全身扩散加权成像与PET/CT在胃肠道肿瘤复发和转移诊断效能方面的对比研究

Comparison of whole body DWI and ^(18)F-FDG PET/CT in detection of gastrointestinal tumor recurrence and metastasis

目的比较全身扩散加权成像(WB-DWI)与PET/CT对胃肠道肿瘤患者复发和转移诊断的准确率;并评估转移灶和正常组织的ADC值。方法通过28例被确诊为胃肠道癌和怀疑肿瘤复发患者WB-DWI和PET/CT检查结果比较,评估两种方法在检测淋巴结和远处转移的效能。以PET/CT和组织学和/或3~6个月的临床随访作为评估参考标准。两位影像诊断医生和一位核医学科医师对MR和PET/CT图像分别进行评估。用Kappa统计比较WB-DWI和FDG-PET/CT用于检测复发和远处转移的一致性。同时对18名健康志愿者的正常组织与转移灶之间的ADC值的差异进行比较。根据受试者工作特征曲线(ROC)分析确定正常组织与转移瘤之间的最佳鉴别诊断阈值(OTV)。结果 28例患者中,5例检出肿瘤复发。PET/CT检出20例淋巴结阳性共72个病灶,WB-DWI检出18例共64个病灶。远处转移部位包括肝脏、肺、肾上腺、腹腔和骨。WB-DWI发现1处脑转移灶。WB-DWI与PET/CT总体诊断性能之间无显著统计学差别(t=1.332,P=0.194)。WB-DWI在显示局部复发和远处转移方面与PET/CT有很好的一致性,κ=0.877。在b值为600 s/mm2的WB-DWI中,淋巴结、肝、骨转移与各自正常组织之间的ADC值差异有显著统计学意义(P<0.05)。通过ROC得出其ADC值分别为1.67×10-3、1.95×10-3和1.30×10-3 mm2/s时,诊断转移的准确率最高、效能最佳。结论在胃肠道肿瘤分期应用方面,WBDWI是一种可靠的无电离辐射的成像方法,可以达到与PET/CT一致的诊断性能。此外,ADC值是一种定量值,它在转移瘤的诊断方面有很高的价值。

Objective To compare whole body diffusion-weighted MR imaging （DWI） with 18F-FDG PET/CT in detecting recurrent or metastatic gastrointestinal cancer. Methods 28 patients with suspected gastrointestinal tumor recurrence or metastasis underwent both whole body DWI and 18F-FDG PET/CT. All DWI studies were evaluated by two radiologists and the PET/CT images were assessed by one nuclear medicine physician. Agreement between the two examinations for detecting tumors was analyzed using kappa statistics. The ADC values of metastases Receiver-operating characteristic curve （ROC curve） analysis was used to determine the optimal threshold ADC value in differentiating metastases from normal tissues. Results There was no significant difference （P＆gt;0.05） in the overall diagnostic performances between whole body DWI and PET/CT with good agreement （κ=0.877） for detecting recurrent and metastatic tumor..The ADC values of lymph node,.liver and bone （1.30×10^-3 mm^2/s） metastases were significantly lower than that of healthy volunteers（P〈0.05） with optimal diagnostic accuracy at threshold ADC values of 1.67×10^-3 mm^2/s for the lymph node,.1.95×10 ^-3 mm2/s for the liver and 1.30 ×10 ^-3 mm^2/s for the bone metastases..Conclusion Whole body DWI is comparable to 18F-PET/CT for detecting recurrent or metastatic gastrointestinal cancer without ionizing radiation.