Sinonasal small cell carcinoma of the left ethmoidal sinus (arrows) imaged by fluorine-18 fluorodeoxyglucose positron emission tomography (¹⁸F-FDG PET) in sagittal (a) and axial projection (b), magnetic resonance imaging (MRI) in axial projection (c), and fused PET/MRI (d). This tumor was well-characterized by MRI which showed invasion of the adjacent structures. PET demonstrated increased glucose metabolism of this tumor without metastatic spread

Metastatic laryngeal small cell carcinoma imaged by fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT). ¹⁸F-FDG PET (a) showed an area of increased tracer uptake corresponding to a laryngeal tumor (red arrow) at CT (c1) and fused PET/CT images in sagittal (b) and axial projection (c2). Furthermore several right cervical lymph nodal metastases (yellow arrows) were detected by PET (a), CT (c1, d1), and fused PET/CT images (c2, d2). Interestingly, ¹⁸F-FDG PET detected bone metastases (green arrows) without significant morphological abnormalities at co-registered CT (e1, e2)