Journal of the Medical Association of Thailand Vol 100, No 5:MAY 2017 0125-2208 100 5 2017 Jun Relationship between Fasting Blood Glucose Level and 18F-FDG PET/CT Biodistribution Quality in Patients with Cancer: How Much Should We Concern? 578 EN Tanyaluck Thientunyakit Nantaporn Wongsurawat Chompoonut Hannanthawiwat Akarin Nimmannit Original Article This study was performed to evaluate the relationship between the fasting blood glucose (FBG) level and 18F-FDG biodistribution quality in patients with cancer for suitable patient preparation in our institute. We also investigated the relationship between the FBG level and the standardized uptake value (SUV) of the liver and bilateral gluteal muscles. This retrospective case-control study involved 69 patients who underwent 18F-FDG PET/computed tomography from November 2006 to February 2011. The biodistribution quality of 18F-FDG PET images was visually defined using a 5-point scoring system. Twenty-three patients with an altered biodistribution (score of 3-4) and 46 controls with an adequate biodistribution (score of 0-2) were matched for sex, age (±5 years), and lean body mass (±5 kg) (case:control = 1:2). The relationship between the FBG level and 18F-FDG biodistribution quality, the SUV of the liver and bilateral gluteal muscles, the SUV ratio of these regions and tumor positivity rate were analyzed. Among 69 patients (51 male, 18 female) with an FBG level of 64 to 155 mg/dL (mean, 94.67±17.78 mg/dL), there was no significant difference in the FBG level between those with an adequate versus altered biodistribution (mean, 96.00±16.76 and 95.65±14.75 mg/dL, respectively; p = 0.74). The biodistribution quality of 18F-FDG was not significantly correlated with the serum glucose level using cut-off levels of 120, 130, and 150 mg/dL (p = 1.00, 1.00, and 0.55, respectively). There was no significant correlation between the FBG level and SUV of the liver or bilateral gluteal muscles. No significant correlation between the tumor positivity rate and any blood sugar cut-off level (p = 0.100-1.000), or biodistribution quality (p = 0.205) was found. 18F-FDG PET can be performed when the FBG level is ≤155 mg/dL without a significantly altered biodistribution. Moreover, no significant correlation between the tumor detection rate and either FBG level or biodistribution quality was observed. 18F-FDG PET/CT blood glucose level hyperglycemia biodistribution quality