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Age-related changes in CT attenuation of the thymus in children
M Sklair-Levy1, R Agid, T Sella
1Department of Radiology, Hadassah University Hospital, Jerusalem, Israel.
Insights
Childhood thymus CT attenuation decreases with age after the first year, differing from adult values. This study establishes normal CT attenuation ranges for pediatric thymus glands.
Area of Science:
- Pediatric Radiology
- Medical Imaging
- Anatomy
Background:
- Previous studies described thymus CT appearance and age-related changes.
- Limited data exists on thymus CT attenuation values in children.
Purpose of the Study:
- Evaluate normal thymus CT attenuation in infants and children.
- Determine the age at which thymus CT attenuation begins to decline.
Main Methods:
- Retrospective analysis of CT attenuation values in 152 children (1 day to 14 years).
- Comparison of thymic CT attenuation with chest wall and cardiac muscles.
- Multivariate linear regression used to analyze correlations with gender and disease.
Main Results:
- Thymus CT attenuation declines with age, starting after the first year of life.
- In infants under 1 year, the thymus is hyperdense compared to surrounding muscles.
- Thymus is denser in males; malignant conditions in infants show decreased attenuation.
Conclusions:
- Age-related decline in thymus CT attenuation is attributed to fatty infiltration.
- Provides reference CT attenuation values for assessing pediatric thymus normality or pathology.
Background:
The CT appearance of the normal and abnormal thymus and its age-related changes have been described. However, there is no information regarding the change in thymus CT attenuation values in children.
Objective:
The aim of the present study was to evaluate the normal CT attenuation of the thymus in infants and children and discover when the decline begins.
Materials And Methods:
CT attenuation values of the thymus were retrospectively evaluated in 152 children between ages of 1 day and up to 14 years. For each patient the mean value of the CT thymus attenuation was calculated and compared to CT attenuation of the chest wall and cardiac muscles. We also examined the correlation between thymic attenuation, gender, and disease. The statistical analysis used was multivariate linear regression.
Results:
CT attenuation of the thymus declines with age, beginning only after the 1st year of life. The thymus is more hyperdense than the chest wall and cardiac muscles in infants less than 1 year. The thymus is denser in males than females. In malignant conditions, in infants less than 1 year, thymus CT attenuation is decreased. In older children thymus attenuation was similar to that for the chest wall and cardiac muscles.
Conclusion:
The decline in thymic CT attenuation with age is consistent with fatty infiltration of the gland. The measurements given in this report can serve as a basis for comparison to determine whether the thymus of a young child is normal or pathological.