shows the relationship between the SUV and tumor size in patients with primary lung cancer (not including metastatic lymph nodes), using both with FDG and 11C-choline. If the tumor size increased, the SUV of FDG increased (Y = 0.916X; r = 0.510 [where Y is the SUV of FDG and X is tumor size]). In contrast, the SUV of 11C-choline was almost constant at around 3.5 (mean [± SD], 3.53 ± 1.23) for every tumor size. The tumors were mostly adenocarcinomas (49 tumors) and squamous cell carcinomas (31 tumors), and there was no significant difference in the SUV of FDG and 11C-choline between these tumor types. When other tumor types were examined, there were eight cases of small cell carcinoma with tumor sizes of 1.3, 1.6, 1.7, 2.5, 2.9, 3.1, 3.8, and 7.0 cm in which the SUVs of FDG were 2.88, 2.95, 2.19, 7.71, 1.86, 4.85, 6.99, and 6.75, respectively, and the SUVs of 11C-choline were 2.99, 2.61, 3.20, 6.22, 2.37, 2.08, 4.82, and 4.96, respectively. There were also two cases of bronchioloalveolar carcinoma with tumor sizes of 2.8 and 7.4 cm in which the SUVs of FDG were 4.16 and 2.10, respectively, and the SUVs of 11C-choline were 4.16 and 3.64, respectively. Although there was no significant difference in the SUVs of FDG and 11C-choline among all the tumor types named above, a single exception was found in one case of bronchioloalveolar carcinoma (tumor size, 7.4 cm) in which the SUV of FDG was very low (2.10), but the SUV of 11C-choline was normal (3.64).