【摘要】 目的正电子断层显像(PET)通常以标准摄取值(SUV)≥2.5为肺癌诊断标准,但仍有部分SUV<2.5的孤立性肺结节(SPN<2.5)为肺癌。本研究旨在分析SPN<2.5氟代脱氧葡萄糖(18F-FDG)PET/CT表现及其诊断价值。方法 51例18F-FDG PET/CT早期显像SUV平均值(SUVavg)<2.5的孤立性肺结节病人纳入研究。对SPN放射性摄取测量采用两种方法:视觉分析及半定量分析。测量SPN的早期及延迟显像的SUVavg、SUVmax及其早期-延迟变化率(△SUVavg、△SUVmax)。37例以病理诊断及14例以2年以上临床随诊结果为最终诊断标准。统计学分析采用SPSS 16.0软件。结果 51例SPN<2.5患者中,良性11例,恶性40例。虽然良恶性SPN<2.5患者各项SUV值间均无统计学差异(P>0.05),但恶性SPN<2.5患者各项SUV值均有高于良性的趋势,特别是△SUVavg、△SUVmax。以△SUVmax>0为诊断阈值,18 F-FDG PET/CT诊断恶性SPN的敏感性68.4%、特异性60.0%、准确性66.7%、阳性预测值86.7%及阴性预测值33.3%。视觉分析:无FDG摄取的SPN<2.59例中,5例为良性,4例为恶性;有FDG摄取的SPN<2.542例中,6例良性,36例恶性,两组之间有显著的统计学差异,P=0.02。良恶性SPN<2.5的CT密度及大小之间均无统计学差异(P>0.05)。综合PET和CT信息分析SPN<2.5,18 F-FDG PET/CT诊断恶性SPN<2.5的敏感性97.5%、特异性54.5%、准确性88.2%、阳性预测值88.6%、阴性预测值85.7%。结论单纯以SUV≥2.5为标准鉴别诊断SPN会导致肺癌的漏诊。对于此类结节,△SUV有较高的肺癌阳性预测值;FDG摄取视觉分析能提高结节的良恶性鉴别准确率;综合FDG PET和CT分析的PET/CT能显著提高诊断肺癌的敏感性和准确性,但特异性较低。更多还原

【Abstract】 Objective Traditionly,a FDG standardized uptake value(SUV) of 2.5 is used as a cutoff of pulmonary malignancies.However,the frequency of malignancies with an SUV of <2.5 is significant,and this study aimed to evaluate the value of 18F-FDG PET/CT for diagnosis of solitary pulmonary nodules(SPNs) with 18F-FDG uptake below the initial average standardized uptake value(SUVavg) of 2.5.Methods We retrospectively analyzed 51 patients who had SPNs with an initial SUVavg of <2.5.The uptake of 18F-FDG was graded by semiquantitative methods(SUVavg,SUVmax,△SUVavg,△SUVmax) and a visual method.Besides above,we analyzed the density and size of SPNs.Final classification was based on histopathologic findings or at least 24 months of clinical follow-up.Results We found 40 malignant and 11 benign lesions.Though there were no significant differences between SUV(including all the SUVs and △SUV) of benign and malignant SPNs,there was a tendency that SUV of malignant SPNs was higher than that of benign ones(especially △SUV).When a cutoff of △SUVmax above 0 was used,the sensitivity,specificity,accuracy,positive and negative predictive values of 18F FDG PET/CT in diagnosis SPN were 68.4%,60.0%,66.7%,86.7%,33.3%,respectively.There were 5 benign SPNs and 4 malignant SPNs in total 9 absent FDG uptake SPNs.There were 6 benign SPNs and 36 malignant SPNs in total 42 visually evident FDG uptake SPNs(P=0.02).There was no significant difference between benign and malignant SPNs in CT density and diameter(P=0.71,0.24).The sensitivity,specificity,accuracy,the positive and negative predictive values of 18F-FDG PET/CT in diagnosis SPNs were 97.5%,54.5%,88.2%,88.6%,85.7%,rospectively.Conclusion These results suggested that SPNs with low 18F-FDG uptake,SUVavg and SUVmax did not improve the accuracy of 18F-FDG PET /CT.△SUV might be helpful in differential diagnosis.Visual analysis was more valuable than semiquantitative analysis.18F-FDG PET/CT demonstrates an excellent performance in classifying SPNs with an SUVavg of <2.5 as benign or malignant with a highly sensitivity and accuracy,though the specificity was low.更多还原