^18F-FDG肿瘤显像前低碳水化合物饮食对心肌放射性摄取的影响

目的探讨^18F—FDG肿瘤显像前采用低碳水化合物饮食以减少心肌放射性摄取的可行性。方法选取2011年4月至2012年1月行^18F—FDG肿瘤显像患者70例，按完全随机法将其分为对照组（34例）和实验组（36例）。对照组显像前一天晚餐为正常饮食，实验组为低碳水化合物饮食。所有患者检查当天空腹，并在注射^18F—FDG前抽血检测血糖、血清游离脂肪酸、胰岛素及酮体水平。行双探头符合线路显像，目测分析心肌FDG摄取程度，进行分级评分：0分，不显影；1分，摄取低于肝脏；2分，摄取与肝脏相当；3分，摄取高于肝脏；4分，显著摄取。计算心肌与肝脏放射性摄取比值（H／L）。采用两样本t检验、Wilcoxon秩和检验和直线相关分析处理数据。结果实验组心肌^18F—FDG摄取明显低于对照组，H／L分别为0．94±0．57和1．50±1．04，差异有统计学意义（t=-2．75，P〈0．05）。实验组血清游离脂肪酸和酮体水平[（0．671±0．229）mmol／L、（0．88±0．60）mmol／L]较对照组[（0．547±0．207）mmol／L、（0．57±0．32）mmol／L]显著升高（t=2．38和2．67，均P〈0．05）；2组血糖和胰岛素水平分别为（5．28±1．06）mmol／L、（35．16±33．70）pmol／L和（5．19±0．78）mmol／L、（41．64±35．13）pmol／L，差异均无统计学意义（t=0．39和-0．79，均P〉0．05）。心肌摄取^18F-FDG程度与血清游离脂肪酸和酮体水平均呈负相关（r=-0．40和-0．33，均P〈0．01），但与血糖和胰岛素水平相关性均无统计学意义（r=-0．02和0．13，均P〉0．05）。结论^18F-FDG肿瘤显像前采用低碳水化合物饮食可以降低心肌对^18F—FDG的摄取，从而减少其对周围病灶检出的干扰。

Low carbohydrate diet before 18F-FDG tumor imaging contributes to reduce myocardial 18F-FDG uptake

Objective To evaluate whether low carbohydrate diet before 18F-FDG tumor imaging could reduce myocardial 18F-FDG uptake. Methods From April 2011 to January 2012, 70 patients were enrolled in this study. They were randomly divided into control group （34 cases） and test group （36 cases）. Patients in control group were on regular diet, while those in test group had low carbohydrate diet in the evening before imaging. Blood samples were taken before injection of 18F-FDG for the measurement of serum glucose, free fatty acid, insulin and ketone body. Whole body 18F-FDG tomography was performed with dualhead coincidence SPECT. The myocardial uptake of FDG was assessed visually and scored as 0 for no uptake, 1 for uptake lower than liver, 2 for uptake similar to liver, 3 for uptake higher than liver, and 4 for remarkable uptake. The ratio of myocardium to liver （H/L） was calculated. Two-sample t test, Wilcoxon rank sum test and linear correlation analysis were performed. Results The myocardial uptake in test group was significandy lower than that in control group with H/L ratios of 0.94±0.57 and 1.50±1.04, respectively（ t= -2.75,P〈 0. 05）. The concentrations of serum free fatty acid and ketone body in test group were significantly higher than those in control group： （0.671±0.229） mmol/L vs （0.547±0.207） mmol/L and （0.88±0.60） mmol/L vs （0.57±0.32） mmoL/L, t = 2.38 and 2.67,both P〈0.05. The concentrations of glucose and insulin were （5.28±1.06） mmol/L and （35.16± 33.70） pmol/L in test group, which showed no significant difference with those in control group （（5.19±0.78） mmol/L and （41.64±35.13） pmol/L, t=0.39 and-0.79, both P〉 0.05）. A negative correlation was found between the myocardial uptake of 18F-FDG and serum free fatty acid/ketone body concentration （r=-0.40, -0.33, both P〈0.01 ）, respectively. There was no correlation between the myocardial uptake of 18F-FDG and glucose/insulin （r =-0.02, 0.13, both P〉0.05）, respectively. Conclusion Low carbohydrate diet before 18F-FDG tumor imaging can reduce myocardial uptake, thus facilitating detection of lesions near the heart.