1. Department of Nuclear Medicine, Ditmanson Medical Foundation Chia-Yi Christian Hospital, Chia-Yi, Taiwan.
2. Institute of Statistical Science, Academia Sinica, Taipei, Taiwan.
3. Division of Nuclear Medicine, Department of Medical Imaging, Chi Mei Medical Center, Liouying, Tainan, Taiwan.
4. Department of Medical Imaging Chi Mei Medical Center, Liouying, Tainan, Taiwan.
5. Department of Biomedical Engineering, National Cheng Kung University, Tainan, Taiwan.
6. Department of Radiation Oncology, Ditmanson Medical Foundation Chia-Yi Christian Hospital, Chia-Yi, Taiwan.
7. Department of Radiation Oncology, Chi Mei Medical Center, Liouying, Tainan, Taiwan.
Purpose: A multistage approach to diagnose lateral retropharyngeal nodes (LRPNs) of nasopharyngeal carcinoma (NPC) had been proposed and warranted for validation.
Methods: Between 2012 and 2017, the patients with newly diagnosed NPC were enrolled. The responsive nodes or those that progressed during follow-up were positive. The criteria for the multistage approach delimited LRPNs with a minimal axial diameter (MIAD) ≥ 6.1 mm were assessed as positive and if the mean standard uptake value ≥ 2.6, or if the maximal coronal diameter ≥ 25 mm and maximal axial diameter ≥ 8 mm with nodes MIAD < 6.1 mm were also considered as positive. The outcomes were compared with the MIAD cutoff value ≥ 6 mm (traditional method). A chi-squared test was used to compare two areas under the curve of the receiver operating characteristic curves.
Results: A total of 67 eligible NPC cases and 155 LRPNs (72 positive and 83 negative) were analyzed. The accuracy, specificity, and sensitivity of the traditional method were 0.91, 0.93, and 0.89, respectively. The values for the multistage approach all reached 0.94. The area under the curve was significantly greater for the multistage approach compared with the traditional method (p = 0.023).
Conclusion: The results support the advantage of the multistage approach.
Keywords: diagnosis, nasopharyngeal carcinoma, retropharyngeal nodes, radiotherapy