Prognostic Value of 18F-FDG PET-CT in Nasopharyngeal Carcinoma: Is Dynamic Scanning Helpful?

Objectives. To evaluate the differences in prognostic values of static and dynamic PET-CT in nasopharyngeal carcinoma (NPC). Material and Methods. Forty-five patients who had static scan were recruited. Sixteen had dynamic scan. The primary lesions were delineated from standardized uptake value (SUV) maps from static scan and K-i maps from dynamic scan. The average follow-up lasted for 34 months. The patients who died or those with recurrence/residual disease were considered "poor outcome"; otherwise they were considered "good outcome." Fisher's exact test and ROC analysis were used to evaluate the prognostic value of various factors. Results. Tumor volume thresholded by 40% of maximal SUV (VOLSUV40) significantly predicted treatment outcome (P = 0.024) in the whole cohort. In 16 patients with dynamic scan, all parameters by dynamic scan were insignificant in predicting the outcome. The combination of maximal SUV, maximal K-i, VOLSUV40, and VOLKi37 (the tumor volume thresholded by 37% maximal K-i) achieved the highest predicting accuracy for treatment outcome with sensitivity, specificity, and accuracy of 100% in these 16 patients; however this improvement compared to VOLSUV40 was insignificant. Conclusion. Tumor volume from static scan is useful in NPC prognosis. However, the role of dynamic scanning was not justified in this small cohort.