磁共振扩散成像在鼻咽癌靶区勾画临床应用价值

Clinic significance of diffusion-weighted magnetic resonance imaging for evaluating the clival invasion in nasopharyngeal carcinoma patients

目的鼻咽癌发生位置深在，解剖结构复杂，毗邻颅底，故鼻咽癌颅底斜坡侵犯发生率较高。本研究探讨磁共振弥散成像（diffusion weighted imaging，DWI））表观扩散系数值（apparent diffusion coefficient，ADC）值在鼻咽癌靶区勾画，尤其在斜坡侵犯识别中的临床价值。方法回顾性分析2013-01-01—2016-01-01贵州省人民医院收治的76例鼻咽癌初诊患者临床资料。所有病例分别在放疗前、放疗结束后1和4个月行常规MRI平扫和增强及轴位DWI扫描，并进行对比分析。根据治疗前增强MRI、DWI及定位CT勾画靶区和正常器官。观察治疗前后鼻咽腔内病灶、肿瘤侵犯斜坡在弥散加权图像上的表现，并测量其表观弥散系数ADC值。结果76例患者中斜坡侵犯患者40例，斜坡侵犯患者在放化疗前磁共振显示T1WI呈等低信号，T2WI呈等高信号，增强后可见强化；DWI呈高信号，ADC图呈低信号；受侵斜坡ADC值为（0．618±0．269）×10 -3mm2／s，正常斜坡ADC值为（0．197±0．197）×10^（-3） mm2／s。放化疗前，肿瘤侵犯腭帆张肌和（或）腭帆提肌ADC值为（0．516±0．183）×10^（-3）mm2／s，受侵犯斜坡ADC值为（0．618±0．269）×10^（-3） mm2／s；放化疗后1个月，ADC值分别为（1．235±0．356）×10^（-3） mm2／s和（1．237±0．298）×10^（-3）mm2／s；放化疗后4个月，ADC值分剐为（1．371±0．347）×10^（-3）mm2s和（1．218±0．296）×10^（-3）mm2／s。鼻咽腔内病灶及受侵斜坡ADC值在放化疗前与放化疗后1和4个月比较，差异均有统计学意义，P〈0．05。结论DWI的ADC值可在鼻咽癌靶区勾画中斜坡侵犯识别提供帮助，对鼻咽癌治疗方案的制定、疗效评价均有一定参考价值。

OBJECTIVE DWI -MRI is an important non-invasive method for nasopharyngeal carcinoma diagnosis and expected to detect clival invasion and to help for the design of RT. This study evaluated the use of apparent diffusion coefficient（ADC） of MR diffusion-weighted imaging（DWI-MRI） in detecting clival invasion by nasopharyngeal carcinoma （NPC） and in evaluating therapeutic efficiency in NPC patients. METHODS From January 2013 to January 2015,76 pa tients with pathologically confirmed NPC have been examined by both conventional magnetic resonance imaging（MRI） and diffusion weighted imaging（DWI） scan. The DWI MRI data of the 76 patients were compared before and after radiotherapy（RT） （1 months and 4 months after RT）. The evolution of the signals of DWI MRI and the mean ADC values were analyzed at the the primary tumor sites and clival invasion sites. RESULTS The clival invasion was detected in 40 patients out of 76 patients by DWI-MRI. Before RT,the DWI-MRI in these 40 patients with clival invasion showed slightly equal and hypointense signals on T1-weighted imaging（T1WI） and hyperintense signals on T2-weighted imaging（T2WI） signals with marked enhancement of after administration of contrast agent. The mean ADC values in these patients at the primary tumor sites were （0. 516±0. 183） × 10^（-3） mm2/s. The mean ADC values at clival invasion sites were （0. 618±0. 269） × 10^（-3） mm2/s in comparison with （0. 197±0. 197）× 10^（-3） mm2/s in healthy person（P〈0.05）. After RT,the ADC values was increased. The mean ADC values in the primary tumor sites and clival invasion sites after 1 month RT increased to （1. 235±0. 356） × 10^（-3） mm2/s and （1. 237±0. 298） × 10^（-3） mm2/s,respectively. After 4 months RT,the mean ADC val ues were （1. 371±0. 347） × 10^（-3） mm2/s at the primary tumor sites and （1. 218±0. 296） × 10^（-3） mm2/s at the clival sites. The differences of the ADC values before and after RT were statistically significant in these patients（P〈0.05）. CONCLUSIONS It indicates that the recording and the interpretation of ADC values in these patients could help clinicians for the diagnosis in case of clival invasion and clinic follow-up during the therapy. DWI is very important in making therapeutic decisions and in evaluating effects of the therapy.