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Normal cross-sectional dimensions of the thyroid gland on routine chest CT scans
1Radiology Service, VA San Diego Health Care System, La Jolla, CA 92161, USA.
Purpose:
The purpose of this work was to determine the range of normal measurements for the thyroid gland on chest CT scans and relate it to the dimensions of the trachea.
Method:
Chest CT scans in 118 patients were examined prospectively for visibility of the thyroid gland and its relationship to the trachea. The greatest transverse dimensions of the lobes and the transverse tracheal diameter were measured. A thyroid/trachea ratio was determined.
Results:
The mean value for the transverse diameter of the thyroid gland was 28.79 mm (SD 6.57 mm). The right lobe averaged 15.05 mm (SD 3.51 mm). The left lobe averaged 13.74 mm (SD 3.91 mm). Measurements for the trachea showed a mean value of 19.97 mm (SD 2.37 mm). A thyroid/trachea index was calculated with a mean value of 1.46 (SD 0.39).
Conclusion:
Our investigation provides initial values for assessing the thyroid gland on CT scans, defining the limits of normal and the border zones of abnormal size.