摘要目的 探讨胸腺向颈部延伸在止常儿童中出现的比例及临床意义.方法 回顾性分析400例正常儿童的颈部或胸部MRI资料.并将其按小儿年龄分期标准分为4组:婴幼儿组(0～3岁)42例,学龄前组(>3～6岁)87例,学龄期组(>6～12岁)168例,青春期组(>12～18岁)103例.在矢状面MR图像上,以胸腔入口水平(胸骨柄上缘)为界,判断胸腺是否向颈部延伸,并测量延伸的距离,分析胸腺向颈部延伸这一征象在儿童各年龄组中出现的比例.采用趋势检验分析年龄组间的趋势差异.结果 400例中,288例(72.0%)胸腺向颈部不同程度的延伸,其中婴幼儿组92.9%(39/42)、学龄前组82.8%(72/87)、学龄期组70.0%(118/168)、青春期组57.3%(59/103),符年龄组之间胸腺向颈部延伸的比例存在显著的等级趋贽性差异(X2=4.9684,P<0.05),年龄越小出现几率越高.随年龄组的增人胸腺向颈部延伸的平均距离无明显缩短趋势差异(F=2.28,P>0.05).结论 胸腺向颈部延伸足儿童时期的一种正常表现,正确认识这一现象可避免将其误诊为颈部病理性包块.

abstractsObjective To determine the proportion and the clinical value of the thymus extending superiorly into the lower neck in children.Methods The MR images of 400 normal children were retrospectively reviewed.According to the childhood staging criteria.all children were divided into four groups:the infancy and toddlerhood group(0-3 yo,42),the pre-school age group(>3-6 yo,87),the school age group(>6-12 yo,168),and the adolescence group(>12-18 yo,103).The presence or absence of the superior extension of the thymus above the manubrium Was determined on sagittal T2-weighted images.If so,the distance between manubrium and thymic apex was measured.The associations between frequency of ccrvicaI extension and age and sex were evaluated using correlation analysis.Results Superior extension of the thymus was detected in 288(288/400,72.0%)children,with 39(39/42,92.9%)in the infancy and toddlerhood group,72(72/87,82.8%)in the pre-school age group,118(118/168,70.0%)in the school age group,and 59(59/103)in the adolescence group(57.3%).There Was a statistically significant relationship between age group and frequency of cervical extension of the thymus (X2=4.9684,P<0.05).There was no significant decreasing trend in the mean distance of cervical extension between age increasing groups(F=2.28,P>0.05).Conclusions Cervical extension of the thymus occurs in the majority of children,and should be considered as a normal finding.Through recognizing this finding,doctors can avoid misdiagnosing it as a pathologic mass.