Positron emission tomography combined with computed tomography (PET/CT) enables assessment of not only anatomical and structural but also metabolic changes in tumor mass. F-fluoroethyl tyrosine (F-FET) PET/CT is based on evaluation of transport of F-labeled tyrosine in tissues. We present a clinical case of a patient with a newly diagnosed brain tumor, demonstrating the capabilities ofF-FET PET/CT in assessing the reliable volume and degree of tumor anaplasia, which is important when choosing the treatment approach for a patient.

Clinical case of the patient with nasopharyngeal carcinomaafter stereotactic radiosurgical treatment for the persistent disease after chemoradiotherapyare presented. The diagnostic data of PET/CTwith  18F-Fluoroethyl-Ltyrosine (18F-FET)and MRI with intravenous contrastof head and neck were included in analysis. There was  analyzeda clinical case of differential diagnosis of changes in thetemporal lobe of the brain after stereotactic radiation therapy of  nasopharyngeal carcinoma using PET/CT with 18F-FET. Identified high  diagnostic accuracy in the differential diagnosis of delayed changes in  the brain (tumor or radiation necrosis) after radiation therapy  ofnasopharyngeal carcinoma.