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目的 探讨18F-FDG PET-CT在非小细胞肺癌(NSCLC)患者术前区域淋巴结(N)分期方面的价值,以及CT密度和双时相扫描在淋巴结性质判定方面的作用.方法 43例手术病理证实的NSCLC患者均于术前行18F-FDG PET-CT扫描,对常规扫描图像采用PET法(单纯根据18F-FDG摄取水平判断淋巴结性质)和PET+CT密度法(结合CT密度和摄取水平判断淋巴结性质)分析.摄取水平通过目测法和半定量分析法结合判定.双时相扫描的储留指数(RI)>10%为摄取升高.以病理检查作为金标准对所得结果进行分析.结果 以区域淋巴结组为单位,PET法的诊断敏感度、特异度、准确度、阳性预测值和阴性预测值分别为88.0%、88.4%、88.3%、59.5%和97.4%,PET+CT密度法的相应值分别为84.0%、94.6%、92.9%、75.0%和96.8%,其中2种方法的特异度和准确度之间差异有统计学意义(P<0.05).28组淋巴结行双时相扫描,良恶性组摄取变化值(△SUVmax)之间和砒之间差异无统计学意义(P>0.05);在23组延迟相摄取升高的淋巴结中,11组为转移;在5组无摄取升高的淋巴结中,1组为转移.结论 18F-FDG PET-CT在肺癌患者术前N分期方面有较高的诊断价值,结合淋巴结CT密度和18F-FDG摄取水平可进一步提高诊断的特异度和准确度.对于常规相摄取增高的淋巴结,延迟相摄取升高对判断淋巴结性质的价值有限,但无摄取升高则更支持良性诊断.

Objective To evaluate the diagnostic value of PET-CT with 18F-FDG in preoperative N staging of non-small cell lung cancer (NSCLC), especially the additional value of CT attenuation and the dual-time-point imaging in determining the lymph nodes status. Methods Forty-three NSCLC patients underwent curative surgical resection after integrated 18F-FDG PET-CT examination. The initial scan images were analyzed by two methods. In the first method, the nodal status was determined by 18F-FDG uptake only (method PET). In the second method, the nodal status was determined by uptake associated with CT attenuation (method PET and CT attenuation). Nodal uptake was interpreted visually and semi quantitatively. For dual-time-point imaging, a retention index (RI) >10% was regarded as increasing trend. Histopathologic results served as the reference standard. Results On the per-nodal-station (group) basis, the diagnostic sensitivity, specificity, accuracy, PPV, and NPV were 88.0%, 88.4%, 88.3%, 59.5% and 97.4%, respectively, by the method 1; 84.0%, 94.6%, 92.9%, 75.0% and 96.8%, respectively, by the method 2. The specificity and accuracy between these two methods had statistically significant difference (P<0.05). Twenty-eight nodal groups underwent dual-time-point imaging and the differences of △SUVmax and RI between benign and malignant groups had no statistically significant difference (P>0.05). Eleven groups were malignant in 23 lymph nodal groups which had an increasing trend. Among the 5 nodal groups which did not show increase in delayed scan, one group was malignant. Conclusion 18F-FDG PET-CT has high diagnostic value in the preoperative N staging of NSCLC, and combining uptake with CT attenuation of lymph nodes can improve the specificity and accuracy. For the lymph nodes with high uptake in the initial scan, increasing uptake in delayed scan has little effect in differentiatial diagnosis, but no increasing in delayed phase is more prone to benign diagnosis.