The Significance of Incidental 18F-FDG Uptake in PET/CT at the Gastroesophageal Junction in Predicting Benign and Malignant Disease

Abstract

Purpose: Positron emission tomography (PET), using the positron-emitting glucose analogue 18F-FDG, relies on the observation that neoplasms metabolize glucose at a higher rate than normal tissues. The rate or intensity of tissue metabolism can be assessed by semi quantitative metrics such as standardized uptake value, or SUV. The goal of this study is to correlate esophageal 18F-FDG uptake by PET with esophageal disease identified endoscopically to identify functional imaging factors that might distinguish benign and malignant esophageal disorders. Methods: We reviewed medical records for the period June, 2009 through May, 2012 to identify patients who had both a PET/CT scan and an endoscopy (EGD) performed within six months of one another. Metabolic activity was quantified utilizing volumetric SUV max and SUV mean at the gastro-esophageal junction (GEJ) for all patients. PET characteristics were correlated with EGD findings at the GEJ. Results: From an initial cohort of 285, we identified 220 patients who had both PET/CT and EGD performed within a six months. Patients were grouped into the following categories based on EGD results: esophageal malignancy (n=34), esophagitis (n=21), Barrett's esophagus (n=8), other non-malignant disorders (n=5) and normal (n=151). The average SUV max values for esophageal malignancy, esophagitis, Barrett's esophagus, other and normal were 6.72, 2.47, 2.40, 3.48 and 2.06, respectively. SUV measurements differed significantly between patients with malignancy and normal (p<0.001); these values also differed significantly between patients with malignancy compared to those with Barrett's and esophagitis (p<0.001). There was no significant difference in SUV max that would allow differentiation of normal EGD findings from any individual benign esophageal disorder; however, there was a significant difference in SUV mean comparing normal to the total group of 34 patients with proven benign esophageal disorders (p<0.04). Conclusion: The current study establishes PET SUV values which may be useful in distinguishing patients with concern for esophageal malignancy, benign disorders, or normal findings. Clinicians might find these results useful in determining the need for EGD in patients with unexpectedly high PET 18F-FDG uptake at the gastro-esophageal junction.