Fig. 17
From: FDG-PET/CT pitfalls in oncological head and neck imaging
a Axial PET/CT image reveals a FDG-avid mass in the nasopharynx in keeping with a known nasopharyngeal carcinoma (asterisk). No separate retropharyngeal adenopathy is seen on this image. b Corresponding axial CECT image shows the infiltrative nasopharyngeal carcinoma (asterisk). No definite retropharyngeal adenopathy is seen. c Corresponding axial T2W MR image demonstrates the infiltrative nasopharyngeal carcinoma (asterisk) and an enlarged left retropharyngeal node (white arrow) suspicious for nodal metastasis. This node was missed on PET/CT due to its close proximity to the FDG-avid primary tumour and on CECT due to poor soft tissue contrast as compared to MRI. Detection of retropharyngeal lymph nodes in nasopharyngeal cancer affects TNM classification