Related Experiment Videos
Sonographic study of the thymus in infants and children
1Department of Pediatrics, Chang Gung Children's Hospital, Kaohsiung Hsien, Taiwan, ROC.
Insights
This study establishes normal thymus size in children up to 8 years old using ultrasound. Findings help differentiate normal thymus from abnormal masses, reducing unnecessary investigations in pediatric imaging.
Area of Science:
- Pediatric Radiology
- Medical Imaging
- Anatomy
Background:
- Imaging the thymus in children presents challenges due to size variability.
- Differentiating normal thymus from mediastinal masses can lead to unnecessary investigations.
Purpose of the Study:
- To determine the normal size range of the thymus gland in children from newborn to 8 years old.
- To aid in differentiating normal thymus from abnormal mediastinal masses in pediatric patients.
Main Methods:
- Prospective sonographic study of 140 infants and children (newborn to 8 years).
- Thymus visualized using suprasternal, transsternal, and parasternal windows with a Sonos 1000 scanner and 5.5-MHz probe.
- Width and thickness of the thymus were measured in 133 cases.
Main Results:
- The thymus was visualized in most children studied.
- Mean thymus width was 3.67 cm (boys) and 3.45 cm (girls); mean thickness was 1.30 cm (boys) and 1.20 cm (girls).
- Thymus width showed a statistically significant increase with age (0.05 cm/year).
Conclusions:
- Sonography is effective for visualizing the thymus in children.
- This study provides established normal size ranges for the thymus in children under 8 years old.
- These findings can improve diagnostic accuracy and reduce unnecessary investigations.
Abstract:
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.