Evaluation of thoracic tumors with 18F-FMT and 18F-FDG PET-CT: A clinicopathological study

L-[3-¹⁸F]-α-methyltyrosine (¹⁸F-FMT) is an aminoacid tracer for positron emission tomography (PET). The aim of this study was to determine whether PET-CT with ¹⁸F-FMT provides additional informationfor the preoperative diagnostic workup as compared with ¹⁸F-FDG PET. PET-CT studies with ¹⁸F-FMT and ¹⁸F-FDG were performed as a part of the preoperative workup in 36 patients with histologically confirmed bronchial carcinoma, 6 patients with benign lesions and a patient with atypical carcinoid. Expression of L-type amino acid transporter 1 (LAT1), CD98, Ki- 67 labeling index, VEGF, CD31 and CD34 of the resected tumors were analyzed by immunohistochemical staining, and correlated with the uptake of PET tracers. For the detection of pulmonary malignant tumors, ¹⁸F-FMT PET exhibited a sensitivity of 84% whereas the sensitivity for ¹⁸F-FDG PET was 89% (p 5 0.736). ¹⁸F-FMT PET-CT and 18F-FDG PET-CT agreed with pathological staging in 85 and 68%, respectively (p 5 0.151). ¹⁸F-FMT uptake was closely correlated with LAT1, CD98, cell proliferation and angiogenesis. The specificity of ¹⁸F-FMT PET for diagnosing thoracic tumors was higher than that of ¹⁸F-FDG PET. Our results suggest that coexpression of LAT1 and CD98 in addition to cell proliferation and angiogenesis is relavant for the progression and metastasis of lung cancer.