FDG-PET/CT in cancers of the head and neck: What is the definition of whole body scanning?

Abstract

Purpose: The role of 2-deoxy-2-[F-18]fluoro-D-glucose-positron emission tomography (FDG-PET) was studied in a variety of cancers, including head and neck squamous cell carcinomas (HNSCC) and nasopharyngeal carcinomas (NPC), with several presentations indicating that for these clinical entities a "whole-body" (i.e., eyes to thighs) may yield little additional information. Therefore, we were prompted to review our experience with PET/computed tomography (CT) in the management of patients with HNSCC and NPC. Materials and Methods: This is a retrospective study of 133 patients with HNSCC, 23-90 years old (average: 58.2(plus or minus)12.7) and 26 patients with NPC, ages 16-75 (average: 47.3(plus or minus)17.1), who had whole body PET/CT at our institution from Jan 2003 to Nov 2006. Reinterpretation of the imaging studies for accuracy and data analysis from medical records was performed. Lesions identified on PET/CT below the level of the adrenal glands were recorded and tabulated. Results: Lesions were identified below the adrenal glands in seven patients (5.2%) with HNSCC. These included hepatic and osseous metastases from HNSCC in two patients (1.5%), a new renal cancer (0.75%), a new pancreatic cancer (0.75%), a new colon cancer (0.75%) and findings proven benign on follow-up (focal colon uptake in one patient and an inflammatory inguinal lymph node in another patient; 1.5%). Lesions were identified below the adrenal glands in three patients (11.5%) with NPC. These included osseous metastases from NPC in two patients (7.7%) and findings proven benign on follow-up (focal colon uptake in one patient; 3.84%). Conclusion: This study suggests that whole body PET/CT imaging in HNSCC has a relatively low yield (3%, 95% CI: 1.33-8.42) of significant findings below the level of the adrenal glands. Therefore, implementing a more limited protocol (through the level of adrenal glands), especially in low-risk cases of HNSCC, may be considered. However, whole body PET/CT imaging in NPC may have a significant yield (7.7%, 95% CI: 1.02-25.26) of medically relevant findings below the level of the adrenal glands. Thus, the whole body (i.e., vertex to thighs) PET/CT scan of NPC patients appears to be the appropriate imaging protocol for this population. This recommendation requires further evaluation and validation in larger prospective studies. (copyright) Academy of Molecular Imaging and Society for Molecular Imaging, 2010.