正常胸腺的螺旋CT表现

Appearance of the Normal Thymus on Spiral CT

目的 总结正常胸腺的螺旋CT表现。方法 对 316例 ,1～ 82岁的病人进行胸部螺旋CT扫描 ,依年龄分为 7组 ,测量每叶胸腺的厚度、宽度、奇静脉弓层面两叶胸腺面积和、胸腺平均CT值 ,6组数值进行统计学处理 ,并记录胸腺上下界及两外缘位置。结果 胸腺的厚度 ,5 9岁以下均小于 2 1mm ,6 0岁以上部分胸腺厚度可达 30mm ,胸腺宽度随年龄的增长而增大 ,胸腺的密度随年龄的增长而减低 ,最终与脂肪密度相似 ,胸腺的面积和仅随年龄而变化 ,但变异系数较大。胸腺的上界不超过胸骨柄上缘 ,下界不超过左心室上缘 ,两外缘不超过上腔静脉、主动脉弓外缘 ,胸腺左叶通常大于右叶。结论 认识正常胸腺的螺旋CT表现对异常胸腺的诊断有重要价值。

Purpose To summarize the appearance of the normal thymus on spiral CT. Methods Spiral CT scan of thymus was performed in 316 normal patients,aged from 1 to 82 years old,which was classified into seven groups. The thickness\,width of both lobes,CT attenuation value and the bilobe area of thymus in level of azygos vein were measured. The edge and location of the thymus were recorded,the result were analyzed statistically. Results The thickness was less than 21 mm under age 59,some cases were up to 30mm over 60 years of age. The width increase with the age,the density decrease with the age,finally approaching that of fat,the bilobe area of the thymus changed with the age,but a wide variation was considorable. The location of the thymus is between the manubrium of sternum and upper edge of left ventricule,the bilateral edges of thymus was smaller than the edge of superior cava vena or aortic arch. The left leaf of thymus was greater than right in most cases. And the diagnostic criterion of the abnormal thymus was discussed.Conclusion Recognition of variations in size and shape of the normal thymus on spiral CT scan is of importance value at the diagnosis of the abnormal thymus. [