Fluorodeoxyglucose–Positron-Emission Tomography Imaging of Head and Neck Squamous Cell Cancer

Abstract

SUMMARY:The hybrid technique of PET/CT has significantly impacted the imaging and management of HNSCC since its introduction in 2001 and has become the technique of choice for imaging of this cancer. Diagnostic FDG-PET/CT is useful for identification of an unknown primary tumor, delineation of extent of primary tumor, detection of regional lymph node involvement even in a normal-sized node, detection of distant metastases and occasional synchronous primary tumor, assessment of therapy response, and long-term surveillance for recurrence and metastases. The role of PET/CT is evolving in radiation therapy planning. Combined diagnostic PET/CT provides the best anatomic and metabolic in vivo information for the comprehensive management of HNSCC.ABBREVIATIONS: CR ϭ complete response; DCT ϭ contrast enhanced diagnostic CT;18 F ϭ fluorine-18; FDG ϭ fluorodeoxyglucose; FDG-PET ϭ fluorodeoxyglucose-positron-emission tomography; FNA ϭ fine-needle aspiration; GTV ϭ gross tumor volume; HNSCC ϭ head and neck squamous cell carcinomas; IMRT ϭ intensity modulated radiation therapy; M ϭ metastasis; N ϭ node; PET ϭ positron-emission tomography; PTV ϭ planning target volume; RD ϭ residual disease; SCC ϭ squamous cell carcinoma; SUV ϭ standard uptake value; SUV max ϭ maximum SUV; T ϭ tumor M ore than 40,000 people are diagnosed with head and neck cancer each year in the United States.1 The overall annual mortality rate for this cancer in the United States is 23%, and the 5-year survival rate is 56%.1-3 More than 80% of early-stage tumors are cured, but nearly one-half of patients have evidence of advanced local disease or lymph node metastases at the time of diagnosis. Surgery and radiation therapy, either alone or in combination with chemotherapy, are used for definitive locoregional treatment of head and neck cancers. For patients with advancedstage and high-risk features, postoperative chemoradiation improves locoregional control and overall survival. 4,5 Cross-sectional imaging with CT and MR imaging is commonly used for tumor staging and may allow detection of subcentimeter lesions. Locoregional lymph node metastases have a major impact on survival. Patients with lymph-node involvement have a worse prognosis (approximately 30%) than patients without lymph node involvement (Ͼ50% 5-year survival). 6,7 PET using the radiotracer 18 F FDG is widely used to evaluate patients with HNSCC. The hybrid technique, PET/CT, provides anatomic and functional information and can be performed as PET and DCT with intravenous contrast-enhancement (PET/ DCT) or PET and noncontrast CT (PET/CT) for attenuation correction and anatomic localization. PET/CT is useful for identification of an unknown primary tumor, delineation of the extent of regional lymph node involvement, detection of distant metastases and occasional synchronous primary tumor, radiation-therapy planning, assessing therapy response, and long-term surveillance for recurrence and metastases.PET/CT Protocols PET/CT imaging was developed to improve PET imaging by expediting attenuation c...

Prognostic Value of Metabolic Tumor Volume Measured by 18F-FDG PET/CT in Locally Advanced Head and Neck Squamous Cell Carcinomas Treated by Surgery

“…FDG PET/CT simultaneously providing anatomical and functional information is useful for the initial detection of primary tumor, metastases, synchronous primary tumor, RT planning, assessment of treatment response, and surveillance for tumor recurrence and metastases after treatment [1,24]. FDG PET/ CT imaging has shown high sensitivity, ranging from 82% to 90%, and performance superior to CT or MRI in the detection of primary tumor, regional nodal involvement and distant metastases for the evaluation of HNSCC [25,26].…”

“…These essentially include tumor size, the stage of tumor at presentation, extent of lymph node involvement, extracapsular lymph node spread, surgical margin involvement and anatomic subsite. However, despite careful evaluation of these factors, it is not possible to reliably predict the outcome of treatment in individual patients [1,2].…”

Biologic Imaging of Head and Neck Cancer: The Present and the Future

“…FDG-PET/CT is useful in aiding GTV contouring because the metabolic activity of the tumor demarcates the boundary between active tumor and normal surrounding tumor. 57 FDG-PET may also reduce interobserver variability in GTV delineation, reduce the size of the GTV, identify tumor areas or lymph nodes missed by CT or MR imaging, and identify parts of the GTV potentially requiring an additional radiation dose. 58 While all modalities may overestimate the extent of tumor (FDG-PET by 29%, CT by 65%, and MR imaging by 89%), a reduction in GTV by using 18F-FDG-PET has been demonstrated in laryngeal cancer, with FDG-PET coming closest to depicting the true tumor volume.…”

Addition of 18F-FDG PET/CT to Clinical Assessment Predicts Overall Survival in HNSCC: A Retrospective Analysis with Follow-up for 12 Years

“…Imaging of the primary tumor is recommended within 6 mo of treatment completion (8), but the value of follow-up imaging for asymptomatic patients after 6 mo has not been established. Treatment with radiotherapy and surgery causes inflammation, scarring, and tissue distortion, which can limit the interpretation of anatomic imaging techniques such as CT and MR imaging (9,10). In contrast, the metabolic information provided by 18 F-FDG PET/CT allows it to serve as an effective tool for detecting recurrence, regional lymphatic spread, and distant metastases (11).…”