18 F-FDG metabolic tumor volume (MTV) and total glycolytic activity (TGA) have been proposed as potential prognostic imaging markers for patient outcome in human solid tumors. The purpose of this study was to establish whether MTV and TGA add prognostic information to clinical staging in patients with oral and oropharyngeal squamous cell carcinomas (SCCs). Methods: The Institutional Review Board approved this Health Insurance Portability and Accountability Act-compliant singleinstitution retrospective study. Forty-five patients with histologically proven oral or oropharyngeal SCC underwent PET/CT for initial cancer staging and were included in the study. MTV was measured using a gradient-based method (PET Edge) and fixed-threshold methods at 38%, 50%, and 60% of maximum standardized uptake value (SUV). The TGA is defined as MTV · mean SUV. Bland-Altman analysis was used to establish the reliability of the methods of segmentation. Outcome endpoints were overall survival (OS) and progression-free survival. Cox proportional hazards univariate and multivariate regression analyses were performed. Results: In Cox regression models, MTV and TGA were the only factors significantly associated with survival outcome after adjusting for all other covariates including American Joint Committee on Cancer (AJCC) stage, with hazards ratio of 1.06 (95% confidence interval, 1.01-1.10; P 5 0.006) and 1.00 (95% confidence interval, 1.00-1.01; P 5 0.02). The model fit was significantly better when MTV was added to AJCC stage in model I (x 2 value change, 1.16-6.71; P 5 0.01) and when TGA was added to AJCC stage in model II (x 2 value change, 1.16-4.37; P 5 0.04). The median cutoff point of 7.7 mL for primary tumor MTV was predictive of time to OS (log rank P 5 0.04). The median cutoff point of 55 g for PET Edge primary tumor TGA was predictive of time to OS (log rank P 5 0.08), though the result was not statistically significant. Conclusion: Gradient-based segmentations of primary tumor MTV and TGA are potential 18 F-FDG markers for time to survival in patients with oral and oropharyngeal SCC and may provide prognostic information in addition to AJCC stage. These exploratory imaging markers need validation in larger cohort studies.
Quantification of FDG uptake in CS correlates with lower EFs, clinical events, and immunosuppression treatment.
FDG PET metabolic tumor volume estimated using gradient segmentation had superior correlation and reliability with the estimated ellipsoid pathologic volume of the tumors compared with threshold method segmentation.
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...
BMI has the highest effect and correlation on mediastinal and liver FDG uptake. FDG uptake time has a greater effect on mediastinal than liver SUVlbm mean.
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