Comparison of fluorine-18-fluorodeoxyglucose PET, MRI and endoscopy for staging head and neck squamous-cell carcinomas.

Unlabelled: Accurate, preoperative assessment of tumor extent and lymph node involvement is mandatory for individualized therapy in patients with squamous-cell carcinomas (SCCs) of the head and neck region. Metabolic imaging, [18F]fluorodeoxyglucose (FDG) PET and MRI were compared with postoperative, histologic tissue characterization.

Methods: Dynamic and static PET with 370 MBq [18F]FDG up to 60 min postinjection and MRI were compared prospectively in 22 patients with head and neck SCCs. PET results with and without attenuation correction were compared with postoperative T and N stages based on pathologic findings.

Results: Kinetic characteristics and tracer uptake intensity were similar in primary tumors and lymph node metastases. In both, FDG uptake did not reach a plateau phase 60 min postinjection. There was no statistically significant correlation of FDG uptake with plasma glucose level or histologic grading. All primary tumors were clearly demonstrated by PET, which tended to overestimate tumor size. The sensitivity and specificity for detecting individual lymph node involvement were 90% and 96%, respectively, for PET and, thus, significantly higher for MRI (78% and 71%, respectively; p < 0.05). N stages were correctly identified by MRI in only 4 patients; PET correctly staged lymph nodes in 15 of 17 patients. Based on "neck sides", the sensitivity and specificity were higher for PET, 89% and 100%, respectively, compared with MRI values of 72% and 56%, respectively.

Conclusion: FDG-PET may be helpful in detecting occult primary tumors with positive lymph nodes.