18F-FAMT-PET Is Useful for the Diagnosis of Lymph Node Metastasis in Operable Esophageal Squamous Cell Carcinoma

Abstract

The role and potential usefulness of positron emission tomography (PET) scanning in certain tumors has been widely investigated in recent years. (18)F-FAMT (L-[3-(18)F]-α-methyltyrosine) is an amino acid tracer for PET. This study investigated whether PET/CT with (18)F-FAMT provides additional information for preoperative diagnostic workup of esophageal squamous cell carcinoma compared with that obtained by (18)F-FDG (fluorodeoxyglucose) PET or CT. PET/CT studies with (18)F-FAMT and (18)F-FDG were performed as a part of the preoperative workup in 21 patients with histologically confirmed esophageal squamous cell carcinoma. For the detection of primary esophageal cancer, (18)F-FAMT-PET exhibited a sensitivity of 76.2%, whereas the sensitivity for (18)F-FDG-PET was 90.5% (P = 0.214). (18)F-FAMT uptake in primary tumors showed significant correlation with depth of invasion (P = 0.005), lymph node metastasis (P = 0.045), stage (P = 0.031), and lymphatic invasion (P = 0.029). In the evaluation of individual lymph node groups, (18)F-FAMT-PET exhibited 18.2% sensitivity, 100% specificity, 71.9% accuracy, 100% positive predictive value, and 70.0% negative predictive value, compared with 24.2%, 93.7%, 69.8%, 66.6%, and 70.2%, respectively, for (18)F FDG-PET. CT exhibited 39.4% sensitivity, 85.7% specificity, 69.8% accuracy, 59.1% positive predictive value, and 73.0% negative predictive value. The specificity of (18)F-FAMT-PET is significantly higher than that of (18)F-FDG-PET (P = 0.042) and CT (P = 0.002). (18)F-FAMT-PET did not have any false-positive findings compared to those with (18)F-FDG-PET. Our findings suggest that the addition of (18)F-FAMT-PET to (18)F-FDG-PET and CT would permit more precise staging of esophageal cancer.