Assessment of a new 18F-FDG PET/CT protocol in the staging of oral cavity carcinomas.

Unlabelled: Because image fusion using (18)F-FDG PET/CT allows a better localization of the pathologic uptake, this modality has a greater sensitivity than PET alone in examining the head-neck region. However, examination of this area is particularly critical because the head and neck are close to other anatomic structures and because of the high physiologic uptake of the radiocompound. The purpose of this study was to evaluate the utility of a new imaging protocol in the staging of oral carcinoma.

Methods: Thirty-four consecutive patients (21 women and 13 men; age range, 20-84 y) with untreated biopsy-proven oral squamous cell carcinomas were examined using whole-body (18)F-FDG PET/CT fusion imaging. All patients observed strict regulations before undergoing the PET/CT examination. At the end of the whole-body acquisition, another open-mouth scan was obtained. To compare the open- and closed-mouth methods, we analyzed features such as the feasibility of an accurate topographic localization of the tumor, evaluation of tumor extent, detection of tumor involvement with adjacent structures, and involvement of lymph nodes to which we assigned a score from 1 to 5.

Results: No cases of (18)F-FDG physiologic uptake in the tongue or muscles were observed. The open-mouth scan obtained a better score than did the closed-mouth scan when considering the tumor localization, tumor extent, and evaluation of adjacent anatomic structures near the clinically evident tumor. For lymph node involvement, the 2 methods showed similar results.

Conclusion: The open-mouth scan improved the anatomic tumor localization and extent and detection of tumor involvement in adjacent anatomic structures achieved by the standard PET/CT procedure. In addition, time of the examination (mid morning), relaxation of muscles before the compound was administered, and an upright position while the patient waited caused a reduction of the frequent equivocal physiologic uptake in the head and neck region. The open-mouth method does not influence the nodal staging.