FDG-PET/CT Skull Base to Mid-Thigh FDG-PET/CT allows for the detection and localization of primary tumor site, identification of regional nodal disease, and distant metastases. FDG-PET/CT is recommended by the National Comprehensive Cancer Network for stage III and IV cancer [42]. FDG-PET/CT alone is not considered sufficient for initial staging because it may not provide detailed anatomic delineation of the primary site or detection of upstaging features needed for correct staging [43,44]. FDG-PET/CT will typically be used in conjunction with CECT or MRI of the neck. One advantage of FDG-PET/CT is that the whole body can be imaged, and FDG-PET is more sensitive in the detection of distant metastasis and synchronous tumors over radiography, CT, and MRI [10,42,45]. Although FDG-PET/CT is sensitive (72%-96%), there are some variations in the reported specificity rate for cervical nodal metastases [36,45-48], likely due to reactive lymph nodes resulting in false-positive findings on PET. Assessment of Head and Neck Cancer The utility of FDG-PET in lower-stage cancer is more controversial. There are conflicting results when evaluating the ability of FDG-PET/CT to accurately detect occult nodal disease in clinical node-negative cancer. A range of sensitivities and specificities and contradictory results when compared to CECT and MRI are reported, either performing similar to or outperforming these modalities [35-39]. This controversy led to the American College of Radiology Imaging Network 6685 multicenter trial, which conclusively demonstrated that FDG-PET/CT confers a high negative predictive value (NPV) of 87% (visual analysis) and 94% (standardized uptake value max analysis) for lymph node metastasis in N0 cancer, with moderate to substantial reader agreement and 99% for distant metastatic disease [37,42,49]. In addition, it changed surgical management in the 20% of the study population.
Staging and Post Therapy Assessment of Head and Neck Cancer. FDG-PET/CT Skull Base to Mid-Thigh FDG-PET/CT allows for the detection and localization of primary tumor site, identification of regional nodal disease, and distant metastases. FDG-PET/CT is recommended by the National Comprehensive Cancer Network for stage III and IV cancer [42]. FDG-PET/CT alone is not considered sufficient for initial staging because it may not provide detailed anatomic delineation of the primary site or detection of upstaging features needed for correct staging [43,44]. FDG-PET/CT will typically be used in conjunction with CECT or MRI of the neck. One advantage of FDG-PET/CT is that the whole body can be imaged, and FDG-PET is more sensitive in the detection of distant metastasis and synchronous tumors over radiography, CT, and MRI [10,42,45]. Although FDG-PET/CT is sensitive (72%-96%), there are some variations in the reported specificity rate for cervical nodal metastases [36,45-48], likely due to reactive lymph nodes resulting in false-positive findings on PET. Assessment of Head and Neck Cancer The utility of FDG-PET in lower-stage cancer is more controversial. There are conflicting results when evaluating the ability of FDG-PET/CT to accurately detect occult nodal disease in clinical node-negative cancer. A range of sensitivities and specificities and contradictory results when compared to CECT and MRI are reported, either performing similar to or outperforming these modalities [35-39]. This controversy led to the American College of Radiology Imaging Network 6685 multicenter trial, which conclusively demonstrated that FDG-PET/CT confers a high negative predictive value (NPV) of 87% (visual analysis) and 94% (standardized uptake value max analysis) for lymph node metastasis in N0 cancer, with moderate to substantial reader agreement and 99% for distant metastatic disease [37,42,49]. In addition, it changed surgical management in the 20% of the study population.