Use of single MRI and 18F-FDG PET-CT scans in both diagnosis and radiotherapy treatment planning in patients with head and neck cancer: Advantage on target volume and critical organ delineation

Background The use of a single MRI and 18F‐fluoro deoxyglucose positron emission tomography‐CT (18F‐FDG PET‐CT) was evaluated, both in diagnostic procedure and radiotherapy planning, in patients with head and neck cancer. Methods Thirty‐five patients with nasopharyngeal and oropharyngeal tumors were studied. The MRI and 18F‐FDG PET‐CT were used for both diagnostic work‐up and gross tumor volume and critical structure delineation. The interobserver variation (IOV) of volumes determined on MRI and CT by a radiotherapist and by a radiologist were compared as well as their impact on dose distribution. Results The CT‐MRI decreased the IOV of parotid glands in 12 of 35 and target volume in 15 of 35 patients. The use of 18F‐FDG PET‐CT changed the treatment design in 6 of 21 patients. Conclusions Diagnostic imaging performed in the treatment position can improve the accuracy of radiotherapy planning in case of intracranial tumor extension, heavy dental work, or contraindication for contrast‐enhanced CT, but not in the absence of these conditions. © 2008 Wiley Periodicals, Inc. Head Neck, 2009