Usefulness of Positron Emission Tomography-Computerized Tomography Uptake according to Early Gastric Cancer Gross Morphology

ABSTRACT

BACKGROUND/AIMS: The role of 18F-fluorodeoxyglucose (18F-FDG) PET-CT for early gastric cancer (EGC) was undetermined due to its low sensitivity. The aim of this study was to assess the usefulness of 18F-FDG PET-CT according to endoscopic classification of EGC. MATERIALS AND METHODS: We retrospectively reviewed 206 patients who had undergone PET-CT due to gastric cancer from June 2009 to June 2012. Among those patients, 120 including 65 patients who underwent gastrectomy were analyzed. RESULTS: According to endoscopic gross morphology, 50 (41.7%) patients were classified as EGC and 70 (58.3%) patients were classified as advanced gastric cancer (AGC). Compared with the EGC group, the AGC group showed significantly higher rate of positive 18F-FDG uptake of primary lesions (98.6% vs. 28.0%, P<0.001) and lymph nodes (50.0% vs. 6.0%, P<0.001), and higher standardized uptake value max of primary lesions (7.65+/-3.51 vs. 4.82+/-2.18, P=0.012). Among 65 patients who underwent gastrectomy, PET-CT positive lesions were found in patients with tumor size greater than 3 cm (86.4% vs. 9.5%, P<0.001), lesions detected by stomach CT (90.9% vs. 9.5%, P<0.001) and PET-CT lymph node positive lesions (4.8% vs. 31.8%, P=0.025). Among 31 patients with EGC, elevated types (type I and IIa) showed no difference of positive 18F-FDG uptake compared with flat or depressed types (IIb, IIc, and III) (55.6% vs. 31.8%, P=0.253). CONCLUSIONS: 18F-FDG PET-CT has positive detection rate for EGC greater than 3 cm and there was no differences of 18F-FDG PET-CT uptake rates between elevated types and flat or depressed types of EGC.