Liang C D, Huang S C
Department of Pediatrics, Chang Gung Children's Hospital, Kaohsiung Hsien, Taiwan, ROC.
J Formos Med Assoc. 1997 Sep;96(9):700-3.
Because of variability in the size of the thymus, imaging in children is a challenge. Difficulties in differentiating an abnormal mediastinal mass from a normal thymus may lead to unnecessary investigations. We performed a prospective sonographic study of the normal thymus in 140 infants and children aged newborn to 8 years to determine the size of the normal thymic gland. Patients were classified into five groups by age: 1) less than 6 months, 2) 6-12 months, 3) 13-24 months, 4) 25-48 months, 5) more than 48 months. The thymus was scanned through the suprasternal, transsternal, and parasternal windows with a Sonos 1000 scanner and a 5.5-MHz sector probe. The thymus was visualized in at least one of the three windows and the width and thickness were measured in 133 of the 140 cases. The mean +/- standard deviation width and thickness were 3.67 +/- 0.64 cm and 1.30 +/- 0.25 cm in boys, and 3.45 +/- 0.59 cm and 1.20 +/- 0.26 cm in girls (p = 0.047 and p = 0.033 in width and thickness, respectively). Regression analysis demonstrated an increase, mainly in the width, with increasing age (width = 3.48 + (0.05 x age) cm, p = 0.009), indicating an increase of 0.05 cm per year. In conclusion, the thymus was clearly and easily visualized on sonograms in the majority of children we studied. This study established the normal size range of the thymus in children less than 8 years old.
由于胸腺大小存在变异性，对儿童进行影像学检查具有挑战性。难以区分异常纵隔肿块与正常胸腺可能会导致不必要的检查。我们对140名年龄从新生儿到8岁的婴儿和儿童的正常胸腺进行了一项前瞻性超声研究，以确定正常胸腺的大小。患者按年龄分为五组：1）小于6个月；2）6 - 12个月；3）13 - 24个月；4）25 - 48个月；5）大于48个月。使用Sonos 1000扫描仪和5.5兆赫扇形探头通过胸骨上、胸骨旁和胸骨旁窗对胸腺进行扫描。在140例病例中的133例中，至少在三个窗口之一中观察到了胸腺，并测量了其宽度和厚度。男孩的平均宽度±标准差为3.67±0.64厘米，厚度为1.30±0.25厘米；女孩的平均宽度±标准差为3.45±0.59厘米，厚度为1.20±0.26厘米（宽度和厚度的p值分别为0.047和0.033）。回归分析表明，随着年龄增长，胸腺大小增加，主要是宽度增加（宽度 = 3.48 +（0.05×年龄）厘米，p = 0.009），表明每年增加0.05厘米。总之，在我们研究的大多数儿童中，超声检查能清晰、容易地观察到胸腺。本研究确定了8岁以下儿童胸腺的正常大小范围。
