中文摘要：

目的评估18F－FDG PET/CT显像对直肠癌区域淋巴结转移的诊断价值。方法纳入2013年5月至2015年5月48例直肠癌患者（男37例，女11例，平均年龄59.7岁），术前均行18F－FDG PET/CT显像，在PET/CT图像上测量区域淋巴结长径、短径及SUVmax，将目标淋巴结同术后病理对照，确定转移性、非转移性淋巴结。2组间长径、短径、SUVmax比较采用两样本t检验；绘制ROC曲线，计算AUC，确定上述指标最佳诊断界值，比较不同指标及指标组合诊断直肠癌区域淋巴结转移的灵敏度、特异性和准确性。结果48例患者共切除淋巴结739枚，其中204枚（转移性淋巴结88枚，非转移性淋巴结116枚）可与PET/CT图像上淋巴结准确匹配。以SUVmax≥2.5为转移性淋巴结诊断标准，灵敏度、特异性、准确性分别为38.6%（34/88）、95.7%（111/116）、71.1%（145/204）。非转移性淋巴结、转移性淋巴结的长径分别为（6.13±1.94）和（8.49±3.78） mm，短径分别为（4.73±1.51）和（6.37±2.57） mm，SUVmax分别为1.13±0.74和2.54±1.76，二者间差异均有统计学意义（t＝－5.788、－5.691和－7.775，均P〈0.01）。淋巴结长径、短径和SUVmax判断淋巴结转移的ROC AUC分别为0.709、0.731和0.851；最佳界值分别为7.50 mm、5.05 mm和1.45。分别以各界值为诊断标准，基于单个淋巴结的灵敏度分别为：54.5%（48/88）、67.0%（59/88）和68.2%（60/88），特异性分别为：86.2%（100/116）、85.3%（99/116）和87.9%（102/116），准确性分别为：72.5%（148/204）、77.5%（158/204）和79.4%（162/204）。将短径≥5.05 mm、SUVmax≥1.45二者满足其一作为转移性淋巴结诊断标准，基于单个淋巴结的灵敏度、特异性、准确性分别为：84.1%（74/88）、83.6%（97/116）和83.8%（171/204）。结论18F－FDG PET/CT显像对直肠癌区域淋巴结转移的诊断有重要价值，SUVmax≥1.45为诊断标准的诊断价值优于长径≥7.50 mm?

英文摘要：

ObjectiveTo evaluate the diagnostic value of 18F-FDG PET/CT imaging in detection of regional lymph node metastasis in patients with rectal cancer.MethodsA total of 48 patients （37 males, 11 females; average age 59.7 years） with rectal cancer who underwent preoperative PET/CT examination from May 2013 to May 2015 were enrolled. The long diameter, short diameter and SUVmax of lymph nodes on axial images were recorded. Metastatic lymph nodes （MLN） and non-metastatic lymph nodes （NMLN） were confirmed by postoperative pathology. Two-sample t test was used to compare the diameters and SUVmax between 2 groups; ROC curve was drawn to determine the optimal cutoff value and to assess the sensitivity, specificity, and accuracy of each index for differentiating MLN from NMLN.ResultsA total of 739 lymph nodes were resected, 204 lymph nodes （88 MLN and 116 NMLN） were matched with those on PET/CT images. The long diameters of NMLN and MLN were （6.13±1.94） mm and （8.49±3.78） mm, respectively, and the short diameters were （4.73±1.51） mm and （6.37±2.57） mm, respectively（t=-5.788, -5.691, both P〈0.01）. The SUVmax of NMLN and MLN were 1.13±0.74 and 2.54±1.76, respectively（t= -7.775, P〈0.01）. For long diameter, short diameter and SUVmax, the ROC AUCs were 0.709, 0.731 and 0.851 respectively, the optimal cutoff values were 7.50 mm, 5.05 mm and 1.45 respectively, with the corresponding sensitivities of 54.5%（48/88）, 67.0%（59/88）and 68.2%（60/88）, specificities of 86.2%（100/116）, 85.3%（99/116）and 87.9%（102/116）, accuracies of 72.5%（148/204）, 77.5%（158/204）and 79.4%（162/204）. When a lymph node with SUVmax≥1.45 or short diameter≥5.05 mm was considered malignant, the sensitivity, specificity and accuracy were 84.1%（74/88）, 83.6%（97/116）and 83.8%（171/204）, respectively.Conclusions18F-FDG PET/CT imaging has significant value in detection of regional lymph node metastasis in patients with rectal cancer. The SUVmax≥1.45 showed better diagnost