PURPOSE: The stomach is used as a substitute for the esophagus after esophagectomy because of its abundant blood supply and its favorable elasticity. However poor vascularization of proximal region of the gastric tube can be impaired, leading to anastomotic leakage or gastric tube ischemia. It is still controversial whether difference of the gastric tube vascularization depends on its diameter. The purpose of this study is to compare the gastric tube viability between a narrow and a wide gastric tube by using thermal image. METHODS: Twelve patients who underwent esophagectomy and esophago-gastric anastomosis between January 2004 and October 2005 were randomly allocated to either reconstruction using a narrow gastric tube (n=6, diameter: 3.0-3.5cm) or using a wide gastric tube (n=6, diameter: 4.5-5.5cm). Surface temperature of the gastric tube and the devascularized stomach were measured as its viability by thermal imaging system from the proximal end to the pylorus. Correlations between the type of gastric tube and postoperative complications such as leakage and anastomotic stricture were examined. RESULTS: Mean surface temperature at the proximal region of the narrow gastric tube and wide gastric tube were 26.6 degrees C and 28.8 degrees C, respectively (p<0.05). Mean decline rate of surface temperature at the proximal region of a narrow gastric tube and a wide gastric tube compared to the devascularized stomach were 14.2% and 7.9%, respectively (p<0.01). On the contrary, there was no significant difference in the mean surface temperature and decline rate between the types of gastric tubes. None of patients developed anastomotic leakage, however, 4 of 6 patients with a narrow gastric tube had an anastomotic stricture as compared to 0 of 6 patients with a wide gastric tube. CONCLUSION: Our preliminary results suggest that thermal camera is non-invasive with high reproducibility in detecting gastric viability after devascularization or gastric tube construction. Although there was no difference in anastomotic leakage, a wide gastric tube seems to have higher viability than a narrow gastric tube, which may lead to a better anastomotic healing. Practical application of thermal imaging systems for routine intraoperative determination of the gastric tube viability may be anticipated.