新生儿胸腺的声像图表现及正常值研究

目的探讨正常新生儿胸腺的超声表现、正常值范围及其临床意义。方法连续观察230例正常足月儿及144例早产儿，高频微凸探头经胸骨进行胸腺扫查。显示最大横断面且左右叶外缘边界清晰时，冻结图像测量两外缘间距离作为胸腺最大横径。在此断面上垂直旋转探头，分别显示左右叶最大矢状断面时，测量胸腺上下两极间的距离为最大长径。超声测量胸腺的同时记录新生儿出生体质量。保持仪器设置不变，观察并记录经胸骨上窝扫查胸腺的声像图特点与同一新生儿甲状腺进行比较。结果经胸骨扫查，374例新生儿胸腺显示清晰，最大横径测量成功率为91．4％（342／374）。胸腺最大横径与出生体质量相关（r=0．605，P=0．000），足月儿与早产儿胸腺平均最大横径间有显著性差异（P=0．002）。经胸骨上窝扫查，胸腺内部回声略低于甲状腺，实质内可见特征性的细线状及点状强回声。结论新生儿胸腺各径线超声测值变化范围较大。胸腺超声正常值研究结合其较有特征性的实质回声特点，有助于超声对胸腺疾病的诊断及鉴别诊断。

Neonatal Thymus: Sonographic Appearance and Its Normal Value

Objective To evaluate sonographic appearance and measurements of neonatal thymus.Methods A prospective sonographic study of thymus in 230 term infants and 144 preterm infants was performed by scanning directly on sternum or suprasternal fossa.When exterior margin demonstrated clearly,the largest transverse diameter,the largest sagittal diameter of the two lobes were measured.With the same technique using the same transducer,we compared thymus and thyroid parenchymal patterns.We also recorded every neonatal birth weight.Results The thymus was identified in all 374 infants studied,and 342(91.4%)largest transverse diameters were measured successfully.A statistically significant correlation was found between largest transverse diameter and birth weight(r=0.605,P=0.000)and a significant difference was found in average largest transverse diameter between term and preterm infants.The intensity of thymic echogenicity through suprasternal fossa was less than that of the thyroid.Specific fine thread-like and dot-like intensive echoes were found in thymic parenchyma of all infants.Conclusions Neonatal thymic diamaters changed variously.The normal value of thymic diamater and its characteristic appearance will allow us to recogenize thymic abnormality.