Fig. 16
From: FDG-PET/CT pitfalls in oncological head and neck imaging
a Axial PET/CT image shows asymmetric uptake in the nasopharynx (arrowhead) and expected high uptake in the explored hindbrain. A lytic lesion in the clivus with well-defined sclerotic borders and without FDG uptake is also detected (arrow). The remaining of the total body PET/CT was normal. b Corresponding axial contrast-enhanced T1weighted MR image obtained in the same patient illustrates an infiltrative, poorly delineated tumour invading the clivus, the right jugular fossa, the right petrous apex and the brainstem (arrows), not revealed by PET/CT. Subsequent biopsy of the clivus, intracranially and of the nasopharynx showed a primary adenocarcinoma of the skull base. The increased FDG uptake in the left nasopharynx corresponds to tumour invasion of the longus colli muscle. Due to intratumoral areas with variable FDG avidity and due to tumor vicinity to the highly metabolic brain parenchyma, this lesion is less well depicted by PET/CT than MRI