Fig. 4
From: FDG-PET/CT pitfalls in oncological head and neck imaging
a Axial PET/CT image demonstrates asymmetrical FDG uptake of the tonsillar fossae (arrowhead) and parotid glands (increased uptake on the left, arrow) in a patient previously irradiated for SCC of the right base of the tongue with sparing of the left side. Note increased FDG uptake of the non-irradiated left parotid gland (arrow) and fatty infiltration of the irradiated right parotid gland (asterisk). b Corresponding axial contrast-enhanced T1-weighted image shows no pathological findings in the left tonsillar fossa (arrowhead) and left parotid gland (arrow). Note atrophy and fatty infiltration of the right parotid gland (asterisk). c Corresponding b1,000 DW MR image reveals physiological hyperintensity in the tonsillar fossae more pronounced on left (arrowhead) compared with the right (arrow) due to normal lymphoid tissue on the left and atrophy of lymphoid tissue on the right. d Corresponding ADC map showing physiologically low ADC values on the left (arrowhead) due to normal lymphoid tissue. Dashed arrows point at radiation port on the right