Variety and complexity of fluorine-18-labelled fluoro-2-deoxy-d-glucose accumulations in the oral cavity of patients with oral cancers

Abstract

Objectives: To elucidate the points that require attention when interpreting fluorine-18-labelled fluoro-2-deoxy-D-glucose ( 18 F-FDG)/positron emission tomography (PET) images by demonstration of 18 F-FDG accumulation in various areas of the oral cavity other than primary lesions in patients with oral cancers. Methods:18 F-FDG accumulations with a maximal standardized uptake value of over 2.5 in various areas of the oral cavity other than primary lesions were identified in 82 patients with oral cancers. Results:18 F-FDG/PET-positive areas, excluding primary tumours, included the front intrinsic muscles of the tongue (89.0%), upper and lower marginal parts of the orbicularis oris muscle (64.6%), sublingual glands, palatine tonsil, pharyngeal tonsil, and lingual tonsil. In addition, some areas in the jaws also showed accumulation. Conclusions: In patients with oral cancers, areas of 18 F-FDG accumulation in the oral cavity should be precisely identified and appropriately diagnosed, because accumulations can be seen in areas other than the primary tumour.

Alterations in 18F-FDG accumulation into neck-related muscles after neck dissection for patients with oral cancers

“…Moreover, SUVmax values of 18F-FDG-PET-positive areas of the trapezius, sternocleidomastoid, and posterior neck muscles after surgery were relatively low, but ranged from 1.5 to 4.04. In previous studies, as well as in the present study (1.50 to 49.70), the SUVmax of carcinomas in the oral cavity ranged from 1.38 to 15.9; there is some overlap in the SUVmax caused by dental inflammation and that caused by carcinomas ( 7 , 13 - 16 ). It is important to perform an appropriate differential diagnosis between normal variations after surgery and malignant tumors on CT and/or MRI, in addition to paying attention to alterations in the distribution of 18F-FDG accumulations.…”

Changes in the distributions of fluorine-18-labelled fluoro-2-deoxy-d-glucose accumulation into tongue-related muscles after dissection in patients with tongue cancer

“…Before surgery, 18 F-FDG-PE-positive areas could be visualized in the anterior area of the tongue of most patients (about 80%), as in our previous study. 6 At the same time, when the anterior area of the tongue remained after all four kinds of surgeries, 18 F-FDG-PETpositive areas remained in the anterior area of the tongue. However, according to the increasing extent of excision of the tongue by HMGS and STGS, 18 F-FDG-PETpositive areas that were detected at the back of the intrinsic muscles of the tongue remained after surgery despite the absence of abnormal findings on CT and MRI.…”

“…A value of 2.5 was selected as the cut-off SUVmax, because the extent of 18 F-FDG accumulation into malignant tumours was commonly .2.5. [6][7][8] In the respective areas, the precise SUVmax of 18 F-FDG was measured on PET-CT images.…”

PET/CT findings within the contralateral tonsil following unilateral tonsillectomy

“…Intense physiological FDG uptake within the palatine tonsil is a well‐known phenomenon established from studies investigating oral cavity and other head and neck malignancies, in addition to nonhead and neck cancers . Symmetrical FDG uptake within the Waldeyer's ring is one of the main methods for distinguishing benign and suspicious malignant tumors; therefore, unilateral tonsillectomy may potentially diminish the accuracy of PET/CT in ongoing surveillance of these patients.…”

“…This is becoming increasingly important considering the rising incidence of SCC of the tonsil and other oropharyngeal subsites, which may be related to the recognized association with human papillomavirus infection over and above traditional risk factors such as alcohol abuse and smoking. 8 Intense physiological FDG uptake within the palatine tonsil is a well-known phenomenon established from studies investigating oral cavity 9 and other head and neck malignancies, 10 in addition to nonhead and neck cancers. 11 Symmetrical FDG uptake within the Waldeyer's ring is one of the main methods for distinguishing benign and suspicious malignant tumors 3 ; therefore, unilateral tonsillectomy may potentially diminish the accuracy of PET/CT in ongoing surveillance of these patients.…”