MR对鼻咽癌局部侵犯规律及其临床靶区勾画指导意义分析

Magnetic resonance imaging in detecting extension of local disease in nasopharyngeal carcinoma and guiding clinical target volume delineation

目的:应用磁共振成像(MR)评价鼻咽癌局部侵犯的规律性,探讨临床靶区(CTV)勾画。方法:连续收集具备鼻咽及颈部MR扫描的初诊鼻咽癌患者345例。由两位影像学医师独立阅片,根据受侵的发生率,将各解剖结构划分为高危组(≥35%)、中危组(≥5%～35%)和低危组(<5%)3个等级。结果:高危组解剖结构毗连于鼻咽腔,中危组和低危组解剖结构与鼻咽腔间隔解剖屏障。高危组解剖结构受侵时,毗连中危组解剖结构受侵发生率高达54.3%。高危组解剖结构未受侵时,毗连中危组解剖结构受侵的发生率<10.0%。高危组或中危组解剖结构受侵时,毗连低危组解剖结构受侵的发生率高达40.0%。鼻咽癌非中线结构双侧同时受侵的发生率较低(<10%),椎前肌除外(11.9%)。结论:鼻咽癌遵循从近到远逐步进行局部侵犯,跳跃性扩散较为罕见,神经孔道是重要的扩散途径。鼻咽癌非中线结构双侧同时受侵的发生率较低,鼻咽周围解剖结构的选择性CTV勾画是可行的。

OBJECTIVE： To define the local extension patterns in patients presenting with nasopharyngeal carcinom, （NPC） by using magnetic resonance imaging （MR）, and approach clinical target volume delineation. METHODS：Patients with newly diagnosed and untreated NPC （345 consecutive） were included in this study. All patients had an MR exam ot the nasopharynx and neck, which was reviewed by two radiologists. According to incidence rates of tumor invasion, the anatomical sites surrounding the nasopharynx were initially classified into three risk grades： high risk （≥35 %）, medium risk （5 %—35 % ） and low risk （〈5 %）. RESULTS： The anatomical sites at high risk were adjacent to the nasopharynx, and the anatomical sites at medium or low risk were separated from the nasopharynx. The incidence rates of tumor invasion into the anatomical sites at medium risk were increased with the highest rate of 54.3%, when their adjacent anatomical sites at high risk were involved. The rates were mainly 〈10% when their adjacent anatomical sites at high risk were not involvedl The incidence rates of tumor invasion ＇into anatomical sites at low risk increased significantly when adjacent anatomical sites were involved, with the highest rate of 40.0%. The incidence rates of concurrent tumor invasion into bi- lateral anatomical sites were less than 10%, except prevertebral muscle （11.9%）. CONCLUSIONS：In patients presenting with NPC, local disease spreads from proximal sites to more distal sites. Tumors extend quickly through privileged pathways such as neural foramina. The incidence rates of concurrent tumor invasion into bilateral anatomical sites are low. Selective radiotherapy of the local disease in NPC may be feasible.