[18F]Fluorodeoxyglucose-PET/CT differentiation between physiological and pathological accumulations in head and neck.
OBJECTIVE
The purposes of this study were to evaluate various physiological fluorodeoxyglucose (FDG) accumulations in the head and neck and to compare those with tumor (pathological) FDG accumulation.


METHODS
One hundred and twelve patients with head and neck carcinomas were studied. PET/computed tomography examinations were performed 1 h after intravenous injection of fluorine-18-labeled FDG. The tumor and the physiological FDG accumulations were identified with PET/computed tomography images, and the maximum of the standardized uptake value (SUVmax) was calculated.


RESULTS
Physiological FDG accumulation was observed in tonsil, extraocular muscle, masticatory muscle, vocal cord, and the major salivary glands: parotid, submandibular, and sublingual gland. The accumulation in tonsil, extraocular muscle, and sublingual gland showed relatively high SUVmax. The tumor FDG accumulation was significantly higher than any physiological FDG accumulation. The optimal cut-off values of SUVmax for differentiating physiological FDG accumulation from pathological FDG accumulation were 4.0 for parotid gland, 4.5 for submandibular gland, 5.5 for sublingual gland, 8.0 for tonsil, and 10.0 for extraocular muscle. The right-to-left ratio of SUVmax was less than 1.5 in any physiological accumulation.


CONCLUSIONS
Tonsil, extraocular muscle, and sublingual gland showed relatively high FDG accumulation, which was sometimes similar to tumor accumulation. The right-to-left ratio of SUVmax was considered useful in differentiating tumor from physiological accumulation, and the presence of tumor might be highly suspected in cases with a ratio of 1.5 or more.
Department of Oral and Maxillofacial Radiology, Tokyo Medical and Dental University, Tokyo, Japan. shin.orad@tmd.ac.jp
Shin
S
Nakamura
Kiyoshi
K
Okochi
Yuji
Y
Murata
Hitoshi
H
Shibuya
Tohru
T
Kurabayashi
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000378:metabolism*; D006257:Head / Q000502:physiology*; D006258:Head and Neck Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009333:Neck / Q000502:physiology*; D049268:Positron-Emission Tomography; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed
D019788:Fluorodeoxyglucose F18