双示踪剂PET-CT在头颈部肿瘤生物适形调强放疗的初步研究

目的 探讨¹⁸F-脱氧葡萄糖（¹⁸F-FDG）和¹⁸F-赤硝基咪唑（¹⁸F-FETNIM）双示踪剂PET-CT确定头颈部肿瘤生物适形调强放射治疗（BIMRT）靶区的可行性。方法 经病理证实且未经治疗的头颈部肿瘤患者12例，治疗前行CT模拟定位扫描、¹⁸F-FDG PET-CT和¹⁸F-FETNIM PET-CT扫描，分别勾画大体肿瘤靶区（GTV_CT）、葡萄糖代谢亚靶区（GTV_FDG）、乏氧亚靶区（GTV_FETNIM），测量并比较原发肿瘤和转移性淋巴结体积，分别表示为GTV_P-CT、GTV_N-CT、GTV_P-FDG、GTV_N-FDG、GTV_P-FETNIM 和GTV_N-FETNIM。 结果 12例患者原发肿瘤和转移淋巴结均摄取¹⁸F-FDG，SUVmax-P和SUVmax-N分别为12.3±5.5和 5.1±2.8。9例患者原发肿瘤摄取¹⁸F-FETNIM，其中5例患者转移性淋巴结有摄取，未见摄取4例；3例患者原发肿瘤未见¹⁸F-FETNIM 摄取，其中转移性淋巴结有摄取1例，未见摄取2例。GTV_P-CT、GTV_P-FDG 和GTV_P-FETNIM分别为 （22.23±12.11）、（20.83±11.59）和（1.98±1.81）cm³，GTV_N-CT、GTV_N-FDG 和GTV_N-FETNIM分别为 （10.77±8.87）、（10.41±8.61）和（0.61±1.08）cm³。GTV_P-FETNIM < GTV_P-CT，GTV_P-FETNIM < GTV_P-FDG，GTV_N-FETNIM < GTV_N-CT，GTV_N-FETNIM < GTV_N-FDG（P<0.01），GTV_P-CT与GTV_P-FDG、GTV_N-CT与GTV_N-FDG差异无统计学意义。结论 不同示踪剂PET-CT显像反映肿瘤细胞不同方面的生物学信息，根据PET-CT影像所显示的示踪剂高摄取区域将肿瘤组织划分为若干个子区域是可行的，为实现生物调强放疗提供了可靠的研究基础。

Preliminary investigation of 18F-FDG and 18F-FETNIM PET-CT applied in head and neck cancer patients undergoing biological intensity modulated radiotherapy

Objective To evaluate the feasibility of using Fluorine-18 fluorodeoxyglucose (¹⁸F-FDG) and Fluorine-18 fluoroerythronitroimidazole (¹⁸F-FETNIM) in positron emission tomography with computed tomography (PET-CT) to define biological target volume during the biological intensity modulated radiotherapy (BIMRT). Methods Twelve patients with pathologically confirmed head and neck cancer were scanned with CT simulation, ¹⁸F-FDG PET-CT and ¹⁸F-FETNIM PET-CT respectively before treatment. Three gross target volumes, GTV_CT, GTV_FDG and GTV_FETNIM, were delineated correspondingly with three modalities. The volumes of primary tumor (P-) and metastatic lymph nodes (N-), denoted as GTV_P-CT, GTV_N-CT, GTV_P-FDG, GTV_N-FDG, GTV_P-FETNIM and GTV_N-FETNIM, were compared respectively. Results Both primary tumor and metastatic lymph node of the 12 patients had ¹⁸F-FDG uptake, and the average maximal standard uptake values (SUV_max) were 12.3±5.5 and 5.1±2.8, respectively. Positive primary tumor ¹⁸F-FETNIM uptake was observed in 9 patients, yet only 5 of whom had positive ¹⁸F-FETNIM uptake in lymph node metastases. Three patients had no ¹⁸F-FETNIM uptake in the primary tumor, among whom 1 had positive ¹⁸F-FETNIM uptake in lymph node metastases. The volumes of GTV_P-CT, GTV_P-FDG and GTV_P-FETNIM were (22.23±12.11), (20.83±11.59) and (1.98±1.81) cm³, respectively. The volumes of GTV_N-CT, GTV_N-FDG and GTV_N-FETNIM were (10.77±8.87), (10.41±8.61) and (0.61±1.08) cm³, respectively. Compared to CT imaging, the volume differences of primary tumor and metastatic lymph nodes shown on ¹⁸F-FDG PET-CT imaging were statistically not significant. Compared with CT and ¹⁸F-FDG PET-CT, the corresponding volumes were significantly smaller at ¹⁸F-FETNIM PET-CT (P<0.01). Conclusions The study demonstrated that PET-CT imaging using different tracers may define subregions of the tumor for biological target volume delineation, which provides foundations for BIMRT.