MRI随访观察鼻咽癌放疗前后腮腺及颌下腺体积变化

Volume change of parotid and submandibular gland of patients with nasopharyngeal carcinoma before and after radiotherapy on MRI

目的基于鼻咽癌放疗前后的MRI图像,观察放疗后腮腺及颌下腺体积变化。方法回顾性分析43例鼻咽癌放疗患者,基于轴位T2W压脂图像,逐层手动勾画各唾液腺边界,以面积求和法获得各腺体体积,计算放疗后首次随访(3个月)、1年及2年的唾液腺萎缩率。采用配对t检验对放疗后3个月患、健侧腮腺及颌下腺萎缩率进行比较。患、健侧腮腺及颌下腺萎缩率随时间变化(3个月、1年、2年)的比较采用重复测量检验。结果 1放疗后3个月患、健侧腮腺及颌下腺萎缩率的差异均无统计学意义(P均>0.05)。患侧及健侧腮腺萎缩率均明显大于颌下腺(P均<0.05)。2放疗后3个月、1年及2年患、健侧腮腺萎缩率均逐渐减小,两两比较差异均有统计学意义(P均<0.05),而患、健侧颌下腺萎缩率差异均无明显统计学意义(P均>0.05)。结论鼻咽癌放疗后腮腺体积下降较颌下腺更加明显,患、健侧唾液腺体积变化无明显差异;长期随访显示腮腺体积呈恢复趋势,而颌下腺体积无明显变化。

Objective To evaluate the volume of parotid and submandibular gland, based on MR images of patients with nasopharyngeal carcinoma （NPC） before and after radiotherapy （RT）. Methods MR images of a total of 43 patients with NPC were retrospectively analyzed. The border of the salivary glands was delineated using an operator-defined ROI on T2- weighted fat-saturated images. The volumes of the gland were obtained from the sum of the areas multiplied by the slice in- terval. The reduction percentage of the volume of each salivary gland after RT was calculated. Paired t test was used for pairwise comparison of the reduction percentage of the parotid and submandibular glands in the affected and unaffected side 3 months after RT. Repeated-measure analysis was used to assess the longitudinal change of the reduction percentage of each gland 3 months, 1 year and 2 year after RT. Results （!）The reduction percentage of parotid gland was higher than that of the submandibular gland, both in the affected and unaffected sides （both P〈0.05）. While no significant difference was found between the affected and unaffected side in either parotid or submandibular gland （all P〉0.05）. ~）The reduc- tion percentage of parotid gland of both sides decreased gradually along follow-up （3 months, 1 year, 2 year） after RT （all P〈0.05）, while that of submandibular gland showed no significant change in both sides （all P〉0.05）. Conclusion The volume of parotid gland decreases more apparently than that of submandibular gland in NPC patients after RT, with no sig- nificant difference between the affected and unaffected side. The atrophic parotid gland after RT appeares as a tendency of recovery in the long-term follow-up, while the volume of the atrophic submandibular gland seems stable.