摘要目的 基于SPECT/CT同机融合显像的内乳前哨淋巴结(IM-SLN)位置分布,探讨内乳淋巴结(IMLN)引流区预防性照射的靶区范围.方法 回顾性选取2014—2018年709例初诊为乳腺癌并在术前对IM-SLN进行了SPECT/CT前哨淋巴结显像检查的患者,其中97例患者IM-SLN显像阳性,显像的IM-SLN总数为136枚.依据放射治疗肿瘤协作组(RTOG)和丹麦乳腺癌合作小组(DBCG)指南勾画IMLN临床靶区(CTV),分别定义为CTVRTOG和CTVDBCG,确定CTVRTOG及CTVDBCG与IM-SLN的位置关系.结果 位于第1～5肋间的IM-SLN个数分别为55、41、33、6和1枚,第1～3肋间IM-SLN数占总数的94.9％.CTVRTOG边缘到IM-SLN中心点及5 mm直径IM-SLN外侧缘的平均距离分别为4.10 mm(95％CI 3.54～4.65 mm)和6.40 mm(95％CI 5.81～6.98 mm),两者比较差异有统计学意义(t=-30.486,P<0.05),而CTVDBCG到两者的平均距离分别为1.60 mm(95％CI 1.16～2.05 mm)和3.34 mm(95％CI 2.78～3.89 mm),两者比较差异有统计学意义(t=-16.364,P<0.05).CTVRTOG边缘到IM-SLN中心点及5 mm直径IM-SLN外侧缘的平均距离均明显大于CTVDBCG(t=16.640、19.815,P<0.05).CTVRTOG、CTVDBCG分别可覆盖18.4％、60.3％的IM-SLN中心点.覆盖90％及100％的IM-SLN中心点时,CTVRTOG需外扩8和15 mm,而CTVDBCG需外扩5和13 mm.设定IM-SLN的直径为5 mm时,覆盖90％及100％的IM-SLN时,CTVRTOG需外扩11和17 mm,而CTVDBCG需外扩7和16 mm.结论 基于SPECT/CT显像图像上IM-SLN的分布,内乳淋巴结预防性照射靶区范围包括第1～3肋间是合理的;无论基于RTOG还是DBCG指南所勾画内乳靶区均不足以覆盖90％的IM-SLN.

abstractsObjective To explore the target definition for internal mammary lymph nodes ( IMLNs) irradiation based on the distribution of internal mammary sentinel lymph nodes ( IM-SLNs ) developing on SPECT/CT fusion imaging. Methods A total of 709 breast cancer patients who underwent&nbsp;preoperative SPECT/CT fusion imaging examination in IM-SLN from 2014 to 2018 were selected. All of the selected patients were first diagnosed and did not receive neoadjuvant treatment before SPECT/CT examination. Finally, totally 97 patients with 136 positive imaging IM-SLNs were included in this study. The clinical target volumes ( CTVs) were delineated according to the consensus guidelines from RTOG and DBCG and defined as CTVRTOG and CTVDBCG , respectively. The positional relationship of CTVRTOG , CTVDBCG and IM-SLNs were determined. Results The number of IM-SLNs from the first to fifth intercostal spaces were 55, 40, 33, 6 and 1, respectively. And the number of IM-SLNs in the first three intercostal spaces accounted for 94. 85％ of the total. The average distance from the edge of CTVRTOG to the centre points and the edges of IM-SLNs were 4. 10 mm ( 95％CI 3. 54-4. 65 mm) and 6. 40 mm ( 95％CI 5. 81-6. 98 mm), respectively (t=-30. 486,P<0. 05). For the CTVDBCG, the average distance was 1. 60 mm ( 95％CI 1. 16-2. 05 mm) and 3. 34 mm ( 95％CI 2. 78-3. 89 mm) , respectively ( t=-16. 364,P<0. 05) . The average distances from the edge of CTV to the centre points and the edge of IM-SLNs for CTVRTOG were all significantly greater than those for CTVDBCG(t=16. 640, 19. 815, P<0. 05). The rate of covering IM-SLN center points for CTVRTOG and CTVDBCG were 18. 4％ and 60. 3％, respectively. In order to cover 90％or 100％ of the IM-SLN center points, the edge of CTVRTOG should be expanded by 8 or 15 mm, respectively, and the edge of CTVDBCG should be expanded by 5 or 13 mm, respectively. If the diameter of IM-SLN was assumed as 5 mm, the edge of CTVRTOG needed an expansion of 11 or 17 mm to contain 90％or 100％ of IM-SLNs, respectively, while the edge of CTVDBCG needed 7 or 16 mm to cover 90％ or 100％of IM-SLNs, respectively. Conclusions It is reasonable to include the first three intercostal spaces IMLNs for prophylactic irradiation based on the distribution of IM-SLNs. However, CTVs based on the two guidelines are both insufficient to cover 90％ of IM-SLNs.