Tumor Volume in Pharyngolaryngeal Squamous Cell Carcinoma: Comparison at CT, MR Imaging, and FDG PET and Validation with Surgical Specimen

Twenty-nine patients with stages II-IV squamous cell carcinoma treated with radiation therapy or chemotherapy and radiation therapy (n = 20) or with total laryngectomy (n = 9) were enrolled. Ten patients had oropharyngeal, 13 had laryngeal, and six had hypopharyngeal tumors. CT, MR imaging, and PET were performed with patients immobilized in a customized thermoplastic mask, and images were coregistered. GTVs obtained with the three modalities were compared quantitatively and qualitatively. If patients underwent total laryngectomy, images were validated with the surgical specimen after three-dimensional coregistration. The effect of each modality was estimated with linear mixed-effects models. Adjustments for multiple comparisons were made with the Bonferonni or Sidak method.

For oropharyngeal tumors and for laryngeal or hypopharyngeal tumors, no significant difference (P >.99) was observed between average GTVs delineated at CT (32.0 and 21.4 cm(3), respectively) or MR imaging (27.9 and 21.4 cm(3), respectively), whereas average GTVs at PET were smaller (20.3 [P