FDG PET/MR for lymph node staging in head and neck cancer

Objective
To assess the diagnostic value of PET/MR (positron emission tomography/magnetic resonance imaging) with FDG (18F-fluorodeoxyglucose) for lymph node staging in head and neck cancer.

Materials and Methods
This prospective study was approved by the local ethics committee; all patients signed informed consent. Thirty-eight patients with squamous cell carcinoma of the head and neck region underwent a PET scan on a conventional scanner and a subsequent PET/MR on a whole-body hybrid system after a single intravenous injection of FDG. The accuracy of PET, MR and PET/MR for lymph node metastases were compared using receiver operating characteristic (ROC) analysis. Histology served as the reference standard.

Results
Metastatic disease was confirmed in 16 (42.1%) of 38 patients and 38 (9.7%) of 391 dissected lymph node levels. There were no significant differences between PET/MR, MR and PET and MR (p > 0.05) regarding accuracy for cervical metastatic disease. Based on lymph node levels, sensitivity and specificity for metastatic involvement were 65.8% and 97.2% for MR, 86.8% and 97.0% for PET and 89.5% and 95.2% for PET/MR.

Conclusions
In head and neck cancer, FDG PET/MR does not significantly improve accuracy for cervical lymph node metastases in comparison to MR or PET.