Thorax, Mediastinum, Heart, and Great Vessels: Thymus Size from 0 to 2 Years of Age

10.1055/b-0034-87953

Thorax, Mediastinum, Heart, and Great Vessels: Thymus Size from 0 to 2 Years of Age

Material and Methods

Mediastinal ultrasonography was performed in 151 infants (79 boys and 72 girls; Table 6.2 ). All children were healthy and had no stress factors affecting their thymic size. The maximum transverse diameter, right lobe AP, and left lobe AP were assessed. Perpendicular to the transverse plane, the longest craniocaudal dimension (length) was assessed. The thymic index was calculated by multiplying the transverse diameter by the largest sagittal area ( Fig. 6.3 ).

**Table 6.2 Thymus size from 0 to 2 years of age**
		Thymic dimensions (cm)
Age (months)	Number of cases	Transverse (mm)	AP right (mm)	AP left (mm)	Length (mm)	Thymic index (cm)
Premature	20	2.9. (0.3)*	1.5 (3.7)	1.5 (0.3)	3.1 (0.4)	11.9 (3.9)
0–1	25	3.3 (0.3)	1.6 (0.3)	1.8 (0.3)	3.6 (0.3)	18.1 (6.7)
1–2	21	3.6 (0.6)	1.9 (0.3)	2.0 (0.3)	3.9 (0.4)	25.4 (9.4)
2–3	11	3.7 (0.5)	1.9 (0.3)	2.1 (0.3)	3.8 (0.3)	22.3 (6.9)
3–4	15	3.8 (0.4)	1.9 (0.5)	2.2 (0.6)	4.0 (0.4)	26.8 (10.3)
4–5	7	4.0 (0.6)	2.0 (0.6)	2.2 (0.4)	4.1 (0.3)	29.7 (17.6)
5–6	8	3.9 (0.2)	1.9 (0.4)	2.3 (0.3)	4.0 (0.2)	24.2 (9.3)
6–8	8	3.6 (0.5)	1.8 (0.4)	1.9 (0.5)	3.6 (0.6)	22.2 (8.9)
8–10	14	3.7 (0.5)	1.7 (0.5)	1.9 (0.5)	3.7 (0.4)	21.5 (6.8)
10–12	5	3.7 (0.5)	1.9 (0.6)	1.8 (0.5)	3.6 (0.2)	23.2 (7.2)
12–18	7	2.8 (0.5)	1.2 (0.5)	1.4 (0.4)	3.2 (0.9)	17.2 (6.4)
18–24	10	3.3 (0.4)	1.2 (0.4)	1.2 (0.3)	3.4 (0.7)	15.4 (5.6)
*Standard deviation.
Reproduced with permission of American Institute of Ultrasound in Medicine – AIUM from Yekeler E, Tambag A, Tunaci A, et al. Analysis of the thymus in 151 healthy infants from 0 to 2 years of age. J Ultrasound Med 2004;23:1321–1326; permission conveyed through Copyright Clearance Center, Inc.