according to the changes in lymph node size before and after treatment. If the change in the product of the maximum diameter and maximum vertical transverse diameter of the lymph node before and after treatment was greater than or equal to 50%, they would be included in the valid group. If the change was less than 50%, they would be included in the invalid group. Their K_i values were measured on dynamic PET-CT and compared under different conditions. Then, we conducted a correlation analysis between various factors and K_i values. Finally, diagnostic tests were conducted to compare the sensitivity and specificity of K_i and SUV-Max. Result: We included 67 cervical lymph nodes from different regions of 51 nasopharyngeal cancer patients and divided them into valid and invalid groups based on changes before treatment. The valid group included 50 lymph nodes, while the invalid group included 17. There wer significant differences (<i>p</i> < 0.001) between the valid and the invalid groups in SUV-Max, K_i-Mean, and K_i-Max values. When the SUV-Max was ≤4.5, there was no significant difference in the K_i-Mean and K_i-Max between the two groups (<i>p</i> > 0.05). When the SUV-Max was ≤4.5 and pre-treatment lymph nodes were <1.0 cm, the valid group had significantly higher K_i-Mean (0.00910) and K_i-Maximum (0.01004) values than the invalid group (K_i-Mean = 0.00716, K_i-Max = 0.00767) (<i>p</i> < 0.05). When the SUV-Max was ≤4.5, the pre-treatment lymph nodes < 1.0 cm, and the EBV DNA replication normal, K_i-Mean (0.01060) and K_i-Max (0.01149) in the valid group were still significantly higher than the invalid group (K_i-Mean = 0.00670, K_i-Max = 0.00719) (<i>p</i> < 0.05). The correlation analysis between different factors (SUV-Max, T-stage, normal EB virus DNA replication, age, and pre-treatment lymph node < 1.0 cm) and the K_i value showed that SUV-Max and a pre-treatment lymph node < 1.0 cm were related to K_i-Mean and K_i-Max. Diagnostic testing was conducted; the AUC value of the SUV-Max value was 0.8259 (95% confidence interval: 0.7296–0.9222), the AUC value of the K_i-Mean was 0.8759 (95% confidence interval: 0.7950–0.9567), and the AUC value of the K_i-Max was 0.8859 (95% confidence interval: 0.8089–0.9629). After comparison, it was found that there was no significant difference in AUC values between K_i-Mean and SUV-Max (<i>p</i> = 0.220 > 0.05), and there was also no significant difference in AUC values between K_i max and SUV-Max (<i>p</i> = 0.159 > 0.05). By calculating the Youden index, we identified the optimal cut-off value. It was found that the sensitivity of SUV-Max was 100% and the specificity was 66%, the sensitivity of K_i-Mean was 100% and the specificity was 70%, and the sensitivity of K_i-Max was 100% and the specificity was 72%. After Chi-Square analysis, it was found that there was no significant difference in specificity between K_i-Mean and SUV-Max (<i>p</i> = 0.712), and there was also no significant difference in specificity between K_i-Max and SUV-Max (<i>p</i> = 0.755). Conclusion: Dynamic PET-CT has shown a significant diagnostic value in diagnosing cervical lymph node metastasis of nasopharyngeal cancer, especially for the small SUV value, and lymph nodes do not meet the metastasis criteria before treatment, and EBV DNA replication is normal. Although the diagnostic accuracy, sensitivity, and specificity of dynamic PET-CT were not significantly different from traditional static PET-CT, the dynamic PET-CT had a more accurate tendency.