Effect of long fasting on myocardial accumulation in 18F-fluorodeoxyglucose positron emission tomography after chemoradiotherapy for esophageal carcinoma.

This study sought to evaluate the effect of fasting time prior to 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) on myocardial accumulation of FDG in patients receiving radiotherapy for esophageal carcinoma, and the spatial relationship between the irradiated dose and myocardial accumulation of FDG. Forty-one patients with thoracic esophageal carcinoma received FDG-PET with <18-h (24 patients) or ≥18-h (17 patients) fasting status. Their myocardial accumulation patterns of FDG were categorized using the maximal standardized uptake value (SUVmax) into three types: physiological, focal and no pathological accumulation. The incidence rates of each pattern were then compared using the Fisher's exact test between two types of fasting, ≥18-h and <18-h, prior to FDG-PET. Additionally, the left ventricle was defined using four subsites depending on the irradiated doses, and the SUVmax values were compared among the subsites using the Kruskal-Wallis test. The incidence of the physiological accumulation pattern decreased significantly more in the ≥18-h fasting status group than in the <18-h fasting group (18% versus 71%, P = 0.002), and the focal accumulation of FDG was detected at a significantly higher rate (65% versus 13%, P = 0.001). The left ventricular subsites receiving the higher doses showed significantly higher SUVmax values than did the subsites receiving the lower doses (P < 0.001). In conclusion, radiotherapy was associated with abnormal myocardial accumulation of FDG. Long fasting for 18 h or more prior to FDG-PET would be useful in detecting subsequent myocardial damage from chemoradiotherapy compared with <18-h fasting prior to FDG-PET.