PET/MR versus PET/CT for locoregional staging of oropharyngeal squamous cell cancer

Abstract

Background The value of fluorine-18-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) for TN staging in head and neck cancer (HNC) has been proven in numerous studies. A few studies have investigated the value of FDG-PET/magnetic resonance imaging (MRI) in the staging of HNC; the combined results indicate potential for FDG-PET/MRI, but the scientific evidence remains weak. Purpose To compare performance of FDG-PET/CT and FDG-PET/MRI for locoregional staging in patients with oropharyngeal carcinomas. Material and Methods Two radiologists independently of each other retrospectively reviewed primary pre-therapeutic FDG-PET/CT and FDG-PET/MRI examinations from 40 individuals with oropharyngeal carcinomas. TN stage and primary tumor size were noted. The results were compared between observers and modalities and against TN stage set at a multidisciplinary conference. Results For nodal staging, PET/MRI had slightly higher specificity and accuracy than PET/CT for the most experienced observer. Both methods demonstrated excellent sensitivity (≥ 0.97 and 1.00, respectively), as well as high negative predictive values (≥ 0.95 and 1.00, respectively). No significant differences were found for tumor staging or measurement of maximum tumor diameter. There was a weak agreement (κ = 0.35–0.49) between PET/CT and PET/MRI for T and N stages for both observers. Inter-observer agreement was higher for PET/MRI than for PET/CT, both for tumor staging (κ = 0.57 vs. 0.35) and nodal staging (κ = 0.69 vs. 0.55). The agreement between observers was comparable to the agreement between methods. Conclusion PET/MRI may be a viable alternative to PET/CT for locoregional staging (TN staging) and assessment of maximal tumor diameter in oropharyngeal squamous cell cancer.

Comparable Accuracy of Quantitative and Visual Analyses of [18F]FDG PET/CT for the Detection of Lymph Node Metastases from Head and Neck Squamous Cell Carcinoma

“…Some recent studies have demonstrated that PET/MR could improve the accuracy of the workup for evaluating the nodal involvement in HNSCC. By combining the advantages of MRI and [ 18 F]FDG PET, the sensitivity and specificity can be increased, detecting, respectively, more metastatic lymph nodes (small and cystic lymph nodes) with fewer false positives (reactive lymph nodes) [ 28 , 29 , 30 , 31 ].…”

PET/MR Imaging in Head and Neck Cancer

“…42 In a retrospective study including 36 patients with oropharyngeal SCC, Flygare and colleagues found no significant differences in T staging or in measurement of maximum tumor diameter between PET/DWIMR imaging and PET/CT; the standard of reference for the T stage was, however, not specified. 43 In the study of Flygare and colleagues, the interobserver agreement between two readers was higher for PET/DWIMR imaging than for PET/CT. However, there was only a weak agreement between PET/CT and PET/DWIMR imaging for the T stage.…”

“…However, there was only a weak agreement between PET/CT and PET/DWIMR imaging for the T stage. 43 In a prospective study including 113 patients with nasopharyngeal carcinoma, Chan and colleagues reported that PET/MR imaging was more accurate than MR imaging and PET/CT for the staging of nasopharyngeal cancer, however, the investigators did not report any P values for pairwise comparisons; for the assessment of deep submucosal tumor spread, MR imaging served as the standard of reference. 44 Kuhn and colleagues found slight advantages of PET/MR imaging over PET/CT for the local assessment of HNSCC, especially for invasion of adjacent structures and PNS; however, the standard of reference for deep tumor spread was not specified.…”

“…56 Among the studies using the N stage set at the multidisciplinary tumor board (MDTB) as standard of reference, Flygare and colleagues found that PET/MR imaging was more accurate than PET/ CT in 40 patients with oropharyngeal SCC. 43 In the series of Chan and colleagues (113 patients with nasopharyngeal cancer), the standard of reference consisted of the N stage set at the MDTB after having performed ultrasonographyguided fine needle aspiration cytology (US FNAC) or biopsy in cases with discordant imaging findings. 44 The investigators found that the sensitivity of PET/MR imaging (99.5%) was higher than that of PET/CT (91%) or MR imaging alone (94%); PET/MR imaging was particularly useful for distinguishing retropharyngeal nodal metastases from nasopharyngeal tumors.…”

Editorial: Reviews in radiation oncology

“…In addition, FDG-avid lesions potentially could be dose-escalated simultaneously, allowing greater dose delivery while minimizing dose to the surrounding critical structures such as the duodenum. PET/MRI imaging is also being evaluated in other such as prostate and head and neck for target delineation, initial staging, and treatment response assessment (3)(4)(5). We await to see whether PET/MRI could be incorporated into routine radiation oncology practice.…”