MRI表观扩散系数在诊断鼻咽癌颈部小淋巴结转移瘤及勾画放疗靶区中的应用效果

Effects of MRI apparent diffusion coefficient applied to diagnosing small cervical lymph node metastases of nasopharyngeal carcinoma and delineating radiotherapy target volume

目的探讨MRI表观扩散系数(ADC)在诊断鼻咽癌颈部小淋巴结转移瘤及勾画放疗靶区中的应用效果。方法选择35例鼻咽癌患者,均行常规MRI及扩散加权成像检查,计算ADC值,并给予诱导化疗及调强放化疗治疗。以治疗后随访结果为金标准,评价ADC值诊断鼻咽癌颈部小淋巴结转移瘤的效能。抽取其中20例患者,对其颈部小淋巴结靶区同时采用勾画(勾画组)与未勾画(未勾画组)的模拟治疗方法,勾画组采用ADC值勾画颈部小淋巴结靶区,比较两组正常腮腺组织受照射剂量及体积。结果 ADC值诊断鼻咽癌颈部小淋巴结转移瘤的灵敏度、特异度、准确度分别为88.10%、95.35%、92.97%。勾画组右侧腮腺组织受照射剂量及体积高于未勾画组(P<0.05)。结论 ADC可作为诊断鼻咽癌颈部小淋巴结转移瘤及勾画靶区的辅助参考指标。

Objective To investigate the effects of MRI apparent diffusion coefficient（ADC） applied to diagnosing small cervical lymph node metastases of nasopharyngeal carcinoma and delineating radiotherapy target volume. Methods Thiru-five patients with nasopharyngeal carcinoma were enrolled and received conventional MRI and diffusion-weighted imaging, then ADC value was calculated, and all subjects were given induced chemotherapy and intensity-modulated radiation therapy. The follow-up result after treatment was taken as the golden standard,and the diagnostic efficiency of ADC value for small cervical lymph node metastases of nasopharyngeal carcinoma was assessed. Twenty out of the 35 patients were selected to receive simulated treatment with and without delineating the target volume of small cervical lymph nodes（ delineation group and non-delineation group）, and ADC value was used to delineate the target volume of small cervical lymph nodes in the delineation group. The irradiation dose and volume of norxual parotid tissues were compared between the two groups. Results Tire sensitivity,specificity and accuracy of ADC value for diagnosing small cervical lymph node metastases of nasopharyngeal carcinoma were 88.10% ,95.35% and 92.97%, respectively. Tire irradiation dose and volume of right parotid tissues in the delineation group were higher than those in tire non-delineation group （P 〈 0. 05 ）. Conclusion ADC can be used as an auxiliary reference indicator for diagnosing small cervical lymph node metastases of nasopharyngeal carcinoma and delineating target volume.