呼吸门控PET／CT对肺部结节SUV的影响

The effect of respiratory gated PET/CT on SUV of lung nodules

目的观察呼吸门控与非门控PET／CT显像测定肺部结节SUV的差异，探讨不同呼吸时相SUV变化趋势。方法2010年5月至2011年3月进行PET／CT显像、发现有多个肺部结节并同意进行呼吸门控显像者共19例，最终14例共37个结节纳入该研究，其中男6例，女8例，年龄29～80（63．74-7．1）岁。对所有患者进行常规和呼吸门控PET／CT采集。经过后台处理得到呼吸时相相匹配的1个呼吸周期内6个时相的PET／CT融合图像。测得SUV，每个肺部结节的每个指标均进行非门控与门控显像6个时相共7次测量。采用SPSS13．0软件对数据行t检验、秩和检验和相关分析。结果37个肺部结节呼吸门控显像的SUVmax和SUVmean。分别为13．69±6．70和8．56±4．11，明显高于非门控PET／CT的12．764-6．74及7．66±4．00（t=3．475和Z=一3．661，P均〈0．001）；但2种显像技术SUV。。与SUV～相关性好（r=0．971和0．969，P均〈0．05）；在门控显像中，6个时相不同时相间SUV以时相1即吸气末最高，而时相4（呼气末吸气初）最低。37个结节中4个结节常规显像SUV〈2．5（定义为轻度摄取），其中有1个结节SUVmax由非门控显像的2．13升至门控显像的2．52。结论采用呼吸门控PET／CT显像所得到的肺部结节suVmax和SUVmean。比非门控常规采集高，但两者相关性好；SUV不同时相间以吸气末最高。对轻度摄取FDG的结节，经呼吸门控PET／CT其SUV有所提高，有可能影响临床诊断。

Objective To analyze the difference of SUV between respiratory gated （RG） and nongated PET/CT scans, and to investigate the trend of SUV change in different respiratory phases. Methods Fourteen patients （6 male, 8 female, age range ： 29 to 80 years, average age ： 63.7 ±7.1 years） with pulmonary nodules who had undergone both RG and non-gated PET/CT between May 2010 to March 2011 were enrolled in the study. A total of 37 pulmonary nodules were identified. Both PET and CT gated data were divided into 6 phases. PET images were matched with CT at different respiratory phases. Each nodule was measured 7 times including gated data of 6 phases and non-gated data. The t-test, rank-sum test and Spearman correlation analysis were used. Results The SUVm~ and SUV of RG PET/CT （ 13.69 ＋ 6.70 and 8.56 -＋4.11, respectively） were higher than those of non-gated PET/CT （ 12.76 ＋ 6.74 and 7.66 -＋ 4.00, respectively） （ t = 3. 475, Z = - 3. 661, both P 〈 0. 001 ）. The two sets were correlated with each other （ r = 0.971 and 0.969, both P 〈 0.05）. SUVmaX was the highest at phase 1 （ end of expiration） and lowest at phase 4 （ end of inspiration）. In non-gated scans, there were 4 nodules with SUVmax 〈 2. 5, inclu- ding 1 nodule with a higher SUV of 2.52 in the RG scan than SUV of 2.13 in the non-gated scan. Conclusions SUv of lung nodules in RG scans is higher than that in non-gated scans. The highest SUVmax could be obtained at the end of expiration. RG scans might improve the detection of lung nodules with low-grade FDG untake.