垂体瘤与原发性甲状腺功能减低致垂体增生的MRI鉴别

MRI Differentiation of Pituitary Tumor from Pituitary Hyperplasia Caused by Primary Hypothyrosis

目的探讨垂体瘤与原发性甲状腺功能减低(甲减)致垂体增生的MRI影像表现及鉴别诊断。方法对术后病理已确诊垂体瘤64例及治疗后确诊原发性甲减致垂体增生17例患者的年龄、性别及MRI影像表现进行回顾性分析。结果垂体瘤组平均年龄为(53.2±18.9)岁,明显高于原发性甲减致垂体增生组[(24.5±16.3)岁],差异有显著统计学意义(t=4.282,P<0.01);两组患者性别差异无统计学意义(χ2=0.594,P>0.05);垂体大腺瘤组的平均高度为(18.2±7.2)mm,高于原发性甲减致垂体增生组病变平均高度[(10.6±2.6)mm],差异有统计学意义(t=2.432,P<0.05)。垂体瘤因其血供差而易发生囊变、出血和坏死,MRI上常呈高低混杂信号影,常侵犯附近组织结构,垂体后叶高信号消失,垂体柄偏移或中断,增强扫描垂体瘤不均匀异常强化;原发性甲减致垂体增生MRI表现为垂体前叶均匀增大,上缘对称性山包状隆起,呈等T1、等T2信号,其垂体后叶高信号清晰可见,垂体柄居中,增强扫描均匀一致强化,无异常强化或延迟强化区域。结论两者具有一定特征性的影像表现,MRI具有重要的诊断与鉴别诊断价值。

Objective To investigate MRI manifestations of pituitary tumor and pituitary hyperplasia caused by primary hypothyrosis,and to discuss the differentiation between the two diseases. Methods A total of 64 patients with pathologically-proved pituitary tumor（ tumor group） and 17 patients with pathologically-proved pituitary hyperplasia caused by primary hypothyrosis（ hyperplasia group） were included in this study. The clinical data,including age,sex and MRI features,were retrospectively analyzed. Results The average age of the tumor group was（ 53. 2 ± 18. 9） years old,which was significantly higher than that of the hyperplasia group（ 24. 5 ± 16. 3 years old）,and the difference between the two groups was statistically significant（ t = 4. 282,P〈0. 01）. No statistically significant difference in sex existed between the tumor group and the hyperplasia group（ χ^2= 0. 594,P〈0. 05）. The average height of pituitary tumor in the tumor group was（ 18. 2 ± 7. 2） mm,which was significantly larger than that of the hyperplasia group（ 10. 6 ± 2. 6） mm,and the difference was statistically significant（ t = 2. 432,P〈0. 05）. Due to its poor blood supply,pituitary tumor was liable to develop cystic degeneration,hemorrhage and necrosis,. On MRI the tumor often showed high-low mixed signals,the surrounding tissues were usually affected,the high signal of posterior pituitary disappeared,and displaced or interrupted pituitary stalk could be observed; on enhanced scan the tumor displayed inhomogeneous abnormal enhancement. In hyperplasia group,the anterior pituitary became uniform enlarged,its upper edge showed symmetric hill-shaped projection; the lesion presented as iso-signal on T1 and T2and the posterior pituitary presented clear high signal,the pituitary stalk was situated in the middle,on enhanced scan the pituitary showed homogeneous enhancement with no abnormal or delayed enhancement areas. Conclusion Both the pituitary tumor and the pituitary hyperplasia have its own imaging characteristics; MRI has important value in their diagnosis and differentiation.