FDG-PET/CT of Head and Neck Squamous Cell Carcinoma in a Rat Model

Purpose: The aim of this study was to demonstrate the ability to use human clinical positron emission tomography/computed tomography (PET/CT) to detect and investigate head and neck cancers chemically induced by 4-nitroquinoline-1-oxide (4-NQO) in a rat model. Study design: The study design was prospective animal research. Procedures: A head and neck squamous cell carcinoma was established in 20 immunocompetent rats, who drank a 4-NQO solution during 16 weeks. 2-Deoxy-2-[F-18] fluoro-D-glucose (FDG)-PET/CT was performed for five of them, 34 weeks after the start of the experiment to characterize the tumors. A day following the FDG-PET/CT, rats were euthanized and pathological features were evaluated by hematoxylin-eosin staining. Results: All rats had head and neck tumor at various locations at 34 weeks. Among the five rats selected for having FDG-PET/CT, the clinical examination detected exophytic tumors grown in the oral cavity for three of them (one on the inferior lip, one on the hard palate, and one on the internal side of the cheek). FDG-PET/CT confirmed the presence of those tumors and detected ones located on the base of tongue for three of them. Tumor extensions were characterized and tumor metabolic volumes were measured. The smallest lesion detected measured 3 x 3 x 4 mm. Pathologic examination using hematoxylin-eosin staining confirmed squamous cell carcinoma. Conclusions: This study demonstrated that FDG-PET/CT is a feasible examination to detect occult primary tumors in rat models. It is useful to follow tumor progression and evaluate therapeutics efficacy.